WO2013050516A1

WO2013050516A1 - Cooling and heating facility for air conditioning systems

Info

Publication number: WO2013050516A1
Application number: PCT/EP2012/069698
Authority: WO
Inventors: Pierre Benaros
Original assignee: Wabi Sas
Priority date: 2011-10-06
Filing date: 2012-10-05
Publication date: 2013-04-11
Also published as: FR2981144A1

Abstract

The invention relates to the field of refrigeration cycles, and in particular to a Rankine cycle exploiting the enthalpy of condensation of a superheated refrigerant after its compression in a refrigeration cycle, the captured thermal energy helps to evaporate the driving fluid of a turbine, said driving fluid is in this case the refrigerant of the refrigeration facility itself. The therms captured after the compression of the refrigerant of a refrigeration cycle, evaporate the driving fluid of a turbine coupled to the electric motor of the refrigeration cycle compressor comprising a circuit for a refrigerant, means for heating the refrigerant configured for vaporizing it into driving fluid, a turbine system (11) coupled to a compressor (10) and an electric motor (8), means for condensing and cooling the refrigerant, characterized by the fact that the means for condensing the refrigerant are also the means for evaporating the turbine (11) driving fluid.

Description

"Installation of cooling and heating of air conditioning systems"

The present invention relates to a cooling cycle of air conditioning systems.

The efficiency of the refrigeration production depends on the thermodynamic operation of the refrigeration machine, it is deduced its instantaneous energy efficiency or EER (Energy Efficiency Ratio) which is the coefficient of refrigeration efficiency, representing the energy performance of the pump. with heat operating in cooling mode. This is the ratio between the amount of heat absorbed by the evaporator and the amount of total electrical energy absorbed by the installation, mainly the compressor, but also the ancillary equipment (fans, circulation pumps water and air). EER catalogs have values in the range of 2.5 to 4, the invention proposes a value ranging from 5.5 to 9.

In all the refrigeration cycles of existing machines, the heat generated by the compressor is discharged to the outside without being exploited. The advantage of the heat recovery produced by the refrigerant compression of a refrigerating cycle is to use this energy to produce a mechanical work which is the subject of the invention.

US Pat. No. 5,761,921 discloses a refrigerating plant that can operate both in cooling mode and in heating mode in which the turbine of a Rankine cycle fed by a hot source. from the heat of a thermal machine, the compressor drives a refrigerating cycle.

It is therefore extremely interesting to develop a refrigeration cycle to improve the energy efficiency of it. The refrigeration plant will therefore be energy efficient if it requires little electrical energy to achieve the same refrigerating capacity as existing refrigeration cycles.

The invention brings a lot of improvement to a refrigerating machine, in particular by deducing the work produced by the turbine whose energy comes from the recovery of the thermal energy produced by the compression of the refrigerant of a refrigerating cycle. This thermal energy is normally rejected by a condenser whose cold source is outside air, the invention exploits this thermal energy and transforms it into mechanical work.

According to other aspects of the invention, the efficiency of the installation is optimized by various additional means.

Overall, the invention proposed here ensures, on the one hand, an increase in efficiency and, on the other hand, the possibility of adaptable operation with regard to climatic variations and the need for thermal energy supply for heating or air conditioning. .

This installation further comprises an electric motor for rotating a compressor and a turbine connected to the shaft of said compressor to reduce the work of said electric motor. In the context of the present invention, the term "compressor" in the broadest sense, that is to say any machine for compressing a gaseous refrigerant, such as a scroll compressor or a piston engine powered by an electric motor.

The term "turbine" in the widest sense, that is to say any engine, such as a scroll turbine or screw motor, actuated by the expansion of a compressible fluid, such as R134a or any other refrigerant or gas.

The present invention aims at providing a cooling cycle which improves the energy efficiency in the conversion of electrical energy into frigories.

In an installation according to an embodiment of the present invention, this object is achieved by virtue of the fact that the condenser of the refrigerating cycle is also the evaporator of a Rankine cycle intermediate device. The said additional device to the installation of a refrigeration cycle comprises a turbine, a condenser, a divider, a food cover and a pump. Said turbine is adapted to receive at high pressure said refrigerant in the gaseous state and to relax so as to extract mechanical work. Said condenser allows the phase change of the engine fluid output of said turbine from the gaseous state to the liquid state and the condensation pressure depending on the temperature of the cold source, the outside air.

