HIGH-TEMPERATURE HEAT PUMP PLANT, REVERSIBLY USABLE IN ALTERNATIVE OPERATIONAL MODE AS A CO-TRI-GENERATION PLANT

Abstract

The present invention relates to the field of energy conversion plants and, in particular, concerns a same plant configuration that can be reversibly used according to two alternative operational modes, wherein each operating unit work in both said operational modes. The first operational mode involves operating as a co-tri-generation plant for supplying the end-user with electrical/mechanical power and simultaneously with heating power and/or refrigeration power through the conversion of thermal power supplied by any heat source (renewable or non-renewable). The second operational mode involves operating as a high-temperature heat pump without the mechanical and/or electrical power supplied by an external source for supplying the end-user with high-temperature heating power through the conversion of the low to medium-temperature thermal power supplied by the aforementioned heat source.

Claims

1. An energy conversion plant making use of a single working fluid apt to absorb a thermal power transferred by a heat source, the plant comprising: i) Isenthalpic flow rate regulation means(S) apt to divide the overall flow rate of said working fluid circulating in the plant into a first and a second share of the working fluid; ii) Downstream of said isenthalpic flow rate regulation means(S), a first circuit (C.sub.1) apt for the circulation of at least said first share of the working fluid, said first circuit comprising: first adiabatic two-phase compression means (TC.sub.1,M) apt to increase the pressure and consequently the temperature of said working fluid, powered by a fraction of the overall electrical or mechanical power generated by said plant; first isobaric heat exchange means (HE.sub.1,N); first adiabatic two-phase expansion means (TE.sub.1,O) apt to generate said electrical power or mechanical power due to the decrease in the pressure and consequently the temperature of said working fluid; first isobaric thermal regeneration means (TR.sub.1,P) functionally associated with said first adiabatic two-phase compression means (TC.sub.1,M) and said first adiabatic two-phase expansion means (TE.sub.1,O), apt to promote a transfer of thermal power between the working fluid circulating downstream of at least one stage of said first adiabatic two-phase expansion means (TE.sub.1,O) and the same working fluid circulating downstream of at least one stage of said first adiabatic two-phase compression means (TC.sub.1,M); iii) Downstream of said isenthalpic flow rate regulation means (S), a second circuit (C.sub.2) apt for the circulation of said second share of the working fluid, said second circuit comprising: second isobaric heat exchange means (HE.sub.2); second adiabatic two-phase expansion means (TE.sub.2,O*) apt to generate said electrical power or mechanical power due to the decrease in the pressure and consequently the temperature of said working fluid; third isobaric heat exchange means (HE.sub.3,N); second adiabatic two-phase compression means (TC.sub.2,M*) apt to increase the pressure and consequently the temperature of said working fluid, powered by a fraction of the overall electrical or mechanical power generated by said plant; wherein said first and second circuits (C.sub.1, C.sub.2) are in communication with each other so as to be apt to combine said first share of the working fluid of said first circuit (C.sub.1) downstream of said first adiabatic two-phase expansion means (TE.sub.1,O) and said second share of the working fluid of said second circuit (C.sub.2) downstream of said second adiabatic two-phase compression means (TC.sub.2,M*); iv) A third circuit (C.sub.3) downstream of said second adiabatic two-phase compression means (TC.sub.2,M*) for the circulation of the overall flow rate of said working fluid (i.e., consisting of said first and second share of the working fluid) towards said isenthalpic flow rate regulation means (S), further comprising, upstream of the latter, fourth isobaric heat exchange means (HE.sub.4); v) Control means configured to distribute the working fluid between said first and second circuit and to perform the switching of said first and second circuit according to a first operational mode of the plant as a high-temperature heat pump for supplying the end-user with heating power at different temperature values, wherein: the overall mechanical or electrical power produced by said first adiabatic two-phase expansion means (TE.sub.1,O) and said second adiabatic two-phase expansion means (TE.sub.2,O*) is equal to or greater than the overall mechanical or electrical power required by said first adiabatic two-phase compression means (TC.sub.1,M) and said second adiabatic two-phase compression means (TC.sub.2,M*), wherein in said first operational mode of the plant as a high-temperature heat pump; said second isobaric heat exchange means (HE.sub.2) and said fourth isobaric heat exchange means (HE.sub.4) are configured to operate, according to said first operational mode of the plant as a high-temperature heat pump, as means for the isobaric vapor generation of said working fluid, being fed by said medium-low temperature thermal power provided from said heat source; said first isobaric heat exchange means (HE.sub.1,N) are configured to operate, according to said first operational mode of the plant as a high-temperature heat pump, at least as means for isobaric condensation apt to condense said working fluid, resulting in the supply of heating power to said end-user at different temperature values; said third isobaric heat exchange means (HE.sub.3,N*) are configured to operate, according to said first operational mode of the plant as a high-temperature heat pump, at least as means for isobaric heat transfer (thermal dissipation) from the working fluid to the external environment; said first and second adiabatic two-phase compression means (TC.sub.1,M, TC.sub.2,M*) are configured to increase the pressure and consequently the temperature of the working fluid by converting mechanical/electrical power supplied to said same first and second adiabatic two-phase compression means, operating according to said first operational mode of the plant as a high-temperature heat pump, wherein the two-phase working fluid has a variable quality within a wide range: i) up to values near one in the inlet sections of said first adiabatic two-phase compression means (TC.sub.1,M), wherein in this limiting condition said two-phase working fluid predominantly consists of the vapor phase; ii) up to values near zero in the inlet sections of said second adiabatic two-phase compression means (TC.sub.2,M*), wherein in this limiting condition said two-phase working fluid predominantly consists of the liquid phase; said first and second adiabatic two-phase expansion means (TE.sub.1,O, TE.sub.2,O*) are configured to decrease the pressure and consequently the temperature of the working fluid, resulting in the production of mechanical/electrical power, operating according to said first operational mode of the plant as a high-temperature heat pump, wherein the two-phase working fluid has a variable quality within a wide range: i) up to values near zero in the inlet sections of said first adiabatic two-phase expansion means (TE.sub.1,O); ii) up to values near one in the inlet sections of said second adiabatic two-phase expansion means (TE.sub.2,O*).

2. The plant according to claim 1, wherein said control means are configured to distribute the working fluid between said first and second circuit and furthermore to execute the switching of said first and second circuit, according to a second operational mode of the plant as a co-tri-generation plant, for supplying the end-user with electrical or mechanical power, heating power or cooling power at different temperature values, wherein: said second isobaric heat exchange means (HE.sub.2) and said fourth isobaric heat exchange means (HE.sub.4) are configured to operate, according to said second operational mode of the plant as a co-tri-generation plant, at least as isobaric condensation means apt to condense said working fluid with consequent thermal dissipation to the external environment or supply to said end-user of heating power; said first isobaric heat exchange means (HE.sub.1,N) are configured to operate, according to said second operational mode of the plant as a co-tri-generation plant, at least as isobaric condensation means apt to condense said working fluid with consequent supply to said end-user of heating power at different temperature values, except for the first isobaric heat exchange means associated with the maximum pressure (and consequently the maximum temperature) of the working fluid of said plant, in which said first isobaric heat exchange means associated with the maximum pressure are configured to operate, according to said second operational mode of the plant as a co-tri-generation plant, at least as means for isobaric vapor generation of said working fluid, being fed by high-temperature thermal power provided from the heat source; -said third isobaric heat exchange means (HE.sub.3,N*) are configured to operate, according to said second operational mode of the plant as a co-tri-generation plant, at least as isobaric evaporation means apt to evaporate said working fluid with consequent supply of cooling power to the end-user.

3. The plant according to any one of claims 1, wherein said control means are configured to distribute the working fluid between said first and second circuit and furthermore to execute the switching of said first and second circuit, according to said second operational mode of the plant as a co-tri-generation plant, wherein: said first and second adiabatic two-phase compression means (TC.sub.1,M, TC.sub.2,M*) are configured to determine the increase of the pressure and consequently the temperature of the working fluid by converting of mechanical/electrical power supplied to said first and second adiabatic two-phase compression means, operating according to said second operational mode of the plant as a co-tri-generation plant, wherein the two-phase working fluid has a variable quality in a wide range: i) up to values close to zero in the inlet sections of said first adiabatic two-phase compression means (TC.sub.1,M); ii) up to values close to one in the inlet sections of said second adiabatic two-phase compression means (TC.sub.2,M*); said first and second adiabatic two-phase expansion means (TE.sub.1,O, TE.sub.2,O*) are configured to determine the decrease of the pressure and consequently the temperature of the working fluid with consequent production of mechanical/electrical power, operating according to said second operational mode of the plant as a co-tri-generation plant, wherein the two-phase working fluid has a variable quality in a wide range: i) up to values close to one in the inlet sections of said first adiabatic two-phase expansion means (TE.sub.1,O); ii) up to values close to zero in the inlet sections of said second adiabatic two-phase expansion means (TE.sub.2,O*)

4. The plant according to claim 1, further comprising first spillover working fluid flow rate means (B.sub.1,Q) functionally associated with said first adiabatic two-phase compression means (TC.sub.1,M) and said first adiabatic two-phase expansion means (TE.sub.1,O), configured to perform, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-tri-generation plant, the circulation of a portion of the working fluid flow rate (B.sub.1,Q) between said first adiabatic two-phase compression means (TC.sub.1,M) and said first adiabatic two-phase expansion means (TE.sub.1,O) through interposed first connection means or through said first isobaric heat exchange means (HE.sub.1,N), wherein said first isobaric heat exchange means (HE.sub.1,N) are further configured to perform, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-tri-generation plant, the heat transfer from or to the working fluid at respective distinct temperature values.

