Refrigeration circuit and method for operating a refrigeration circuit

Abstract

The present invention relates to a refrigeration circuit (100), comprising: - at least one compressor device (110) which is designed to circulate a refrigerant in the refrigeration circuit (100); - at least one generator (120) for electrical energy, which is arranged downstream of the compressor device (110) in the refrigeration circuit (100) and is designed to be driven, in order to generate electrical energy, by the refrigerant compressed by the at least one compressor device (110); - at least one first expansion valve (130) which is arranged downstream of the at least one generator (120) in the refrigeration circuit (100) in order to expand the refrigerant after it flows through the at least one generator (120); and - at least one evaporator (140) which is arranged downstream of the at least one first expansion valve (130) in the refrigeration circuit (100) in order to evaporate the refrigerant after it flows through the at least one first expansion valve (130).

Description

[0001] 24-0661 24-0224

[0002] Refrigeration cycle and methods for operating a refrigeration cycle

[0003] The present disclosure relates to a refrigeration cycle and a method for operating a refrigeration cycle. The present disclosure relates in particular to a refrigeration cycle with energy recuperation.

[0004] State of the art

[0005] Conventional refrigeration systems require a condenser to release the heat energy absorbed by the evaporator back into the environment. This principle, used in heat pump operation, has specific disadvantages, particularly in applications where pure cooling is desired. In such cases, releasing the generated heat into the environment leads to undesirable energy loss and requires additional energy to dissipate this heat.

[0006] Disclosure of the invention

[0007] It is an objective of the present disclosure to specify a refrigeration cycle and a method for operating a refrigeration cycle that enable energy-efficient operation of the refrigeration cycle.

[0008] This problem is solved by the subject matter of the independent claims. Advantageous embodiments are specified in the dependent claims.

[0009] According to an independent aspect of the present disclosure, a refrigeration circuit, in particular for an air conditioning system of a vehicle, is specified. The refrigeration circuit comprises at least one compressor device configured to circulate a refrigerant in the refrigeration circuit; at least one generator for electrical energy, which is located downstream of the at least one compressor device in the refrigeration circuit.

[0010] 28.08.2024 24-0661 24-0224 is arranged and is set up to be driven by the refrigerant compressed by the at least one compressor device in order to generate electrical energy; at least one first expansion valve arranged downstream of the at least one generator in the refrigeration circuit to expand the refrigerant after it has passed through the at least one generator; and at least one evaporator arranged downstream of the at least one first expansion valve in the refrigeration circuit to evaporate the refrigerant after it has passed through the at least one first expansion valve.

[0011] According to the invention, a generator is integrated into a refrigeration cycle, which converts the heat energy absorbed by the evaporator into electrical energy. This provides a recuperation mechanism that prevents the heat energy absorbed by the evaporator from being released unused into the environment. As a result, energy-efficient operation of the refrigeration cycle is enabled.

[0012] Preferably, the refrigeration cycle is integrated into a heat pump or forms a heat pump.

[0013] The at least one compressor unit is configured to circulate the refrigerant in the refrigeration cycle. Furthermore, the at least one compressor unit increases the pressure and temperature of the refrigerant, which is in a gaseous state. The aim is to compress the gaseous refrigerant after it has evaporated, before it enters the at least one generator. The compressor unit can also be referred to as a "refrigerant compressor".

[0014] The first expansion valve (or at least one) controls the refrigerant flow and ensures that the refrigerant can efficiently absorb its energy in the evaporator (or at least one evaporator). Specifically, the refrigerant enters the first expansion valve (or at least one evaporator) at high pressure and high temperature and is evaporated in the evaporator (or at least one evaporator).

[0015] 28.08.2024 24-0661 24-0224 a first expansion valve is released to a lower pressure. This pressure reduction causes the temperature of the refrigerant to also drop significantly.

[0016] Preferably, at least one first expansion valve is selected from the group comprising, or consisting of, a thermostatic expansion valve, an electronic expansion valve, a capillary tube and combinations thereof.

