Thermal cycling system and method of operating a thermal cycling system

Abstract

A thermal circulation system includes a working fluid that circulates in a loop comprising a compressor (10), a condenser (11a, 11b), an expander unit (130), and an evaporator (14). The expander unit (130) is configured to generate rotary mechanical motion. The expander unit (130) is connected between the outlet of the condenser (11a, 11b) and the inlet of the evaporator (14). The pressure drop of the working fluid through the condenser is less than about 5 bar.

Description

Technical Field

[0001] This disclosure relates to a thermal circulation system applied to a cooling system and a method of operating the thermal circulation system. Background Technology

[0002] Thermal cycling systems that operate based on cyclic thermal processes (such as the Carnot process) are used in many applications.

[0003] In some applications, such as in heat pump systems used to heat a space by extracting heat from the ground, bedrock, water, or air and supplying that heat to a heating system for use in the space, the purpose is to provide heat.

[0004] In other applications, the purpose is to remove heat (i.e., cool something), such as in air conditioning systems or in cooling / refrigeration systems, where the purpose is to remove heat from a space or from an object.

[0005] In the Carnot process, energy is input in the form of heat Q obtained by the evaporator and mechanical energy W supplied by the compressor. Mechanical energy can be provided by converting it into electrical energy using an electric motor. Furthermore, energy is output in the form of heat QH supplied by the condenser. The coefficient of performance for heating (COPH) is defined as QH / W, and the coefficient of performance for cooling (COPC) is defined as OC / W.

[0006] Figure 1 A conventional thermal circulation system in which the working fluid circulates is illustrated schematically.

[0007] The system includes a compressor 10 having a compressor input end and a compressor output end. At the compressor input end, the working fluid is in a first state having a first pressure P1, a first temperature T1 and a first enthalpy H1, and at the compressor output end, the working fluid is in a second state having a second pressure P2, a second temperature T2 and a second enthalpy H2.

[0008] The compressor 10 is configured to increase the pressure of the working fluid such that P2 > P1.

[0009] The compressor can be electric.

[0010] The system further includes a condenser 11 having a condenser inlet and a condenser outlet. The condenser inlet is connected to the compressor outlet to receive working fluid in a second state, and the working fluid at the condenser outlet is in a third state P3, T3, H3.

[0011] The condenser 11 can be configured to exchange heat with the heat delivery loop 12, wherein heat is delivered from the condenser 11, thereby reducing the temperature of the working fluid such that T3 < T2, and reducing the enthalpy of the working fluid such that H3 < H2. At least a portion of the working fluid changes from a vapor state to a liquid state.

[0012] Alternatively, the condenser 11 can be configured to deliver heat to the airflow or simply dissipate heat to the surrounding air (as is the case in a refrigeration system).

[0013] The heat delivery circuit 12 can be, for example, a heating circuit used to provide heating for a space (such as the interior of one or more homes or vehicles). In other applications, the heat can be used in drying processes, etc.

[0014] The system further includes an expansion valve 13 connected to the condenser output.

[0015] Expansion valve 13 is configured for isenthalpic expansion to allow the working fluid to expand to the fourth state P4, T4, H4, such that the working fluid at the outlet of the expansion valve has a lower pressure than the third state, such that P4 < P3.

[0016] The system further includes an evaporator 14, which can be configured to exchange heat with the heat supply circuit 15, causing the working fluid to undergo evaporation, wherein heat is received by the evaporator 14, thereby increasing the enthalpy of the working fluid so that H1 > H4. Moreover, the temperature can increase so that T1 > T4.

[0017] The heat supply circuit 15 can be a cooling circuit in a cooling device or an air conditioning unit. Alternatively, the heat supply circuit 15 can also be configured to obtain heat from, for example, air, ground, bedrock, or water in a heat pump system.

[0018] The evaporator inlet is connected to receive the working fluid in its fourth state from the expansion valve 13. The evaporator outlet is connected to the inlet of the compressor 10.

