Improvement of the reverse liquid thawing system and method

Abstract

A method is provided in which one evaporator selected from multiple evaporators in a reverse liquid defrost system and closed loop vapor cycle cooling system has its own expansion device supplying all evaporators in normal flow. During defrosting, liquid refrigerant (the one that gives up heat in the selected evaporator is subcooled) is circulated through the remaining unselected evaporators by this expansion device or finally by an auxiliary expansion device to supply at least two independent unselected evaporators at different evaporation pressures (the higher evaporation pressure can be the compression suction pressure through the use of additional liquid flow lines and check valves, exhaust devices, vapor liquid separators, and isolation valves (which can be valves that automatically close when the suction pressure type rises)). It can be used in vehicles as a heat pump mobile system with various reheat performance levels.

Description

Field of the Invention

[0001] The present invention modifies and improves cooling systems with multiple evaporators in a closed-loop steam cycle of any type that require a thawing cycle to remove ice formed on the outside of the evaporator coils, enable automatic operation, and improve efficiency. Specifically, the present invention relates to reverse liquid thawing of one selected evaporator from multiple evaporators in a closed-loop steam cycle cooling system having its own expansion unit that supplies all evaporators in a normal flow when the selected evaporator is one of multiple evaporators. More specifically, the present invention is directed to a method of reverse liquid thawing system and selected evaporator, which is one of multiple evaporators, and which is a cooling system with multiple evaporators in a closed-loop steam cycle having its own expansion unit that supplies all evaporators in a normal flow, in which thawing is achieved by circulating liquid refrigerant through the selected evaporator in the opposite direction to the normal flow using a dedicated pipe that carries the liquid in the reverse direction. Then, the ice accumulated on the coil of the selected evaporator is thawed by heat dissipation, and the liquid refrigerant that has passed through this system is subcooled. Subsequently, by utilizing additional dedicated pipes and check valves to allow the liquid to flow in the reverse direction, the subcooled liquid refrigerant is circulated to a separate expansion unit that supplies all other unselected evaporators. Alternatively, while defrosting one selected evaporator, which is one of several evaporators in a closed-loop vapor cycle cooling system with multiple evaporators, the subcooled liquid refrigerant passes through the selected evaporator and circulates through both the separate expansion unit and auxiliary expansion unit that supply all evaporators in the normal flow, so as to supply two different unselected evaporators at two different evaporation pressures.As a result, by using additional liquid-carrying pipes, additional check valves, discharge devices, vapor-liquid separators, and separation valves, the suction pressure of the compressor ultimately becomes the higher evaporation pressure of the two different unselected evaporators without causing a pressure drop. The separation valve can be a control valve (such as a solenoid valve) or a valve that automatically closes when the suction pressure rises. Further improvements in the efficiency of this system according to the present invention are achieved by utilizing a second compression stage connected to a second vapor-liquid separator and by utilizing additional auxiliary expansion devices that can be replaced by an expander compressor group. The system according to the present invention can be used as a mobile heat pump system for in-vehicle air conditioning at various reheating performance levels. Background of the present invention

[0002] Cooling systems with multiple evaporators may require thawing cycles to remove ice that forms on the outside of the evaporator coils. In fact, during normal operation, evaporators operate at low temperatures that cause the vapor to freeze on the outside of their coils, leading to ice formation. This ice can accumulate, restricting airflow and ultimately resulting in a loss of cooling function. The rate at which ice accumulates in a particular device depends on its type, capacity, the temperature of the device and refrigerant, and the humidity of the air within the device being cooled. As a result, the surface of the evaporator coils must be thawed intermittently. The frequency at which a particular evaporator needs to be thawed depends on the rate of ice accumulation, the cooling load on the evaporator, and the rate at which it can be thawed. Generally, the time required for thawing depends on the degree of ice accumulation on the evaporator coils and the rate at which heat can be applied to melt the ice. Therefore, ice accumulation varies depending on the type of installation, the conditions inside the device, and the frequency of thawing. Generally, thawing can be achieved by passing a hot vaporized refrigerant through an evaporator, but Alsenz, in a U.S. patent (No. 6,000,231), has discovered a system and method for thawing one selected evaporator from a group of evaporators in a cooling system having multiple evaporators in a closed-loop vapor cycle by introducing liquid refrigerant into the coil of a selected evaporator in the opposite direction to the normal flow through a dedicated tube for reverse flow of liquid. This dedicated tube for reverse flow of liquid allows the subcooled liquid refrigerant, having left the selected evaporator, to return to the liquid-flowing tube, in a path where the coil is subcooled so that it can pass through a group of separate expansion units, each supplying one of the unselected evaporators among the group of evaporators. More specifically, Alsenz's invention comprises a system and method for reverse liquid thawing one selected evaporator from a cooling system having multiple evaporators in a closed-loop vapor cycle.This cooling system includes one or more compressors for compressing liquid refrigerant, a condenser for condensing the compressed, high-temperature gaseous refrigerant, a receiver for storing the condensed refrigerant, multiple evaporators for evaporating the liquid refrigerant from the receiver into a low-pressure, low-temperature gaseous refrigerant, multiple expansion units, each supplying one of the multiple evaporators, and an intake manifold for combining multiple flows of low-pressure, low-temperature gaseous refrigerant from the multiple evaporators into a single intake pipe connected to the compressor, and a dedicated pipe for reverse-flowing liquid refrigerant connecting the outlet of the condenser or receiver to the outlet / discharge port and control valve of the selected evaporator, in order to introduce the liquid refrigerant released from the condenser or receiver into a selected evaporator in the opposite direction to the normal flow to defrost the selected evaporator by heat dissipation. This liquid refrigerant is simultaneously subcooled as it passes through the selected evaporator, restoring the cooling effect stored in the accumulated frost and ice. This cooling effect is transferred to the unselected evaporators by supplying the subcooled liquid refrigerant to the individual expansion units. Each expansion unit is supplied with a low-temperature liquid by an unselected evaporator from among several evaporators. Technical problem.

[0003] Alsenz claims his invention works even with a single expansion unit in a cooling system having multiple evaporators, but his system and method are not directly applicable to cases where there is a separate expansion unit supplying all of the multiple evaporators in a normal flow, when the selected evaporator is one of several. In addition, his drawings do not depict the case of a separate expansion unit supplying all of the multiple evaporators in a normal flow. Finally, his claim for his system does not mention any expansion unit.

[0004] In cases where there is a separate expansion device that supplies all evaporators of multiple evaporators in the normal flow, unless an additional pipe and check valve that allow liquid to flow in the reverse direction, which were not discovered by Alsenz, are introduced, Alsenz's invention has a technical problem in that the selected evaporator cannot become one of the multiple evaporators when the thawing of the selected evaporator is achieved by introducing the liquid refrigerant into the coil of the selected evaporator in the reverse direction of the normal flow, in the path through which the selected evaporator is subcooled, so that the subcooled liquid refrigerant that has left the selected evaporator is released back into the pipe that carries the liquid, in order to pass through the separate expansion device that supplies all other evaporators of the multiple evaporators that have not been selected.

[0005] Another technical problem in Alsenz's invention is that while the selected evaporator is being defrosted, the suction pressure of the compressor cannot be set to the higher evaporation pressure of the two different unselected evaporators operating at different evaporation pressures without ultimately causing a pressure drop, and is inevitably set to the lowest pressure. How to solve this technical problem?

[0006] One object of the present invention is to solve the first technical problem of Alsenz's system and method in the case where the selected evaporator is one of several evaporators, and a unique expansion device supplies all of the multiple evaporators in the normal flow by utilizing a tube and check valve for additional liquid flow in the reverse direction. More specifically, one object of the present invention is to discover a system and method for defrosting a selected evaporator, which is one of several evaporators in a cooling system having multiple evaporators in a closed-loop vapor cycle, having a unique expansion device that supplies all of the multiple evaporators in the normal flow, by introducing the subcooled liquid refrigerant that has left the selected evaporator into the selected evaporator in the reverse direction of the normal flow via a dedicated tube for liquid flow in the reverse direction of the normal flow, and supplying all of the multiple evaporators in the normal flow, by a dedicated tube for liquid refrigerant flow in the reverse direction of the normal flow, in a path where the selected evaporator is subcooled. As mentioned above, in contrast to Alsenz's more common system in which each evaporator has its own expansion unit, the system according to the present invention achieves improvement by having its own expansion unit that supplies all evaporators of the multiple evaporators in a normal flow, and by connecting the outlet of the unique expansion unit to the inlet of each evaporator of the multiple evaporators by a refrigerant-carrying pipe, each having a check valve. The outlet of the condenser or receiving unit is connected to the inlet of the unique expansion unit by a pipe that carries the liquid in the forward direction. In addition to using check valves for the refrigerant-carrying pipes as previously stated, the solution to the first technical problem is implicitly achieved by using an additional pipe that carries the liquid in the reverse direction. This additional liquid-reverse pipe connects a portion of the refrigerant-carrying pipe, each located downstream of its respective check valve, to the pipe that carries the liquid in the forward direction, and each of the additional liquid-reverse pipes has its own check valve.Because of the presence of these check valves, the refrigerant does not flow through the reverse-flow pipe of the additional liquid during normal operation, but only flows through the reverse-flow pipe of the liquid while the selected evaporator is thawing. In particular, the refrigerant only flows through the reverse-flow pipe of the additional liquid that connects a portion of the refrigerant flow pipe of the selected evaporator to a portion of the forward-flow pipe of the liquid. On the other hand, under no circumstances does the refrigerant flow through any other reverse-flow pipe of the additional liquid. These other reverse-flow pipes of the additional liquid connect a portion of the refrigerant flow pipe and a portion of the forward-flow pipe of any unselected evaporator while the selected evaporator is thawing.

[0007] Another object of the present invention is to solve a second technical problem related to the Alsenz system and method described above. This problem is always applicable to a separate expansion unit that supplies all evaporators of the multiple evaporators in a normal flow, in order to achieve, while a selected evaporator, which is one of the multiple evaporators, is undergoing reverse liquid thawing, the suction pressure of the compressor to the higher evaporation pressure of two different unselected evaporators operating at different evaporation pressures, without ultimately causing a pressure drop. The solution to this second technical problem is achieved by further additional discharge and vapor-liquid separators located in the pipe through which the liquid flows forward, and further liquid-flow pipes including further check valves, separation valves, and auxiliary liquid-flow pipes branching off from the pipe through which the liquid flows forward and extending to an auxiliary expansion unit. This auxiliary expansion unit supplies the second unselected evaporator of the multiple evaporators at an evaporation pressure somewhat higher than the evaporation pressure supplied by the separate expansion unit that supplies all evaporators of the multiple evaporators in a normal flow, while the first unselected evaporator undergoes reverse liquid thawing of the selected evaporator.

[0008] Furthermore, a further object of the present invention is to enhance the efficiency of the discovered system by utilizing a second compression stage connected to a second vapor-liquid separator and by utilizing additional auxiliary expansion devices that can be replaced by an expander-compressor group. The final objective of this invention is to use it as a heat pump mobile system for in-vehicle air conditioning at various reheating performance levels. The important features of the present invention are broadly summarized in the order that will be best understood from the detailed description below, and from the order that will be best understood from the contributions of the present invention. Additional features of the present invention are described in detail below and form the subject matter of the claims attached to this document. [Brief explanation of the drawing]