5. The plant according to claim 1, comprising first spillover working fluid flow rate means (B.sub.1,Q): functionally associated with said first adiabatic two-phase expansion means (TE.sub.1,O) and configured to perform, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-tri-generation plant, the circulation of a portion of the working fluid flow rate between said first adiabatic two-phase expansion means (TE.sub.1,O) through interposed said first isobaric heat exchange means (HE.sub.1,N), and optionally to determine the circulation of the working fluid flow rate exiting from said first adiabatic two-phase expansion means (TE.sub.1,O) towards said first adiabatic two-phase compression means (TC.sub.1,M) through interposed first connection means or through said interposed first isobaric heat exchange means (HE.sub.1,N), wherein said first isobaric heat exchange means (HE.sub.1,N) are further configured to perform, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-tri-generation plant, the heat transfer from or to the working fluid at respective distinct temperature values; or vice versa functionally associated with said first adiabatic two-phase compression means (TC.sub.1,M) and configured to perform, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-tri-generation plant, the circulation of a portion of the working fluid flow rate between said first adiabatic two-phase compression means (TC.sub.1,M) through said interposed first isobaric heat exchange means (HE.sub.1,N), and optionally to determine the circulation of the working fluid flow rate exiting from said first adiabatic two-phase compression means (TC.sub.1,M) towards said first adiabatic two-phase expansion means (TE.sub.1,O) through interposed first connection means or through said interposed first isobaric heat exchange means (HE.sub.1,N), wherein said first isobaric heat exchange means (HE.sub.1,N) are further configured to perform, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-tri-generation plant, the heat transfer from or to the working fluid at respective distinct temperature values.

6. The plant according to claim 4, in which said first spillover working fluid flow rate means (B.sub.1,Q) are furthermore: functionally associated with said first adiabatic two-phase expansion means (TE.sub.1,O) and configured to execute, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the circulation of a portion of the working fluid flow rate between said first adiabatic two-phase expansion means (TE.sub.1,O) through interposed said first isobaric heat exchange means (HE.sub.1,N), and optionally to determine the circulation of the working fluid flow rate exiting from said first adiabatic two-phase expansion means (TE.sub.1,O) towards said first adiabatic two-phase compression means (TC.sub.1,M) through interposed first connection means or through said interposed first isobaric heat exchange means (HE.sub.1,N), wherein said first isobaric heat exchange means (HE.sub.1,N) are further configured to execute, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the heat transfer from or to the working fluid at respective distinct temperature values; or vice versa functionally associated with said first adiabatic two-phase compression means (TC.sub.1,M) and configured to execute, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the circulation of a portion of the working fluid flow rate between said first adiabatic two-phase compression means (TC.sub.1,M) through said interposed first isobaric heat exchange means (HE.sub.1,N), and optionally to determine the circulation of the working fluid flow rate exiting from said first adiabatic two-phase compression means (TC.sub.1,M) towards said first adiabatic two-phase expansion means (TE.sub.1,O) through interposed first connection means or through said interposed first isobaric heat exchange means (HE.sub.1,N), wherein said first isobaric heat exchange means (HE.sub.1,N) are further configured to execute, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the heat transfer from or to the working fluid at respective distinct temperature values.

7. The plant according to claim 1, comprising second spillover working fluid flow rate means (B.sub.2,Q*), functionally associated with said second adiabatic two-phase compression means (TC.sub.2,M*) and said second adiabatic two-phase expansion means (TE.sub.2,O*), and configured to execute, according to the first operational mode of the plant as a high-temperature heat pump and alternatively according to the second operational mode of the plant as a co-trigeneration plant, the circulation of a portion of the working fluid flow rate between said second adiabatic two-phase compression means (TC.sub.2,M*) and said second adiabatic two-phase expansion means (TE.sub.2,O*) through interposed second connection means or through said third isobaric heat exchange means (HE.sub.3,N*), wherein said third isobaric heat exchange means (HE.sub.3,N*) are also configured to execute, according to the first operational mode of the plant as a high-temperature heat pump and alternatively according to the second operational mode of the plant as a co-trigeneration plant, the heat transfer from or to the working fluid at respective distinct temperature values.

8. The plant according to claim 1, comprising second spillover working fluid flow rate means (B.sub.2,Q*): functionally associated with said second adiabatic two-phase expansion means (TE.sub.2,O*), and configured to execute, according to said first operational mode of the plant as a high-temperature heat pump, and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the circulation of a portion of the working fluid flow rate between said second adiabatic two-phase expansion means (TE.sub.2,O*) through said interposed third isobaric heat exchange means (HE.sub.3,N*), and optionally to determine the circulation of the working fluid flow rate exiting from said second adiabatic two-phase expansion means (TE.sub.2,O*) to said second adiabatic two-phase compression means (TC.sub.2,M*) through interposed second connection means or through said interposed third isobaric heat exchange means (HE.sub.3,N*), wherein said third isobaric heat exchange means (HE.sub.3,N*) are further configured to execute, according to said first operational mode of the plant as a high-temperature heat pump, and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the heat transfer from or to the working fluid at respective distinct temperature values; or vice versa functionally associated with said second adiabatic two-phase compression means (TC.sub.2,M*), and configured to execute, according to said first operational mode of the plant as a high-temperature heat pump, and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the circulation of a portion of the working fluid flow rate between said second adiabatic two-phase compression means (TC.sub.2,M*) through said interposed third isobaric heat exchange means (HE.sub.3,N*), and optionally to determine the circulation of the working fluid flow rate exiting from said second adiabatic two-phase compression means (TC.sub.2,M*) to said second adiabatic two-phase expansion means (TE.sub.2,O*) through interposed second connection means or through said interposed third isobaric heat exchange means (HE.sub.3,N*), wherein said third isobaric heat exchange means (HE.sub.3,N*) are further configured to execute, according to said first operational mode of the plant as a high-temperature heat pump, and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the heat transfer from or to the working fluid at respective distinct temperature values.

9. The plant according to claim 8, wherein said second spillover working fluid flow rate means (B.sub.2,Q*) are further: functionally associated with said second adiabatic two-phase expansion means (TE.sub.2,O*), and configured to execute, according to said first operational mode of the plant as a high-temperature heat pump, and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the circulation of a portion of the working fluid flow rate between said second adiabatic two-phase expansion means (TE.sub.2,O*) through said interposed third isobaric heat exchange means (HE.sub.3,N*), and optionally to determine the circulation of the working fluid flow rate exiting from said second adiabatic two-phase expansion means (TE.sub.2,O*) towards said second adiabatic two-phase compression means (TC.sub.2,M*) through interposed second connection means or through said interposed third isobaric heat exchange means (HE.sub.3,N*), wherein said third isobaric heat exchange means (HE.sub.3,N*) are further configured to execute, according to said first operational mode of the plant as a high-temperature heat pump, and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the heat transfer from or to the working fluid at respective distinct temperature values; or vice versa functionally associated with said second adiabatic two-phase compression means (TC.sub.2,M*), and configured to execute, according to said first operational mode of the plant as a high-temperature heat pump, and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the circulation of a portion of the working fluid flow rate between said second adiabatic two-phase compression means (TC.sub.2,M*) through said interposed third isobaric heat exchange means (HE.sub.3,N*), and optionally to determine the circulation of the working fluid flow rate exiting from said second adiabatic two-phase compression means (TC.sub.2,M*) towards said second adiabatic two-phase expansion means (TE.sub.2,O*) through interposed second connection means or through said interposed third isobaric heat exchange means (HE.sub.3,N*), wherein said third isobaric heat exchange means (HE.sub.3,N*) are further configured to execute, according to said first operational mode of the plant as a high-temperature heat pump, and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the heat transfer from or to the working fluid at respective distinct temperature values.

10. The plant according to claim 1, wherein said second circuit comprises second isobaric thermal regeneration means (TR.sub.2,P*) functionally associated with said second adiabatic two-phase compression means (TC.sub.2,M*) and said second adiabatic two-phase expansion means (TE.sub.2,O*), and configured to execute, according to said first operational mode of the plant as a high-temperature heat pump, and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the heat transfer between the working fluid circulating downstream of at least one stage of said second adiabatic two-phase expansion means (TE.sub.2,O*) and the same working fluid circulating downstream of at least one stage of said second adiabatic two-phase compression means (TC.sub.2,M*).

11. The plant according to claim 1, wherein said control means comprise: first deviation means (DM.sub.1,K) configured to execute, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the deviation of said working fluid in said first circuit (C.sub.1), bypassing said respective first isobaric heat exchange means (HE.sub.1,N) except for said first isobaric heat exchange means associated with the maximum pressure (and consequently the maximum temperature) of the working fluid in said plant; and second deviation means (DM.sub.2,K*) configured to execute, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the deviation of said working fluid in said second circuit (C.sub.2), bypassing said respective third isobaric heat exchange means (HE.sub.3,N*) except for said third isobaric heat exchange means associated with the minimum pressure (and consequently the minimum temperature) of the working fluid in said plant; and third deviation means (DM3) configured to execute, according to said first operational mode of the plant as a high-temperature heat pump and alternatively according to said second operational mode of the plant as a co-trigeneration plant, the deviation of said working fluid between said first circuit (C.sub.1) downstream of said first adiabatic two-phase expansion means (TE.sub.1,O) and said third circuit (C.sub.3) upstream of said fourth isobaric heat exchange means (HE.sub.4), bypassing said second circuit (C.sub.2).