[0019] The general expectation is to improve the performance of thermal cycling systems and thus improve the coefficient of performance.

[0020] For example, as known from WO 2013141805 A1, a thermal cycle system includes an energy converter that converts the energy of a pressurized fluid into mechanical energy, which can then be used to generate electrical energy.

[0021] There remains a general need to improve thermal cycling systems, particularly in terms of electrical energy efficiency and / or production. Summary of the Invention

[0022] The purpose of this disclosure is to provide a thermal cycle system capable of generating electrical energy and preferably also having improved efficiency.

[0023] The specific objective is to provide a thermal circulation system and operating method suitable for so-called water-water systems and water-air systems, that is, suitable for systems where the external heat source is a liquid such as water and systems where the external radiator is a liquid or gas.

[0024] Specific objectives include providing a thermal circulation system suitable for use as a cooling system for cooling spaces or material volumes.

[0025] The present invention is defined by the appended independent claims, wherein embodiments are set forth in the dependent claims, the following description and the accompanying drawings.

[0026] According to a first aspect, a thermal circulation system is provided, comprising a working fluid that circulates in a loop including a compressor, a condenser, an expander unit, and an evaporator, wherein the expander unit is configured to generate rotary mechanical motion, and wherein the expander unit is connected between the condenser outlet and the evaporator inlet. The pressure drop of the working fluid through the condenser is less than about 5 bar.

[0027] In a conventional thermal cycle system, the pressure drop of the working fluid passing through the condenser will be at least 6 to 7 bar.

[0028] However, the cooling capacity of the system can be increased by installing a condenser that is suitable for providing a lower pressure drop.

[0029] Therefore, the system can be a dedicated cooling system, that is, an irreversible system that cannot be used for both cooling and heating at the same time.

[0030] The working fluid pressure drop after passing through the condenser can be approximately 0.50 to 0.75 bar; approximately 0.75 to 1.00 bar; approximately 1.00 to 1.25 bar; approximately 1.25 to 1.50 bar; approximately 1.50 to 1.75 bar; approximately 1.75 to 2.00 bar; approximately 2.00 to 2.25 bar; approximately 2.25 to 2.50 bar; approximately 2.50 to 2.75 bar; approximately 2.75 to 3.00 bar; approximately 3.00 to 3.25 bar; approximately 3.25 to 3.50 bar; approximately 3.50 to 3.75 bar; approximately 3.75 to 4.00 bar; approximately 4.00 to 4.25 bar; approximately 4.25 to 4.50 bar; approximately 4.50 to 4.75 bar; or approximately 4.75 to 5.00 bar.

[0031] The thermal cycle system may further include a subcooler connected between the working fluid outlet of the condenser and the inlet of the expander unit, wherein the subcooler is configured to transfer heat to the working fluid at a location between the working fluid outlet of the evaporator and the inlet of the compressor.

[0032] The thermal cycle system may further include a first condenser and a second condenser connected in parallel with the first condenser, and a condenser distributor configured to distribute the working fluid flow rate between the first condenser and the second condenser.

[0033] By using a pair of condensers connected in parallel, the risk of liquid working fluid clogging the condensers can be reduced. The condenser capacity can be dynamically controlled as needed (e.g., based on the selected thermal cycle operating mode).

[0034] Therefore, the thermal cycle system configured according to the claims is particularly suitable for use in conjunction with a heat pump system for capturing heat from the ground or water or for capturing waste heat.

[0035] The condenser distributor may include a pressure sensor configured to detect the pressure at the inlet of a first condenser among the condensers, and a controllable valve configured to control the flow rate into a second condenser among the condensers based on the pressure.

[0036] The thermal cycling system may further include an expander bypass for at least partially bypassing the expander unit to provide a connection between the expander inlet and the expander outlet.

[0037] The expander bypass may include a control valve for controlling the flow rate in the expander bypass.

[0038] The expander bypass may be provided with at least one control valve, which can be configured to control the distribution of working fluid between the expander unit and the expander bypass.