[0009] The following list of figures provides a brief description of the figures that constitute the figures of the present invention, where similar elements are identified by the same reference numerals. [Figure 1] Figure 1 illustrates a closed-loop vapor cycle cooling system that reverses the liquid flow of the coil of one evaporator selected from several evaporators, particularly by using a dedicated tube for reverse-flowing the liquid, as is well known in the (latest) art; [Figure 2] Figure 2 illustrates a closed-loop vapor cycle cooling system that reverses the liquid flow of a coil in one evaporator selected from multiple evaporators by using an additional reverse-flow pipe and check valve in an example of a unique expansion device that supplies all evaporators in the normal flow according to the present invention, in addition to a dedicated pipe for reverse-flowing liquid; [Figure 3]Figure 3 illustrates a closed-loop steam cycle cooling system that reverses the liquid flow of a coil in one of several evaporators by using an additional reverse-flow pipe and check valve, in an example of a unique expansion system that supplies all evaporators in a normal flow, further comprising a discharge device and a vapor-liquid separator located in a pipe that allows liquid to flow in the forward direction, in addition to a dedicated pipe for reverse-flowing liquid according to the present invention; [Figure 4] Figure 4, as described above with reference to Figure 3, illustrates the closed-loop steam cycle cooling system, which consists of an auxiliary liquid-carrying pipe branching off from a forward-carrying pipe extending to an auxiliary expansion device. This auxiliary expansion device supplies a second unselected evaporator among several evaporators while the selected evaporator is thawing. The evaporation pressure in this case is somewhat higher than that of the first unselected evaporator supplied by its own expansion device. This unique expansion device supplies all evaporators in a normal flow by using further liquid-carrying pipes, additional check valves, and separation valves, in accordance with the present invention. Thus, the higher evaporation pressure of the two different unselected evaporators among several evaporators is achieved at the suction pressure of the compressor without causing a final pressure drop; [Figure 5] Figure 5, as previously described with reference to Figure 4, illustrates a closed-loop steam cycle cooling system, in which the more common separation control valve in Figure 4 is replaced by a valve that automatically closes when the pressure at the intake port rises, and which has a check valve on the outlet side. This valve that automatically closes when the pressure at the intake port rises opens only when the pressure at the intake port falls somewhat below a reference pressure. This reference pressure is, according to the present invention, the pressure at a convenient section of the closed-loop steam cycle cooling system that is supplied by a narrow tube to the valve that automatically closes when the pressure at the intake port rises; [Figure 6]Figure 6, as described above with reference to Figure 5, illustrates the closed-loop steam cycle cooling system, which, according to the present invention, consists of a second compression stage connected to a second steam-liquid separator, in addition to a further auxiliary expansion device; [Figure 7] Figure 7 is a flowchart of the process of reverse liquid thawing a selected evaporator in connection with the embodiment of this system, as described above with reference to Figure 6. In Figure 7, thick lines with arrows indicate the refrigerant circuit, and letters enclosed in boxes indicate the relevant sections of this system according to the present invention; [Figure 8] Figure 8 is a Mollier diagram showing the thermodynamic state of the low-boiling point refrigerant circulating within this system according to the present invention, as described above with reference to an embodiment in Figure 6, where Figure 6 is the relevant section of this system in the flow diagram of Figure 7. Figure 7 is a diagram of one selected evaporator being defrosted, where the Greek letters in Figure 8 indicate the various pressure levels of the thermodynamic cycle; [Figure 9] Figure 9, as described above with reference to Figure 6, embodies this system according to the present invention, and is modified and adapted for use as a heat pump mobile system for in-vehicle air conditioning, in addition to using an external heat exchanger located in the processing unit of the in-vehicle air expansion and compression group, particularly together with a condenser, in the location of a further auxiliary expansion device, an internal heat exchanger, a tube for carrying supplemental liquid, and supplemental valves; [Figure 10] Figure 10 is a typical flow diagram relating to the embodiment of this system according to the present invention, as described above with reference to Figure 9, during operation in a series flow configuration with low reheating performance corresponding to the "cooling" function of the air inside the vehicle, where thick lines with arrows indicate the refrigerant circuit; [Figure 11] Figure 11 is a typical flowchart relating to the embodiment of this system according to the present invention, as described above with reference to Figure 9, showing the operation in a series flow configuration with intermediate reheating performance corresponding to the "series dehumidification and heating" function of the air inside the vehicle, where thick lines with arrows indicate the refrigerant circuit; [Figure 12] Figure 12 is a typical flowchart relating to the embodiment of this system according to the present invention, as described above with reference to Figure 9, during operation in a parallel flow configuration with high reheating performance corresponding to the "parallel dehumidification and heating" function of the air inside the vehicle, where thick lines with arrows indicate the refrigerant circuit; [Figure 13] Figure 13, as previously mentioned with reference to Figure 9, is a flowchart of the process of reverse liquid thawing the coil of a selected evaporator in relation to the embodiment of this system, during operation in a parallel flow configuration with high reheating performance corresponding to the "parallel dehumidification heating" function of the air inside the vehicle, in accordance with the present invention, where thick lines with arrows indicate the refrigerant circuit, and letters enclosed in boxes indicate the same relevant sections in the reverse liquid thawing process flowchart of Figure 7; [Figure 14] Figure 14, as previously mentioned with reference to Figure 9, is a flowchart of the process of reverse liquid thawing the coil of a selected evaporator in relation to the embodiment of this system, during operation in a no-reheating configuration corresponding to the "no-dehumidification heating" function of the in-vehicle air according to the present invention, where thick lines with arrows indicate the refrigerant circuit, and letters enclosed in boxes indicate the same relevant sections in the reverse liquid thawing process flowchart of Figure 7; [Figure 15] Figure 15 is a flowchart relating to the embodiment of this system, as previously described with reference to Figure 9, and shows the "pump-down" operation to collect the refrigerant in the first vapor-liquid separator, which functions as a storage device, according to the present invention, where the thick lines with arrows indicate the refrigerant circuit; [Figure 16] Figure 16 is a scaled-down and rearranged version of the standard flow diagram already shown in Figure 10, where the elements of this system, affected by the circulation of the refrigerant, are arranged from bottom to top as a pressure rise function; [Figure 17]Figure 17 is a scaled-down and rearranged version of the standard flow diagram already shown in Figure 11, where the elements of this system, affected by the circulation of the refrigerant, are arranged from bottom to top as a pressure rise function; [Figure 18] Figure 18 is a scaled-down and rearranged version of the standard flow diagram already shown in Figure 12, where the elements of this system, affected by the circulation of the refrigerant, are arranged from bottom to top as a pressure rise function; [Figure 19] Figure 19 is a reduced and rearranged version of the flow diagram of the reverse liquid thawing process already shown in Figure 13, where the elements of this system, affected by the circulation of the refrigerant, are arranged from bottom to top as a pressure rise function, and the Greek letters indicate the same pressure levels as the Mollier diagram in Figure 8, according to the present invention; [Figure 20] Figure 20 is a reduced and rearranged version of the flow diagram of the reverse liquid thawing process already shown in Figure 14, where the elements of this system, affected by the circulation of the refrigerant, are arranged from bottom to top as a pressure rise function, and the Greek letters indicate the same pressure levels as the Mollier diagram in Figure 8, according to the present invention; [Figure 21] Figure 21 shows a section of an automatic valve of the type that automatically closes when the pressure at the intake port rises, and this valve only opens when the intake pressure is somewhat lower than the reference pressure. The reference pressure is, according to the present invention, the pressure at a convenient section of the closed-loop steam cycle cooling system supplied to the automatic valve by a narrow tube; [Figure 22] Figure 22 shows a section of one variation of an automatic valve, a type of valve that automatically closes when the pressure at the intake port rises. This valve only opens when the intake pressure is somewhat lower than the reference pressure. Unlike the aforementioned valve shown in Figure 21, the section of this valve has its main body simply located on the piston. This is essential for the elastic sealing element; [Figure 23]FIG. 23 is a specific flowchart of the reverse liquid thawing process shown in FIG. 14 and is related to embodying this system in accordance with the present invention shown in FIG. 9 and described above. Here, one group incorporating an appropriate number of valves, related sections, and tubes through which liquid flows is emphasized; [Figure 24] FIG. 24 is a flowchart of the reverse liquid thawing process shown in FIG. 14 and is related to embodying this system in accordance with the present invention shown in FIG. 9 and described above. This system is housed in the front bonnet of a general vehicle, and here an appropriate number of valves, related sections, and tubes through which liquid flows are incorporated into the group shown and described in FIG. 23; [Figure 25] FIG. 25 is during operation in a no-reheat configuration corresponding to the "heating without dehumidification" function of in-vehicle air conditioning housed in the front bonnet of a general vehicle, and is a flowchart related to a conventional heat pump mobile system using gas injection for in-vehicle air conditioning, as is well-known in the (latest) art. Here, the thick line with arrows indicates the refrigerant circuit, and the alphabet enclosed in a frame indicates some related sections similar to the flowchart of FIG. 24; [Figure 26] FIG. 26 is a flowchart of a thawing process related to the embodiment of a closed-loop vapor cycle type cooling system. Here, the thawing of the coil of one evaporator selected from a plurality of evaporators is achieved by a liquid refrigerant, which circulates through the said coil in the same direction as the normal flow, as is well-known in the art. This uses only and all the same devices as those that embody the discovered invention, as described above with reference to FIG. 6. Here, the thick line with arrows indicates the refrigerant circuit, and the alphabet enclosed in a frame indicates the same related sections shown in FIG. 7; [Figure 27] FIG. 27 is a KA curve of a gas cooling device that verified a case study for quantifying the overall efficiency improvement of the discovered system compared to those related to the state of the art, and is drawn as a power exchange function; [Figure 28] Figure 28 shows the efficiency of the first and second compression stages (isentropic and volumetric measurements) that verified a case study to quantify the overall efficiency improvement of the discovered system compared to those related to the prior art, and is reported as a function of the compression ratio; [Figure 29] Figure 29 consists of two graphs related to the verification of a case study to quantify the overall efficiency improvement of the discovered system compared to those related to the prior art. From the start of the conventional operating sub-cycle of the system taken as the reference, as time elapsed, and according to the first moment that coincided with the start of the first three consecutive operating sub-cycles of the discovered system, each shows the refrigerant temperature at the outlet of various "unthawed" evaporators and the overall heat transfer coefficient of various "unthawed" evaporators; [Figure 30] Figure 30 consists of four graphs related to the verification of a case study to quantify the overall efficiency improvement of the discovered system compared to those related to the prior art. As time elapsed from the start of the complete operating cycle of both the latest and the discovered systems, each shows the trend of the useful heat power ("heat"), the overall power consumption (including auxiliary devices), the effective COP, and the thawing heat power. Here, the values enclosed in the frames show the respective average values of each cycle; [Figure 31] Figure 31 consists of four graphs related to the variations of a case study verified to further quantify the overall efficiency improvement of the discovered system compared to those related to the prior art. As time elapsed from the start of the complete operating cycle of both the latest and the discovered systems, each shows the trend of the useful heat power ("heat"), the overall power consumption (including auxiliary devices), the effective COP, and the thawing heat power. Here, the values enclosed in the frames show the respective average values of each cycle. Description of the Embodiment and Its Operation

[0010] A detailed description of a closed-loop steam cycle type cooling system having multiple evaporators, in which one evaporator selected from among several evaporators is reverse-liquid-thawed by an appropriate comparative method, will be provided in comparison to the latest models.

[0011] Referring to Figure 1, as is well known in the (modern) art, this illustrates an embodiment of a closed-loop vapor cycle cooling system 10, which includes one or more compressors, such as compressors 12 and 13, for compressing a liquid refrigerant. The compressed refrigerant, now in a heated gaseous state, flows through or passes into a condenser 21 for cooling and condensation, and moves to a storage or receiving device 31 for accumulating the condensed refrigerant. The liquid refrigerant, having left the receiving device 31, then circulates through three expansion devices 43a-c to evaporate into three evaporators 41a-c, so as to cool the cooling space around the device or each evaporator. The evaporated refrigerant, in a cooled gaseous state, leaves the evaporators 41a-c and flows through three pipes 76a-c carrying individual cooled gases, moving to an intake manifold 77. This intake manifold 77 combines the flows of the three cooled gaseous refrigerants in the three cooled gaseous pipes 76a-c into a single intake pipe 79. This suction pipe 79 is connected to the inlets of compressors 12 and 13 to move the gaseous refrigerant from the evaporators 41a-c to the compressors 12 and 3. Generally, the condenser 21 includes a fan 221 to pass air into the condenser 21 to promote the condensation of the refrigerant. Furthermore, a pipe 71 carrying compressed heated gas connects the outlets of compressors 12 and 13 to the inlets of the condenser 21 to move the heated gas of the compressed refrigerant to the condenser 21. A pipe 72 carrying condensed refrigerant connects the outlet of the condenser 21 to the inlet of the receiving device or storage device 31 to accumulate the condensed refrigerant moving from the condenser 21 to the receiving device 31. A pipe 73 carrying liquid forward connects the outlet of the receiving device 31 to the inlets of each of the evaporators 41a-c by its three final sections 74a-c of liquid-carrying pipes. Each of the three final sections 74a-c of the forward-flowing liquid tube 73 passes through the corresponding expansion device: for example, the final section 74a of the forward-flowing liquid tube 73 passes through the expansion device 43a to supply liquid refrigerant to the evaporator 41a so that the liquid refrigerant can be evaporated by the coil 42a of the evaporator 41a. The same thing happens in the other evaporators.Furthermore, valve 110 is located upstream of the final section 74a-c of the liquid-carrying pipes in the forward-flowing pipe 73, and valve 111 is included in the bypass pipe of the forward-flowing pipe 73 surrounding valve 110. During normal operation of the closed-loop steam cycle cooling system 10, valve 110 is open while valve 111 is closed; conversely, during the thawing process of the selected evaporator, valve 110 is closed and valve 111 is open. In addition, the system 10 consists of three reverse-flowing liquid pipes 75a-c connecting the outlet of the receiving device 31 or the outlet of the condenser 21 to the outlet of the evaporators 41a-c in order to supply liquid refrigerant in the opposite direction to the normal flow during the thawing process. For example, the reverse-flow pipe 75a connects the outlet of the receiving device 31 or the outlet of the condenser 21 to the outlet of the evaporator 41a in order to supply liquid refrigerant to the evaporator 41a in the opposite direction to the normal flow during the thawing process of the evaporator 41a. Thus, the reverse-flow pipe 75a functions as a pipe that supplies the thawed liquid during the thawing process of the evaporator 41a. In Figure 1, the reverse-flow pipe 75a is depicted as branching off from the forward-flow pipe 73 located upstream of the valve 110, but it should be understood that this pipe could similarly start from the outlet of the receiving device 31 or the outlet of the condenser 21. Furthermore, in Figure 1, the reverse-flow pipe 75a is depicted as merging with the cooling gas pipe 76a, but it should be understood that this pipe could similarly terminate directly at the outlet of the evaporator 41a. A similar phenomenon occurs in the relationship between the pipes 75b and 75c, which carry liquid in the reverse direction, and the evaporators 41b and 41c.

[0012] Referring to Figure 1, the evaporator 41a is described in detail. The description of the evaporator 41a also applies equally to the evaporators 41b and 41c. The evaporator 41a includes one or more coils, such as coil 42a. The evaporator 41a also includes one or more temperature sensors 301a and 302a, which are located in the airflow entering coil 42a and in the pipe 76a that carries the cooling gas at the end of coil 42a, respectively. Temperature sensors 301a and 302a supply signals to the control unit 700. The evaporator 41a also includes a freeze detection device 308a that provides a signal to the control unit 700 to indicate whether a frozen state exists in coil 42a of the evaporator 41a. The evaporator 41a also includes a fan 241a for moving air over coil 42a and for circulating the cooling gas to the device and product being cooled. Furthermore, a pressure center 309a is also located in the tube 76a through which cooling gas flows at the end of the coil 42a, in order to provide a signal to the control device 700.