12. A method for energy conversion by making use of a single working fluid in a thermodynamic cycle apt to absorb a thermal power transferred by a heat source, the method comprising: i) dividing the overall flow rate of said working fluid circulating in the thermodynamic cycle into a first and a second share through isenthalpic regulation (S); ii) circulating at least said first share of the working fluid downstream of said isenthalpic regulation (S) in a first sequence of thermodynamic transformations in said first circuit (C.sub.1) which includes: first adiabatic two-phase compression transformations (TC.sub.1,M) apt to increase the pressure and consequently the temperature of said working fluid, operated by making use of a fraction of the overall electrical or mechanical power generated by said thermodynamic cycle; first isobaric heat exchange transformations (HE.sub.1,N); first adiabatic two-phase expansion transformations (TE.sub.1,O) apt to generate said electrical power or mechanical power due to the decrease in the pressure and consequently the temperature of said working fluid; first isobaric thermal regeneration transformations (TR.sub.1,P) functionally associated with at least one stage of said first adiabatic two-phase compression transformations (TC.sub.1,M) and at least one stage of said first adiabatic two-phase expansion transformations (TE.sub.1,O), apt to promote the heat transfer between the working fluid circulating downstream of at least one stage of said first adiabatic two-phase expansion transformations (TE.sub.1,O) and the same working fluid circulating downstream of at least one stage of said first adiabatic two-phase compression transformations (TC.sub.1,M); iii) circulating at least said second share of the working fluid downstream of said isenthalpic regulation (S) in a second sequence of thermodynamic transformations in said second circuit (C.sub.2) which includes: second isobaric heat exchange transformations (HE.sub.2); second adiabatic two-phase expansion transformations (TE.sub.2,O*) apt to generate said electrical power or mechanical power due to the decrease in the pressure and consequently the temperature of said working fluid; third isobaric heat exchange transformations (HE.sub.3,N); second adiabatic two-phase compression transformations (TC.sub.2,M*) apt to increase the pressure and consequently the temperature of said working fluid, operated by making use of a fraction of the overall electrical or mechanical power generated by said thermodynamic cycle; wherein said first share of the working fluid in said first sequence of thermodynamic transformations of said first circuit (C.sub.1) downstream of said first adiabatic two-phase expansion transformations (TE.sub.1,O) and said second share of the working fluid in said second sequence of thermodynamic transformations of said second circuit (C.sub.2) downstream of said second adiabatic two-phase compression transformations (TC.sub.2,M*) are combined with each other. iv) circulating the overall flow rate of said working fluid, obtained due to the mixing of said first and second shares of the working fluid, in a third circuit (C.sub.3), located downstream of said second adiabatic two-phase compression transformations (TC.sub.2,M*), towards said isenthalpic regulation (S), further comprising, upstream of said isenthalpic regulation (S), fourth isobaric heat exchange transformations (HE.sub.4); v) control transformations apt to distribute the working fluid between said first and second sequence of thermodynamic transformations in said first and second circuits, respectively, and switching said first and second sequence of thermodynamic transformations according to a first operational mode of the method associated with a high-temperature heat pump thermodynamic cycle for supplying the user with heating power at different temperature values, in which: the overall mechanical or electrical power produced by said first adiabatic two-phase expansion transformations (TE.sub.1,O) and said second adiabatic two-phase expansion transformations (TE.sub.2,O*) is equal to or greater than the overall mechanical or electrical power required by said first adiabatic two-phase compression transformations (TC.sub.1,M) and said second adiabatic two-phase compression transformations (TC.sub.2,M*), in which in said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle: said second isobaric heat exchange transformations (HE.sub.2) and said fourth isobaric heat exchange transformations (HE.sub.4) generate isobarically, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle, vapor of said working fluid being fed by said medium-low temperature thermal power supplied by said heat source; said first isobaric heat exchange transformations (HE.sub.1,N) condense isobarically, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle, said working fluid with the consequent supply to said end-user of heating power at different temperature values; said third isobaric heat exchange transformations (HE.sub.3,N*) isobarically transfer (dissipate) thermal power from the working fluid to the external environment, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle; said first and second adiabatic two-phase compression transformations (TC.sub.1,M, TC.sub.2,M*) increase the pressure and consequently the temperature of the working fluid by converting mechanical/electrical power supplied to said first and second adiabatic two-phase compression transformations, operating according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle in which the two-phase working fluid has a variable quality over a wide range: i) up to values close to one in the inlet sections of said first adiabatic two-phase compression transformations (TC.sub.1,M), wherein in this limiting condition said two-phase working fluid consists almost exclusively of the vapor phase; ii) up to values close to zero in the inlet sections of said second adiabatic two-phase compression transformations (TC.sub.2,M*), wherein in this limiting condition said two-phase working fluid consists almost exclusively of the liquid phase; said first and second adiabatic two-phase expansion transformations (TE.sub.1,O, TE.sub.2,O*) decrease the pressure and consequently the temperature of the working fluid with the consequent production of mechanical/electrical power, operating according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle in which the two-phase working fluid has a variable quality over a wide range: i) up to values close to zero in the inlet sections of said first adiabatic two-phase expansion transformations (TE.sub.1,O); ii) up to values close to one in the inlet sections of said second adiabatic two-phase expansion transformations (TE.sub.2,O*).

13. The method according to claim 12, wherein said control transformations distribute the working fluid into said first and second sequence of thermodynamic transformations in said first and second circuit, and further switch said first and second sequence of thermodynamic transformations in said first and second circuit into a second operational mode of the method associated with a co-tri-generation thermodynamic cycle for supplying the end-user with electrical or mechanical power, heating power, or cooling power at different temperature values, wherein: said second isobaric heat exchange transformations (HE.sub.2) and said fourth isobaric heat exchange transformations (HE.sub.4) condense, according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, said working fluid with the consequent dissipation of thermal power to the external environment or supply of heating power to said end-user; said first isobaric heat exchange transformations (HE.sub.1,N) condense, according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, said working fluid with the consequent supply of heating power at different temperature values to said end-user, except for the first isobaric heat exchange transformations associated with the maximum pressure (and consequently the maximum temperature) of the working fluid in said thermodynamic cycle, wherein said first isobaric heat exchange transformations associated with the maximum pressure isobarically generate vapor of said working fluid, being fed by high-temperature thermal power supplied by the heat source, according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle; said third isobaric heat exchange transformations (HE.sub.3,N*) evaporate isobarically, according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, said working fluid with the consequent supply of cooling power to the end-user.

14. Method according to any one of claims 12, wherein said control transformations distribute the working fluid between said first and second sequence of thermodynamic transformations in said first and second circuit, and further switch said first and second sequence of thermodynamic transformations in said first and second circuit in said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, in which: said first and second isobaric two-phase compression transformations (TC.sub.1,M, TC.sub.2,M*) increase the pressure and consequently the temperature of the working fluid through the conversion of mechanical/electrical power supplied to said first and second isobaric two-phase compression transformations, operating according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, in which the two-phase working fluid has a variable quality in a wide range: i) up to values close to zero in the inlet sections of said first isobaric two-phase compression transformations (TC.sub.1,M); ii) up to values close to one in the inlet sections of said second isobaric two-phase compression transformations (TC.sub.2,M*); said first and second isobaric two-phase expansion transformations (TE.sub.1,O, TE.sub.2,O*) decrease the pressure and consequently the temperature of the working fluid, resulting in the production of mechanical/electrical power, operating according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, in which the two-phase working fluid has a variable quality in a wide range: i) up to values close to one in the inlet sections of said first isobaric two-phase expansion transformations (TE.sub.1,O); ii) up to values close to zero in the inlet sections of said second isobaric two-phase expansion transformations (TE.sub.2,O*).

15. The method according to claim 12, further comprising first working fluid flow spillover transformations (B.sub.1,Q), functionally associated with said first isobaric two-phase compression transformations (TC.sub.1,M) and said first isobaric two-phase expansion transformations (TE.sub.1,O), and transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow (B.sub.1,Q) between said first isobaric two-phase compression transformations (TC.sub.1,M) and said first isobaric two-phase expansion transformations (TE.sub.1,O) through interposed first connection transformations or through said interposed first isobaric heat exchange transformations (HE.sub.1,N), wherein said first isobaric heat exchange transformations (HE.sub.1,N) further transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power from or to the working fluid at respective distinct temperature values.

16. The method according to claim 12, comprising first working fluid flow spillover transformations (B.sub.1,Q): functionally associated with said first isobaric two-phase expansion transformations (TE.sub.1,O) and transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow between said first isobaric two-phase expansion transformations (TE.sub.1,O) through said interposed first isobaric heat exchange transformations (HE.sub.1,N), and possibly circulating the working fluid flow exiting from said first isobaric two-phase expansion transformations (TE.sub.1,O) towards said first isobaric two-phase compression transformations (TC.sub.1,M) through interposed first connection transformations or through said first interposed isobaric heat exchange transformations (HE.sub.1,N), wherein said first isobaric heat exchange transformations (HE.sub.1,N) further transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power from or to the working fluid at respective distinct temperature values; or vice versa functionally associated with said first isobaric two-phase compression transformations (TC.sub.1,M) and transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow between said first isobaric two-phase compression transformations (TC.sub.1,M) through interposed first isobaric heat exchange transformations (HE.sub.1,N), and possibly circulating the working fluid flow exiting from said first isobaric two-phase compression transformations (TC.sub.1,M) towards said first isobaric two-phase expansion transformations (TE.sub.1,O) through interposed first connection transformations or through said first isobaric heat exchange transformations (HE.sub.1,N), wherein said first isobaric heat exchange transformations (HE.sub.1,N) further transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power from or to the working fluid at respective distinct temperature values.

