COMBINED-TYPE CASCADE REFRIGERATING APPARATUS

Abstract

There is disclosed a combined-type cascade refrigerating apparatus that comprises a compression refrigerating apparatus having a refrigerating circuit and a sorption refrigerating apparatus having an evaporator. The refrigerating circuit is coupled with the evaporator so as to increase the efficiency of a refrigerating circuit.

Claims

1. Combined-type cascade refrigerating apparatus comprising a compression refrigerating apparatus having a refrigerating circuit; and a sorption refrigerating apparatus having an evaporator; wherein the refrigerating circuit is coupled with the evaporator.

2. The cascade refrigerating apparatus as claimed in claim 1, wherein solid sorbent (adsorber) is used in the sorption refrigerating apparatus.

3. The cascade refrigerating apparatus as claimed in claim 1, wherein a liquid sorbent (absorber) is used in the sorption refrigerating apparatus.

4. The cascade refrigerating apparatus as claimed in claim 1, wherein refrigerants such as water are selected for positive temperatures and methanol, ethylene glycol, or ammonia for negative temperatures.

5. The cascade refrigerating apparatus as claimed in claim 1, wherein the evaporator is used as a subcooler.

7. The cascade refrigerating apparatus as claimed in claim 1, further provided with a medium heat-carrier connected between the evaporator and the refrigerating circuit.

8. The cascade refrigerating apparatus as claimed in claim 7, wherein the refrigerating circuit is connected to the medium heat-carrier via a receiver to ensure stable temperatures.

9. The cascade refrigerating apparatus as claimed in claim 1, wherein the sorption refrigerating apparatus is supplied with low-grade heat via an open circuit.

10. The cascade refrigerating apparatus as claimed in claim 1, wherein the sorption refrigerating apparatus is supplied with low-grade heat via a closed circuit with a medium hot heat-carrier.

11. The cascade refrigerating apparatus as claimed in claim 8, wherein the receiver is used to stabilize the input temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Embodiments are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the embodiments. In this regard, no attempt is made to show structural details in more detail than is necessary for a fundamental understanding, the description taken with the drawings making apparent to those skilled in the art how several forms may be embodied in practice.

[0048] FIG. 1 depicts a refrigerating circuit of a compression apparatus coupled in cascade directly with an evaporator of a sorption apparatus, in accordance with preferred embodiment of the disclosed subject matter.

[0049] FIG. 2 depicts a refrigerating circuit of a compression apparatus coupled in cascade with an evaporator of a sorption apparatus by means of a medium heat-carrier, in accordance with preferred embodiment of the disclosed subject matter.

[0050] FIG. 3 depicts a refrigerating circuit of a compression apparatus coupled in cascade with an evaporator of a sorption apparatus by means of a medium heat-carrier via a receiver used for temperature stabilization, in accordance with preferred embodiment of the disclosed subject matter.

[0051] FIG. 4 depicts a sorption-type apparatus coupled with a hot heat-carrier by means of an open circuit, in accordance with preferred embodiment of the disclosed subject matter.

[0052] FIG. 5 illustrates a sorption-type apparatus coupled with a hot source of heat by means of a medium heat-carrier, in accordance with preferred embodiment of the disclosed subject matter.

[0053] FIG. 6 depicts a sorption-type apparatus coupled with a hot source of heat by means of a medium heat-carrier via a receiver used for temperature stabilization, in accordance with preferred embodiment of the disclosed subject matter.

[0054] FIG. 7 presents a thermodynamic diagram of a refrigerating circuit both with and without a subcooler, in accordance with preferred embodiment of the disclosed subject matter, for comparison reasons.

[0055] For convenience of demonstration FIGS. 4, 5, 6 do not depict circulating pumps.

DESCRIPTION OF THE SUBJECT MATTER

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

[0057] Before explaining at least one embodiment in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. In addition, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. In discussion of the various figures described herein below, like numbers refer to like parts. The drawings are generally not to scale.