[0013] Referring again to Figure 1, liquid control valves are located in the pipes through which the liquid flows: in particular, defrosting liquid supply valves 101a-c are located in the pipes 75a-c that carry the liquid in the reverse direction, respectively; cooling gas valves 102a-c are located in the pipes 76a-c that carry the cooling gas, respectively. All of these valves are electrically connected to and under the control of the control circuit 700. A sensor 304 is located in one of the suction pipes 79 through which the liquid refrigerant is present to provide a signal to the control device 700. The control device 700 includes a control circuit having an input 701 for receiving signals from various sensors and an output 702 for sending control signals to various valves and other devices in order to control the operation of the cooling system 10. The bypass valve 111 is a differential pressure valve provided to create a pressure difference in the liquid refrigerant around the coil of the selected evaporator being defrosted during the defrosting process of the selected evaporator, thereby allowing the liquid refrigerant exiting the selected evaporator in the opposite direction to the normal flow to be released again into the forward-flowing pipe 73 downstream of the valve 110, and to supply liquid refrigerant to the expansion devices that supply other unselected evaporators. In particular, if the selected evaporator to be thawed is evaporator 41a, during the thawing process, the differential pressure valve 111 creates a pressure difference of liquid refrigerant around the coil 42a of the selected evaporator 41a to be thawed, thereby allowing the liquid refrigerant that has left evaporator 41a in the opposite direction to the normal flow to be released again into the liquid-forward flow pipe 73 downstream of the valve 110, circulate through the final sections 74b and 74c of the liquid-forward flow pipe 73, pass through expansion devices 43b and 43c, and then evaporate by passing through the coils 42b and 42c of evaporators 41b and 41c, respectively.

[0014] As is well known in the (modern) art, a multiple evaporator in a closed-loop vapor cycle cooling system that reverses liquid thawing one evaporator selected from multiple evaporators is achieved with at least two evaporators arranged in parallel in a normal flow. While the description of a particular embodiment compared to the latest is depicted as consisting of three evaporators arranged in parallel in a normal flow, as shown in Figure 1, this is intended to be valid for any number of evaporators, two or more.

[0015] Herein, in relation to a closed-loop vapor cycle type cooling system having multiple evaporators that reverse liquid thaw one selected evaporator, a reference is made to a detailed description of this system according to the present invention. This selected evaporator is one of the multiple evaporators and has its own expansion unit that supplies all evaporators in a normal flow.

[0016] Referring here to Figure 2, a recommended embodiment in this system according to the present invention is shown. Here, a closed-loop vapor cycle cooling system includes one or more compressors as compressors 12 and 13 for compressing a liquid refrigerant. Although compressors 12 and 13 are depicted as reciprocating compressors in Figure 2, it should be understood that they may also be centrifugal compressors, rotary compressors, scroll compressors, venturi compressors, jet enthalpy compressors, or other types of compressors, as are well known in the art, without departing from the scope of the present invention. The refrigerant, compressed into a heated gaseous state, flows through or passes into a condenser 21 for cooling and condensation, and moves to a storage or receiving device 31 for accumulating the condensed refrigerant. In the case of a transcritical cycle, the condenser 21 is replaced by a gaseous cooler, but this does not mean departing from the scope and concept of the present invention. This is resolved by defining the high-pressure, high-density refrigerant that leaves the gaseous cooler 21 and reaches the storage or receiving device 31 as a liquid refrigerant for appropriate simplification, in the case of a transitional criticality cycle. The liquid refrigerant leaving the receiving device 31 then moves to its own expansion device 61, which supplies three expansion devices 41a-c to cool the cooling space around the device or each evaporator, and evaporates. The evaporated refrigerant leaves the evaporators 41a-c in a cooled gaseous state, flows through three pipes 76a-c carrying the respective cooled gases, and moves to the intake manifold 77. This intake manifold 77 combines the flows of the three cooled gaseous refrigerants in the three cooled gaseous pipes 76a-c into a single intake pipe 79. This intake pipe 79 is connected to the intakes of the compressors 12 and 13. Generally, the condenser 21 includes a fan 221 to pass air into the condenser 21 to promote the condensation of the refrigerant. Furthermore, the pipe 71 through which the compressed heated gas flows connects the outlets of the compressors 12 and 13 to the inlet of the condenser 21 in order to move the compressed heated gaseous refrigerant to the condenser 21. The pipe 72 through which the condensed refrigerant flows connects the outlet of the condenser 21 to the inlet of the receiving device or storage device 31 in order to store the condensed refrigerant moving from the condenser 21 to the receiving device 31.A forward-flowing pipe 73 connects the outlet of the receiving device 31 to the inlet of its own expansion device 61. The liquid refrigerant leaving the receiving device 31 flows through its own expansion device 61. Three refrigerant-flowing pipes 74a-c connect the outlet of its own expansion device 61 to each of the multiple evaporators 41a-c in order to supply liquid refrigerant to the evaporators, with refrigerant-flowing pipe 74a supplying liquid refrigerant to the evaporator 41a. Furthermore, a valve 110 is located in the forward-flowing pipe 73, and a bypass pipe of the forward-flowing pipe 73 surrounding valve 110 includes valve 111. During normal operation, valve 110 is open while valve 111 is closed; conversely, during the thawing process of a selected evaporator, valve 110 is closed and valve 111 is open. Furthermore, system 10 consists of three reverse-flow liquid pipes 75a-c connecting the outlet of the receiving device 31 or the outlet of the condenser 21 to the outlets of the evaporators 41a-c in order to supply liquid refrigerant in the opposite direction to the normal flow during the thawing process. For example, reverse-flow liquid pipe 75a connects the outlet of the receiving device 31 or the outlet of the condenser 21 to the outlet of the evaporator 41a in order to supply liquid refrigerant to the evaporator 41a in the opposite direction to the normal flow during the thawing process of the evaporator 41a. Thus, reverse-flow liquid pipe 75a functions as a pipe that supplies thawing liquid during the thawing process of the evaporator 41a. In Figure 2, reverse-flow liquid pipe 75a is depicted as branching off from forward-flow liquid pipe 73 located upstream of valve 110, but it should be understood that this pipe can also be started in an equivalent manner from the outlet of the receiving device 31 or the outlet of the condenser 21. Furthermore, although Figure 2 depicts the pipe 75a carrying the liquid in the reverse direction merging with the pipe 76a carrying the cooling gas, it should be understood that this pipe can similarly terminate directly at the outlet of the evaporator 41a. The same applies to the relationship between the pipes 75b and 75c carrying the liquid in the reverse direction and the evaporators 41b and 41c.

[0017] As described above and shown in Figure 1, in contrast to the latest embodiment, as shown in Figure 2, the recommended embodiment of this system according to the present invention does not include multiple expansion devices (each expansion device is provided for each of the multiple evaporators). However, the individual expansion devices are common to all evaporators. Furthermore, the liquid-carrying pipes 74a-c in this recommended embodiment of this system according to the present invention (which, in the latest embodiment, are the final part of the liquid-carrying pipe 73, so that unexpanded liquid refrigerant traverses at least the section up to each expansion device 43) are pipes that carry the expanded refrigerant from the first part, and are further equipped with check valves.

[0018] Referring to Figure 2, the evaporator 41a is described in detail. The description of the evaporator 41a also applies equally to the evaporators 41b and 41c. As described above and shown in Figure 1, and as in the latest embodiment, the evaporator 41a includes one or more coils, such as coil 42a. The evaporator 41a also includes one or more temperature sensors 301a and 302a, which are located in the airflow entering coil 42a and in the pipe 76a that carries the cooling gas at the end of coil 42a, respectively. The temperature sensors 301a and 302a supply signals to the control device 700. The evaporator 41a also includes a freeze detection device 308a that provides a signal to the control device 700 to indicate whether a frozen state exists in coil 42a of the evaporator 41a, as is well known in the art. The evaporator 41a also includes a fan 241a for moving air over coil 42a and for circulating the cooling gas to the device and product being cooled. Furthermore, a pressure center 309a is also located at the end of the coil 42a in the pipe 76a through which the cooling gas flows, in order to provide a signal to the control device 700.

[0019] Referring again to Figure 2, liquid control valves are located in the pipes through which the liquid flows: in particular, the defrosting liquid supply valves 101a-c are located in the pipes 75a-c, respectively, through which the liquid flows in the reverse direction; and the cooling gas valves 102a-c are located in the pipes 76a-c, respectively, through which the cooling gas flows. All of these valves are electrically operated valves (such as solenoid valves), but a person skilled in the art will recognize that other types of valves can also be used without departing from the scope of the present invention. All of these valves are electrically connected to and under the control of the control circuit 700. A sensor 304 is located in one of the suction pipes 79 through which the liquid refrigerant is present, in order to provide a signal to the control device 700. The control device 700 includes a control circuit having an input 701 for receiving signals from various sensors and an output 702 for sending control signals to various valves and other devices in order to control the operation of the cooling system 10. Not all possible temperature and pressure sensors are shown for operating this cooling system. The control device 700 can be a programmable logic control device (PLC), a microcontroller, a microcomputer, or some microprocessor based on a control circuit well known in the art for controlling the operation of a closed-loop steam cycle cooling system. All possible connections of the output 702 of the control system 700 are not shown in this figure or subsequent figures. In further detail, only the connection of the output 702 from the control system 700 to some type of control device is shown. This type of control device can completely stop the flow of refrigerant in the pipe through which the liquid in which such a device is inserted flows. In contrast to the most recent embodiment as described above and shown in Figure 1, in the recommended embodiment of this system according to the present invention, as shown in Figure 2, the bypass pipe valve 111 is a more general electrically operated valve rather than a differential pressure valve. This bypass pipe valve 111 can be a throttle valve.Furthermore, system 10 includes three additional reverse-flow pipes 78a-c, each additional reverse-flow pipe 78 connecting a portion of the corresponding refrigerant-flow pipe 74 (located downstream of each check valve) to the low-pressure side of valve 110; each additional reverse-flow pipe 78 has a check valve, which allows the liquid refrigerant to flow during the thawing process of the corresponding evaporator. In fact, the refrigerant does not flow through these additional reverse-flow pipes 78a-c under normal operation, but only during the thawing process, which is described in detail below. This is the subject of the claims attached herein. Furthermore, in Figure 2, valves 101a-c, 102a-c, 110, and 111 are represented graphically in a different (less schematic) manner compared to Figure 1.

[0020] Referring to Figure 2, this is the normal operation of the cooling system 10 according to the present invention, and the operating state is such that none of the evaporators have been defrosted. Thus, valves 110 and 102a-c are open, but valves 111 and 101a-c are closed. The low-pressure gaseous refrigerant is compressed to high pressure by the compressors 12 and 13. The compressed heated gaseous refrigerant is then released into the heated gas pipe 71 and passes through the condenser 21. The condenser 21 cools and condenses the gaseous refrigerant by transferring heat from the refrigerant to the air. This can be forced through the condenser 21 by the fan 221. This condensed refrigerant is released from the condenser 21 into the receiving device 31 through the condensed refrigerant pipe 72. The liquid refrigerant that leaves the receiving device 31 flows through the liquid forward pipe 73, circulates through the open valve 110, and moves to its own expansion device 61. This liquid refrigerant expands into a layered cooling refrigerant as it passes through the expansion device 61. Subsequently, the cooling liquid refrigerant flows through refrigerant pipes 74a-c, circulates through individual check valves, and moves to the evaporators 41a-c. Specifically, pipe 74a supplies the cooling liquid refrigerant to the evaporators 41a-c. In the evaporators 41a-c, the cooling liquid refrigerant passes through coils 42a-c, where it evaporates and cools in a manner that circulates air to the device or cooling space being cooled. The heat circulated and transferred from the device or cooling space to the refrigerant can be increased by fans 241a-c. The refrigerant then changes from a cooling liquid state at the intake of the evaporators 41a-c to a cooled gas state that has evaporated at the outlets of those evaporators. Subsequently, the evaporated cooled gas refrigerant flows through cooling gas pipes 76a-c, moves to the intake manifold 77, and circulates through the corresponding open valves of cooling gas pipes 102a-c. The intake manifold 77 combines the flows of three evaporated refrigerant gases in three separate tubes 76a-c into a single intake pipe 79. This intake pipe 79 is connected to the intake ports of the compressors 12 and 13 to move the evaporated refrigerant gases from the evaporators 41a-c to the compressors 12 and 13. The cooling cycle of the cooling system 10 in the normal flow described above occurs when each of the multiple evaporators 41a-c operates normally and continuously.In other words, none of the evaporation devices have been defrosted.