17. The method according to claim 15, wherein said first working fluid flow spillover transformations (B.sub.1,Q) are also: functionally associated with said first isobaric two-phase expansion transformations (TE.sub.1,O) and transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow between said first isobaric two-phase expansion transformations (TE.sub.1,O) through said interposed first isobaric heat exchange transformations (HE.sub.1,N), and possibly circulate the working fluid flow exiting from said first isobaric two-phase expansion transformations (TE.sub.1,O) towards said first isobaric two-phase compression transformations (TC.sub.1,M) through interposed first connection transformations or through said interposed first isobaric heat exchange transformations (HE.sub.1,N), wherein said first isobaric heat exchange transformations (HE.sub.1,N) further transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power from or to the working fluid at respective distinct temperature values; or vice versa functionally associated with said first isobaric two-phase compression transformations (TC.sub.1,M) and transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow between said first isobaric two-phase compression transformations (TC.sub.1,M) through interposed first isobaric heat exchange transformations (HE.sub.1,N), and possibly circulate the working fluid flow exiting from said first isobaric two-phase compression transformations (TC.sub.1,M) towards said first isobaric two-phase expansion transformations (TE.sub.1,O) through interposed first connection transformations or through said first isobaric heat exchange transformations (HE.sub.1,N), wherein said first isobaric heat exchange transformations (HE.sub.1,N) further transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power from or to the working fluid at respective distinct temperature values.

18. The method according to claim 12, comprising second working fluid flow spillover transformations (B.sub.2,Q*) functionally associated with said second isobaric two-phase compression transformations (TC.sub.2,M*) and said second isobaric two-phase expansion transformations (TE.sub.2,Q*), and transfer, according to said first operating mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow between said second isobaric two-phase compression transformations (TC.sub.2,M*) and said second isobaric two-phase expansion transformations (TE.sub.2,Q*) through interposed second connection transformations or through said third isobaric heat exchange transformations (HE.sub.3,N*), wherein said third heat exchange transformations (HE.sub.3,N*) further transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power from or to the working fluid at respective distinct temperature values.

19. The method according to claim 12, comprising second working fluid flow spillover transformations (B.sub.2,Q*): functionally associated with said second isobaric two-phase expansion transformations (TE.sub.2,O*) and transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow between said second isobaric two-phase expansion transformations (TE.sub.2,O*) through interposed third isobaric heat exchange transformations (HE.sub.3,N*), and optionally circulating the working fluid flow exiting from said second isobaric two-phase expansion transformations (TE.sub.2,O*) to said second isobaric two-phase compression transformations (TC.sub.2,M*) through intermediate second linking transformations or through said third isobaric heat exchange transformations (HE.sub.3,N*), wherein said third isobaric heat exchange transformations (HE.sub.3,N*) further transfer, in accordance with said first operating mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively in accordance with said second operating mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power to or from the working fluid at respective distinct temperature values. or vice versa functionally associated with said second isobaric two-phase compression transformations (TC.sub.2,M*) and transferring, in accordance with said first operating mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively in accordance with said second operating mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow between said second isobaric two-phase compression transformations (TC.sub.2,M*) through intermediate third isobaric heat exchange transformations (HE.sub.3,N*), and optionally circulate the working fluid flow exiting from said second isobaric two-phase compression transformations (TC.sub.2,M*) towards said second isobaric two-phase expansion transformations (TE.sub.2,O*) through interposed second connection transformations or through said third isobaric heat exchange transformations (HE.sub.3,N*), wherein said third isobaric heat exchange transformations (HE.sub.3,N*) further transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power from or to the working fluid at respective distinct temperature values.

20. The method according to claim 19, wherein said second working fluid flow spillover transformations (B.sub.2,Q*) are further: functionally associated with said second isobaric two-phase expansion transformations (TE.sub.2,O*) and transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow between said second isobaric two-phase expansion transformations (TE.sub.2,O*) through interposed third isobaric heat exchange transformations (HE.sub.3,N*), and optionally circulate the working fluid flow exiting from said second isobaric two-phase expansion transformations (TE.sub.2,O*) to said second isobaric two-phase compression transformations (TC.sub.2,M*) through interposed second connection transformations or through said third isobaric heat exchange transformations (HE.sub.3,N*), wherein said third isobaric heat exchange transformations (HE.sub.3,N*) further transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power from or to the working fluid at respective distinct temperature values. or vice versa functionally associated with said second isobaric two-phase compression transformations (TC.sub.2,M*) and transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, a portion of the working fluid flow between said second isobaric two-phase compression transformations (TC.sub.2,M*) through interposed third isobaric heat exchange transformations (HE.sub.3,N*), and optionally circulate the working fluid flow exiting from said second isobaric two-phase compression transformations (TC.sub.2,M*) to said second isobaric two-phase expansion transformations (TE.sub.2,O*) through interposed second connection transformations or through said third isobaric heat exchange transformations (HE.sub.3,N*), wherein said third isobaric heat exchange transformations (HE.sub.3,N*) further transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power from or to the working fluid at respective distinct temperature values.

21. The method according to claim 12, wherein said second sequence of thermodynamic transformations in said second circuit (C.sub.2) comprises second isobaric thermal regeneration transformations (TR.sub.2,P*) functionally associated with said second isobaric two-phase compression transformations (TC.sub.2,M*) and said second isobaric two-phase expansion transformations (TE.sub.2,O*), and transfer, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, thermal power between the working fluid circulating downstream of at least one stage of said second isobaric two-phase expansion transformations (TE.sub.2,O*) and the same working fluid circulating downstream of at least one stage of said second isobaric two-phase compression transformations (TC.sub.2,M*).

22. The method according to claim 12, wherein said control transformations comprise: first deviation transformations (DM.sub.1,K) deviate, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle, and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, said working fluid in said first sequence of thermodynamic transformations in said first circuit (C.sub.1), bypassing said respective first isobaric heat exchange transformations (HE.sub.1,N) except for said first isobaric heat exchange transformations associated with the maximum pressure (and consequently the maximum temperature) of the working fluid in said thermodynamic cycle; and second deviation transformations (DM.sub.2,K*) deviate, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle, and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, said working fluid in said second sequence of thermodynamic transformations in said second circuit (C.sub.2), bypassing said respective third isobaric heat exchange transformations (HE.sub.3,N*) except for said third isobaric heat exchange transformations associated with the minimum pressure (and consequently the minimum temperature) of the working fluid in said thermodynamic cycle; and third deviation transformations (DM3) deviate, according to said first operational mode of the method associated with said high-temperature heat pump thermodynamic cycle, and alternatively according to said second operational mode of the method associated with said co-tri-generation thermodynamic cycle, said working fluid between said first sequence of thermodynamic transformations in said first circuit (C.sub.1) downstream of said first isobaric two-phase expansion transformations (TE.sub.1,O) and said third sequence of thermodynamic transformations in said third circuit (C.sub.3) upstream of said fourth isobaric heat exchange transformations (HE.sub.4), bypassing said second sequence of thermodynamic transformations in said second circuit (C.sub.2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The features and advantages of the plant and method according to the invention will become apparent from the following description of its embodiments, with reference to the attached drawings in which: [0017] FIG. 1 is a circuital scheme of a plant according to the invention; [0018] FIGS. 2 and 3 depict the scheme of FIG. 1 with functional indications referring respectively to the first operational mode (co-tri-generation plant) and the second operational (high-temperature heat I pump system operating without electrical/mechanical power supplied from an external source); [0019] FIGS. 4, 5a, and 5b are temperature-specific entropy qualitative diagrams representing the operation of the plant respectively in the first operational mode, i.e., co-tri-generation plant (FIG. 4), and in the second operational mode, i.e., high-temperature heat pump plant operating without electrical/mechanical power supplied from an external source (FIGS. 5a and 5b, referring to respective variations).

DETAILED DESCRIPTION OF THE INVENTION

[0020] With reference to said figures, and particularly FIG. 1, from the perspective of the overall layout, the plant according to the invention follows that of the plant known from Italian patent no. 102016000027735, to which reference is made, noting that in terms of nomenclature there is a correspondence among the three indicated circuits (C.sub.1, C.sub.2, C.sub.3), while for the individual operating units updated indices are used, with a correspondence nevertheless readily reconstructible by an expert in the field, considering the use of standard symbols, which are not analytically expressed here.

[0021] Regarding the aforementioned known layout, however, in the illustrated embodiment, the addition of the following operating units must be noted (FIG. 1): [0022] In the first circuit C.sub.1, operating units enclosed in the dashed box B, which consists of (first) spillover means of the working fluid flow (B.sub.1,Q) functionally associated with (first) adiabatic two-phase compression means (TC.sub.1,M) and (first) adiabatic two-phase expansion means (TE.sub.1,O) to promote the circulation of a portion of the working fluid flow between said (first) adiabatic two-phase compression means (TC.sub.1,M) and said (first) adiabatic two-phase expansion means (TE.sub.1,O) through interposed (first) connection means or through interposed (first) isobaric heat exchange means (HE.sub.1,N);

[0023] In the second circuit C.sub.2, operating units enclosed in the dashed box C, which consists of (second) isobaric thermal regeneration means (TR.sub.2,P) and (second) spillover means of the working fluid flow (B.sub.2,Q*), where TR.sub.2,P and B.sub.2,Q* are functionally associated with (second) adiabatic two-phase compression means (TC.sub.2,M*) and (second) adiabatic two-phase expansion means (TE.sub.2,O*). In particular, TR.sub.2,P promote the heat transfer between the working fluid circulating downstream of at least one stage of the (second) adiabatic two-phase expansion means (TE.sub.2,O*) and the same working fluid circulating downstream of at least one stage of the (second) adiabatic two-phase compression means (TC.sub.2,M*). Furthermore, B.sub.2,Q* promote the circulation of a portion of the working fluid flow between said (second) adiabatic two-phase compression means (TC.sub.2,M*) and said (second) adiabatic two-phase expansion means (TE.sub.2,O*) through interposed (second) connection means or through interposed (third) isobaric heat exchange means (HE.sub.3,N*).