[0058] An objective of the disclosed subject matter is to increase the efficiency of a refrigerating circuit of the frequently utilized compression-type refrigerating apparatuses by adding a sorption-type refrigerating apparatus into the existing circuit in the capacity of a subcooler.

[0059] The technical hypothesis herewith is that power efficiency of the entire cascade refrigerating apparatus can be increased should the top circuit of the cascade, representing a sorption-type apparatus, used to transform low-grade heat of an ambient utility into cold, be connected to the subcooler of the compression apparatus.

[0060] In order to practice the disclosed refrigerating apparatus, a subcooler, which is not an evaporator-condenser, is the common module of the combined-type cascade refrigerating apparatus. The subcooler comprises a sorption-type refrigerating apparatus in its top circuit and a vapor compression refrigerating apparatus in its lower circuit. Thereby, the sorption-type refrigerating apparatus is connected to the subcooler of the vapor compression refrigerating apparatus, rather than to its condenser. This embodiment provides a number of advantages over the existing embodiments. First, the refrigerating power of the sorption-type apparatus can be much lower than the one of the vapor compression apparatus. The top circuit of the existing embodiments is normally connected to a condenser, wherein the power of the top-circuit surpasses the power of the lower circuit, which in turn due to the low heat coefficient requires considerable amount of thermal energy. This approach utilizes even the smallest utilities of low-grade heat, and therefore, broadens noticeably the field of application of the disclosed subject matter. Furthermore, the disclosed embodiments do not require rigorous temperature control, and thereby come with a simplified automation system. Moreover, there is no need to produce a special-type of evaporator-condenser, which is an integral part of the existing cascade refrigerating apparatuses. Hence, the sorption-type apparatus can easily be integrated into the existing refrigerating systems, and meet well lowered financial expenditures and limited deadlines. The reliability of the entire system is significantly high, since the fault of the sorption-type apparatus is no longer critical, and does not affect operation of the vapor compression apparatus.

[0061] In accordance with other embodiments of the disclosed subject matter, the sorption apparatus can be supplied with both a solid-body sorbent (adsorber) and a liquid sorbent (absorber). Furthermore, the refrigerants herein can be represented by substances, which are normally utilized under negative temperatures. This approach allows optimization of the present embodiments for each circumstance of use, and provide higher power efficiency.

[0062] It is important to state herewith, that there are two major alternative embodiments:

[0063] the evaporator of the sorption-type apparatus is used as a subcooler (evaporator-subcooler) per se or;

[0064] the evaporator of the sorption-type apparatus is connected to the subcooler by a medium heat-carrier, for example, by water for positive temperatures and ethylene glycol mortar for negative temperatures.

[0065] Heat exchange is most efficient within the first alternative. Therefore, this embodiment is possible with any sorption-type apparatus, where the evaporator represents a standalone unit. Should the sorption-type apparatus have no direct evaporator outlet (as example, some adsorption-type apparatuses of two independent modules, which work in turns), then a medium heat-carrier can be used.

[0066] Optionally and alternatively, in order to achieve more stable temperatures in the subcooler and thereby provide stable temperature regime, the circuit of the medium heat-carrier is connected via a receiver. This fact is especially important when adsorption-type apparatuses are part of the embodiment. Other embodiments of the disclosed subject matter of practical value include the following:

[0067] when low-grade heat is supplied into the sorption-type apparatus via an open circuit; or

[0068] when the heat is supplied via a closed circuit, but with a medium hot heat-carrier.

[0069] The first alternative above is more effective from the heat-transfer point of view, especially when non-aggressive low-grade heat sources are used, as example, vapor or hot low-grade water. The second alternative is advisable for higher temperatures of low-grade heat sources, when control of the input temperature is essential. The second embodiment allows lowering the requirements for the heat source aggressively indexes.

[0070] A receiver can be used to stabilize temperature at the inlet of the sorption-type apparatus. This design is important when both the consumption and thermodynamic indexes of the heat utility are unstable.

[0071] A sorption-type refrigerating apparatus transforms low-grade heat into cold with minimum electricity consumption; thereby it increases the efficiency of the entire apparatus.