[0017] The thermostatic expansion valve automatically adjusts the refrigerant flow rate based on the temperature at the outlet of at least one evaporator. It uses, for example, a sensor line that measures the refrigerant's superheat and adjusts the valve cross-section accordingly. The electronic expansion valve is electronically controlled and allows for more precise regulation of the refrigerant flow rate. The capillary tube does not offer active control but relies on a fixed flow rate due to the tube's resistance.

[0018] The at least one evaporator (also called a "condenser") absorbs heat from a medium to be cooled, such as air. The refrigerant enters the at least one evaporator in a cold, liquid state after being cooled and brought to a low pressure by the at least one expansion valve. In the at least one evaporator, the refrigerant absorbs heat from the surroundings (e.g., from the air in the vehicle interior). This heat absorption causes the refrigerant to begin evaporating, i.e., to change from a liquid to a gaseous state.

[0019] Preferably, the refrigerant is selected from or consists of the group comprising R-134a (tetrafluoroethane), R-1234yf (HFO-1234yf), CO2 (carbon dioxide, R-744) and propane.

[0020] Preferably, the refrigeration cycle does not include a condenser or chiller. In particular, at least one generator can be provided instead of the condenser, so that the

[0021] 28.08.2024 24-0661 24-0224 the heat energy absorbed by at least one evaporator is not released unused into the environment, but is converted into usable electrical energy.

[0022] Preferably, the at least one generator comprises a mechanical rotation mechanism configured to be set in rotation by the refrigerant compressed by the at least one compressor device. In particular, the mechanical rotation mechanism can convert the kinetic energy of the refrigerant compressed by the at least one compressor device into mechanical rotational energy.

[0023] Preferably, the rotation mechanism comprises at least one impeller. An impeller is a mechanical component comprising a hub to which several radially arranged blades or vanes are attached. The flow of the refrigerant can drive the impeller.

[0024] Preferably, the at least one generator comprises an energy generation mechanism configured to generate electrical energy from the rotation of the rotating mechanism. The energy generation mechanism can convert the mechanical rotational energy into electrical energy, for example, using electromagnetic induction or other suitable physical principles.

[0025] Preferably, the at least one generator comprises or is an AC generator and / or a DC generator.

[0026] Preferably, the refrigeration circuit includes at least one bypass for the at least one compressor unit. The at least one bypass connects an inlet and an outlet of the at least one compressor unit.

[0027] 28.08.2024 24-0661 24-0224

[0028] Preferably, at least one bypass is connected in parallel to the (main) circuit consisting of compressor device, generator, first expansion valve and evaporator.

[0029] Preferably, the refrigeration circuit includes at least one second expansion valve configured to open and close the at least one bypass. In particular, the at least one second expansion valve can be integrated into the at least one bypass. The at least one second expansion valve enables stabilization of the cycle, for example, if insufficient heat is absorbed via the at least one evaporator. In this case, the at least one bypass can be at least partially opened to circulate the refrigerant through both circuits (i.e., the main circuit and the bypass), thereby allowing for pH stabilization to the right of the wet vapor curve in the pH diagram. However, if sufficient heat is absorbed via the at least one evaporator, the at least one bypass, or the at least one second expansion valve, can remain closed.

[0030] Preferably, at least one second expansion valve is selected from the group comprising, or consisting of, a thermostatic expansion valve, an electronic expansion valve, a capillary tube and combinations thereof.

[0031] Preferably, the refrigeration circuit includes a control module configured to variably control the at least one second expansion valve in order to set a suction pressure level for the at least one compressor unit. This allows for precise adjustment in the pH diagram, even if insufficient heat is absorbed via the at least one evaporator.

[0032] According to another independent aspect of the present disclosure, an air conditioning system, in particular for a vehicle, is specified. The air conditioning system comprises at least one refrigeration circuit according to the embodiments of the present disclosure.