[0024] For the first operational mode, as a co-tri-generation plant in the operational sub-modes of CCHP, or CHP, or CCP, reference can be made to that described for the previous plant and is explicitly illustrated by the schemes and diagrams in FIGS. 2 and 4.

[0025] In particular, this operational mode enables the simultaneous supply to the end-user of electrical power, heating power, and cooling power (CCHP sub-mode), or electrical power and heating power (CHP sub-mode), or electrical power and cooling power (CCP sub-mode) through the conversion of the thermal power provided by any heat source (renewable or non-renewable).

[0026] Compared to the layout of the plant known from Italian patent no. 102016000027735, the addition of the abovementioned operating units implies the following three modifications for the plant operating in the first operational mode (co-tri-generation plant).

[0027] The first modification (enclosed in box B in FIG. 1) allows for the execution (FIG. 2) of the extraction (in circuit C.sub.1) of a portion of the working fluid flow from first adiabatic two-phase expansion means (TE.sub.1,2 in this case) through first spillover means (B.sub.1,1 in this case). This portion of the working fluid flow is then circulated to first adiabatic two-phase compression means (TC.sub.1,1 in this case) through interposed first connection means or through interposed first isobaric heat exchange means (HE.sub.1,2 in this case). In particular (FIG. 4), the portion of the working fluid flow is extracted from TE.sub.1,2 at intermediate section 5** and then circulates in HE.sub.1,2 to execute the supply of heating power to the end-user at the respective temperature value. The portion of the working fluid flow exiting HE.sub.1,2 (point 5***) enters TC.sub.1,1 where it is isobarically mixed with the working fluid flow circulating therein (point 1*). In particular, the quality of the working fluid (i.e., the ratio of vapor phase mass to two-phase fluid mass) at point 5*** is lower than the quality of the working fluid at point 1*. Due to said isobaric mixing, the overall working fluid flow (point 1** with lower quality compared to point 1*) undergoes the compression process 1**-2 (in the same TC.sub.1,1). The first modification of the plant layout known from Italian patent no. 102016000027735 (described up to this point) implies several effects that are contrasting with each other, as described below. The first effect (advantageous for the thermodynamic performance of the plant) consists of reducing the mechanical power required in the compression process 1-1* (due to the decrease in the circulating working fluid flow rate) and further decreasing the mechanical power required in the compression processes 1**-2 and 2*-3 (due to the decrease in the specific enthalpy difference in the respective processes 1**-2 and 2*-3). The second effect (disadvantageous for the thermodynamic performance of the plant) consists of reducing the mechanical power produced in the expansion processes 5**-6 and 7-8 (due to the decrease in the circulating working fluid flow rate) and increasing the thermal power supplied by the heat source to the working fluid in the transformation 3-4 at the same working fluid flow rate circulating in circuit C.sub.1 (due to the decrease in specific enthalpy at point 3). Under certain operating conditions, the first effect prevails over the second effect, resulting in an increase in the thermodynamic performance of the plant. Conversely, the first modification under consideration can be implemented according to the variant described below. In particular, the extraction of a portion of the working fluid flow is performed (in circuit C.sub.1) from first adiabatic two-phase compression means (TC.sub.1,1 in this case) through first spillover means (B.sub.1,1 in this case). This portion of the working fluid flow is then circulated to first adiabatic two-phase expansion means (TE.sub.1,2 in this case) through interposed first connection means or through interposed first isobaric heat exchange means (HE.sub.1,2 in this case). In this variant, HE.sub.1,2 allows the heat transfer from an additional heat source to the working fluid at the respective temperature value. Further details associated with the implementation of this variant are omitted for brevity, as they can be readily inferred by an expert in the field following the above description. Under certain operating conditions, the first modification (implemented according to the aforementioned variant) leads to an increase in the thermodynamic performance of the plant.

[0028] The second modification (enclosed in box C in FIG. 1) allows the extraction (shown in FIG. 2) of a portion of the working fluid flow from the second adiabatic two-phase expansion means (TE.sub.2,2 in this case) through the second spillover means (B.sub.2,1 in this case) in the C.sub.2 circuit. This portion of the working fluid flow is then circulated to the second adiabatic two-phase compression means (TC.sub.2,1 in this case) through interposed second connection means or through interposed third isobaric heat exchange means (HE.sub.3,1 in this case). In particular (FIG. 4), the portion of the working fluid flow is extracted from TE.sub.2,2 in the intermediate section 10** and then circulates in HE.sub.3,1 (to provide cooling power to the end-user at the respective temperature value). The portion of the working fluid flow leaving HE.sub.3,1 (point 10***) enters TC.sub.2,1 where it is isobarically mixed with the working fluid flow circulating there (point 12*). In particular, the quality of the working fluid at point 10*** is lower than the quality at point 12*. Due to said isobaric mixing, the overall working fluid flow rate (point 12** with lower quality than point 12*) undergoes the compression process 12**-13 (within the same TC.sub.2,1). The second modification to the plant layout as known from Italian patent no. 102016000027735 (described so far) entails several effects that are contrasting with each other, as described below. The first effect (advantageous for the thermodynamic performance of the plant) consists of a decrease in the mechanical power required in the compression process 12-1* (due to the decrease in the circulating working fluid flow rate) and a decrease in the mechanical power required in the compression processes 12**-13 and 13*-14 (due to the decrease in the specific enthalpy difference in the respective processes 12**-13 and 13*-14). The second effect (disadvantageous for the thermodynamic performance of the plant) consists of a decrease in the mechanical power produced in the expansion process 10**-11 (due to the decrease in the circulating working fluid flow rate) and an increase in the mechanical power required in the compression process 12-12* at the same cooling power provided to the end-user in the process 11-12 (due to the increase in the specific enthalpy at point 12 resulting from the decrease in the circulating working fluid flow rate in the process 11-12). Under certain operating conditions, the first effect prevails over the second effect, resulting in an increase in the thermodynamic performance of the plant.

[0029] Vice versa, the second modification under consideration can be implemented according to the variant described below. In particular, a portion of the working fluid flow is extracted (in the C.sub.2 circuit) from the second adiabatic two-phase compression means (TC.sub.2,1 in this case) through the second spillover means (B.sub.2,1 in this case). This portion of the working fluid flow is then circulated to the second adiabatic two-phase expansion means (TE.sub.2,2 in this case) through interposed second connection means or through interposed third heat exchange means (HE.sub.3,1 in this case). In this variant, HE.sub.3,1 allows the heat transfer (thermal power dissipation) from the working fluid to the external environment at the respective temperature value. Further details associated with the implementation of this variant are omitted for brevity, as they can be easily inferred by an expert in the field, similarly to the description provided above. Under certain operating conditions, the second modification (implemented according to the aforementioned variant) results in an increase in the thermodynamic performance of the plant.

[0030] The third modification already mentioned (enclosed in box C) allows for thermal regeneration in circuit C.sub.2. In fact, the working fluid on the hot side (13-13*) of the second isobaric thermal regeneration means (TR.sub.2,1 in this case) transfers thermal power to the same working fluid on the cold side of TR.sub.2,1 (10-10*). The third modification of the plant layout known from Italian patent No. 102016000027735 (described so far) entails several effects that are contrasting with each other, as described below. The first effect (advantageous for the thermodynamic performance of the plant) involves a decrease in the mechanical power required in the compression process 13*-14 (due to the decrease in the specific enthalpy difference in the same 13*-14 process) and an increase in the mechanical power produced in the expansion process 10*-11 (due to the increase in the specific enthalpy difference in the same 10*-11 process). The second effect involves an increase in the circulating working fluid flow rate in circuit C.sub.2, necessary for supplying the end-user with the fixed cooling power (in the third isobaric heat exchange means HE.sub.3,2) (due to the decrease in the specific enthalpy difference in the aforementioned HE.sub.3,2 resulting from the increase in specific enthalpy in point 11). In turn, the increase in the circulating working fluid flow rate in circuit C.sub.2 leads to an increase in the overall mechanical power required by the second adiabatic two-phase compression means in C.sub.2 (disadvantageous effect for the thermodynamic performance of the plant) and an increase in the overall mechanical power produced by the second adiabatic two-phase expansion means in C.sub.2 (advantageous effect for the thermodynamic performance of the plant). Under certain operating conditions, the aforementioned advantageous effects prevail over the aforementioned disadvantageous effects, resulting in an increase in the thermodynamic performance of the plant.

[0031] Vice versa, the third modification under consideration can be implemented according to the variant described below. In particular, the working fluid on the hot side (10-10*) of the second isobaric thermal regeneration means (TR.sub.2,1 in this case) transfers thermal power to the same working fluid on the cold side of TR.sub.2,1 (13-13*). Further details associated with the implementation of this variant are omitted for brevity, as they can be readily inferred by an expert in the field, similarly to the description provided above. Under certain operating conditions, the third modification (implemented according to the aforementioned variant) results in an increase in the thermodynamic performance of the plant.

