The present invention relates to a quasi-azeotropic composition comprising from 60 mol % to 99.9 mol % of 2,3,3,3-tetrafluoropropene and from 0.1 mol % to 40 mol % of trans-1,3,3,3-tetrafluoropropene relative to the total number of moles of the composition, said quasi-azeotropic composition having a boiling point of between 45 C. and 80 C., at a pressure of between 1 and 50 bar abs, preferably between 12 and 20 bar abs. The present invention also relates to the use of said composition in heat transfer applications.

The present invention relates to a quasi-azeotropic composition comprising from 60 mol % to 99.9 mol % of 2,3,3,3-tetrafluoropropene and from 0.1 mol % to 40 mol % of trans-1,3,3,3-tetrafluoropropene relative to the total number of moles of the composition, said quasi-azeotropic composition having a boiling point of between 45 C. and 80 C., at a pressure of between 1 and 50 bar abs, preferably between 12 and 20 bar abs. The present invention also relates to the use of said composition in heat transfer applications.

An energy storage device having: a high-temperature regenerator containing a solid, particularly porous storage material (S); a working gas (A) as the heat transfer medium to transfer heat between the storage material (S) and the working gas (A) flowing through; and a charging circuit and a discharging circuit for the working gas (A). The charging circuit is designed such that starting from a pre-heating unit at least one first heat transfer duct of a recuperator, a first compressor (HO), the high-temperature regenerator, a second heat transfer duct of the recuperator and then a first expander are interconnected, thus forming a circuit, so as to conduct fluid. The first compressor is coupled with the first expander, and the first compressor forms part of a first piston machine (K1) and the first expander forms part of a second piston machine (K2), the piston machines (K1, K2) being operable either as a compressor or as an expander such that the first compressor of the charging circuit forms a second expander in the discharging circuit and that the first expander of the charging circuit forms a second compressor in the discharging circuit. The high-temperature regenerator can be connected to either the charging circuit or the discharging circuit to conduct fluid and can be controlled such that the high-temperature regenerator, the compressor and the expander form either part of the charging circuit or part of the discharging circuit. The charging circuit, the discharging circuit and the high-temperature regenerator have the same working gas (A) so that the working gas (A) comes into direct contact with the storage material of the high-temperature regenerator both in the charging circuit and in the discharging circuit.

An energy storage device having: a high-temperature regenerator containing a solid, particularly porous storage material (S); a working gas (A) as the heat transfer medium to transfer heat between the storage material (S) and the working gas (A) flowing through; and a charging circuit and a discharging circuit for the working gas (A). The charging circuit is designed such that starting from a pre-heating unit at least one first heat transfer duct of a recuperator, a first compressor (HO), the high-temperature regenerator, a second heat transfer duct of the recuperator and then a first expander are interconnected, thus forming a circuit, so as to conduct fluid. The first compressor is coupled with the first expander, and the first compressor forms part of a first piston machine (K1) and the first expander forms part of a second piston machine (K2), the piston machines (K1, K2) being operable either as a compressor or as an expander such that the first compressor of the charging circuit forms a second expander in the discharging circuit and that the first expander of the charging circuit forms a second compressor in the discharging circuit. The high-temperature regenerator can be connected to either the charging circuit or the discharging circuit to conduct fluid and can be controlled such that the high-temperature regenerator, the compressor and the expander form either part of the charging circuit or part of the discharging circuit. The charging circuit, the discharging circuit and the high-temperature regenerator have the same working gas (A) so that the working gas (A) comes into direct contact with the storage material of the high-temperature regenerator both in the charging circuit and in the discharging circuit.

Here is described a process to transform energy in chemical form in fuels into electric power through a thermal process. It combines advantages of the traditional internal combustion engine and the steam engine by producing supercritical combustion to allow direct mixture of combustion gases with additional working fluid to cool the mixture to operational conditions. The process allows the control of the inlet temperature of the turbine or expander and makes direct heat exchange by mixing working fluids. The combustion gases are completely used as working fluid in contrast to steam generator. The process improves the efficiency compared to combined cycle or traditional supercritical plants.

A hydrogen/oxygen stoichiometric combustion turbine system includes: a high-pressure steam turbine (2); a low-pressure steam turbine (3); and a heater (5) disposed between the high-pressure and low-pressure steam turbines. The heater (5) has a combustion portion (53) in which stoichiometric combustion of hydrogen and oxygen is caused, and a mixing portion (55) configured to mix discharged steam (S4) from the high-pressure steam turbine (2) with combustion gas (R) from the combustion portion (53) and to supply the obtained product to the low-pressure steam turbine (3).

An apparatus includes a closed gas system having: a working circuit in which a compressor for a working fluid, a first heat exchanger for heating the working fluid, an expander and a second heat exchanger for cooling the working fluid are arranged; a first pressurised gas tank and a first gas pipe which branches off from the working circuit between the compressor and the first heat exchanger and opens into the first pressurised gas tank; and a second gas pipe which branches off from the first pressurised gas tank and opens into the working circuit between the expander and the second heat exchanger. A method controls pressure in a closed gas system using the apparatus.

An apparatus includes a closed gas system having: a working circuit in which a compressor for a working fluid, a first heat exchanger for heating the working fluid, an expander and a second heat exchanger for cooling the working fluid are arranged; a first pressurised gas tank and a first gas pipe which branches off from the working circuit between the compressor and the first heat exchanger and opens into the first pressurised gas tank; and a second gas pipe which branches off from the first pressurised gas tank and opens into the working circuit between the expander and the second heat exchanger. A method controls pressure in a closed gas system using the apparatus.

Various embodiments of a waste heat recovery and conversion system are disclosed. In one exemplary embodiment, the waste heat recovery system may include a heat exchanger for transferring heat from a first fluid to a second fluid and a power conversion unit configured to convert the energy transferred from the first fluid to the second fluid into usable energy. The heat exchanger may include an outer duct defining an inlet and an outlet through which the first fluid flows in and out, respectively, of the outer duct. The heat exchanger may also include an inner duct disposed inside the outer duct and defining an inner channel inside the inner duct and an outer channel between an outer surface of the inner duct and an inner surface of the outer duct. The inner duct may define an internal flow channel through which the second fluid flows to exchange heat energy with the first fluid.

Various embodiments of a waste heat recovery and conversion system are disclosed. In one exemplary embodiment, the waste heat recovery system may include a heat exchanger for transferring heat from a first fluid to a second fluid and a power conversion unit configured to convert the energy transferred from the first fluid to the second fluid into usable energy. The heat exchanger may include an outer duct defining an inlet and an outlet through which the first fluid flows in and out, respectively, of the outer duct. The heat exchanger may also include an inner duct disposed inside the outer duct and defining an inner channel inside the inner duct and an outer channel between an outer surface of the inner duct and an inner surface of the outer duct. The inner duct may define an internal flow channel through which the second fluid flows to exchange heat energy with the first fluid.