[0072] The above application of the sorption-type apparatus does not increase the risk of a system fault. No malfunction affects operation of the compressor refrigerating apparatus. It keeps on working, although with lesser efficiency, compared to any frequently utilized cascade apparatus, which in that case comes to a standstill. Depending on the field of application, a sorption-type apparatus can be of two types: with liquid sorbent (absorber) and with solid sorbent (adsorber), wherein the refrigerant is either water, used to receive positive temperatures, or spirits, as example methanol or ammonia, used to receive negative temperatures (See Patent PCT/IL2017/050190).

[0073] Furthermore, the design of the sorption-type apparatus as a subcooler allows applying apparatuses of lower refrigerating power than the compression-type apparatus. This fact explains the possibility of utilizing even smaller amounts of low-grade heat, and therefore, broadens the area of application of the present subject matter. The aforementioned does not exclude the use of sorption-type apparatuses of higher power capacity.

[0074] Another advantage of the sorption-type apparatus is its simple integration capability into the existing refrigerating systems. This can be performed by adding a single heat-exchanger to the present embodiment, as an example. Hence, the existing systems can easily be updated, and their power capacity can be increased.

[0075] Reference is now made to FIG. 1 illustrating a refrigerating circuit of a compression apparatus coupled in cascade directly with an evaporator of a sorption apparatus, in accordance with preferred embodiment of the disclosed subject matter. According to disclosed subject matter, a combined-type cascade refrigerating apparatus is provided, wherein a sorption-type apparatus is used as a subcooler. This presentation depicts an embodiment that comprises a compression refrigerating apparatus 1 with a refrigerating circuit 2 as known in the art, coupled in cascade directly with an evaporator 3 of a sorption refrigerating apparatus 4. This embodiment was found to be most effective from the heat transfer point of view. It can be used within all types of sorption apparatuses, wherein the evaporator 3 is a standalone unit. The disclosed embodiment can be used within both positive and negative temperatures.

[0076] Reference is now made to FIG. 2 depicting a refrigerating circuit of a compression apparatus coupled in cascade with an evaporator of a sorption apparatus by means of a medium heat-carrier, in accordance with preferred embodiment of the disclosed subject matter. Refrigerating circuit 2 of the compression refrigerating apparatus is coupled in cascade with the evaporator 3 of a sorption-type apparatus 4 by means of a medium heat-carrier 6 discharged via a heat-exchanger 5 with help of a circulating pump 7. The disclosed embodiment can be used for sorption-type apparatuses that have no immediate evaporator outlet (as example, some adsorption-type apparatuses of two modules that operate in turn). Herein, water is suggested to be used as a medium heat-exchanger 6 within positive temperatures, and ethylene glycol mortarwithin negative temperatures.

[0077] Reference is now made to FIG. 3 illustrating a refrigerating circuit of a compression apparatus coupled in cascade with an evaporator of a sorption apparatus by means of a medium heat-carrier via a receiver used for temperature stabilization, in accordance with preferred embodiment of the disclosed subject matter. The refrigerating circuit 2 of a compression apparatus 1 is coupled in cascade with the evaporator 3 of a sorption-type apparatus 4 by means of a medium heat-carrier 6 that is discharged through a heat-exchanger 5 with help of a circulating pump 7. A receiver 8 is included in the circuit of the medium heat-carrier 6 to ensure stable temperature regime. This design is intended for sorption apparatuses that have no immediate evaporator outlet (as example, like some adsorption-type apparatuses of two modules, which operate in turn). Herein water is suggested to be used as the medium heat-exchanger 6 within positive temperatures, and ethylene glycol mortar within negative temperatures.

[0078] Reference is now made to FIG. 4 depicting a sorption-type apparatus coupled with a hot heat-carrier by means of an open circuit, in accordance with preferred embodiment of the disclosed subject matter. Sorption-type apparatus 4 is coupled with an ambient utility of heat 12 by means of an open circuit via a heater 9. The disclosed embodiment is most efficient from heat-transfer point of view, especially when non-aggressive low-grade utilities of heat are applied, as example vapor or hot low-grade water.