[0032] The transformations of the process according to the first operational mode as a co-trigeneration plant are depicted in the self-explanatory temperature (T)specific entropy(s) diagram in FIG. 4, as previously described in the previous patent, except for the modifications (thoroughly described above) associated with the transformations related to the spillover means in circuits C.sub.1 and C.sub.2 and the thermal regeneration in circuit C.sub.2. However, it is worth emphasizing that, similarly to the plant known from the Italian patent no. 102016000027735, the plant of the present invention (operating according to the first operational mode as a co-trigeneration plant) provides thermal power to the end-user at the first temperature value (transformation 6-7), cooling power at the first temperature value (transformation 11-12), and finally dissipates thermal power to the external environment (transformations 15-1-9). On the other hand, compared to the plant known from the Italian patent no. 102016000027735, the plant of the present invention is characterized by the spillovers in circuits C.sub.1 and C.sub.2 (described above). These spillovers, in addition to enhancing the thermodynamic performance of the plant (explained above), also enable the supply of thermal power to the end-user at the second temperature value (transformation 5**-5***) and the supply of cooling power to the end-user at the second temperature value (transformation 10**-10***).

[0033] The basis of this invention therefore consists of two aspects. The first aspect involves the understanding that a plant with the same layout under consideration (usable in the first operational mode as a co-trigeneration plant) can be surprisingly functional for a reversible use in the second operational mode as a high-temperature heat pump capable of operating without electric/mechanical power provided by an external source. In other words, each operating unit works in both of the aforementioned operational modes. The second aspect, which however can be pursued independently of the first one that will be explained shortly, involves the aforementioned options for modifying the plant layout known from Italian patent No. 102016000027735 in order to enhance its thermodynamic performance.

[0034] In the alternative (second) operational mode, the plant is capable of providing the end-user with high-temperature heating power without the need of electric/mechanical power provided by an external source, by converting the low-to-medium temperature thermal power supplied from any heat source (renewable or non-renewable). In other words, the same plant (without any change of its configuration, i.e., requiring the operation of each operating unit in both of the aforementioned operational modes) can be reversibly used according with said two alternative operational modes (i.e., the first mode as a co-trigeneration plant and the second mode as a high-temperature heat pump without external electric/mechanical power provided by an external source).

[0035] In a version of the plant operating according with the second operating mode (FIG. 3 and FIG. 5a), heating power is supplied from the plant to the end-user at three distinct temperature values (transformations 3-4, 1*-1**, and 6-7), with the heat transfer from the heat source to the working fluid in transformations 15-1-9.

[0036] In more detail, the operating units and corresponding transformations of the thermodynamic cycle according to this version of the second operational mode, as represented in the plant scheme of FIG. 3 and the T-s diagram of FIG. 5a, can be indicated as follows in the circuits C.sub.1, C.sub.2, and C.sub.3 that constitute the thermodynamic cycle: [0037] First and second adiabatic two-phase compression means TC.sub.1,1, TC.sub.1,2, TC.sub.2,1, and TC.sub.2,2 (transformations 1-2, 2*-3, 12-13, and 13*-14, respectively): in each of these, an increase in pressure (and consequent increase in temperature) of the working fluid is achieved due to the supply of mechanical power (provided by the first and second adiabatic two-phase expansion means of the same plant) to the aforementioned first and second adiabatic two-phase compression means; [0038] First isobaric thermal regeneration means TR.sub.1,1 (cold side transformation 2-2* and hot side transformation 5-5*): the heat transfer is accomplished from the working fluid on the hot side of TR.sub.1,1 to the same working fluid on the cold side of TR.sub.1,1; [0039] First, second, and third isobaric heat exchange means HE.sub.1,1, HE.sub.1,2, and HE.sub.1,3 (transformations 3-4, 1*-1**, 6-7, respectively): in each of them, the supply of heating power from the working fluid to the end-user (useful effect) is achieved at the respective temperature value. Therefore, the plant depicted in FIG. 5a allows the supply of heating power to the end-user at three distinct temperature values; [0040] First and second adiabatic two-phase expansion means TE.sub.1,1, TE.sub.1,2, TE.sub.1,3, TE.sub.2,1, and TE.sub.2,2 (transformations 4-5, 5*-6, 7-8, 9-10, and 10*-11, respectively): in each of them, a decrease in pressure (and consequent decrease in temperature) of the working fluid is achieved, resulting in the generation of mechanical and/or electrical power. Furthermore, the overall mechanical (or electrical) power produced by the aforementioned first and second adiabatic two-phase expansion means is used for the operation of said first and second adiabatic two-phase compression means within the same plant, and any surplus of the aforementioned mechanical (or electrical) power is supplied to the end-user; [0041] Third isobaric heat exchange units HE.sub.3,1 and HE.sub.3,2 (transformations 10**-10*** and 11-12, respectively): in each of them, the heat transfer (thermal dissipation) from the working fluid to the external environment is achieved at the respective temperature value; [0042] Second isobaric thermal regeneration units TR.sub.2,1 (hot side transformation 13-13* and cold side transformation 10-10*): the heat transfer is accomplished from the working fluid on the hot side of TR.sub.2,1 to the same working fluid on the cold side of TR.sub.2,1; [0043] Mixing means MI (transformation 8-14-15): isobaric mixing is achieved between the working fluid exiting circuit C.sub.1 (point 8) and the working fluid exiting circuit C.sub.2 (point 14); [0044] Fourth (HE.sub.4) and second (HE.sub.2) isobaric heat exchange means (transformations 15-1 and 1-9, respectively): the heat transfer from the low-to-medium temperature heat source to the working fluid exiting the mixer (point 15) is accomplished. Similarly to the first operational mode, in this different (second) operational mode as well, the plant (box B in FIG. 1) allows for the spillover (in circuit C.sub.1) of a portion of the working fluid flow from first two-phase adiabatic compression means (TC.sub.1,1 in this case) through first spillover means (B.sub.1,1 in this case). This portion of the working fluid flow is then circulated to first two-phase adiabatic expansion means (TE.sub.1,2 in this case) through interposed first connection means or through interposed first isobaric heat exchange means (HE.sub.1,2 in this case). In particular (FIG. 5a), the portion of the working fluid flow is withdrawn from TC.sub.1,1 in the intermediate section 1* and then circulates through HE.sub.1,2 (to provide the end-user with heating power at the respective temperature value). The portion of the working fluid flow exiting HE.sub.1,2 (point 1**) enters TE.sub.1,2, where it is isobarically mixed with the working fluid flow here circulating (point 5**). In particular, the quality of the working fluid at point 1** is higher than the quality of the working fluid at point 5**. Due to the aforementioned isobaric mixing, the overall flow rate of the working fluid (point 5*** with higher quality than that of the working fluid at point 5**) undergoes the adiabatic two-phase expansion process 5***-6 (in the same TE.sub.1,2 operating unit). The transformation (described so far) implies several effects that are contrasting with each other, as described below. The first effect (advantageous for the thermodynamic performance of the plant) involves a decrease in the mechanical power required in the two-phase adiabatic compression processes 1*-2 and 2*-3 (due to the reduction in the working fluid flow rate here circulating), an increase in the mechanical power produced in the two-phase adiabatic expansion processes 5***-6 and 7-8 (due to the increase in specific enthalpy difference in the respective processes 5***-6 and 7-8), and a reduction in the thermal power supplied from the heat source to the working fluid in both HE.sub.4 and HE.sub.2 at the same circulating working fluid flow rate (due to the increase in specific enthalpy at point 8 and consequently also at point 15). The second effect (disadvantageous for the thermodynamic performance of the plant) involves a decrease in the mechanical power produced in the two-phase adiabatic expansion processes 4-5 and 5*-5** (due to the reduction in the working fluid flow rate here circulating). The third effect (disadvantageous for the thermodynamic performance of the plant) involves, at the same heating power supplied from the working fluid to the end-user in the process 3-4, a decrease in the circulating working fluid flow rate in process 3-4, resulting in an increase in the mechanical power required in the two-phase adiabatic compression process 2*-3 (due to the increase in specific enthalpy difference in the two-phase adiabatic compression process 2*-3) and a decrease in the mechanical power produced in the two-phase adiabatic expansion processes 4-5 and 5*-5** (due to the decrease in specific enthalpy difference in the two-phase adiabatic expansion processes 4-5 and 5*-5**). Under certain operating conditions, the advantageous effects are predominant over the disadvantageous ones, resulting in an increase in the thermodynamic performance of the plant.

[0045] Vice versa, the spillover in the C.sub.1 circuit of the plant in the second operational mode under consideration can be implemented according to the variant described below. In particular, the withdrawal (in circuit C.sub.1) of a portion of the working fluid flow from first two-phase adiabatic expansion means (TE.sub.1,2 in this case) is carried out through first spillover units (B.sub.1,1 in this case). This portion of the working fluid flow is then circulated to first two-phase adiabatic compression means (TC.sub.1,1 in this case) through interposed first connection units or through interposed first heat exchange means (HE.sub.1,2 in this case). In this variant, HE.sub.1,2 enables the heat transfer from an additional heat source to the working fluid at the respective temperature value. Further details associated with the implementation of this variant are omitted for brevity, as they can be readily inferred by an expert in the field, similarly to the description provided above. Under certain operating conditions, the spillover in the C.sub.1 circuit of the plant in the second operational mode (implemented according to the aforementioned variant) results in an increase in the thermodynamic performance of the plant.