[0021] Referring to Figure 2, the thawing process of one evaporator selected from several evaporators is explained for a case where a frozen state is detected in the coil 42a of evaporator 41a of the cooling system 10. Therefore, the selected evaporator to be thawed is evaporator 41a, while the unselected evaporators are evaporators 41b and 41c. If sufficient frost or ice accumulates in the coil 42a of evaporator 41a, its cooling performance will decrease, and the cooled device or cooling space will no longer be maintained at the desired temperature. Such a frozen state is detected by the freeze sensor 308a, which then transmits an electrical signal indicating the frozen state to the control device 700. Subsequently, the control device 700 initiates a thawing cycle for evaporator 41a. Alternatively, the thawing cycle can be automatically initiated by another thawing starter or timer. This timer sets how long a particular evaporator must operate normally before the thawing cycle begins. Referring to Figure 2, during the thawing cycle for the example described here, the operation of the cooling system 10 is controlled by the control device 700, and the valve 102a for the cooling gas flow pipe is closed to separate the evaporator 41a from the compressors 12 and 13. Subsequently, the thawing liquid supply valve 101a, located in the pipe 75a for the reverse flow of the liquid, opens slowly or pulsed to slowly pressurize a portion of the cooling gas flow pipe 76a located between the closed valve 102a for the cooling gas flow pipe and the evaporator 41a containing the thawing liquid. This slow pressurization of the portion of the cooling gas flow pipe 76a located between the closed valve 102a for the cooling gas flow pipe and the evaporator 41a prevents shock effects on both the cooling gas flow pipe 76a and the evaporator 41a itself. Subsequently, the valve 110 closes, and then the valve 111 of the bypass pipe opens. This bypass pipe valve 111 can be throttled open. The evaporator 41a is then thawed by the reverse flow of liquid refrigerant through the reverse-flowing pipe 75a and coil 42a. This liquid refrigerant has previously circulated through the open valve 101a for the reverse-flowing pipe.This liquid refrigerant releases heat as it passes through coil 42a in the opposite direction to the normal flow, melting the ice accumulated in coil 42a, thus thawing the coil when the liquid refrigerant is subcooled. The flow of the thawing liquid during the thawing process can be controlled by a pipe valve 101a that allows the liquid to flow in the reverse direction, so this valve functions as a thawing liquid supply valve. This subcooled liquid refrigerant exits the evaporator 41a in the opposite direction to the normal flow, enters a pipe 74a that carries the refrigerant in the opposite direction to the normal flow, exits the refrigerant pipe 74a, enters a pipe 78a that carries additional liquid in the reverse direction, circulates through the relevant check valves, and in this manner passes through the low-pressure side of valve 110. Here, the liquid refrigerant exiting the receiving device 31 and the liquid refrigerant that has passed through valve 111 with a bypass pipe that can be throttled open merge. Subsequently, this subcooled liquid refrigerant (the sum of the subcooled liquid refrigerant from the selected evaporator and the liquid refrigerant that exited the receiving device 31 and passed through the valve 111 with the bypass pipe open) enters the forward-flowing liquid pipe 73 located downstream of the valve 110 and moves to its own expansion device 61. As this subcooled liquid refrigerant passes through the expansion device 61, it flows into a mixture of liquid and vapor: that is, both the subcooled liquid refrigerant from the selected evaporator and the liquid refrigerant that exited the receiving device 31 and passed through the valve 111 with the bypass pipe open flow through it. After exiting its own expansion device 61, this subcooled liquid refrigerant then flows through two refrigerant pipes 74b and 74c, circulating through their respective check valves, and moves to two evaporators 41b and 41c, where it evaporates. This refrigerant changes from a liquid state at the inlets of these two evaporators 41b and 41c to a cooled gaseous state as it evaporates at the outlets of these evaporators. Subsequently, the evaporated refrigerant in a cooling gas state, having exited the two evaporators 41b and 41c, enters the two cooling gas pipes 76b and 76c, circulates through the open valves of the cooling gas pipes 102b and 102c, moves to the intake manifold 77, and then flows through a single intake pipe 79 to the intake ports of the compressors 12 and 13.Therefore, the cooling effect stored in the frost and ice accumulated on coil 42a of evaporator 41a is restored by subcooling with liquid refrigerant and then transmitted to the other two evaporators 41b and 41c. During this thawing cycle, fan 241a can be stopped and a signal from freeze detection device 308a is monitored. When coil 42a is completely thawed, the flow of thawed liquid is stopped by closing the thawed liquid supply valve 101a, then valve 110 opens to initiate the restoration of the normal flow of refrigerant, the cooling gas pipe valve 102a opens, and the bypass pipe valve 111 closes. Fan 241a is restarted if it was stopped during the thawing process of evaporator 41a. The cooling gas pipe valve 102a can be either pulsed or throttled to slowly allow any remaining liquid to flow through the cooling gas pipe 76a. During this time, liquid sensor 304 is carefully monitoring.

[0022] If liquid refrigerant is detected by the liquid sensor 304 while the pipe valve 102a through which the cooling gas flows is pulsed open or throttled open, a waiting period must be imposed or the pipe valve 102a through which the cooling gas flows must be suppressed. The above description regarding the thawing cycle for the selected evaporator 41a applies by analogy if the selected evaporator is evaporator 41b or evaporator 41c.

[0023] As shown in Figure 2, the description of a specific embodiment of this system according to the present invention is depicted as consisting of three evaporators arranged in parallel in a normal flow, but this is intended to be valid for any number of evaporators, two or more.

[0024] Here, this figure differs from the recommended embodiment shown in Figure 2 and described above. Specifically, it differs in that it has a discharge device 500 and a vapor-liquid separator 801 located in a pipe 73 through which the liquid flows in the forward direction. Since the discharge device (discharge device 500) has two inlets (power port and intake port) and one outlet (discharge port), the function of any discharge device (and therefore discharge device 500) can be described as if the discharge device ideally had two independent outlets. That is, two independent discharge ports. Thus, this is traversed by two independent ideal flows: the first ideal flow enters the power port and exits from the first of the two ideal discharge ports, and the second ideal flow enters the intake port and exits from the second of the two ideal discharge ports. The thermodynamic conditions are, of course, identical at the outlets of the discharge device for the two ideal flows. Furthermore, it is possible to ideally describe the function of any vapor-liquid separator as if it had not just one inlet but multiple independent inlets (in particular, the vapor-liquid separator 801). By making this statement, it is possible to ideally describe the function of the vapor-liquid separator 801 located downstream of the discharger 500, which is aligned with the pipe 73 through which the liquid flows in the forward direction, as if it had two independent ideal inlets for the two ideal flows described above: through the first ideal inlet of the vapor-liquid separator 801, the first ideal flow enters the discharger 500 through the power port 501 and exits through the first of the two ideal discharge ports of the discharger 500. Conversely, through the second ideal inlet of the vapor-liquid separator 801, the second ideal flow enters the discharger 500 through the intake port 502 and exits through the second of the two ideal discharge ports of the discharger 500. In either case, it is technically possible to use two parallel pipes, rather than one, to connect the unique physical outlet of the discharge device 500 to the unique physical inlet of the vapor-liquid separator 801.In this example, the two ideal parallel liquid-carrying tubes connecting the unique physical outlet of the discharger 500 and the unique physical inlet of the vapor-liquid separator 801 are understood as the first being a forward-carrying tube 73 and the second being a single inlet tube 79. The remaining components of the circuit 10 are the same as those already described for the preferred embodiment shown in Figure 2. In detail, as shown in Figure 3, the closed-loop vapor cycle type cooling system consists of two compressors 12 and 13 for compressing the gaseous refrigerant. The compressed heated gaseous refrigerant then flows to the condenser 21 by a heated gas-carrying tube 71 for cooling and condensation, and moves to the receiving or storage device 31 by a condensed refrigerant-carrying tube 72 for accumulating the condensed refrigerant. Subsequently, the liquid refrigerant flows through a forward-flowing pipe 73 connecting the outlet of the receiving device 31 to the inlet of its own expansion device 61, circulates through an open valve 110 for the forward-flowing pipe, then passes through the discharge device 500 via a power port, and then passes through the vapor-liquid separator 801. Therefore, under normal operation, the liquid refrigerant that leaves the receiving device 31 (after circulating through the open valve 110 for the forward-flowing pipe) flows mainly as a mixture of liquid and vapor when it passes through the discharge device 500. In this process, such a mixture is simply referred to as the mainly liquid refrigerant. This mainly liquid refrigerant that leaves the discharge device 500 then moves to the vapor-liquid separator 801, where it is separated into two phases: a liquid phase and a vapor phase. The liquid phase of the primarily liquid refrigerant continues to flow from the forward-flowing pipe 73 to its own expansion unit 61; thereafter, the liquid phase of the primarily liquid refrigerant flows through the refrigerant pipes 74a-c, circulating through individual check valves and moving to the inlets of the evaporators 41a-c. This liquid phase of the primarily liquid refrigerant then flows into the evaporators 41a-c so that it can cool the equipment or other cooling spaces surrounding each evaporator. This refrigerant changes from a liquid state at the inlets of the evaporators 41a-c to an evaporated cooling gas state at the outlets of the same evaporators. The evaporated cooling gas produced from the liquid phase of the primarily liquid refrigerant after exiting the evaporators 41a-c then flows through the cooling gas pipes 76a-c, circulating through the open valves 102a-c for the cooling gas pipes and moving to the intake manifold 77.The intake manifold 77 combines the flows of three evaporative cooling gases into a single intake pipe 79. The flow of one evaporative cooling gas, mainly consisting of the liquid phase of the liquid refrigerant, flows through the intake pipe 79 and circulates through the discharge device 500 via the intake port 502, where its pressure increases. Subsequently, the evaporative cooling gas refrigerant flow, which has increased in pressure and mainly consisting of the liquid phase of the liquid refrigerant, flows into the vapor-liquid separator 801, where it merges with the aforementioned vapor phase of the liquid refrigerant and flows together to the intake ports of the compressors 12 and 13. Thus, the vapor-liquid separator 801 functions as a storage device for the compressors 12 and 13.

[0025] Referring to Figure 3, elements 42a-c and all check valves not yet mentioned as 75a-c, 78a-c, 101a-c, 111, 221, 241a-c, 301a-c, 302a-c, 304, 308a-c, 309a-c, 700, 701, and 702 are located within System 10 and have the same function as the recommended embodiment shown in Figure 2 and described above.

[0026] As shown in Figure 3, this description of another embodiment of this system according to the present invention is depicted as consisting of three evaporators arranged in parallel in a normal flow, but this is intended to be valid for any number of evaporators, two or more.

[0027] Referring to Figure 3, the thawing process of the selected evaporator 41a is described in this other embodiment of the system according to the present invention. More specifically, during the thawing process of the selected evaporator 41a, the circulation of the refrigerant proceeds in exactly the same manner as already described for the thawing process of the selected evaporator 41a, compared to the recommended embodiment shown in Figure 2, except that the subcooled liquid refrigerant coming from the selected evaporator 41a and passing through the low-pressure side of the closed valve 110 for the pipe carrying the liquid forward merges with the liquid refrigerant coming out of the receiving device 31 and passes through the open valve 111 of the bypass pipe. From this point onward, in contrast to what has already been described compared to the recommended embodiment shown in Figure 2, these subcooled liquid refrigerants (the sum of the subcooled liquid refrigerants coming from the selected evaporator 41a and the liquid refrigerants coming from the receiving device 31 and passing through the open valve 111 of the bypass pipe) exit the low-pressure side of the valve 110 for the forward-flowing pipe and enter the discharge device 500 through the power port, where they mix with a mixture of liquid and vapor. In this process, these mixtures are shown in a form similar to normal operation, which has already been simply described as mainly liquid refrigerants. Subsequently, the mainly liquid refrigerants move to the vapor-liquid separator 801, where they are separated into two phases: a liquid phase and a vapor phase. The liquid phase of this mainly liquid refrigerant continues to flow through the forward-flowing pipe 73 to its own expansion device 61. Subsequently, the liquid phase of this mainly liquid refrigerant flows through the expansion device 61. Subsequently, the liquid phase flow of this primarily liquid refrigerant flows only through refrigerant pipes 74b and 74c, circulating through their respective check valves and being supplied to two unselected evaporators 41b and 41c, where it evaporates. This refrigerant changes from a liquid state at the inlets of these two evaporators 41b and 41c to a cooled gaseous state as it evaporates at the outlets of these evaporators.Subsequently, the evaporative cooling gas, mainly from the liquid phase of the liquid refrigerant, exits the two unselected evaporators 41b and 41c, flows through two cooling gas pipes 76b and 76c, circulates through open valves 102b and 102c for each cooling gas pipe, moves to the suction manifold 77, then circulates through one suction pipe 79, passes through the discharge device 500 via the suction port 502, and is pressurized thereafter. The evaporative cooling gas, now pressurized and mainly from the liquid phase of the liquid refrigerant, then flows to the vapor-liquid separator 801, from where it merges with the vapor phase of the liquid refrigerant and together flows to the compressors 12 and 13. As shown in Figure 3, the above description of the thawing cycle for the selected evaporator 41a in this other embodiment according to the present invention is applied by analogy when the selected evaporator is evaporator 41b or evaporator 41c. Now referring to Figure 4, another embodiment of this system according to the present invention is shown. In contrast to the embodiment shown in Figure 3 and described above, this system 10 is further comprised of an auxiliary expansion device 62 located at the end of an auxiliary liquid-carrying pipe 80. This auxiliary liquid-carrying pipe 80 branches off from a forward-carrying liquid pipe 73, and in particular connects the low-pressure side of the forward-carrying liquid pipe 110 to the intake of the auxiliary expansion device 62. Three auxiliary refrigerant-carrying pipes connect the outlet of the auxiliary expansion device 62 to portions of the three refrigerant-carrying pipes 74a-c, each portion of which is located between a corresponding check valve and a corresponding evaporator 41. Each of these three auxiliary refrigerant-carrying pipes has a separation valve 401. For example, the auxiliary refrigerant pipe connecting the outlet of the auxiliary expansion device 62 to a portion of the refrigerant pipe 74c (located between the corresponding check valve and the corresponding evaporator 41c) includes a separation valve 401c. The same occurs in the relationship between valves 401a and 401b and evaporators 41a and 41b. These separation valves 401a-c are general control valves (such as solenoid valves).Another difference is that this system 10 is further composed of three separation valves 402a-c, each of which is located in a pipe 76 carrying its respective cooling gas, between the corresponding cooling gas pipe valve 102 and the suction manifold 77. For example, separation valve 402c is located in a pipe 76c carrying the cooling gas, between the corresponding cooling gas pipe valve 102c and the suction manifold 77. The same thing happens with valves 402a and 402b. Another difference is that system 10 is composed of three auxiliary cooling gas pipes 81a-c, each of which directly connects a portion of the corresponding cooling gas pipe 76 (this portion is located between the corresponding cooling gas pipe valve 102 and the corresponding separation valve 402) to the vapor-liquid separator 801. This connection is via an ideal third intake port of the vapor-liquid separator 801. This will be further explained below, as it allows the refrigerant, which has evaporated and become a cooling gas after leaving the evaporators 41a-c, to bypass both the intake manifold 77 and the discharge device 500 and enter the vapor-liquid separator 801. Each of these three auxiliary cooling gas tubes 81a-c has a check valve.

[0028] Referring to Figure 4, element 12 and other check valves not yet mentioned as 13, 21, 31, 42a-c, 61, 71, 72, 75a-c, 78a-c, 79, 101a-c, 111, 221, 241a-c, 301a-c, 302a-c, 304, 308a-c, 309a-c, 501, 502, 700, 701, and 702 are located within the system 10 and in the same positions as the embodiment shown in Figure 3 and described above, and have the same function. In particular, as stated above, the function of the discharge device 500 can ideally be as if the discharge device 500 had two independent outlets; that is, two independent discharge ports. Therefore, this is traversed by two independent ideal flows: the first ideal flow enters the power port 501 and exits through the first of the two ideal discharge ports, and the second ideal flow enters the intake port 502 and exits through the second of the two ideal discharge ports. The thermodynamic conditions are, of course, identical at the outlets of the discharge devices for the two ideal flows.