[0039] An expander bypass may include an expansion valve that can operate based on conditions downstream of the evaporator and upstream of the compressor.

[0040] The thermal cycling system may further include an expansion valve, which may be connected in series with the expander unit and located downstream of the expander unit.

[0041] The expansion valve can operate based on conditions downstream of the evaporator and upstream of the compressor.

[0042] The expansion valve bypass valve can be connected in parallel with the expansion valve.

[0043] The thermal cycle system may further include a control valve connected in series with the expansion valve and in parallel with a bypass valve for controlling the flow rate toward the expansion valve.

[0044] The condenser can be configured to exchange heat with a first external working fluid in liquid form.

[0045] The first external fluid may include water, be composed of water, or be substantially composed of water, and optionally include additives such as antifreeze.

[0046] The condenser can be configured to exchange heat with a first external working fluid in gaseous form.

[0047] The first external fluid may include air, be composed of air, or be substantially composed of air.

[0048] The evaporator can be configured to exchange heat with a second external working fluid in liquid form.

[0049] The second external working fluid may include water, be composed of water, or be substantially composed of water, and optionally include additives such as antifreeze.

[0050] The second external working fluid can be configured to exchange heat with the space or material body to be cooled, so that the thermal circulation system is used as a cooling system.

[0051] The thermal cycle system may further include an auxiliary heat exchanger connected between the evaporator outlet and the compressor inlet, the heat exchanger being configured to transfer heat from a third external working fluid to the working fluid.

[0052] Providing additional heat at this stage can increase the evaporation of the working fluid, thereby reducing the workload required by the compressor.

[0053] The third external working fluid may include water, be composed of water, or be substantially composed of water, and optionally include additives such as antifreeze.

[0054] The thermal circulation system can be configured to operate as an irreversible cooling system for cooling a space or material volume.

[0055] The space can be the interior of a building, the interior of a vehicle, etc. The material can be an ice rink, etc. Therefore, the thermal circulation system can be configured to cool only the space or the material, and not to heat the space or the material in reverse.

[0056] According to a second aspect, a method of operating a thermal circulation system is provided, wherein the thermal circulation system includes a working fluid that circulates in a loop including a compressor, a condenser, an expander unit, and an evaporator, wherein the expander unit is configured to generate rotational mechanical motion, and wherein the method includes operating the compressor to receive the working fluid in a first state having a first pressure, a first temperature, and a first enthalpy and compressing the working fluid to a second state having a second pressure, a second temperature, and a second enthalpy; operating the condenser unit to receive the working fluid in the second state and condense the working fluid to a third state having a third pressure, a third temperature, and a third enthalpy; operating the expander unit to receive the working fluid in the third state and expand the working fluid to a fourth state having a fourth pressure, a fourth temperature, and a fourth enthalpy; and operating the evaporator to receive the working fluid in the fourth state and evaporate the working fluid to the first state. The method includes reducing the pressure of the working fluid passing through the condenser unit to less than 5 bar.

[0057] The method may further include operating a distributor to distribute the working fluid in the adjusted second state between at least one first condenser and at least one second condenser.

[0058] The expander unit can be bypassed at least partially via the expansion valve.

[0059] The method may further include expanding the working fluid in an expansion valve downstream of the expander unit.

[0060] The expansion valve can be bypassed at least partially via the expansion valve bypass valve.

[0061] The method may further include providing additional heat to the working fluid between the evaporator outlet and the compressor inlet.

[0062] It allows the condenser to exchange heat with a first external working fluid in liquid form.

[0063] It allows the condenser to exchange heat with a first external working fluid in gaseous form.

[0064] It allows the evaporator to exchange heat with a second external working fluid in liquid form.

[0065] Thermal circulation systems can be operated as irreversible cooling systems to cool spaces or material volumes.