[0079] Reference is now made to FIG. 5 illustrating a sorption-type apparatus coupled with a hot source of heat by means of a medium heat-carrier, in accordance with preferred embodiment of the disclosed subject matter. Sorption-type apparatus 4 is coupled with ambient utility of heat 12 in a closed circuit by means of a medium heat-carrier 10 that is discharged into a heater 9. The discharge of heat into the medium heat-carrier 10 is carried out via a heat-exchanger 11, which is heated by the ambient utility of heat 12. Application of this embodiment allows lowering requirements to the non-aggressivity of the ambient utility of heat 12.

[0080] Reference is now made to FIG. 6 depicting a sorption-type apparatus coupled with a hot source of heat by means of a medium heat-carrier via a receiver used for temperature stabilization, in accordance with preferred embodiment of the disclosed subject matter. Sorption-type apparatus 4 is coupled with an ambient utility of heat 12 by means of a medium heat-carrier 10 via a receiver 13, which is used for temperature stabilization. The given embodiment is intended for use under the conditions of both unstable temperatures and unstable consumption of the heating source.

[0081] Reference is now made to FIG. 7 presenting a thermodynamic diagram of a refrigerating circuit both with and without a subcooler, in accordance with preferred embodiment of the disclosed subject matter, for comparison reasons. The thermodynamic diagram of a refrigerating cycle of the present subject matter both with and without a subcooler is presented. The hatched area represents increase of the refrigerating efficiency of the apparatus wherein a subcooler is used.

[0082] The top module of a combined-type cascade refrigerating apparatus represents a sorption apparatus 4 that transforms the energy of a low-grade heat utility 12 into cold and cools down the refrigerant of the refrigerating circuit 2 of the bottom module, which in turn represents a steam-compressor-type refrigerating apparatus 1 embodied inside the subcooler. The disclosed embodiments allow higher refrigerating power of the steam-compressor-type refrigerating apparatus and minimizes electricity consumption.

[0083] Furthermore, the present embodiments allow utilizing energy of all types of sources of low-grade heat, including the smaller ones, which cannot be exploited by the existing apparatuses.

[0084] The disclosed embodiments require minimum changes in configuration of the existing refrigerating apparatuses but for the inclusion of a single heat exchanger in the constructions thereof. This fact explains modest expenditures and minimum deadlines expected for modernization of the existing apparatuses.

[0085] Simplicity and reliability of the disclosed embodiments guarantee long-time faultless and emergency-shutdown-free operation, even in case of complete failure of the sorption-type apparatus, especially when the apparatus is used as part of mobile aggregates, for example on board of a transport vehicle.

[0086] An important feature of the disclosed subject matter is its eco-friendliness. The refrigerants of the sorption-type apparatuses are ozone-friendly. The use of the refrigerants reduces emission of heat into the atmosphere. Furthermore, the reduction of electricity consumption by the entire system also leads to the cut in both heat and carbon dioxide emission within the process of electrical energy generation.

Practical Application

[0087] The disclosed embodiments allow using the sorption-type refrigerating apparatuses as subcoolers within all types of existing and novice refrigerating apparatuses, for the purpose of their 10-20% power efficiency rise (the lower the operational temperature, the higher the power capacity) and increase of refrigerating performance by means of utilizing the potential of low-grade heat energy (including the embodiment with the exhaust).

[0088] Water is suggested for use as a refrigerant of the sorption-type apparatus when it is operated within positive temperatures, whereas such antifreeze mortars as spirits (methanol), ammonia, etc. are suggested for use within negative temperatures.

[0089] It is suggested that a single sorption-type apparatus is used within the compression refrigerating apparatuses of low and medium power capacity; and modules of several sorption-type apparatuses are used for refrigerating apparatuses of high power capacity.

[0090] It is appreciated that certain features of the subject matter, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the subject matter, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination.

[0091] Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.