The present disclosure also relates to a method or a heat exchanger is both the evaporator and the condenser of a loopine refrigerant cycle with a Rankine cycle whose refrigerant is both the service fluid and the process fluid in the simultaneous phase of condensation and evaporation of this same refrigerant.

Advantageously, after the step of said compression of the refrigerant the enthalpy required for its condensation is equal to the enthalpy of the same fluid which returns to the same exchanger to be evaporated therein. For reasons of equilibrium, the flow rate of the fluid to be evaporated is always greater than the fluid to be condensed because the priority is to respect the first phase, which is the condensation of the refrigerant. For this purpose the excess of non-evaporated fluid will be separated by a separator and injected into the food sheet arranged upstream of said exchanger.

The present invention relates to a cooling cycle of air conditioning systems, characterized in that it comprises:

a compressor coupled to an electric motor that compresses a refrigerant;

- a gas cooler and heater (arranged between the compressor and the turbine executing a heat exchange by the compressed refrigerant and which heats a driving fluid being the same refrigerant in a loop;

a throttling device which throttles the flow of cooled refrigerant;

an evaporator which evaporates the refrigerant by a heat-absorbing action of a hot source;

a heat exchanger disposed between the turbine and the throttling device, the heat exchanger performing condensation of the refrigerant by heat exchange with a cold source;

- A turbine coupled to an electric motor that relaxes the refrigerant to recover energy and performing work complementary to said engine, said system using the vapor phase of the working fluid as a motor means for the reduction of electrical energy;

characterized in that the refrigerant heating means comprises:

a compressor capable of overheating a refrigerant;

heat exchange means between a refrigerant and a driving fluid;

According to embodiments, the cycle is such that:

the heat resulting from the compression of a refrigerant is used to produce the energy useful for the mechanical work of a machine. - The heat exchange means necessary for the evaporation of the driving fluid downstream of the turbine also allow condensation of the refrigerant downstream of the compressor.

- The turbine is integrated in a refrigeration plant or heat pump.

- The heat exchanger is built to allow the evaporation of a fluid and the condensation of another fluid that intersect.

- the heat exchanger is integrated in a refrigeration system.

the regulation means comprise an exchanger upstream of the compressor controlling the intake temperature of a refrigerant, a separator controlling a 100% gas phase of the inlet fluid of the turbine and a food tank capable of receiving the liquid phase upstream exchanger and downstream of the turbine that allow to apply a nominal flow rate to the pump.

- It comprises a regenerative heat exchanger configured to preheat the refrigerant upstream of the compressor of a refrigerating cycle is integrated in a refrigeration system.

- The turbine is integrated in a refrigeration system.

- A turbine produces mechanical work transmitted to the shaft of a compressor or alternator.

a regenerative heat exchanger is an element of the control means of a refrigerating cycle allowing the regulation of a nominal temperature of the intake of a refrigerant at the inlet of a compressor for a variable temperature of a cold source necessary for the condensation of a refrigerant of a refrigerating cycle.

said heat exchanger is constructed to allow the evaporation of a driving fluid driving a turbine by recovering the thermal energy of a superheated refrigerant by an adiabatic compression at the outlet of a compressor of a refrigerating cycle.

the energy required to evaporate the driving fluid of a turbine of a Rankine cycle comes from the condensation of a superheated refrigerant after its compression in a refrigerating cycle. The invention will be better understood and its advantages will appear better on reading the detailed description which follows, of an embodiment shown by way of non-limiting example. The description refers to the accompanying drawings in which:

Figure 1 schematically shows a first embodiment of a cold production plant.

Figure 2 is a diagram similar to Figure 1 showing a second embodiment of the present invention by the integration of a regenerative heat exchanger placed upstream of the compressor.

Figure 3 shows a second embodiment of the installation of the invention applied with two cycles in parallel.

Fig ure 4 is a d dfferent view of the integration of a turbine applicable to Figures 1, 2 or 3.

Figure 1 illustrates a first version of the installation showing a cooling cycle of air conditioning systems.