[0029] Furthermore, as already anticipated, and similar to the embodiment shown in Figure 3 and described above, in this embodiment shown in Figure 4, it is possible to ideally describe the function of the vapor-liquid separator 801 as if it had three independent ideal inlets: through the first ideal inlet of the vapor-liquid separator 801, the first ideal flow enters the discharge device 500 through the power port 501 and exits through the first of the two ideal discharge ports of the discharge device 500. Conversely, through the second ideal inlet of the vapor-liquid separator 801, the second ideal flow enters the discharge device 500 through the intake port 502 and exits through the second of the two ideal discharge ports of the discharge device 500. Finally, as described above, the third ideal inlet of the vapor-liquid separator 801 is connected to a common end section. In other words, this is the downstream portion of each check valve, which is the pipe 81a-c through which the three auxiliary cooling gases flow, and is not crossed by any refrigerant flow during normal operation, but is crossed only when the selected evaporator is thawed. This will be explained further below.

[0030] As shown in Figure 4, this description of another embodiment of this system according to the present invention is depicted as consisting of three evaporators arranged in parallel in a normal flow, but this is intended to be valid for any number of evaporators, three or more.

[0031] Referring to Figure 4, during normal operation, the three separation valves 401a-c are closed: therefore, the refrigerant does not flow through the auxiliary liquid pipe 80, does not pass through the auxiliary expansion device 62, and does not flow through the three auxiliary refrigerant pipes initiated from the auxiliary expansion device 62. Furthermore, due to the presence of check valves located in the three auxiliary cooling gas pipes 81a-c, during normal operation, the refrigerant does not flow through any of these three auxiliary cooling gas pipes 81a-c. Conversely, during normal operation, the refrigerant enters the intake manifold 77 through the three open separation valves 402a-c. Thus, normal operation is exactly the same as described with reference to the embodiment shown in Figure 3, except that the refrigerant circulates after evaporating and becoming a cooling gas through the three open separation valves 402a-c.

[0032] Referring to Figure 4, the thawing cycle of the selected evaporator 41a is described in detail. In particular, a thawing cycle for an exemplary case is described, in which a frozen state is detected in the coil 42a of the evaporator 41a of the cooling system 10, the coil 42a of evaporator 41a is just thawed, and the coil 42b of evaporator 41b is partially frozen but does not yet need to be thawed. In the initial stage, during normal operation, valve 110, valves 102a-c, and the aforementioned separation valves 402a-c are open, while valve 111, valves 101a-c, and the aforementioned separation valves 401a-c are closed. When the freezing sensor 308a detects the frozen state of the coil 42a in evaporator 41a, the control circuit 700 starts the thawing cycle for evaporator 41a. During the thawing cycle in this exemplary case, the compressed and heated refrigerant exiting the compressors 12 and 13 flows to the condenser 21 via the heated gas channel 71 for cooling and condensation, and the condensed refrigerant moves to the storage or receiving device 31 via the condensed refrigerant channel 72 for storage; the liquid refrigerant then flows through the liquid forward channel 73. Subsequently, the cooling gas channel valve 102a closes, and the evaporator 41a is separated from the compressors 12 and 13. Then, the thawing liquid supply valve 101a, located in the liquid reverse channel 75a, slowly or pulses open to slowly pressurize a portion of the cooling gas channel 76a, which is located between the closed cooling gas channel valve 102a and the evaporator 41a containing the thawing liquid. This slow pressurization of a portion of the cooling gas pipe 76a, positioned between the closed valve 102a for the cooling gas pipe and the evaporator 41a, prevents a shock event between the cooling gas pipe 76a and the evaporator 41a. Subsequently, valve 110 closes, then the bypass pipe valve 111 opens, followed by the separation valve 402c closing, and then the separation valve 401c opening. This bypass pipe valve 111 can be throttled open. At this point, the reverse flow of liquid refrigerant defrosts the evaporator 41a by passing through the reverse liquid flow pipe 75a, circulating through the open defrost liquid supply valve 101a, and then through the coil 42a.As the liquid refrigerant passes through coil 42a in the opposite direction to the normal flow, it releases heat, melting the ice accumulated in coil 42a, thus thawing coil 42a. Simultaneously, the liquid refrigerant is subcooled. The flow of the thawed liquid while coil 42a is thawing can be controlled by the open thawed liquid supply valve 101a. This subcooled liquid refrigerant exits evaporator 41a in the opposite direction to the normal flow, enters pipe 74a which carries refrigerant in the opposite direction to the normal flow, then enters pipe 78a which carries additional liquid in the reverse direction, circulating through individual check valves, and in this manner passes through the low-pressure side of pipe valve 110 which carries liquid in the forward direction. Here, the liquid refrigerant exiting from receiving device 31 and the liquid refrigerant that has passed through the open valve 111 of the bypass pipe merge. Subsequently, one flow of such subcooled liquid refrigerant (the sum of the subcooled liquid refrigerant coming from the selected evaporator 41a and the liquid refrigerant coming from the receiving device 31 and passing through the open valve 111 of the bypass pipe) exits the low-pressure side of the valve 110 for the pipe that allows liquid to flow in the forward direction, and is divided into a first part of subcooled liquid refrigerant and a second part of subcooled liquid refrigerant. This first part of subcooled liquid refrigerant flows through the pipe 73 that allows liquid to flow in the forward direction and passes through the discharge device 500 via the power port 501; conversely, the second part of subcooled liquid refrigerant flows through the pipe 80 that carries auxiliary liquid to move to the auxiliary expansion device 62. This second part of subcooled liquid refrigerant passes through the auxiliary expansion device 62. Subsequently, the second portion of the subcooled liquid refrigerant that exits the auxiliary expansion device 62 flows through an auxiliary refrigerant flow pipe connecting the outlet of the auxiliary expansion device 62 to a portion of the refrigerant flow pipe 74c, circulates through the open separation valve 401c, and enters the coil 42c of the evaporator 41c via the final portion of the refrigerant flow pipe 74c to evaporate. This final portion is located downstream of each check valve. This refrigerant changes from a subcooled liquid state at the inlet of the evaporator 41c to an evaporated cooled gas state at the outlet of the evaporator.Subsequently, the evaporated cooling gaseous refrigerant from the second portion of the subcooled liquid refrigerant exits the evaporator 41c, flows through the cooling gas pipe 76c, circulates through the open valve 102c for the cooling gas pipe, then flows through the auxiliary cooling gas pipe 81c, circulating through its respective check valves. This is how it reaches the vapor-liquid separator 801 directly, without passing through the intake manifold 77 and the discharge device 500, because valve 402c closes. Conversely, the first portion of the subcooled liquid refrigerant, flowing through the forward-flowing liquid pipe 73, enters the discharge device 500 through the power port 501. As this first portion of subcooled liquid refrigerant passes through the discharge device 500, it mixes with a mixture of liquid and vapor; in this process, such a mixture originating solely from the first portion of subcooled liquid refrigerant is referred to as the first portion of subcooled liquid refrigerant. The first portion of this subcooled liquid refrigerant enters the vapor-liquid separator 801, where it is separated into a liquid phase and a vapor phase. The liquid phase of this first portion of subcooled liquid refrigerant, exiting the vapor-liquid separator 801, passes through the expansion unit 61. This liquid phase of the first portion of subcooled liquid refrigerant passes through the expansion unit 61 at a somewhat lower pressure than the second portion of subcooled liquid refrigerant, which exits the auxiliary expansion unit 62. Subsequently, the liquid phase of this first portion of subcooled liquid refrigerant exits the expansion unit 61, flows through the refrigerant pipe 74b, passes through the relevant check valve, and moves to the coil 42b of the evaporator 41b, where it evaporates. This refrigerant changes from a liquid state at the inlet of the evaporator 41b to a cooled gas state at the outlet of the same evaporator. Subsequently, the refrigerant that has evaporated from the liquid phase of the first portion of the subcooled liquid refrigerant and become a cooling gas leaves the evaporator 41b, passes through the cooling gas pipe 76b, circulates through the open valve 102b for the cooling gas pipe, passes through the open separation valve 402b, then passes through the suction manifold 77, then flows through one suction pipe 79, circulates through the suction port 502 of the discharge device 500 and is pressurized.Subsequently, the pressurized, evaporated refrigerant gas generated from the liquid phase of the first portion of the subcooled liquid refrigerant exits the discharge device 500 through one suction pipe 79 and enters the vapor-liquid separator 801, where it merges with both the vapor phase of the first portion of the subcooled liquid refrigerant and the evaporated refrigerant gas generated from the second portion of the subcooled liquid refrigerant that exited the evaporator 41c. Together with these two other refrigerant flows, it flows through the suction pipe 79 and moves to the inlets of the compressors 12 and 13. As a result, the pressure at the inlets of the compressors 12 and 13 is ultimately the pressure of the evaporated refrigerant gas generated from the second portion of the subcooled liquid refrigerant that exited the evaporator 41c, i.e., the evaporation pressure of the evaporator 41c, without any final decrease. This evaporation pressure is, as described above, somewhat higher than the evaporation pressure of the evaporator 41b. Therefore, the suction pressure of the compressors 12 and 13 ultimately does not decrease, but during the thawing cycle of the exemplary case, it remains the higher of the evaporation pressures of the two independent, unselected evaporators 41b and 41c. This is explicitly observed because, during the thawing process of the exemplary case described here, the valve 102a for the pipe carrying the cooling gas is closed, and therefore the open / closed state of the separation valve 402a is unrelated to the fact that it is not supplied to this separation valve. Thus, compared to normal operation, valves 101b-c and 401a-b remain closed during the thawing cycle of the exemplary case, while valves 101a, 111, and 401c are open. Conversely, compared to normal operation, valves 102b, 102c, and 402b remain open during the thawing cycle of the exemplary case, while valves 102a, 110, and 402c are closed. On the other hand, valve 402a can be left open or closed independently.

[0033] Referring to Figure 5, another embodiment of this system according to the present invention is shown. Here, in contrast to the embodiment shown in Figure 4 and described above, the cooling system 10 has a check valve on the outlet side rather than a typical control valve (such as a solenoid valve), and the separation valve is of the type that automatically closes when the pressure at the intake port rises. Each of the valves that automatically closes when the pressure at the intake port rises opens only when the intake pressure is somewhat lower than the reference pressure; the reference pressure is the pressure of a convenient section of a closed-loop steam cycle cooling system that is supplied by a narrow tube to the valves that automatically close when the pressure at the intake port rises, as will be described in more detail below.

[0034] Referring to Figure 5, the valve 401c, which is of the type that automatically closes when the pressure at the intake port rises, is initially closed during normal operation. In fact, the reference pressure of the valve 401c, which is of the type that automatically closes when the pressure at the intake port rises, is the intake pressure of the evaporator 41a. During normal operation, the intake pressure of the evaporator 41a is the low pressure of the refrigerant that has left the expansion device 61. Conversely, in order for the refrigerant to pass through the automatic valve 401c in the direction from the auxiliary expansion device 61 toward the intake port of the evaporator 41c, the pressure upstream of the valve 401c cannot be lower than the pressure downstream of the valve itself. Furthermore, the pressure downstream of the automatic valve 401c is a low pressure at the inlet of the evaporator 41c. That is, it is the pressure of the refrigerant that has left the expansion device 61, and is the reference pressure. Therefore, during normal operation, the intake pressure of the automatic valve 401c cannot be lower than the reference pressure, so the automatic valve 401c is closed. The explanation of the conditions under which valve 401c, which automatically closes when the pressure at the intake port rises, closes during normal operation, applies similarly to automatic valves 401a and 401b. This is because the reference pressure for valve 401a, which automatically closes when the pressure at the intake port rises, is the pressure at the intake port of evaporator 41b, and the reference pressure for valve 401b, which automatically closes when the pressure at the intake port rises, is the pressure at the intake port of evaporator 41c.

[0035] On the other hand, during the thawing process of the exemplary case, the pressure at the inlet of the selected evaporator 41a is high because it is the pressure of the subcooled liquid refrigerant. Always, during the thawing process of the exemplary case, the suction pressure of the automatic valve 401c is the low pressure of the refrigerant exiting the auxiliary expander 62. Therefore, the suction pressure of the automatic valve 401c is certainly somewhat lower than the reference pressure during the thawing process of the exemplary case. Consequently, the automatic valve 401c opens.

[0036] Conversely, during the thawing process of the exemplary case, the suction pressure of automatic valve 401a is higher than the reference pressure: in fact, as mentioned above, the suction pressure of automatic valve 401a is the evaporation pressure of evaporator 41c, which is somewhat higher than the evaporation pressure of evaporator 41b, as mentioned above, so automatic valve 401a remains closed. Finally, during the thawing process of the exemplary case, the suction pressure of automatic valve 401b is the same as the suction pressure of automatic valve 401c, while the reference pressure of automatic valve 401b is the same as the discharge pressure of automatic valve 401c. Therefore, the suction pressure of automatic valve 401b is not lower than the reference pressure: thus, automatic valve 401b remains closed.

[0037] Referring to Figure 5, the valves 402a-c, which are of the type that automatically close when the pressure at the three inlets rises, are initially open during normal operation. In fact, the reference pressure of the three automatic valves 402a-c is the pressure at the common final section of the three auxiliary cooling gas pipes 81a-c (located downstream of each check valve). Here, there are no further elements placed before the vapor-liquid separator 801, and the pressure is the same as that of the vapor-liquid separator 801, i.e., the same as the high pressure at the inlet of the expansion unit 61. Conversely, the suction pressure of the automatic valves 401a-c is the low pressure of the evaporated refrigerant. Therefore, the suction pressure of the automatic valves 401a-c is certainly lower than the reference pressure during normal operation, so the automatic valves 401a-c are open.