[0033] 28.08.2024 24-0661 24-0224

[0034] Preferably, the air conditioning system is an indirect cooling system with multiple (separate) circuits. In an indirect cooling system, heat is not transferred directly to the environment, but via an intermediate medium, usually a secondary coolant. The indirect system typically consists of two separate circuits, generally referred to as the primary circuit and the secondary circuit. A refrigerant circulates in the primary circuit. The secondary circuit contains a coolant that exchanges heat with the primary circuit and is transported to the locations in the vehicle where cooling is required—for example, to the battery cooling system in electric vehicles or to other components that need to be cooled.

[0035] Preferably, the refrigeration cycle described in this document forms the primary circuit of the indirect cooling system.

[0036] According to another independent aspect of the present disclosure, a vehicle, in particular a motor vehicle, is specified. The vehicle comprises the air conditioning system according to the embodiments of the present disclosure.

[0037] Preferably, the air conditioning system is designed for air conditioning a vehicle interior.

[0038] The term "vehicle" includes cars, trucks, vans, buses, motorhomes, motorcycles, etc., used for the transport of people, goods, etc. In particular, the term includes motor vehicles for passenger transport.

[0039] According to another independent aspect of the present disclosure, a method for operating a refrigeration circuit is specified. The method comprises providing the refrigeration circuit with at least one compressor device configured to circulate a refrigerant in the refrigeration circuit; at least one

[0040] 28.08.2024 24-0661 24-0224

[0041] A generator for electrical energy, arranged downstream of the at least one compressor device in the refrigeration circuit and configured to be driven by the refrigerant compressed by the at least one compressor device in order to generate electrical energy; at least one first expansion valve, arranged downstream of the at least one generator in the refrigeration circuit to expand the refrigerant after it has passed through the at least one generator; and at least one evaporator, arranged downstream of the at least one first expansion valve in the refrigeration circuit to evaporate the refrigerant after it has passed through the at least one first expansion valve; and operation of the at least one compressor device to circulate the refrigerant in the refrigeration circuit.

[0042] The process can implement the aspects of the refrigeration cycle described in this document.

[0043] Brief description of the drawings

[0044] Examples of the manifestation of the revelation are shown in the figures and are described in more detail below. They show:

[0045] Figure 1 schematically shows a classic log pH diagram of a heat pump,

[0046] Figure 2 schematically shows a refrigeration cycle according to embodiments of the present disclosure,

[0047] Figure 3 shows a schematic log ph diagram of the refrigeration circuit of Figure 2,

[0048] Figure 4 schematically shows a refrigeration cycle according to further embodiments of the present disclosure,

[0049] 28.08.2024 24-0661 24-0224

[0050] Figure 5 schematically shows a log pH diagram of the refrigeration cycle of Figure 4, and

[0051] Figure 6 shows a flowchart of a method for operating a refrigeration cycle according to embodiments of the present disclosure.

[0052] Implementations of the revelation

[0053] Unless otherwise noted, the same reference symbols are used for identical and equivalent elements in the following.

[0054] Figure 1 schematically shows a classic log pH diagram of a heat pump.

[0055] The diagram shown here illustrates the typical principle of a heat pump using a classic log pH diagram (pressure-enthalpy diagram). This diagram depicts a typical counterclockwise cycle, illustrating the basic principle of the heat pump. This process consists of four main phases, defined by the essential components of the system:

[0056] 1. Compressor: In this step of the cycle, the refrigerant is compressed adiabatically (without heat exchange) in the compressor. This leads to an increase in both the pressure and the enthalpy of the refrigerant. In the diagram, this process is represented as an upward shift. The mechanical energy supplied to the compressor increases the enthalpy of the refrigerant, causing it to transition into a gaseous state.

[0057] 2. Condenser: The compressed refrigerant now flows into the condenser, where it condenses at high pressure and constant temperature. In this process step, the refrigerant releases its heat energy to the surroundings or another medium, and its enthalpy decreases. This is represented in the log pH diagram.

[0058] 28.08.2024 24-0661 24-0224

[0059] The process is represented by a horizontal shift to the left at high pressure. The pressure remains almost constant, while the enthalpy decreases.