The refrigerant R134a was chosen as an exemplary process for describing the invention, the temperatures and pressures are given for this fluid.

This installation comprises a circuit containing a refrigerant with a compressor 10 and a turbine 1 1 mechanically secured to the same motor shaft coupled to an electric motor 8 powered by an electrical network 22. In the refrigerant circuit 20 is placed directly downstream of the compressor 10 an exchanger 12 which condenses the superheated refrigerant.

At the inlet of the compressor 10, the HFC fluid R134a is in the gaseous state and at the process pressure chosen according to the desired refrigeration effect which may be between 1 and 3 bar, at the outlet of the compressor the fluid is compressed at the pressure necessary to reach a temperature of at least 75 °, this pressure is 1 1 bar on average. Downstream of the compressor 10 the condenser is condensed by the exchanger 12. Downstream of the exchanger 12 the refrigerant is expanded by the expander 7 at the pressure imposed by the temperature of the cold source 2 supplying the condenser 4 and injected into the food cover 18. The pressure in the food cover 18 is 7.5 bar for a external temperature of said cold source of 33 ° taking into account a pinch of 4 °. The expander 7 imposes on the refrigerant at the point "f" a pressure equal to that of the point "e" for an isobaric mixture in the food cover 18. At the outlet of the food cover 18 the refrigerant in the liquid phase is raised to the pressure of 21 bar by the pump 17 and feeds the exchanger 12, the pressure of 21 bar is the saturating vapor pressure of the refrigerant imposed by the refrigerant temperature downstream of the compressor 10 before entering the exchanger 12. The exchanger 12 is the condenser of the refrigerant at the outlet of the compressor 10 and the evaporator of the refrigerant before admission into the turbine 1 1. The pump 17 provides the flow of heat transfer fluid required for condensing the refrigerant from the compressor 10 which ensures the evaporation of the refrigerant for its admission into the turbine 1 1. The excess of non-evaporated refrigerant and in the liquid state is separated from the refrigerant in the gaseous state by the separator 25 and returns to the food cover 18.

The turbine 1 1 is adapted to receive the refrigerant at a pressure greater than the pressure imposed on its output by the condenser 4, and to relax so as to extract a mechanical work. The mechanical work produced by the turbine 1 1 and transmitted to the shaft 9 relieves the electric motor 8 and reduces its work necessary to drive the compressor 10, thereby reducing the consumption of said electric motor, W ₈ = Wi ₀ + Wn. The energy performance and its EER index takes into account the consumption of auxiliaries such as the evaporator 3 or condenser 4 fans and in our solution the pump 17, which does not exist in a refrigerating cycle, these energy consumptions are added. to the consumption of the electric motor 8, and it can, depending on the conditions of outdoor temperatures and the process of the refrigerating cycle, be divided by 2.5 and in the best conditions Wi ₀ is barely greater than Wn.

At its entry into the condenser 4 the refrigerant is in the gaseous state and goes to the liquid state at its outlet, the cold source 2 is the outside air in cooling mode of the installation and the space to be heated in the heating the use of the installation. The refrigerant at the outlet of the condenser 4 is separated by the divider 19 the nominal part of the circuit 20 feeds the laminator 5 and the other part between 1 and 15% of the nominal flow is injected to the food cover 18 at the point "e" . The pressure at point "e" is 0.1 bar less than the saturation vapor pressure imposed on the refrigerant by the condenser 4 as a function of the temperature of the cold source 2, for the R134a it is 7.5 bar at the temperature of 29 ° taking into account a pinch of 4 ° and a temperature of the cold source 2 of 33 °. At point "f" the pressure of the refrigerant nominal flow rate is equal to the pressure at point "e" and imposed by the regulator 7.

At the output of the divider 19 the nominal refrigerant flow feeds the laminator 5 or the latter in an adiabatic expansion undergoes a drop in temperature by the Joule-Thomson effect.

At the outlet of the laminator 5 the fluid R134a in the liquid state for an imposed pressure of 3 bar is at a temperature of 0.6 °, it would be -26 ° for a pressure imposed at 1 bar for use of the installation in freezer.