[0038] Referring to Figure 5, the valve 402b, which is of the type that automatically closes when the pressure at the intake rises, remains open during the thawing process in the exemplary case. This is because, in this case, the pressure in the vapor-liquid separator 801, i.e., the reference pressure of valve 402b, is ultimately equal to the evaporation pressure of the evaporator 41c, without decreasing. As mentioned above, this pressure is somewhat higher than the evaporation pressure of the evaporator 41b. Therefore, since the intake pressure of the automatic valve 402b is somewhat lower than the reference pressure, the automatic valve 402b remains open.

[0039] Referring to Section 5, it is clearly shown that during the thawing process of the exemplary case, the pressure upstream of the check valve in the tube 81c carrying the auxiliary cooling gas is the same as, or certainly not lower than, the pressure downstream of the check valve itself. Therefore, during the thawing process of the exemplary case, the valve 402c, which is of the type that automatically closes when the pressure at the intake rises, closes because the intake pressure of this automatic valve 401c is the same as the pressure upstream of its own check valve and certainly not lower than the pressure downstream of its own check valve, i.e., not lower than the reference pressure.

[0040] As has already been stated for the embodiment of the system shown in Figure 4 and described above, and as has already been stated for this other embodiment of the system according to the present invention shown in Figure 5, during the thawing process of the exemplary example, the open / closed state of the separation valve 402a is irrelevant to whether or not it is an automatic valve, because the pipe 102a through which the cooling gas flows is closed. Compared to the embodiment shown in Figure 4 and described above, it is clear that in this other embodiment of the system according to the present invention shown in Figure 5, there are fewer busy states at output 702 of the control device 700.

[0041] Referring to Figure 5, element 12 and other check valves not yet mentioned as 13, 21, 31, 42a-c, 71, 72, 73, 74a-c, 75a-c, 76a-c, 77, 78a-c, 79, 80, 101a-c, 102b-c, 110, 111, 221, 241a-c, 301a-c, 302a-c, 304, 308a-c, 309a-c, 500, 501, 502, 700, 701, and 702 are located within system 10 and in the same positions as in the embodiment shown in Figure 4 and described above, and have the same function. More specifically, for this other embodiment shown in Figure 5 according to the present invention, both the normal operation and defrosting process for exemplary cases are the same as in the embodiment shown in Figure 4 and described above.

[0042] Referring now to Figure 6, another embodiment of this system according to the present invention is shown. Here, in contrast to the embodiment shown in Figure 5 and described above, system 10 further comprises a second auxiliary expansion device 63 and a second vapor-liquid separator 802, arranged by an auxiliary liquid-carrying pipe 80. Furthermore, system 10 comprises two other parallel compressors 14 and 15, which are arranged in series downstream of the parallel compressors 12 and 13, so that this vapor compression is a two-stage compression. Furthermore, system 10 comprises a supplemental liquid-carrying pipe 82 connecting the outlet of the second vapor-liquid separator 802 to the inlet of the second compression stage. This inlet of the second compression stage is the outlet of the first compression stage. Furthermore, two independent ideal liquid-carrying pipes that exit the discharge device 500 and enter the first vapor-liquid separator 801 merge here into a single liquid-carrying pipe. Here, the common final section of the three auxiliary cooling gas pipes 81a-c also converges. This is located downstream of each check valve. This unique liquid pipe, which exits the discharge unit 500 through its own physical discharge port numbered 503 and enters the inlet of the first vapor-liquid separator 801 through its own physical intake port, also converges with the common final section of the three auxiliary cooling gas pipes 81a-c located downstream of each check valve, and is therefore assumed to terminate at the power port 501 of the discharge unit 500, as it is the intake pipe 79. Furthermore, the liquid pipe connecting the first vapor-liquid separator 801 to its own expansion unit 61, which supplies all the evaporators of the multiple evaporators in a normal flow, was previously an integral part of the liquid pipe 73, but is now numbered as a further independent supplemental liquid pipe 83. Finally, an additional check valve is located in the suction pipe 79 to prevent overflow of the discharge device during "shutting down," between the junction of the common final section of the three auxiliary cooling gas pipes 81a-c and the suction port of the first vapor-liquid separator 801.Referring to Figure 6, element 21 and check valves not yet mentioned as 31, 41a-c, 42a-c, 62, 71, 72, 74a-c, 75a-c, 76a-c, 77, 78a-c, 101a-c, 102a-c, 110, 111, 221, 241a-c, 301a-c, 302a-c, 304, 308a-c, 309a-c, 401a-c, 402a-c, 502, 700, 701, and 702 are located within system 10 and in the same positions as the embodiment shown in Figure 5 and described above, and have the same function. More specifically, for this other embodiment shown in Figure 6 according to the present invention, normal operation is the same as that relating to the two embodiments shown in Figures 4 and 5 and described above. Conversely, the thawing process of the exemplary case differs from this embodiment shown in Figure 6 in that, as shown in Figures 4 and 5 and described above, the second portion of the subcooled liquid refrigerant passes through the second auxiliary expansion unit 63 before being separated into two phases, a liquid phase and a vapor phase, in the second vapor-liquid separator 802. The vapor phase of the second portion of the subcooled liquid refrigerant flows through the supplemental liquid pipe 82 and moves to the intake of the second compression stage. Conversely, the liquid phase of the second portion of the subcooled liquid refrigerant entering the first auxiliary expansion unit 62 behaves as described as the "non-flowing" portion of the second portion of the subcooled liquid refrigerant entering the first auxiliary expansion unit 62 during the thawing process of the exemplary case related to the two embodiments shown in Figures 4 and 5 and described above. Finally, the first portion of the subcooled liquid coolant flows in the same manner as already described for the thawing process of the exemplary cases related to the two embodiments shown in Figures 4 and 5 above.

[0043] More specifically, for the operation of the embodiment shown and verified here in Figure 6, during the thawing process of the exemplary case, one can refer to Figure 7, which shows a flow chart of the reverse liquid thawing process for the exemplary case. In other words, to reiterate, this is an example where the frozen state is detected in coil 42a of evaporator 41a of cooling system 10, coil 42c of evaporator 41c is just thawed, and coil 42b of evaporator 41b is partially frozen but does not yet need to be thawed, so the evaporation pressure to coil 42c, which is somewhat higher than the evaporation pressure to coil 42b, eventually matches the suction pressure of compressors 12 and 13 without decreasing. In the flow chart of Figure 7, the thick lines with arrows indicate the refrigerant circuit, and the letters enclosed in boxes indicate some of the relevant sections of system 10.

[0044] For simplicity, with reference to Figure 6, these are not shown in the two similar flow diagrams of the individual reverse liquid thawing processes for evaporators 41b and 41c in relation to the aforementioned embodiment.

[0045] Referring now to Figure 8, which, as previously mentioned with reference to an emulation of Figure 6, shows a Mollier diagram illustrating the thermodynamic state of the low-boiling point refrigerant as carbon dioxide circulating within this system. This diagram represents the thawing process in the relevant section of the system, as indicated by the boxed letters in the flow chart of Figure 7, representing an exemplary example. A larger letter size indicates a larger mass flow rate of the refrigerant in the corresponding section. The Greek letters indicate various pressure levels in the thermodynamic cycle.

[0046] Referring to Figure 9, another embodiment of this system according to the present invention is shown. Here, in contrast to the embodiment shown in Figure 6 and described above, system 10 is modified and adapted for use as a heat pump mobile system for in-vehicle air conditioning at various reheating performance levels. More specifically, this most recent embodiment of this system according to the present invention differs from the embodiment shown in Figure 6 and described above. The main reasons for this are the presence of another auxiliary expansion device 64 and an external heat exchanger 51 located in a further supplemental liquid-flowing pipe 84 branching off from the liquid-forward-flowing pipe 73, the presence of a first end section on the low-pressure side of the liquid-forward-flowing pipe valve 110, and a second end section corresponding to a common part of the three auxiliary cooling gas-flowing pipes 81a-c, i.e., located downstream of their respective check valves. The external heat exchanger 51 is located in the case 901 of the in-vehicle air conditioning unit 900 and its interior is further comprised of a condenser 21, a blower 251 replacing the fan 221, an air mix door 902, and a bypass path 903 around the condenser 21. More specifically, the blower 251 is located on the inlet side of the external heat exchanger 51 and provides ventilation for the entire case 901. The air mix door 902 is located on the exhaust side of the external heat exchanger 51 and on the intake side of the ventilation for both the condenser 21 and the bypass path 903. The air mix door 902 serves to regulate the ratio between the amount of air passing through the condenser 21 and the amount of air passing through the bypass path 903. This air is the ventilation air that has already passed through the external heat exchanger 51. On the discharge side of the ventilation airflow in either the condenser 21 or the bypass path 903, a mixing space (not shown in Figure 9) is provided to mix the ventilation air heated by the condenser 21 with the ventilation air that has passed through the bypass path 903, which is not heated by the condenser 21. An opening (not shown in Figure 9) is provided at a distant location on the downstream side of the ventilation airflow in case 901 for blowing the ventilation air mixed (and thus conditioned) in the mixing space into the vehicle interior (the vehicle interior intended to be a space conditioned by air).The external heat exchanger 51 includes one or more temperature sensors, specifically a temperature sensor 351 located in a pipe 84 that carries additional supplemental liquid to its final section. Furthermore, in this other embodiment shown in Figure 9, the valve 110 is a three-way valve to obstruct the flow of refrigerant in the pipe 84 that carries additional supplemental liquid. In addition, the second auxiliary expander 63 located in the pipe 80 that carries auxiliary liquid is replaced by an expander compressor group 600. Here, a portion of the subcooled liquid refrigerant exiting the low-pressure side of the forward-flowing pipe valve 110 flows through the auxiliary liquid pipe 80, passes through the suction port 601 of the expander in the expander compressor group 600, then through the discharge port 603 of the expander compressor group 600, and then enters the second vapor-liquid separator 802. Due to this replacement, the auxiliary expander 64 added hereafter will be referred to as the second auxiliary expander. The outlet of the expander compressor group corresponds to both the expander outlet and the compressor outlet of the expander compressor group. Furthermore, although Figure 9 depicts the expander compressor group having its own shaft common to both the expander and the compressor, it is intended that other forms of mechanical and / or electrical connections can be used between the two components of the expander compressor group without departing from the scope of the present invention.

[0047] Referring to Figure 9, a third auxiliary expansion device 65 and check valve are located in the pipe 84 carrying the already refined supplemental liquid downstream of the external heat exchanger 51. This third auxiliary expansion device 65 can also be an EPR (Evaporation Pressure Control Unit). Furthermore, in this other embodiment shown in Figure 9, there is no receiving or storage device 31 because the functions of these devices are performed by the first vapor-liquid separator 801. The pipe 72 carrying the condensing refrigerant is incorporated into the pipe 73 carrying the liquid in the forward direction, thus connecting the outlet of the condenser 21 to the power port 501 of the discharge device 500. Furthermore, each pair of valves 101 and 102 is replaced with a suitable three-way valve 103. For example, the pair of valves 101a and 102a is replaced with a suitable three-way valve 103a. The same thing happens with three-way valves 103b and 103c. Furthermore, system 10 comprises a further supplemental liquid flow pipe 85 having a first end section corresponding to a common portion of the three auxiliary cooling gas flow pipes 81a-c, which are located downstream of each check valve and upstream of the second end section of the aforementioned supplemental liquid flow pipe 84, and a second end section corresponding to a portion of the aforementioned supplemental liquid flow pipe 84, which is located between the three-way valve and the second auxiliary expansion device 64. The further liquid flow pipe 85 has a check valve. Furthermore, a further check valve is located in the common end section of the three auxiliary cooling gas flow pipes 81a-c and is located between the first end section of the aforementioned supplemental liquid flow pipe 85 and the second end section of the aforementioned supplemental liquid flow pipe 84. Furthermore, the system 10 comprises a further supplemental fluid-carrying pipe 86 having a first end portion corresponding to a portion of the aforementioned supplemental fluid-carrying pipe 84 located between a third auxiliary expansion device 65 and a check valve, and a second end portion corresponding to a portion of the intake pipe 79 located between the intake manifold 77 and the intake port 502 of the discharge device 500.Furthermore, a separation valve 403 is located in the pipe 86 carrying the additional supplemental liquid: this separation valve 403 has a reference pressure of the first vapor-liquid separator 801 and can be a valve of the type that automatically closes when the pressure at the inlet rises, provided on the discharge side of the check valve. Furthermore, the system 10 consists of a pipe 87 carrying an additional supplemental liquid, having a first end portion corresponding to a common portion of the three refrigerant pipes 74a-c located upstream of the check valve in question, and another end portion corresponding to a three-way valve 112 located in the aforementioned supplemental liquid pipe 84 and positioned between the second end portion of the aforementioned supplemental liquid pipe 85 and the inlet of the second auxiliary expansion device 64. Furthermore, system 10 comprises a further supplemental liquid-carrying pipe 88 having a first terminal portion corresponding to a part of the suction pipe 79 that branches off from the suction pipe 79 and is located between the first vapor-liquid separator 801 and the suction ports of the compressors 12 and 13, and a second terminal portion that is located at the suction port 602 of the compressor of the expander compressor group 600. Furthermore, system 10 comprises an internal heat exchanger 91 located between a forward-carrying liquid pipe 73 and an auxiliary liquid-carrying pipe 80: more specifically, the internal heat exchanger 91 enables heat exchange between the liquid refrigerant flowing in the forward-carrying liquid pipe 73, which exits from the low-pressure side of the forward-carrying liquid pipe valve 110 and heads toward the power port 501 of the discharge device 500, and the refrigerant flowing in the auxiliary liquid-carrying pipe 80, which exits from the discharge port 603 of the expander compressor group 600 and heads toward the second vapor-liquid separator 802. The pipe 80 through which this auxiliary liquid flows consists of a bypass pipe surrounding the internal heat exchanger 91: the bypass pipe has a valve 115, which can be a throttle valve.Furthermore, system 10 comprises a further supplemental liquid-carrying pipe 89 having a first end section corresponding to a common portion of the three auxiliary refrigerant-carrying pipes that exit the first auxiliary expansion device 62, and a second end section corresponding to a common portion of the three refrigerant-carrying pipes 74a-c: the further liquid-carrying pipe 89 has a separation valve 404; such a separation valve 404 may be a type of valve that has a reference pressure of the first vapor-liquid separator 801 and is provided on the discharge side of the check valve, and closes automatically when the pressure at the intake port rises. Finally, system 10 comprises four further new check valves. These are not shown in the embodiment shown in Figure 6 and have not yet been specifically described, but are shown in Figure 9 in any case. These are arranged together with a manual three-way valve 113 and a manual two-way valve 114, which only operate during the "pump-down" operation, the associated liquid-carrying pipes for interconnection, and the rest of circuit 10. Referring to Figure 9, elements 14 and the check valves not yet mentioned as 15, 41a-c, 42a-c, 61, 71, 75a-c, 76a-c, 78a-c, 82, 83, 111, 241a-c, 301a-c, 302a-c, 304, 308a-c, 309a-c, 401a-c, 402a-c, 503, 700, 701, and 702 are located within the system 10 and in the same positions as the embodiment shown in Figure 6 and described above, and have the same function.