[0066] According to a third aspect, a thermal circulation system is provided, comprising a working fluid circulating in a loop including a compressor, a condenser, an expander unit, and an evaporator, wherein the expander unit is configured to generate rotary mechanical motion, and wherein the expander unit is connected between a condenser outlet and an evaporator inlet. The thermal circulation system includes a first condenser and a second condenser connected in parallel with the first condenser, and a condenser distributor configured to distribute the working fluid flow rate between the first condenser and the second condenser.

[0067] The condenser distributor may include a pressure sensor configured to detect the pressure at the inlet of a first condenser among the condensers, and a controllable valve configured to control the flow rate into a second condenser among the condensers based on the pressure. Attached Figure Description

[0068] Figure 1 This is a schematic diagram of a traditional thermal cycle system.

[0069] Figure 2 This is a schematic diagram of an improved thermal cycle system.

[0070] Figure 3 This is a table showing test data for four different scenarios according to the present invention.

[0071] Figure 4 This is a table showing comparative data for four similar scenarios of a commercially available system.

[0072] Figure 5 This is a schematic diagram of another improved thermal cycle system. Detailed Implementation

[0073] refer to Figure 2 A schematic diagram of an improved thermal cycle system is provided. Figure 2 In the improved thermal cycle system with Figure 1 The components of the conventional thermal cycle system shown in the figure are indicated by the corresponding reference numerals.

[0074] Figure 2 The system shown is Figure 1 The difference in the system shown is that expansion valve 13 is replaced by a rotatable expander 130, and evaporator 14 is replaced by an evaporator with greater capacity. Furthermore, it may be advantageous to reduce the pressure drop in evaporator 14 and to make the connection between the output of rotatable expander 130 and evaporator 14 as short and straight as possible. Therefore, the pressure drop across the evaporator can be less than about 5 bar, preferably less than about 4 bar, less than about 3 bar, less than about 2 bar, or less than about 1 bar. Preferably, the pressure drop across the evaporator can be about 0.5 bar.

[0075] Therefore, in Figure 2 The image shows a thermal circulation system in which the working fluid circulates, as indicated by the arrows.

[0076] The system includes a compressor 10 having a compressor input end and a compressor output end. At the compressor input end, the working fluid is in a first state having a first pressure P1, a first temperature T1 and a first enthalpy H1, and at the compressor output end, the working fluid is in a second state having a second pressure P2, a second temperature T2 and a second enthalpy H2.

[0077] The compressor 10 is configured to increase the pressure of the working fluid such that P2 > P1.

[0078] The compressor can be electric.

[0079] The system may further include a condenser 11 or a pair of condensers 11a, 11b, which are arranged downstream of the compressor 10, and will be described in more detail later.

[0080] The condenser should be improved to minimize the pressure drop of the working fluid passing through it. Therefore, the working fluid can be routed through a condenser divided into several pipes, which can have fewer bends and / or a larger cross-sectional area compared to conventional condensers.

[0081] Preferably, the pressure drop of the provided condenser is less than about 5 bar, and even more preferably, it is less than about 4 bar, less than about 3 bar, less than about 2 bar, or less than about 1 bar.

[0082] Condensers 11a and 11b exchange heat with cooling devices 12a and 12b, which include a medium that acts as a cooling medium for the condensers 11a and 11b. In some embodiments, the cooling medium may be a liquid, such as water, brine, or oil, which may circulate in a cooling circuit. In other embodiments, the cooling medium may be a gas, such as air, which may circulate in a cooling circuit or be applied to the condensers by a fan.

[0083] The system further includes a rotatable expander 130, which replaces the expansion valve 13. Figure 1 ) and can take the form of, for example, a turbine, a scroll expander, or a GE rotor expander. Therefore, the rotatable expander 130 replaces the expansion valve 13 ( Figure 1 Otherwise, an expansion valve will be installed at this stage of the thermal cycling process. The rotatable output shaft of the rotatable expander 130 can be mechanically connected to a generator configured to generate electricity.

[0084] Connect the expander input to receive working fluid in the third (P3, T3, H3) state from condensers 11a and 11b.