[0060] 3. Expansion valve: After condensation, the refrigerant passes through the expansion valve. Here, its pressure drops, causing it to partially evaporate and its temperature to fall significantly. In the diagram, this process is represented as an almost vertical pressure drop. This step prepares the refrigerant for further heat exchange in the evaporator.

[0061] 4. Evaporator (Chiller): Finally, the expanded refrigerant enters the evaporator, where, at low pressure, it absorbs heat from the surroundings (e.g., from the air) and evaporates completely. The enthalpy of the refrigerant increases again as it absorbs heat from the environment. In the diagram, this process is represented as a horizontal shift to the right at low pressure. The now gaseous refrigerant is then returned to the compressor, thus restarting the cycle.

[0062] In an adiabatic scenario, where no heat is added or removed from the outside, the enthalpy contained in the refrigerant is the sum of the energy absorbed in the evaporator (chiller) and the compressor. This total enthalpy is then released in the condenser. This closed-loop process, as depicted in the log pH diagram, corresponds to the classic operating principle of a heat pump, in which the refrigerant circulates continuously to transport heat and create the desired temperature gradient.

[0063] Figure 2 schematically shows a refrigeration cycle 100 according to embodiments of the present disclosure. Figure 3 schematically shows a log pH diagram of the refrigeration cycle 100 of Figure 2.

[0064] 28.08.2024 24-0661 24-0224

[0065] Preferably, the refrigeration circuit 100 is integrated into a heat pump or forms a heat pump.

[0066] In some embodiments, the refrigeration circuit 100 of the present disclosure can be used in an air conditioning system of a vehicle. However, the present disclosure is not limited to this, and other areas of application and uses for the refrigeration circuit 100 of the present disclosure are conceivable.

[0067] The refrigeration circuit 100 comprises at least one compressor device 110, which is configured to circulate a refrigerant in the refrigeration circuit; at least one generator 120 for electrical energy, which is arranged downstream of the compressor device 110 in the refrigeration circuit 100 and is configured to be driven by the refrigerant compressed by the at least one compressor device 110 in order to generate electrical energy; at least one first expansion valve 130, which is arranged downstream of the at least one generator 120 in the refrigeration circuit 100 to expand the refrigerant after it has passed through the at least one generator 120; and at least one evaporator 140, which is arranged downstream of the at least one first expansion valve 130 in the refrigeration circuit 100 to evaporate the refrigerant after it has passed through the at least one first expansion valve 130.

[0068] The refrigerant thus flows successively through at least one compressor unit 110, at least one generator 120, at least one first expansion valve 130, and at least one evaporator. Optionally, sensors 150A, 150B for monitoring and / or controlling the refrigeration circuit 100 can be provided upstream and / or downstream of the at least one compressor unit 110. The sensors 150A, 150B can be combined high-resolution pressure and

[0069] These may be temperature sensors, but the present disclosure is not limited to them.

[0070] 28.08.2024 24-0661 24-0224

[0071] The at least one generator 120 is integrated into the refrigeration circuit 100 instead of a condenser or chiller in order to convert the heat energy absorbed by the at least one evaporator 140 into electrical energy. This provides a recuperation mechanism that prevents the heat energy absorbed by the at least one evaporator 140 from being released unused to the environment, for example via a condenser or chiller. As a result, energy-efficient operation of the refrigeration circuit 100 is enabled.

[0072] In some embodiments, the at least one generator 120 comprises a mechanical rotation mechanism configured to be set in rotation by the refrigerant compressed by the at least one compressor device 110. In particular, the mechanical rotation mechanism can convert the kinetic energy of the refrigerant compressed by the at least one compressor device 110 into mechanical rotational energy. The rotation mechanism can be a paddle wheel or a turbine wheel.

[0073] In some embodiments, the at least one generator 120 comprises an energy generation mechanism configured to generate electrical energy from the rotation of the rotational mechanism. The energy generation mechanism can convert the mechanical rotational energy into electrical energy, for example, using electromagnetic induction or other suitable physical principles.

[0074] Preferably, the at least one generator 110 comprises or is a turbine.