[0048] Referring to the specific example shown in Figure 9, it can be observed that normal operation with no evaporators thawed consists not of a single case, but of three independent cases, corresponding to various levels of reheating performance. These three independent cases are individually illustrated by their respective flowcharts in the three independent figures described below.

[0049] Referring now to Figure 10, a typical flow diagram related to the implementation of this system described with reference to Figure 9 is shown, which is during operation in a series flow configuration with low reheating performance corresponding to the "cooling" function of the air inside the vehicle, where the thick lines with arrows indicate the refrigerant circuit.

[0050] Referring now to Figure 11, a typical flow diagram related to the implementation of this system described with reference to Figure 9 is shown, during operation in a series flow configuration with intermediate reheating performance corresponding to the "series dehumidification and heating" function of the air inside the vehicle, where thick lines with arrows indicate the refrigerant circuit.

[0051] Referring now to Figure 12, a typical flow diagram related to the implementation of this system described with reference to Figure 9 is shown, during operation in a parallel flow configuration with high reheating performance corresponding to the "parallel dehumidification and heating" function of the air inside the vehicle, where thick lines with arrows indicate the refrigerant circuit.

[0052] Referring to the embodiment shown in Figure 9, it can be observed that the thawing process according to the present invention consists of two independent cases. These two independent cases are individually represented by their respective flowcharts in the two independent figures described below.

[0053] Referring now to Figure 13, a flowchart of the reverse liquid thawing process in an exemplary case related to the embodiment of this system described with reference to Figure 9 is shown, during operation in a parallel flow configuration with high reheating performance corresponding to the "parallel dehumidification heating" function of the air inside the vehicle, where thick lines with arrows indicate the refrigerant circuit, and letters enclosed in boxes indicate the same relevant sections in the reverse liquid thawing process flowchart of Figure 7.

[0054] Referring now to Figure 14, a flowchart of the reverse liquid thawing process in an exemplary case related to the embodiment of this system described with reference to Figure 9 is shown, during operation in a no-reheating configuration corresponding to the "no-dehumidification heating" function of the air inside the vehicle, where thick lines with arrows indicate the refrigerant circuit, and letters enclosed in boxes indicate the same relevant sections in the reverse liquid thawing process flowchart of Figure 7.

[0055] For completeness, Figure 15 shows a flow chart relating to the implementation of this system described with reference to Figure 9, which is during the "pump-down" operation to collect the refrigerant in the first vapor-liquid separator, which acts as a storage unit, and here the thick lines with arrows indicate the refrigerant circuit.

[0056] Referring now to Figure 16, we see a scaled-down and rearranged version of the standard flow diagram already shown in Figure 10, where the elements of this system, affected by the circulation of the refrigerant, are arranged from bottom to top as a pressure rise function. Furthermore, compared to a similar flow diagram of the process already shown in Figure 10, the control device 700 (and its inputs 701 and outputs 702), all the sensors (301a-c, 302a-c, 304, 308a-c, 309a-c, 351), and all the elements of the closed circuit 10 that are not affected by the circulation of the refrigerant, except for a thin tube, have been intentionally omitted. This thin tube transmits the reference pressure to valves 403 and 404, which are of a type that automatically close when the pressure at the intake rises. The internal heat exchanger 91 is divided into two parts: primary and secondary. For completeness of depiction, elements 241a-c, 251, 900, 902, and 903 are also depicted.

[0057] Referring now to Figure 17, we see a scaled-down and rearranged version of the standard flow diagram already shown in Figure 11, where the elements of this system, affected by the circulation of the refrigerant, are arranged from bottom to top as a pressure rise function. Furthermore, compared to a similar flow diagram of the process already shown in Figure 11, the control device 700 (and its inputs 701 and outputs 702), all the sensors (301a-c, 302a-c, 304, 308a-c, 309a-c, 351), and all the elements of the closed circuit 10, which are not affected by the circulation of the refrigerant except for a thin tube, transmit the reference pressure to valves 403 and 404, which are of a type that automatically closes when the pressure at the intake rises. The internal heat exchanger 91 is divided into two parts: primary and secondary. For completeness of depiction, elements 241a-c, 251, 900, 902, and 903 are also depicted.

[0058] Referring now to Figure 18, we see a scaled-down and rearranged version of the normal flow diagram already shown in Figure 12, where the elements of this system affected by the circulation of the refrigerant are arranged from bottom to top as a pressure rise function. Furthermore, compared to a similar flow diagram of the process already shown in Figure 12, the control device 700 (and its inputs 701 and outputs 702), all the sensors (301a-c, 302a-c, 304, 308a-c, 309a-c, 351), and all the elements of the closed circuit 10 that are not affected by the circulation of the refrigerant, except for a narrow tube, transmit the reference pressure to valves 402a-c, 403, and 404, which are of a type that automatically closes when the pressure at the intake rises, except for the check valves associated with the three auxiliary cooling gas tubes 81a-c. The internal heat exchanger 91 is divided into two parts: primary and secondary. For the sake of completeness of the depiction, elements 241a-c, as well as 251, 900, 902, and 903, are also depicted. In 18, an electric heater is further shown. This heater can be operated to maintain a high temperature (and pressure) of the refrigerant trapped in the common final section of the three auxiliary cooling gas tubes 81a-c.

[0059] Referring now to Figure 19, this is a scaled-down and rearranged flow diagram of the inverse liquid thawing process of an exemplary case already shown in Figure 13, where the elements of this system affected by the circulation of the refrigerant are arranged from bottom to top as a pressure rise function. Furthermore, compared to the similar flow diagram of the process already shown in Figure 13, the control device 700 (and its inputs 701 and outputs 702), all the sensors (301a-c, 302a-c, 304, 308a-c, 309a-c, 351), and all the elements of the closed circuit 10 that are not affected by the circulation of the refrigerant, except for a thin tube, through which the reference pressure is transmitted to valves 401c and 402b, which are of a type that automatically close when the pressure at the intake rises. The internal heat exchanger 91 is divided into two parts, primary and secondary. For completeness of depiction, elements 241a-c, 251, 900, 902, and 903 are also depicted. Furthermore, the Greek letters indicate the same pressure levels as in the Mollier diagram in Figure 8.

[0060] Referring now to Figure 20, this is a scaled-down and rearranged version of the flow diagram of the inverse liquid thawing process in the exemplary case already shown in Figure 14, where the elements of this system affected by the circulation of the refrigerant are arranged from bottom to top as a pressure rise function. Furthermore, compared to the similar flow diagram of the process already shown in Figure 14, the control device 700 (and its inputs 701 and outputs 702), all the sensors (301a-c, 302a-c, 304, 308a-c, 309a-c, 351), and all the elements of the closed circuit 10 that are not affected by the circulation of the refrigerant, except for a thin tube, have been intentionally omitted. This thin tube transmits the reference pressure to valves 401c and 402b, which are of a type that automatically close when the pressure at the intake rises. The internal heat exchanger 91 is divided into two parts, primary and secondary. For completeness of depiction, elements 241a-c, 251, 900, 902, and 903 are also depicted. Furthermore, the Greek letters indicate the same pressure levels in the Moriet diagram in Figure 8. Finally, although not traversed by the refrigerant, an external heat exchanger 51 is also shown in Figure 20 for appropriate comparison with the various figures above.

[0061] Referring here to Figure 21, a section of valve 400 that automatically closes when the inlet pressure rises is shown, and this valve only opens when the inlet pressure is somewhat lower than a reference pressure. The reference pressure is, in accordance with the present invention, the pressure of a convenient section of the closed-loop steam cycle cooling system 10 that is supplied by a narrow tube 411 to valve 400 that automatically closes when the inlet pressure rises. This description of automatic valve 400 applies equally to automatic valves 401a-c, 402a-c, 403, and 404 described above. The valve 400 that automatically closes when the inlet pressure rises, shown in Figure 21, is abbreviated in English as CRI valve (Close on Rise of Inlet pressure valve). In the valve 400 of the type shown in Figure 21, which automatically closes when the pressure in the intake port rises, a narrow tube 411 is connected to an isolation chamber 412 of the automatic valve 400; the isolation chamber 412 is separated from the housing 413 of the automatic valve 400 by an elastic sealing element 414 such as a bellows, diaphragm, or other similar flexible device. The housing 413 has an intake port, an outlet port, a transmission path, a valve seat 417 in the path that defines the lumen of the intake and outlet ports of the housing, a valve member 416 (as a sealing disc) positioned in the lumen of the intake port that contacts the valve seat 417 to create a seal that prevents leakage when the valve is closed, a stem 415 extending from the valve member 416 through the lumen of the outlet port to the elastic sealing element 414, and a coil spring 419 in the lumen of the intake port that is compressed between the body of the valve 410 and the valve member 416. The valve member 416 and its stem 415 can move between a closed position relative to the valve seat 417 to compress the elastic sealing element 414 and an open position in the lumen of the intake port, away from the valve seat 417 to expand the elastic sealing element 414. The reference pressure exerts a force outward on the elastic sealing element 414, thereby causing it to expand.This force is transmitted to the sealing disc 416 (or other similar valve member) through the casing 415 (a rod, spike, or other similar element) to move the elastic sealing element 416 away from the valve seat 417. This force can ultimately be transmitted to the elastic sealing element 414 and the casing 415 by a transmission element, which is positioned as a piston 418 integrated with both the elastic sealing element 414 and the casing 415. The compressed coil spring 419 exerts a force on the sealing disc 416 to push it toward the valve seat 417. Due to the gap 420 between the casing 415 and the body of the valve 410, the discharge pressure acts on the outside of the elastic sealing element 414, thus exerting a crushing force on the elastic sealing element 414. This discharge pressure also acts on the surface of the sealing disc 416 facing the lumen of the outlet to move the sealing disc 416 away from the valve seat 417. Since the external effective area of ​​the elastic sealing element 414 is the same as the surface area of ​​the sealing disc 416 (or other similar valve member) facing the lumen of the outlet, these two forces exerted by the discharge pressure are equal in magnitude and opposite in direction, and therefore cancel each other out, rendering the discharge pressure ineffective. Conversely, this suction pressure acts on the surface of the sealing disc 416 facing the lumen of the inlet to push the sealing disc 416 toward the valve seat 417. Thus, the force acting on the surface of the sealing disc 416 facing the lumen of the inlet due to the suction pressure is the same in direction and magnitude as the force of a compressed coil spring, and these two forces together close the automatic valve 400. These two forces counteract the independent opening force of the automatic valve 400 due to the reference pressure. These three forces are the only forces that actuate the automatic valve 400. Since the internal effective area of ​​the elastic sealing element 414 is approximately the same as the surface area of ​​the sealing disc 416 facing the lumen of the intake port, when the intake pressure is close to the reference pressure, the opening force due to the reference pressure is approximately the same as and in the opposite direction to the closing force due to the intake pressure, so these two forces are effectively in equilibrium. Therefore, essentially, only the closing force of the valve due to the compressed coil spring 419 remains.Furthermore, if the intake pressure is somewhat higher than the reference pressure, the valve will naturally remain closed. Conversely, the valve will only open if the intake pressure is somewhat lower than the reference pressure. In fact, only in this case is the closing force, which is the sum of the two forces—the intake pressure and the compressed coil spring—significantly lower than the opening force due to the reference pressure. Industrial applications.

[0062] As already stated, the present invention can be industrially applied to any type of closed-loop steam cycle cooling system having multiple evaporators that requires a thawing cycle, and can remove ice that forms on the outside of the evaporator coils in any field in which such systems are used. The specific field already mentioned is related to in-vehicle air conditioning. In particular, in Figure 24, with regard to the embodiment of this system as previously mentioned with reference to Figure 9 in the flow diagram of Figure 14, the system is inserted into the front hood of a typical vehicle, where a suitable number of valves, associated sections, and pipes for carrying liquid are incorporated into appropriate groups. Figure 23 shows details of this group as a specific example of the flow diagram of Figure 14. In Figure 24, compared to the flow diagram of a similar process already shown in Figure 14, the control device 700 (and its inputs 701 and outputs 702), the compressors 13 and 15 (for simplification of visualization), and all sensors (301a-c, 302a-c, 304, 308a-c, 309a-c, and 351) are intentionally omitted.