[0085] The rotatable expander 130 is configured to allow the working fluid to expand to an adjusted fourth state P40, T40, H40, such that the pressure and enthalpy of the working fluid at the expander output are lower than in the third state, such that P40 < P3 and H40 <H3。

[0086] The rotatable expander 130 can be characterized as operating near isentropically, which causes not only pressure loss but also enthalpy loss, resulting in enthalpy H40 in the adjusted fourth state (P40, T40) being less than enthalpy (H3) in the third state.

[0087] The system further includes an evaporator 14, which can be configured to exchange heat with a heat supply loop 15, wherein heat is received by the evaporator 14, thereby increasing the enthalpy of the working fluid and causing the working fluid to evaporate, such that H40 < H1.

[0088] The heat supply circuits 15a and 15b can be cooling circuits in a cooling device or an air conditioning unit. Alternatively, the heat supply circuits 15a and 15b can be configured to obtain heat from, for example, air, ground, bedrock, or water in a heat pump system.

[0089] The evaporator inlet is connected to receive the adjusted fourth-state working fluid from the rotatable expander 130. The evaporator outlet is connected to the compressor inlet 10.

[0090] An expander bypass 131 is provided to bypass the expander 130 by providing a direct connection 1311 between the outlets of the condensers 11a and 11b and the inlet of the evaporator 14.

[0091] The expander bypass 131 may be provided with an expansion valve 1312, which can be configured to operate in a manner known per se based on the conditions at the outlet of the evaporator 14.

[0092] Therefore, the expander bypass 131 allows the rotatable expander to be connected in parallel with the expansion valve 1312.

[0093] The expander bypass 131 is provided with a control valve 1313, which can be configured to regulate the flow rate in the expander bypass 131. The regulation can be a two-way (on / off) regulation, a step regulation, or a continuous regulation between the on and off states.

[0094] Optionally, maintenance valves 1314 and 1315 may be provided on the upstream and downstream sides of the rotatable expander 130 to facilitate disconnection and / or replacement of the rotatable expander 130. The maintenance valve may be a binary (on / off) valve, while the control valve may be a binary regulator, a step regulator, or a valve that continuously regulates between the on and off states.

[0095] Optionally, the improved thermal cycle system may include a pair of condensers 11a, 11b connected in parallel and provided with a regulator 110 for distributing the working fluid between the condensers 11a, 11b.

[0096] Therefore, condensers 11a and 11b receive the working fluid in the second state (P2, T2, H2).

[0097] In the example shown, regulator 110 includes a pressure sensor 1101 and a controllable valve 1102. The pressure sensor is configured to determine the pressure at the inlet of the first condenser in condensers 11a and 11b, and the controllable valve is configured to open the inlet of the second condenser in condensers 11a and 11b, such that working fluid is directed to the second condenser 11b only when the pressure at the inlet of the first condenser 11a exceeds a predetermined value.

[0098] Evaporator 14 is configured to transfer heat from the first external fluid loop 15a to the working fluid.

[0099] Optionally, the improved thermal cycle system may include an additional heat exchanger 140 connected between the outlet of the evaporator 14 and the inlet of the compressor 10. The additional heat exchanger is configured to transfer heat from the second external fluid loop 15b to the working fluid.

[0100] The additional heat exchanger 140 can be configured to transfer additional heat from the same external fluid loop 15a as the evaporator or from a different external fluid loop. In particular, the second external fluid loop 15b can be configured to obtain waste heat or heat from, for example, a solar panel.

[0101] The auxiliary heat exchanger 140 can be selected and designed based on the type of external medium available for heat exchange, as well as the amount and flow rate of the external medium.

[0102] Figure 2 The thermal cycling system shown can operate in a variety of different modes, as will be described below.

[0103] A subcooler 150 can be provided to transfer heat from the working fluid leaving the condensers 11a and 11b to the working fluid leaving the evaporator 14. The subcooler 150 can be a heat exchanger.