[0075] With reference to Figure 3, the four main phases of the cycle, defined by the components of the refrigeration cycle 100, are explained below:

[0076] 28.08.2024 24-0661 24-0224

[0077] 1. The at least one compressor unit 110 compresses the refrigerant essentially adiabatically, i.e., essentially without heat exchange. This leads to an increase in both the pressure and the enthalpy of the refrigerant. In the diagram, this process is shown as an upward shift (point 1 to point 2).

[0078] 2. The compressed refrigerant now flows into at least one generator 120, where it drives, for example, a paddle wheel or turbine wheel. In this process step, the refrigerant releases its thermal energy, and its enthalpy decreases. In the log pH diagram, this process is represented by a shift to the left at high pressure (point 2 to point 3). Due to energy losses in at least one generator 120, the pressure also decreases.

[0079] 3. After flowing through at least one generator 120, the refrigerant is passed through at least one expansion valve 130. Here, it experiences a pressure drop, causing the refrigerant to partially evaporate and its temperature to decrease significantly. In the diagram, this process is represented as an almost vertical pressure drop (point 3 to point 4).

[0080] 4. Finally, the expanded refrigerant enters at least one evaporator 140, where, at low pressure, it absorbs heat from the ambient temperature (e.g., from the air) and evaporates. The enthalpy of the refrigerant increases again as it absorbs heat from the surroundings. In the diagram, this process is represented as a horizontal shift to the right at low pressure (point 4 to point 1). The now gaseous refrigerant is then returned to at least one compressor unit 110, thus restarting the cycle.

[0081] Figure 4 schematically shows a refrigeration cycle 100 according to further embodiments of the present disclosure. Figure 5 schematically shows a log pH diagram of the refrigeration cycle of Figure 4. The cycle of Figure 4 is identical in its basic features.

[0082] 28.08.2024 24-0661 24-0224 to the cycle shown in Figure 2, so that reference is made to it for a description of the basic components.

[0083] The refrigeration circuit 100 comprises at least one bypass BP for the at least one compressor unit 110. The at least one bypass BP connects an inlet and an outlet of the at least one compressor unit 110 and is connected in parallel to the (main) circuit consisting of compressor unit 110, generator 120, first expansion valve 130 and evaporator 140.

[0084] The refrigeration circuit 100 further comprises at least one second expansion valve 160, which is configured to open and close the at least one bypass BP. In particular, the at least one second expansion valve 160 can be integrated into the at least one bypass BP. The at least one second expansion valve 160 enables stabilization of the cycle, for example, if too little heat is absorbed via the at least one evaporator (point 5 in Figure 5). Then the at least one bypass can be at least partially opened to circulate the refrigerant through both circuits (i.e., the main circuit and the bypass), thereby allowing for adjustment to the right of the wet vapor curve in the pH diagram (shown in Figure 5 as a dashed arrow between point 5 and point 1). However, if sufficient heat is absorbed via the at least one evaporator 140, the at least one bypass BP can be closed.that at least one second expansion valve 160 remains closed.

[0085] In some embodiments, the refrigeration circuit 100 includes a control module (not shown) configured to variably control the at least one second expansion valve 160 in order to set a suction pressure level for the at least one compressor unit 110. This allows for precise adjustment in the pH diagram, even if insufficient heat is absorbed via the at least one evaporator 140.

[0086] 28.08.2024 24-0661 24-0224

[0087] Figure 6 schematically shows a flowchart of method 600 for operating a refrigeration cycle according to embodiments of the present disclosure.

[0088] Method 600 comprises, in block 610, providing a refrigeration circuit with at least one compressor device configured to circulate a refrigerant in the refrigeration circuit; at least one electrical energy generator arranged downstream of the at least one compressor device in the refrigeration circuit and configured to be driven by the refrigerant compressed by the at least one compressor device to generate electrical energy; at least one first expansion valve arranged downstream of the at least one generator in the refrigeration circuit to expand the refrigerant after it has passed through the at least one generator; and, in block 620, at least one evaporator arranged downstream of the at least one first expansion valve in the refrigeration circuit to evaporate the refrigerant after it has passed through the at least one first expansion valve.and the operation of at least one compressor device to circulate the refrigerant in the refrigeration circuit.