[0046] Similarly to the first operational mode, in this different (second) operational mode as well, the plant (box C in FIG. 1) is capable of performing (FIG. 5a) the withdrawal (in the C.sub.2 circuit) of a portion of the working fluid flow from second two-phase adiabatic expansion means (TE.sub.2,2 in this case) through second spillover means (B.sub.2,1 in this case). This portion of the working fluid flow is then circulated to second two-phase adiabatic compression means (TC.sub.2,1 in this case) through interposed second connection means or through interposed third isobaric heat exchange means (HE.sub.3,1 in this case). In particular (FIG. 5a), the portion of the working fluid flow is withdrawn from TE.sub.2,2 in the intermediate section 10** and then circulates through HE.sub.3,1 (in order to execute the dissipation of thermal power from the working fluid to the external environment at the respective temperature value). The portion of the working fluid flow exiting from HE.sub.3,1 (point 10***) enters TC.sub.2,1 where it is isobarically mixed with the working fluid flow already here circulating (point 12*). In particular, the quality of the working fluid at point 10*** is lower than that of the working fluid at point 12*. Due the aforementioned isobaric mixing, the overall working fluid flow (point 12** with lower quality than point 12*) undergoes the two-phase adiabatic compression process 12**-13 (in the same TC.sub.2,1). The transformation (described so far) implies several effects that are contrasting with each other, as described below. The first effect (advantageous for the thermodynamic performance of the plant) consists of a decrease in the mechanical power required in the two-phase adiabatic compression process 12-12* (due to the reduction in the working fluid flow rate here circulating) and a decrease in the mechanical power required in the two-phase adiabatic compression processes 12**-13 and 13*-14 (due to the reduction in the specific enthalpy difference in the respective processes 12**-13 and 13*-14). The second effect (disadvantageous for the thermodynamic performance of the plant) involves a decrease in the mechanical power produced in the two-phase adiabatic expansion process 10**-11 (due to the reduction in the working fluid flow rate here circulating) and an increase in the thermal power supplied by the heat source to the working fluid in both HE.sub.4 and HE.sub.2 at the same working fluid flow rate here circulating (due to the reduction in the specific enthalpy at point 14 and consequently also at point 15). Under certain operating conditions, the first effect prevails over the second effect, resulting in an increase in the thermodynamic performance of the plant.

[0047] Vice versa, the spillover in the C.sub.2 circuit of the plant in the second operational mode under consideration can be implemented according to the following variant. In particular, a portion of the working fluid flow is withdrawn (in the C.sub.2 circuit) from the second adiabatic two-phase compression means (TC.sub.2,1 in this case) through second spillover means (B.sub.2,1 in this case). This portion of the working fluid flow is then circulated to the second adiabatic two-phase expansion means (TE.sub.2,2 in this case) through interposed second connection means or through interposed third isobaric heat exchange means (HE.sub.3,1 in this case). In this variant, HE.sub.3,1 enables the heat transfer from an additional heat source to the working fluid (for example, supplying the end-user with cooling power) at the respective temperature value. Further details associated with the implementation of this variant are omitted for brevity, as they can be readily inferred by an expert in the field, similarly to the description provided above. Under specific operating conditions, the spillover in the C.sub.2 circuit of the plant in the second operational mode (implemented according to the aforementioned variant) leads to an increase in the thermodynamic performance of the plant.

[0048] Similarly to the first operational mode, in this different (second) operational mode as well, the plant allows for thermal regeneration in the C.sub.1 circuit (FIG. 5a). In fact, the working fluid on the hot side (5-5*) of the first two-phase isobaric thermal regeneration means (TR.sub.1,1 in this case) transfers thermal power to the same working fluid on the cold side of TR.sub.1,1 (2-2*). Such thermal regeneration in the C.sub.1 circuit of the plant in the second operational mode entails several effects that are contrasting with each other, as described below. The first effect involves the reduction in the working fluid flow rate circulating in the C.sub.1 circuit, necessary to supply (in the first isobaric heat exchange means HE.sub.1,1) to the end-user the fixed thermal power (due to the increase in the specific enthalpy difference in the aforementioned HE.sub.1,1 as a result of the increase in specific enthalpy at point 3). In turn, the reduction in the working fluid flow rate in the C.sub.1 circuit leads to a decrease in the overall mechanical power required by the first two-phase adiabatic compression means in C.sub.1 (advantageous effect for the thermodynamic performance of the plant) and a decrease in the overall mechanical power produced by the first two-phase adiabatic expansion means in C.sub.1 (disadvantageous effect for the thermodynamic performance of the plant). The second effect (disadvantageous for the thermodynamic performance of the plant) involves an increase in the mechanical power required in the two-phase adiabatic compression process 2*-3 (due to the increase in the specific enthalpy difference in the same process 2*-3) and a decrease in the mechanical power produced in the two-phase adiabatic expansion process 5*-5** (due to the increase in the specific enthalpy difference in the same process 5*-5**). Under certain operating conditions, the aforementioned advantageous effects prevail over the mentioned disadvantageous effects, resulting in an increase in the thermodynamic performance of the plant.

[0049] Vice versa, thermal regeneration in the C.sub.1 circuit of the plant in the second operational mode under consideration can be implemented according to the variant described below. In particular, the working fluid on the hot side (2-2*) of the first two-phase isobaric thermal regeneration means (TR.sub.1,1 in this case) transfers thermal power to the same working fluid on the cold side of TR.sub.1,1 (5-5*). Further details associated with the implementation of this variant are omitted for brevity, as they can be easily inferred by an expert in the field, similarly to the description provided above. Under specific operating conditions, the thermal regeneration in the C.sub.1 circuit of the plant in the second operational mode (implemented according to the aforementioned variant) leads to an increase in the thermodynamic performance of the plant.

[0050] Similarly to the first operational mode, in this different (second) operational mode as well, the plant allows the thermal regeneration in the C.sub.2 circuit (FIG. 5a). In fact, the working fluid on the hot side (13-13*) of the second two-phase isobaric thermal regeneration means (TR.sub.2,1 in this case) transfers thermal power to the same working fluid on the cold side of TR.sub.2,1 (10-10*). Such thermal regeneration in the C.sub.2 circuit of the plant in the second operational mode implies several effects that are contrasting with each other, as described below. The first effect (advantageous for the thermodynamic performance of the plant) involves a decrease in the mechanical power required in the two-phase adiabatic compression process 13*-14 (due to the decrease in specific enthalpy difference in the same process 13*-14) and an increase in the mechanical power produced in the two-phase adiabatic expansion process 10*-11 (due to the increase in specific enthalpy difference in the same process 10*-11). The second effect (disadvantageous for the thermodynamic performance of the plant) consists of an increase in the thermal power supplied from the heat source to the working fluid both in HE.sub.4 and HE.sub.2 at the same working fluid flow rate here circulating (due to the decrease in specific enthalpy in point 14 and consequently also in point 15). Under certain operating conditions, the aforementioned advantageous effects prevail over the mentioned disadvantageous effects, resulting in an increase in the thermodynamic performance of the plant.

[0051] Vice versa, thermal regeneration in the C.sub.2 circuit of the plant in the second operational mode under consideration can be implemented according to the variant described below. In particular, the working fluid in the hot side (10-10*) of the second isobaric thermal regeneration means (TR.sub.2,1 in this case) transfers thermal power to the same working fluid on the cold side of TR.sub.2,1 (13-13*). Further details associated with the implementation of this variant are omitted for brevity, as they can be easily inferred by an expert in the field, similarly to the description provided above. Under certain operating conditions, thermal regeneration in the C.sub.2 circuit of the plant in the second operational mode (implemented according to the above described variant) leads to an increase in the thermodynamic performance of the plant.

[0052] According to the variant shown in FIG. 5b, the supply of thermal power to the end-user occurs at two temperature values, namely in the transformations 1*-1** and 3-4. For operation according to this variant as a high-temperature heat pump, the bypass (i.e., deactivation) of the first isobaric heat exchange means (HE.sub.1,3) is used by activating their respective first bypass means, enclosed in the small circle (DM.sub.1,3) in FIG. 3. In particular, the working fluid downstream of the first two-phase adiabatic expansion means (TE.sub.1,2) at point 6 circulates through the aforementioned DM.sub.1,3 to the first two-phase adiabatic expansion means (TE.sub.1,3), thus avoiding circulation through said HE.sub.1,3. Similarly, all other isobaric heat exchange means in the C.sub.1 and C.sub.2 circuits can be deactivated (bypassed) (by activating corresponding bypass means analogous to the aforementioned DM.sub.1,3 bypass means), except for the first isobaric heat exchange means HE.sub.1,1 (transformation 3-4) and the third isobaric heat exchange means HE.sub.3,2 (transformation 11-12), otherwise the closed sequence of transformations in the thermodynamic cycle cannot take place.

[0053] In all the aforementioned variants of the second operational mode as a high-temperature heat pump, the plant operates without any mechanical and/or electrical power supplied from an external source, as the overall mechanical (and/or electrical) power produced by the two-phase adiabatic expansion means is used for the operation of the two-phase adiabatic compression means within the same plant, and any possible surplus of the aforementioned mechanical (and/or electrical) power produced is supplied to the end-user.

[0054] The advantages offered by the proposed plant (FIG. 1) are described below.