The refrigerant is then evaporated in the evaporator 3 to absorb the calories from the hot source 1 which is the space to be refrigerated or the outside air for use of the installation in heating mode.

The installation illustrated in FIG. 2 illustrates a variant of the present invention by the integration of a regenerative heat exchanger before the compressor.

Its major interest lies in the heat exchanger 6 which brings a complement of frigories to the exchanger 12 necessary for condensing the refrigerant from the compressor 10 but above all it makes it possible to increase the temperature of the refrigerant at the point "b" which, for the effect of increasing the temperature of the refrigerant at the outlet of the compressor 10 causing only negligible additional work to the electric motor 8, work very largely compensated by an increase in the saturation vapor pressure of the refrigerant supplying the turbine 1 1 obtained by a higher temperature of the refrigerant at the inlet of the exchanger 12 downstream of the compressor 10. The higher the temperature is at the outlet of the compressor 10 plus the vapor pressure of the refrigerant admitted into the turbine is high and the greater W is important. Indeed, in the case of the facility operated as a heat pump exchanger 6 improves the energy efficiency of the invention but also the regulation. The flow of refrigerant distributed by the pump 17 to the evaporator 12 becomes almost identical to all the process temperatures imposed by the outside temperature. At point "a" the temperature is always the same whatever the season, at point "b" the fluid has been heated by itself after its condensation in the exchanger 12 and becomes the service fluid at point "c". At the point "d" the temperature of the engine fluid of the turbine 1 1 varies only a few degrees depending on the season which is important because it becomes the heat transfer fluid of the condenser 12 necessary to condense the refrigerant downstream of the compressor 10, are flow at point "f" before the food cover 18 is about nine times higher than the refrigerant flow at point "e" downstream of the separator 19 which has a very positive influence on the regulation because the mixture at the "g" point is practically identical to a few degrees near even with very variable temperatures of the cold source according to the seasons. The pump 17 has a nominal flow rate corresponding to the maximum of the outside temperature in summer, making it possible to ensure the imperative condensation of the refrigerant upstream of the compressor 10, with a temperature that does not vary at point "b" the flow variation adjusted by the separator 25 does not exceed 1% according to the minimum and maximum external temperature, in fact the separator 25 regulates by separation the possible dysphasic mixture by a return of the condensate to the food cover 18.

Depending on the season, the temperature of the cold source varies and the saturation pressure of the condensate varies at the outlet of the condenser 4 and the pressure of the separated part after the flow divider 19 at the point "e" is sometimes different but always less than the pressure from point "f". The mixture is isobaric in the food cover 18, the expander 7 imposes at the point "f" a pressure equal to that of the point "e". FIG. 3 presents a second embodiment of the installation of the invention with a Rankine cycle in parallel with a refrigerating cycle. The operation of the plant with two circuits in parallel is identical in the operation of a hot source produced by the compressor of a refrigerating cycle.

The physical interest is not better except for the air conditioning units in the tropical zone because it allows the use of two different refrigerants, the R245fa for example for the Rankine 21 cycle which allows condensation for outside temperatures above 40 °.

The description of this embodiment of the installation shows the conversion of the electrical energy into frigories, the heating mode takes again the reasoning of figure 1 and of figure 2.

In the case shown, two fluids are used, including a driving fluid adapted to drive in rotation a turbine 1 1 and a fluid capable of producing the frigories of a space to be refrigerated.

It is possible to choose, by way of example, an HFC fluid and in particular R143a.

The other fluid involved in the installation according to the invention ensures the transport of calories from a hot refrigerant downstream of a compressor 10 to heat exchange means capable of heating the driving fluid of a turbine 1 1 of the cycle of Rankine 21. The coolant necessary for the evaporation of the motor fluid of the Rankine 21 cycle is the refrigerant of a refrigerating cycle 20.

At the output, the electric motor 8 drives the axis of a compressor 10 which by adiabatic compression raises the pressure and overheats the R143a of the refrigerating cycle 20.

At the compressor inlet the R143a is at the process pressure imposed by the laminator 5, in the example of the 3 bar process and a temperature of 35 °, at the outlet of the compressor the fluid is at the pressure of 1 1 bar and its temperature is about 90 °. Downstream of the compressor 10 the refrigerant of the circuit 20 is condensed by the exchanger 12 and cooled by the heat exchanger 6 to enter the laminator 5 or the refrigerant in an adiabatic expansion undergoes a drop in temperature by the Joule effect -Thomson.