[0104] test

[0105] A water-air test system was established, including a Maneurop 11 kW compressor 10, wherein the evaporator is heated by water-based brine and the condenser is cooled by airflow.

[0106] A pair of condensers 11a and 11b are installed, which are gas-cooled (typically air-cooled) condensers. In this case, a pair of 600x800x3 finned coils with 3 / 8” connectors can be used. The pressure drop of the condensers is approximately 0.5 bar. A Ziehl-Abegg FB063-6EK.4 fan from Ziehl-Abegg GmbH, Germany, is used to drive the cooling air flow through the condensers.

[0107] The fan is controlled based on the condensation pressure measured in the liquid line at K6. A Johnson Controls P15ST-9100 fan speed controller was used in the test setup.

[0108] A DENSO SCSA06C 447220-6572 HFC134a type scroll expander 130 was installed. The scroll expander was improved by removing its one-way check valve and increasing the flow area at the expander inlet to approximately 14 mm in diameter. The expander was connected to a Delta AC Servo Modell ECMA-J11330R4 kW 3.0 / 3000 rpm brake from Delta Electronics (Sweden) AB, which was used to simulate a generator connected to the output shaft of the rotatable expander 130.

[0109] Evaporator 14 is installed, using a brazed plate heat exchanger M29-60 LG from Multichannel AB of Lanskrona, Sweden. The pressure drop of the evaporator is approximately 0.5 bar.

[0110] 5 / 8-inch piping is used from the expander to the evaporator, while 7 / 8-inch piping is used from the evaporator to the compressor.

[0111] At the first condenser 11a, the pressure sensor 1101 is a Johnson Controls Penn P77AAW-9350, 6-30 bar. The controller is configured to engage the second condenser 11b when a pressure exceeding the rated setpoint of 1.5 bar is detected at the inlet of the first condenser 11a, and disengage the second condenser 11b when a pressure equal to the rated setpoint is detected.

[0112] An expansion valve 1312 is provided, and like the control valve 1313, is configured to control the flow rate to the expansion valve 1312.

[0113] In the first set of tests, the evaporator was configured to exchange heat with the first liquid (brine-water based), and the condenser was configured to exchange heat with the air. The tests used several combinations of inlet and outlet water temperatures at the evaporator:

[0114]

[0115] Set the following measurement points:

[0116]

[0117] Temperature and pressure were measured according to the table above, as were the torque (%M) and speed (RPM) of expander unit 130. In the table below, Pex is the power generated by expander unit 130; Qo is the cooling effect on the water; Pc is the power consumed by the compressor; and COP... This results in cooling efficiency.

[0118] Results of different runs in different scenarios are shown below Figure 3 The table provided in the document.

[0119] For comparison, measurements were performed on the ARGO R32 AG4HP163PH reference system (10.2 kW, power input 2.13 kW, EER W / W: 4.79) under the same scenario. The corresponding measurement points were set. Results for different runs under different scenarios are shown below. Figure 4 The table provided in the document.

[0120] The test data shows that the improved system achieved a significantly higher COP compared to the reference system. Value. Therefore, it can be concluded that by introducing a reference... Figure 2 At least some of the disclosed improvements enable a more efficient thermal cycle system.

[0121] refer to Figure 5 A method with Figure 2 The system disclosed herein corresponds to the system in which the expansion valve 1312 is connected in series downstream of the expander unit 130 and upstream of the evaporator 14, and an expansion valve bypass valve 1316 is provided therein, so that the working fluid leaving the expander unit 130 can be distributed between the expansion valve 1312 and the direct connection to the evaporator 14.

[0122] This arrangement effectively provides a way to control the pressure drop through the expander unit 130.

[0123] Preliminary tests have shown that this arrangement has the potential to improve efficiency, particularly in terms of the thermal cycle itself.

[0124] It should be understood that the system disclosed herein can be used in heating systems, i.e. systems that supply heat to radiators such as spaces or bodies by primarily extracting heat at the condenser.