[0089] According to the invention, a generator is integrated into a refrigeration cycle, which converts the heat energy absorbed by the evaporator into electrical energy. This provides a recuperation mechanism that prevents the heat energy absorbed by the evaporator from being released unused into the environment. As a result, energy-efficient operation of the refrigeration cycle is enabled.

[0090] Although the invention has been further illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a multitude of possible variations exist. It is also clear that the embodiments mentioned as examples are indeed only examples and are not in any way intended to represent the invention as a whole.

[0091] 28.08.2024 24-0661_24-0224

[0092] The preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various modifications, for example, with regard to the

[0093] function or arrangement of individual elements mentioned in an exemplary embodiment can be carried out without leaving the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description.

[0094] August 28, 2024

Claims

24-0661 24-0224 Patent claims 1. Refrigeration circuit (100) comprising: at least one compressor device (110) configured to circulate a refrigerant in the refrigeration circuit (100); at least one generator (120) for electrical energy, arranged downstream of the at least one compressor device (110) in the refrigeration circuit (100) and configured to be driven by the refrigerant compressed by the at least one compressor device (110) to generate electrical energy; at least one first expansion valve (130) arranged downstream of the at least one generator (120) in the refrigeration circuit (100) to expand the refrigerant after it has passed through the at least one generator (120); and at least one evaporator (140) arranged downstream of the at least one first expansion valve (130) in the refrigeration circuit (100) to evaporate the refrigerant after it has passed through the at least one first expansion valve (130).

2. Refrigeration circuit (100) according to claim 1, wherein the refrigeration circuit (100) does not include a condenser.

3. Refrigeration circuit (100) according to claim 1 or 2, wherein the at least one generator (120) comprises a mechanical rotation mechanism which is arranged to be set in rotation by the refrigerant compressed by the at least one compressor device (110), in particular wherein the rotation mechanism comprises at least one impeller.

4. Refrigeration circuit (100) according to claim 3, wherein the at least one generator (120) comprises an energy generation mechanism which is configured to generate electrical energy from the rotation of the rotation mechanism. August 28, 2024 24-0661 24-0224 5. Refrigeration circuit (100) according to one of claims 1 to 4, further comprising at least one bypass (BP) for the at least one compressor device (110), wherein the at least one bypass (BP) connects an inlet and an outlet of the at least one compressor device (110).

6. Refrigeration circuit (100) according to claim 5, further comprising at least a second expansion valve (160) configured to open and close the at least one bypass (BP).

7. Refrigeration circuit (100) according to claim 6, further comprising a control module configured to variably control the at least one second expansion valve (160) in order to set a suction pressure level for the at least one compressor device (110).

8. Air conditioning system comprising at least one refrigeration circuit (100) according to any one of claims 1 to 7.

9. Vehicle (10), in particular motor vehicle, comprising the air conditioning system according to claim 8.

10. Method (600) for operating a refrigeration cycle (100), comprising: Provision (610) of the refrigeration circuit (100) with at least one compressor device (110) configured to circulate a refrigerant in the refrigeration circuit (100); at least one generator (120) for electrical energy, arranged downstream of the at least one compressor device (110) in the refrigeration circuit (100) and configured to be driven by the refrigerant compressed by the at least one compressor device (110) to generate electrical energy; at least one first expansion valve (130) arranged downstream of the at least one generator (120) in the refrigeration circuit (100) to expand the refrigerant after it has passed through the at least one generator (120). August 28, 2024 24-0661_24-0224 expand; and at least one evaporator (140) arranged downstream of the at least one first expansion valve (130) in the refrigeration circuit (100) to evaporate the refrigerant after it has passed through the at least one first expansion valve (130); and - operating (620) the at least one compressor device (110) to expand the To circulate refrigerant in the refrigeration circuit (100). August 28, 2024

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