At the output of the laminator 5 the fluid R134a in the liquid state for an imposed pressure of 3 bar and its temperature of 0.6 °. The fluid is then evaporated in the evaporator 3 to absorb the calories from the hot source 1 which is the space to be cooled. It will then be heated by the exchanger 6 and returns to the compressor 10. This heating is essential for the temperature of the fluid output of the compressor is greater than 85 °.

In parallel, the circuit 21 containing R143a for example, feeds a Rankine cycle comprising a turbine 1 1, a condenser 4, a pump 17 and an evaporator 12. The refrigerant circuit fluid 20 is the heat transfer fluid of the evaporator 12 realizing here the heat exchange means between the heat transfer fluid of the circuit 20 and ensures the evaporation of the motor fluid of the circuit 21. And conversely the fluid of the circuit 21 is the heat transfer fluid of the condenser 12 realizing here the heat exchange means between the heat transfer fluid of the circuit 21 and ensures the condensation of the fluid of the circuit 20 of the refrigerating cycle.

The R134a of the circuit 21 is in the liquid state when it enters the exchanger

12 and gaseous as it leaves. The enthalpy required for its phase change is exactly equal to the enthalpy required for the condensation of the fluid of the circuit 20.

Unlike the embodiment of the figure, in this version of the invention, that according to the temperature variation of the cold source 2 the enthalpies are no longer equal for the same flow rate corresponding to a given temperature. If the temperature of the cold source 2 increases, the temperature of the fluid of the circuit 21 increases at the outlet of the condenser 4, the fluid of the circuit 21 being the operating fluid of the refrigerating cycle whose flow is nominal, more flow is required at the exchanger 12 for condensing the process fluid of the refrigerating cycle of the circuit 20.

In order to very precisely adjust the flow rate of the circuit 21 necessary for condensing the refrigerant of the circuit 20, the volumetric flow rate is dependent on the speed of the pump 17. The regulation of the flow rate of the pump 17 is done by varying its engine speed, plus it is necessary to flow more the motor must turn quickly and the control means 13 receive from the temperature sensor 24 the information on the temperature of the fluid before the pump 17 and orders the frequency converter 23 to supply the electric motor of the pump 17 the adequate current frequency for an engine speed corresponding to the heat transfer fluid flow required to condense the refrigerant of the refrigerating cycle. The frequency converter designates an electronic system capable of controlling a synchronous motor which it will allow to adjust the speed and the flow with precision. If it is incorrectly adjusted the gauge 15 of the condensate tank 16 informs the control means 13 of the condensate level in the tank 16, if it drops its average level it orders the frequency converter 23 to raise the frequency of the power supply of the motor and conversely to lower the frequency of the electric current supplying the motor of the pump 17 if the condensate level rises.

In the exchanger 12 the driving fluid of the circuit 21 changes from the liquid state in the gaseous state to the saturating vapor pressure imposed by the refrigerant temperature of the circuit 20, at 69 ° the pressure of the R143a is about 21 bar. .

Downstream of the exchanger 12 the fluid of the circuit 21 is dried by the separator 25 and feeds the turbine 1 1 to produce a job communicated to the shaft 9 to reduce the work of the electric motor. The power consumption of the motor 8 driving the compressor 10 is significantly reduced, on average by half.

Downstream of the turbine 1 1 the fluid is condensed by the heat exchanger 4, the coolant, which may be external air or water, comes from the cold source 2. Here the R134a goes from the gaseous state to the liquid state and the condensation pressure imposed by the temperature of the cold source 2. The hotter the more the r134a liquid phase pressure is high which reduces the work of the turbine by a lower ΔΡ. In the case of tropical condition with an outside temperature of 43 ° the EER drops to 5.5 and it reaches 9 with a temperature of 26 °.

Figure 4 is a different view of the integration of a turbine to the refrigeration plant and applicable to Figures 1, 2 or 3.