[0125] Furthermore, the systems and methods disclosed herein can be used in cooling systems, primarily for cooling heat sources such as space or the body by supplying heat at the evaporator.

[0126] The systems and methods disclosed herein can also be used in combined energy systems in which heat is transferred from a heat source (which is therefore cooled) to a radiator (which is therefore heated).

[0127] It should also be understood that by using an expander unit instead of just an expansion valve, an evaporator with a larger capacity can be used. Therefore, compared to a system with only an expansion valve, the size of the evaporator can be increased by at least 20%, preferably at least 30% or at least 40%.

Claims

1. A thermal cycle system, comprising: The working fluid circulates in a loop comprising a compressor (10), condensers (11a, 11b), an expander unit (130), and an evaporator (14). The expander unit (130) is configured to generate rotary mechanical motion. The expander unit (130) is connected between the outlet of the condenser (11a, 11b) and the inlet of the evaporator (14). Its features are, The working fluid pressure drop after passing through the condenser is less than about 5 bar.

2. The thermal cycling system as described in claim 1, wherein, The working fluid pressure drop across the condenser is approximately 0.50 to 0.75 bar; approximately 0.75 to 1.00 bar; approximately 1.00 to 1.25 bar; approximately 1.25 to 1.50 bar; approximately 1.50 to 1.75 bar; approximately 1.75 to 2.00 bar; approximately 2.00 to 2.25 bar; approximately 2.25 to 2.50 bar; approximately 2.50 to 2.75 bar; approximately 2.75 to 3.00 bar; approximately 3.00 to 3.25 bar; approximately 3.25 to 3.50 bar; approximately 3.50 to 3.75 bar; approximately 3.75 to 4.00 bar; approximately 4.00 to 4.25 bar; approximately 4.25 to 4.50 bar; approximately 4.50 to 4.75 bar; or approximately 4.75 to 5.00 bar.

3. The thermal cycle system as claimed in claim 1 or 2, further comprising a subcooler (150) connected between the working fluid outlet of the condenser (11a, 11b) and the inlet of the expander unit (130), wherein, The subcooler (150) is configured to transfer heat to the working fluid at a location between the working fluid outlet of the evaporator (14) and the inlet of the compressor (10).

4. The thermal cycling system as described in any of the preceding claims, wherein, The thermal cycle system includes a first condenser (11a) and a second condenser (11b) connected in parallel with the first condenser (11a), and a condenser distributor (110) configured to distribute the working fluid flow rate between the first condenser and the second condenser (11a, 11b).

5. The thermal cycling system as described in claim 4, wherein, The condenser distributor (110) includes a pressure sensor (1101) and a controllable valve (1102), the pressure sensor being configured to detect the pressure at the inlet of the first condenser among the condensers (11a, 11b), and the controllable valve being configured to control the flow rate into the second condenser among the condensers (11a, 11b) based on the pressure.

6. The thermal cycling system as claimed in any of the preceding claims further includes an expander bypass (131) for at least partially bypassing the expander unit to provide a connection between the expander inlet and the expander outlet.

7. The thermal cycling system as described in claim 6, wherein, The expander bypass (131) includes a control valve (1313) for controlling the flow rate in the expander bypass (131).

8. The thermal cycling system as described in claim 6 or 7, wherein, The expander bypass (131) includes an expansion valve (1312) that is capable of operating based on conditions downstream of the evaporator (14) and upstream of the compressor (10).

9. The thermal cycling system as claimed in any one of claims 1 to 5, further comprising an expansion valve (1312) capable of being connected in series with the expander unit and located downstream of the expander unit.

10. The thermal cycling system of claim 9, further comprising an expansion valve bypass valve (1316) which is capable of being connected in parallel with the expansion valve (1312).

11. The thermal cycling system of claim 9 or 10, further comprising a control valve (1313) connected in series with the expansion valve (1312) and in parallel with the expansion valve bypass valve (1316) for controlling the flow rate to the expansion valve (1312).