1) Reversibility of the Plant

[0055] The same plant configuration (without any modifications, i.e., requiring the operation of each operating unit in both of the aforementioned operational modes) can be used reversibly according to the two aforementioned alternative operational modes (i.e., the first mode as a co-tri-generation plant and the second mode as a high-temperature heat pump plant operating without electrical/mechanical power provided by an external source).

[0056] In order to enable the same plant configuration to operate reversibly according to the two operational modes described above (either as a co-tri-generation plant or as a high-temperature heat pump plant without electrical/mechanical power provided by an external source), it is necessary to use adiabatic two-phase fluid machines (compressors, expanders) and heat exchangers with specific characteristics. In particular, the adiabatic two-phase fluid machines must be able to work with working fluid in their respective inlet sections with variable quality over a wide range. Furthermore, the heat exchangers must be able to operate as condensers (i.e., with the working fluid having decreasing quality between the respective inlet and outlet sections due to the heat transfer from the working fluid to the thermal fluid circulating in the same condensers) or as evaporators (i.e., with the working fluid having increasing quality between the respective inlet and outlet sections due to the heat transfer from the thermal fluid circulating in the same evaporators to the working fluid).

[0057] In particular, as mentioned above, the adiabatic two-phase fluid machines must be able to operate with working fluid in their respective inlet section with variable quality over a wide range: [0058] First operational mode (co-tri-generation plant): in circuit C.sub.1, each adiabatic two-phase compressor operates with working fluid in its respective inlet section with variable quality in a wide range, approaching values close to zero in the limit condition, where in this limit condition, the said two-phase working fluid is predominantly composed of the liquid phase; and each adiabatic two-phase expander operates with working fluid in its respective inlet section with variable quality in a wide range, approaching values close to one in the limit condition, where in this limit condition, the said two-phase working fluid is predominantly composed of the vapor phase. Conversely, in circuit C.sub.2, each adiabatic two-phase compressor operates with working fluid in its respective inlet section with variable quality in a wide range, approaching values close to one, and each two-phase expander operates with working fluid in its respective inlet section with variable quality in a wide range, approaching values close to zero. [0059] Second operational mode (high-temperature heat pump plant without electric/mechanical power provided by an external source): in circuit C.sub.1, each adiabatic two-phase compressor operates with working fluid in its respective inlet section with variable quality in a wide range, approaching values close to one, and each two-phase expander operates with working fluid in its respective inlet section with variable quality in a wide range, approaching values close to zero. Conversely, in circuit C.sub.2, each adiabatic two-phase compressor operates with working fluid in its respective inlet section with variable quality in a wide range, approaching values close to zero, and each adiabatic two-phase expander operates with working fluid in its respective inlet section with variable quality in a wide range, approaching values close to one.

[0060] Only for the sake of example, in order to operate with working fluid in the respective inlet section with variable quality in a wide range, two-phase fluid machines can be realized with variable geometry according to solutions already extensively tested on single-phase fluid machines, as well-known, for example, from [Haglind F. Variable geometry gas turbines for improving the part-load performance of marine combined cyclesGas turbine performance, Energy 2010; 35: 562-570] and from [Herbst F, Eilts P. Experimental investigation of variable geometry compressor for highly boosted gasoline engines, SAE Technical Paper 2015-01-1289, 2015].

[0061] Again just for the sake of example, in order to operate as condensers or as evaporators, heat exchangers can be realized using solutions that have been widely experimented with and as known, for instance, from [Kelvion https://www.kelvion.com/products/product/td-series/] and [Swep https://www.swep.net/refrigerant-handbook/7.-condensers/asd1/].

[0062] Furthermore, all the other aforementioned operating units are to be considered inherently known in their nature and construction by the skilled person.

[0063] As mentioned previously, there are known examples of reversible plants capable of operating according to two alternative operational modes, namely the first operational mode (ORC) for supplying the end-user with electrical power and the second operational mode (HP) for supplying the end-user with heating power. However, in the aforementioned known reversible plants: i) some operating units work in one of the two operational modes while they do not work (i.e., they are bypassed) in the other operational mode. In other words, each operating unit does not work in both operational modes; ii) adiabatic single-phase fluid machines are used, where the same machine can work as an adiabatic single-phase compressor (in the HP operational mode) or as an adiabatic single-phase expander (in the ORC operational mode). Conversely to the present invention, there is no known reversible plant where: i) each operating unit works in both the first operational mode (as a plant for supplying the end-user with electrical power or as a co-trigeneration plant) and the second operational mode (as a high-temperature heat pump plant); ii) two-phase fluid machines (compressors and expanders) are used, where each machine exclusively works as an adiabatic two-phase fluid compressor to increase (via conversion of the mechanical/electrical power supplied from an external source) the pressure of the two-phase working fluid, or exclusively works as an adiabatic two-phase expander to decrease (in order to produce mechanical/electrical power) the pressure of the two-phase working fluid. Furthermore, each two-phase fluid machine works with variable quality over a wide range in its respective inlet section to allow the operation of the plant in both the first mode (as a plant for supplying the end-user with electrical power or as a co-trigeneration plant) and the second mode (as a high-temperature heat pump plant).

2) High Thermodynamic Performance of the Plant

[0064] In the first operational mode (co-trigeneration plant), circuit C.sub.1 works according to a suitable combination of direct Carnot thermodynamic cycles (i.e., in order to produce mechanical/electrical power) using a two-phase fluid. Similarly, circuit C.sub.2 works according to a suitable combination of reverse Carnot thermodynamic cycles (i.e., using mechanical/electrical power supplied from an external source) using a two-phase fluid. As well-known in the literature, direct and reverse Carnot thermodynamic cycles represent cycles with maximum efficiency. Consequently, the plant layout known from Italian Patent No. 102016000027735 is characterized by high thermodynamic performance. In addition, the three modifications to the aforementioned plant layout (extensively described earlier, i.e., spillovers of the working fluid in circuits C.sub.1 and C.sub.2 and thermal regeneration in circuit C.sub.2) allow for an increase in the (already high) thermodynamic performance of the plant operating in the first operational mode. Therefore, these modifications can be advantageously applied to a co-trigeneration plant regardless of its predisposition (also) for switching to the second operational mode. In other words, while supplying the end-user with the same powers (mechanical/electrical, heating, and/or cooling), the thermal power supplied by the heat source to the working fluid is reduced. Alternatively, at the same thermal power supplied by the heat source to the working fluid, the powers (mechanical/electrical, heating, and/or cooling) provided by the plant to the end-user are increased.

[0065] Similarly, in the second operational mode (high-temperature heat pump), the C.sub.1 and C.sub.2 circuits work as an appropriate combination of inverse and direct Carnot thermodynamic cycles using a two-phase fluid, respectively, which represent thermodynamic cycles with maximum efficiency, as well known in literature. In addition, both in the C.sub.1 and C.sub.2 circuits, thermal regeneration and spillovers (described extensively before) contribute to enhancing the (already high) thermodynamic performance of the plant operating in the second operational mode. In other words, at the same high-temperature heating power provided from the plant to the end-user, there is a reduction in the low-to-medium-temperature thermal power supplied from the heat source to the working fluid. Conversely, at the same low-to-medium-temperature thermal power supplied from the heat source to the working fluid, there is an increase in the high-temperature heating power supplied from the plant to the end-user.

3) Use of the Plant in the Second Operational Mode (High-Temperature Heat Pump) Without Mechanical/Electrical Power Supplied From an External Source

[0066] The mechanical/electrical power required to operate the entire set of two-phase adiabatic compressors in the plant is provided by the two-phase adiabatic expanders within the same plant. Therefore, the plant solely relies on being fed by a low-to-medium-temperature heat source, namely it does not require any mechanical/electrical power supplied from an external source. This implies that the plant can be used in locations without connection to the electrical grid (stand-alone plant). In addition, the plant can generate surplus mechanical/electrical power (beyond what is strictly necessary for driving the two-phase adiabatic compressors in the same plant), which can be supplied to the end-user (in particular, the electrical power can be fed into the electrical grid).

[0067] In contrast to the present invention, no heat pump (both compression and absorption types) is known capable to operate without mechanical/electrical power supplied from an external source. In fact, currently known heat pumps require the mechanical/electrical power supplied from an external source.

4) High Flexibility of the Plant in the Second Operational Mode (High-Temperature Heat Pump)

[0068] The plant according to the present invention in the second operational mode (high-temperature heat pump) allows the supplying the end-user with several required values of heating power within a significantly wider range (wideness to be understood both in terms of heating power values and their corresponding temperatures) compared to currently known high-temperature heat pumps. This is achieved without any deficit or surplus of the aforementioned heating power provided from this plant to the end-user. The remarkable flexibility of the plant's usage according to the present invention enables the fulfilling of the energy requirements of the end-user that are variable over time (in terms of heating powers and respective temperatures). This considerable flexibility arises from the control/regulation of the following multiple independent process parameters: each of the two portions of the working fluid circulating in C.sub.1 and C.sub.2, the outlet quality from each HE.sub.2, HE.sub.4, HE.sub.1,N, HE.sub.3,N*, TR.sub.1,P, and TR.sub.2,P, and the outlet pressure from each TE.sub.1,O, TE.sub.2,O*, TC.sub.1,M, and TC.sub.2,M*. The control/regulation of the aforementioned process parameters is carried out through means and methods accessible to an average technician and is therefore not further detailed here.

[0069] Variations and/or modifications can be brought to the high-temperature heat pump plant without mechanical/electrical power supplied from an external source, which can be reversibly used in an alternative operational mode as a co-trigeneration plant according to the present invention, without departing from the scope of protection defined by the attached claims.