The principle of operation of the installation with a turbine 1 1 connected to an alternator 26 is identical in the operation of a hot source produced by the compression of a refrigerant with the difference that the work of said turbine drives an alternator 22 connected to a network 22. REFERENCES

1. Hot source

2. Cold source

3. Evaporator

4. Condenser

5. Laminator

6. Heat exchanger

7. Regulator

8. Electric motor

9. Tree

10. Compressor

11. Turbine

12. Heat exchanger

13. Means of order

14. Control valve

15. Gauge

16. Condensate tank

17. Pump

18. Food cover

19. Divider

20. Refrigeration cycle circuit

21. Rankine Cycle Circuit

22. Network

23. Frequency inverter

24. Temperature probe

25. Separator

26. Alternator

30

Claims

1. Cooling device for air conditioning systems, characterized in that it comprises:

- a compressor (10) coupled to an electric motor (8) which compresses a refrigerant;

- a gas cooler and heater (12) disposed between the compressor (10) and the turbine (1 1) performing a heat exchange by the compressed refrigerant and which heats a driving fluid being the same refrigerant in a loop;

a throttling device (5) which throttles the flow of the cooled refrigerant;

an evaporator (3) which evaporates the refrigerant by a heat-absorbing action of a hot source (1);

- a heat exchanger (4) disposed between the turbine (1 1) and the throttling device (5), the heat exchanger performing condensation of the refrigerant by heat exchange with a cold source (2);

- a turbine (1 1) coupled to an electric motor (8) which relaxes the refrigerant to recover the energy and performing work complementary to said engine, said device using the vapor phase of the working fluid as a driving medium for the reduction of 'electric energy ;

further characterized in that refrigerant heating means comprises:

- the compressor (10) capable of overheating a refrigerant;

- Thermal exchange means (12) between the refrigerant and the driving fluid;

2. Cooling device according to claim 1, characterized in that the heat resulting from the compression of a refrigerant is used to produce the energy useful to the mechanical work of a machine (1 1).

3. Cooling device according to claim 2 wherein the heat exchange means (12) necessary for the evaporation of the driving fluid downstream of the turbine (1 1) also allow condensation of the refrigerant downstream of the compressor (10). .

4. Cooling device according to claim 3, characterized in that the turbine (1 1) is integrated in a refrigeration plant or heat pump.

5. Cooling device according to claim 4, characterized in that the heat exchanger (12) is constructed to allow the evaporation of a fluid and the condensation of another fluid that intersect.

6. Cooling device according to claim 5, characterized in that the heat exchanger (12) is integrated in a refrigeration system.

7. Cooling device according to claims 1 and 2 wherein the regulating means comprise an exchanger (6) upstream of the compressor (10) controlling the intake temperature of a refrigerant, a separator (25) controlling a phase 100 gaseous fluid of the inlet fluid of the turbine (1 1) and a food cover (18) adapted to receive the liquid phase upstream of the exchanger (1 2) and downstream of the turbine (1 1) that allow i apply a nominal flow rate to the pump (17).

8. Cooling device according to claims 1 and 7 comprising a regenerative heat exchanger (6) configured to preheat the refrigerant upstream of the compressor of a refrigerating cycle is integrated in a refrigeration system.

9. Cooling device according to claim 1 characterized in that the turbine (1 1) is integrated in a refrigeration system.

10. Cooling device according to claims 1 and 9, characterized in that a turbine (1 1) produces a work mechanical transmission to the shaft of a compressor or alternator.

11. Cooling device according to any one of claims 1 or 7 characterized in that a regenerative heat exchanger (6) is an element of the control means of a refrigerating cycle for regulating a nominal temperature of the admission of a refrigerant at the inlet of a compressor (10) for a variable temperature of a cold source (2) necessary for condensing a refrigerant of a refrigerating cycle.

12. Cooling device according to any one of claims 1 to 11, wherein said heat exchanger (12) is constructed to allow the evaporation of a driving fluid driving a turbine (11) by recovery of the thermal energy of a refrigerant overheated by adiabatic compression at the outlet of a compressor (10) of a refrigerating cycle.

Cooling device according to any one of claims 1 to 12, wherein the energy required to evaporate the driving fluid of a turbine (11) of a Rankine cycle comes from the condensation of an overheated refrigerant after its compression. in a refrigerating cycle.