12. The thermal cycling system as described in any of the preceding claims, wherein, The condenser (11a, 11b) is configured to exchange heat with a first external working fluid in liquid form.

13. The thermal cycling system according to any one of claims 1 to 11, wherein, The condenser (11a, 11b) is configured to exchange heat with a first external working fluid in gaseous form.

14. The thermal cycling system as described in any of the preceding claims, wherein, The evaporator (14) is configured to exchange heat with a second external working fluid in liquid form.

15. The thermal cycle system as claimed in any of the preceding claims, further comprising an auxiliary heat exchanger (140) connected between the evaporator outlet and the compressor inlet, the heat exchanger being configured to transfer heat from a third external working fluid to the working fluid.

16. The thermal cycling system as described in any of the preceding claims, wherein, The thermal cycle system is configured to operate as an irreversible cooling system for cooling a space or material volume.

17. An operating method for a thermal cycle system, in, The thermal cycle system includes a working fluid that circulates in a loop comprising a compressor (10), a condenser (11), an expander unit (130), and an evaporator (14). The expander unit (130) is configured to generate rotary mechanical motion. The method includes: The compressor (10) is operated to receive a working fluid in a first state having a first pressure (P1), a first temperature (T1), and a first enthalpy (H1), and to compress the working fluid to a second state having a second pressure (P2), a second temperature (T2), and a second enthalpy (H2). The condenser (11a, 11b) is operated to receive the working fluid in the second state and to condense the working fluid to a third state having a third pressure (P3), a third temperature (T3), and a third enthalpy (H3). The expander unit (130) is operated to receive the working fluid in the third state and to expand the working fluid to a fourth state having a fourth pressure (P4), a fourth temperature (T4), and a fourth enthalpy (H4). The evaporator (140) is operated to receive the working fluid in the fourth state and to evaporate the working fluid to the first state. Its features are, The method involves reducing the pressure of the working fluid passing through the condenser to less than 5 bar.

18. The method of claim 17, wherein, The method further includes operating a distributor to distribute the working fluid in the adjusted second state between at least one first condenser and at least one second condenser.

19. The method of claim 17 or 18, wherein, The expander unit is at least partially bypassed via the expansion valve (1312).

20. The method of claim 17 or 18, wherein, The working fluid is further expanded in an expansion valve located downstream of the expander unit.

21. The method of claim 20, wherein, The expansion valve is at least partially bypassed via the expansion valve bypass valve (1316).

22. The method of any one of claims 17 to 21, further comprising providing additional heat to the working fluid between the outlet of the evaporator (14) and the inlet of the compressor (10).

23. The method according to any one of claims 17 to 22, wherein, The condenser (11a, 11b) exchanges heat with a first external working fluid in liquid form.

24. The method according to any one of claims 17 to 23, wherein, The condenser (11a, 11b) exchanges heat with a first external working fluid in gaseous form.

25. The method according to any one of claims 17 to 24, wherein, The evaporator (14) exchanges heat with a second external working fluid in liquid form.

26. A thermal cycling system, comprising: The working fluid circulates in a loop comprising a compressor (10), condensers (11a, 11b), an expander unit (130), and an evaporator (14). The expander unit (130) is configured to generate rotary mechanical motion. The expander unit (130) is connected between the outlet of the condenser (11a, 11b) and the inlet of the evaporator (14). Its features are, The thermal cycle system includes a first condenser (11a) and a second condenser (11b) connected in parallel with the first condenser (11a), and a condenser distributor (110) configured to distribute the working fluid flow rate between the first condenser and the second condenser (11a, 11b).

27. The thermal cycling system of claim 26, wherein, The condenser distributor (110) includes a pressure sensor (1101) and a controllable valve (1102), the pressure sensor being configured to detect the pressure at the inlet of the first condenser among the condensers (11a, 11b), and the controllable valve being configured to control the flow rate into the second condenser among the condensers (11a, 11b) based on the pressure.

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