[0063] For proper comparison, Figure 25 shows a flow chart relating to a heat pump mobile system using gas injection used for in-vehicle air conditioning, as is well known in the (modern) art, during operation in a no-reheating configuration corresponding to the "no-dehumidification heating" function of an in-vehicle air conditioning system inserted in the front hood of a typical vehicle, where, similar to the flow chart in Figure 24, the letters enclosed in boxes indicate several relevant sections. This comparison shows that the total number of expansion devices (four) in this system according to the present invention, whatever type they may be, such as temperature-controlled expansion valves, electric expansion valves, pressure-controlled valves, capillary valves, etc., is the same as in modern systems. Furthermore, this comparison shows that the system according to the present invention has approximately 50% more replacement area for the evaporator compared to the latest system, and is divided into three identical parts: during the defrost cycle of the exemplary case, two parts are in the evaporation process, characterized by open fins of two Venetian shutters positioned between the fan and the evaporator to allow the passage of outside air; and the other part is in the defrost process, characterized by closed fins of a corresponding Venetian shutter positioned between the fan and the evaporator to prevent the passage of outside air. Finally, using the same refrigerant, it can be proven that the thermodynamic cycle associated with the flow diagram in Figure 25 is qualitatively the same as that shown in Figure 8, and that this is related to the flow diagram in Figure 14. The only exceptions are points L, O, P, and Q, and the related deformation tubes connecting them, which are not depicted because this related section is not present in the latest conventional mobile system in Figure 25. Furthermore, in this particular case, points M and N coincide with point K; point E coincides with point D; and point G coincides with point F. Variations

[0064] Referring now to Figure 26, this is a flow diagram of the thawing process associated with the embodiment of a closed-loop steam cycle type cooling system, as is well known in the art, where the thawing of the coil of one evaporator selected from several evaporators is achieved by a liquid refrigerant, which circulates through the coil in the same direction as the normal flow. This uses all the same equipment as the embodiment of the discovered invention, as previously mentioned with reference to Figure 6. Here, thick lines with arrows indicate the refrigerant circuit, and letters enclosed in boxes indicate the same relevant sections shown in Figure 7. More specifically, with reference to Figure 6, as mentioned above, the flow diagram shown in Figure 26 for the embodiment of the discovered invention consists of the following two modifications: The first modification is that the liquid-carrying pipes 75a-c, which in the previous diagrams were pipes for the liquid to flow in the reverse direction, are now pipes for the liquid to flow in the forward direction in Figure 26, and always have the first final portion of the liquid-carrying pipe 73 upstream of valve 110, and instead of the corresponding cooling gas-carrying pipes 76a-c, have a portion of the final portion of the corresponding refrigerant-carrying pipes 74a-c. The second change is in the three liquid-carrying pipes 78a-c, which in the previous figures were pipes for carrying additional liquid in the reverse direction, but in Figure 26 are pipes for carrying additional liquid in the forward direction, always having a second end portion on the low-pressure side of valve 110 for the pipes for carrying liquid in the forward direction, and having a first end portion of part of the corresponding cooling gas-carrying pipe 76a-c instead of part of the corresponding refrigerant-carrying pipes 74a-c. It can be easily shown that all the devices shown in the embodiment of Figure 9 (whatever they may be) are located in the embodiment. In contrast, in the flow diagram of Figure 26, with the sole exception of the three-way valve 103, the same positions (occupied by the embodiment of the discovered invention, which has already been accurately described in Figure 9) are referenced and perform the same function. In fact, the disadvantage of this variation is that valves 101 and 102 are no longer on the same side of their respective evaporators, but precisely on opposite sides.In this variation, valve 101 is located on the intake side of the evaporator, while valve 102 remains on the outlet side. This causes a structural problem as it makes it impossible to replace the two valves 101 and 102 with a single suitable three-way valve 103. Finally, it is noted that the Mollier diagram showing the thermodynamic state of the low-boiling refrigerant circulating in the relevant section identified by the boxed alphabet in the flow diagram of Figure 26 is the same as that shown in Figure 8, with reference to Figure 6. This corresponds to the relevant section shown in the flow diagram of Figure 7, during the thawing process of the selected evaporator using the same refrigerant liquid.

[0065] Another possible variation of the cooling system according to the present invention is achieved by providing the discharge pressure instead of the inlet pressure for the evaporator 41b, 41c, and 41a, as a reference pressure for the automatic valves 401a, 401b, and 401c.

[0066] Finally, Figure 22 shows a section of a variation of the valve that automatically closes when the pressure in the intake port rises, which differs from the original 400 shown and described in Figure 21, in that the main body 415 is simply located on the piston 418. This piston 418 is essential for the elastic sealing element 414.

[0067] The improvements achieved according to the present invention, as already described, lead to numerous advantages. The first advantage compared to Alsenz's patent is quite obvious: the number of expansion devices required for normal flow is reduced (to one). This results in immediate savings, both economically due to the elimination of expensive devices and in the simplification of the overall system construction, and the operation of this system, which is controlled by a control circuit, is safe and simple.

[0068] The second advantage, a more general one, is the use of isolation valves as valves that automatically close when the intake pressure rises. This valve offers immediate economic savings by eliminating expensive electrical actuators, further simplifying the system by reducing electrical wiring and decreasing the amount of operation that the control circuit must manage. In addition, these valves that automatically close when the intake pressure rises require no calibration whatsoever, making them inherently inexpensive.

[0069] The third advantage lies particularly in the combined use of the discharge device, the first vapor-liquid separator, and the first described auxiliary expansion device. This improves overall efficiency by ensuring that the intake pressure does not ultimately decrease, but instead becomes the higher of the two independent evaporation pressures (not the lower one) of the two independent unselected evaporators.

[0070] The fourth advantage lies in the further use of a second compression stage connected to a second vapor-liquid separator compared to previous cases, and in the additional auxiliary expansion device located in the tube carrying the auxiliary liquid. This results in a more decisive improvement in overall efficiency. To quantify such improvements in overall efficiency under the conditions described herein, we examine, as a reference basis, a case study that considered a conventional heat pump mobile system using gas injection, as is well known in the art (modern), during a complete cycle. This complete cycle consists of operating a subcycle in a no-reheating configuration corresponding to the "no-dehumidification heating" function of the cabin air, the flow diagram of which has already been shown in Figure 25, and that of the thawing subcycle as well. Such a system taken as a reference is compared to the discovered system in Figure 6: in fact, the embodiment of the discovered invention shown in Figure 6 (as the relevant flow diagram 24 in Figure 7) can be very well understood as what is called a heat pump mobile system. In this system, a condenser 21 is inserted inside the cabin air conditioning processing unit (not shown). More specifically, the flow chart in Figure 7 can be very well understood as a flow chart of the reverse liquid thawing process of a selected evaporator associated with a heat pump mobile system for in-vehicle air conditioning during operation in a no-reheating configuration corresponding to the "no-dehumidification heating" function of the in-vehicle air, when the condenser 21 is inserted inside the internal air processing unit (not shown). In this example, the complete operating cycle consists of three similar, sequentially operating thawing subcycles, in which the first operating subcycle thaws evaporator 41a, the second operating subcycle thaws evaporator 41b, and the third operating subcycle thaws evaporator 41c, each selected according to timing. Furthermore, referring to the discovered system in Figure 6, valves of the type that automatically close when the pressure at the intake port on the exhaust side rises, equipped with check valves, are sized so that each valve opens only when the intake pressure is lower than 0.5 bar of the reference pressure.Below, we report the reference conditions for the case study described here, for a hypothetical electric bus: a) Refrigerant: Carbon dioxide; b) Average effective heat: 26.7 kW; c) Release temperature of the second compression stage: 121°C; d) Overheating: 0K; e)

[0071] f) The KA of the gaseous cooling system—in this case study, this replaces the condenser with carbon dioxide as the refrigerant and is plotted as a power exchange function, as shown in Figure 27; g) The efficiency of the first and second compression stages (isentropy and volumetric measurements) plotted as a function of the compression ratio, as shown in Figure 28; h) Inlet temperature of the secondary liquid-gas cooler: 30°C; i) Outlet temperature of the secondary liquid-gas cooler: 70°C; j) Replacement area of ​​conventional evaporators: 180 (2 x 90) m² 2 ; k) Replacement area of ​​the discovered evaporator: 270 (3 x 90) m 2 ; l) Outside temperature: -15°C; m) Relative humidity of the outside air: 72%; n) Power consumption of auxiliary equipment: 0.872 kW; o) Displacement of the first compression stage: 6.38 m 3 / h; p) Displacement of the second compression stage: 5.62 m 3 / h.

[0072] Here, "average" refers to the average value over the entire cycle as defined above, and "evaporator exchange area" refers to the total external surface area of ​​the evaporator in contact with the outside air. However, graphs A and B in Figure 29 show the refrigerant temperature at the outlets of various "unthawed" evaporators and the overall heat exchange coefficients of various "unthawed" evaporators, plotted according to the time elapsed from both the start of a conventional operating subcycle for the system taken as a reference and the start of the first of three consecutive operating subcycles for the system discovered. Table 1 below shows the refrigerant flow rate values ​​and thermodynamic condition values ​​in the relevant section of Figure 25. These are the "start" conditions of the operating subcycle of the conventional system taken as a reference for the case study being examined here. Conversely, Table 2 below shows the refrigerant flow rate values ​​and thermodynamic condition values ​​in the relevant section of Figure 25. These are the "end" conditions of the operating subcycle of the conventional system taken as a reference for the case study being examined here.

[0073] [Table 1]

[0074] [Table 2]

[0075] Table 3 below shows the refrigerant flow rate values ​​and thermodynamic condition values ​​in the relevant sections of Figure 7. These are the "start" conditions for each of the three consecutive operating subcycles of the system discovered for the case study being examined here. Table 4 below shows the refrigerant flow rate values ​​and thermodynamic condition values ​​in the relevant sections of Figure 7. These are the "end" conditions for each of the three consecutive operating subcycles of the system discovered for the case study being examined here.

[0076] [Table 3]

[0077] [Table 4]

[0078] Graphs A, B, C, and D in Figure 30 show the results of quantifying the overall efficiency improvement of the discovered system compared to the latest version for the validated case study. More specifically, these results are represented by four figures showing the temporal trends of effective thermal power, total power consumption (including auxiliary equipment), effective COP, and defrosting thermal power, respectively, over time from the start of a full operating cycle for both the latest and discovered systems. The values ​​enclosed in boxes represent the individual average values ​​for each cycle. This quantification process of overall efficiency improvement is shown to represent a 13.6% improvement in the average effective COP, given that the average effective thermal power (26.7 kW as defined at point b of the reference conditions) remains unchanged, resulting in a change from 2.13 for the conventional system to 2.42 for the discovered system.

[0079] The fifth benefit lies in the additional use of an expander compressor group in the discovered system. This is installed in an additional auxiliary expansion and internal heat exchanger located in a tube carrying an auxiliary liquid, contributing to a further improvement in overall efficiency. To quantify the further improvement in overall efficiency due to the introduction of the components in the discovered system described here, we examine, as a reference basis, a variation of a previously verified case study that re-examined a conventional heat pump mobile system with gas injection, as is well known in the art (modern), used for in-vehicle air conditioning, during a full cycle. This full cycle consists of operating a subcycle in a no-reheating configuration corresponding to the "no-dehumidification heating" function of the in-vehicle air, the flow diagram of which has already been shown in Figure 25, and that of the thaw subcycle as well. Such a system, again taken as a reference basis, is compared to the discovered system shown in Figure 9, the relevant flows of which are in Figures 14, 20, and 24, which relate to a group of valves, referring to Figure 23. Furthermore, this is during operation in a no-reheating configuration corresponding to the "heating without dehumidification" function of the in-vehicle air conditioning during a complete cycle, and consists of three continuously operating defrosting subcycles, in which the first operating subcycle defrosts evaporator 41a, the second operating subcycle defrosts evaporator 41b, and the third operating subcycle defrosts evaporator 41c, each selected according to timing. Moreover, referring to the discovered system in Figure 9, the related flows are in Figures 14, 20, and 24, which relate to a group of valves referring to Figure 23, where valves of the type that automatically close when the pressure at the intake port on the exhaust side with a check valve rises are sized so that each valve opens only when the intake pressure is lower than 0.5 bar of the reference pressure. The reference conditions (valid for a hypothetical electric bus) are the same as those described in the already verified case studies, with the exception of the displacements of the first and second compression stages, which are 4.61 m in each of the discovered systems. 3 / h and 5.36 m 3While it is given as / h, the conventional system used as the reference standard is 6.38 m 3 / h and 5.62 m 3 It remains at / h. Furthermore, the isentropy efficiency of the expander in the expander compression device group is fixed at 0.68, while the isentropy efficiency of the compressor in the expander compression device group is fixed at 0.70.

[0080] The refrigerant flow rate values ​​and thermodynamic condition values ​​in the relevant sections of Figure 25 are the same as those already shown in Tables 1 and 2, respectively, for the "start" and "end" conditions of the conventional system's operating subcycle, which were again taken as a reference standard for these variations of the case study being examined here. Conversely, Table 5 below shows the refrigerant flow rate values ​​and thermodynamic condition values ​​in the relevant sections of Figures 14, 20, 23, and 24. This is for the variations of the case study being examined here, for the "start" conditions of each of the three consecutive operating subcycles of the discovered system.

[0081] [Table 5]

[0082] Finally, Table 6 below shows the values ​​for refrigerant flow rates and thermodynamic conditions in the relevant sections of Figure 14, Figures 20, 23, and 24. This is for variations of the case study examined here, under the “termination” conditions of each of the three consecutive operating subcycles of the discovered system.

[0083] [Table 6]

[0084] Graphs A, B, C, and D in Figure 31 show the results of quantifying the further improvement in the overall efficiency of the discovered system, compared to the most recent for the verified case study variation. More specifically, these results are represented by four figures showing the temporal trends of effective thermal power, total power consumption (including auxiliary equipment), effective COP, and defrosting thermal power, respectively, according to the time elapsed from the start of a full operating cycle for both the most recent and discovered system. The values ​​enclosed in boxes represent the individual average values ​​for each cycle. In particular, what is observed as Figure A of effective thermal power in Figure 31 is identical to Figure A of effective thermal power in Figure 30. Furthermore, for this variation of the verified case study, since the quantification process of further improvement in overall efficiency was started under the condition that the average effective thermal power (26.7 kW) remained unchanged, the 19.7% improvement in the average effective COP is shown to be a change from 2.13 for the conventional system to 2.55 for the discovered system.

[0085] The descriptions made so far have been illustrative and descriptive, focusing on specific embodiments of the invention. However, it should be obvious to those skilled in the art that many modifications and changes to such embodiments described herein are possible without departing from the scope and spirit of the invention. It is intended that the following claims may be interpreted as encompassing such modifications and changes.

Claims

[Claim 1] A closed-loop steam cycle cooling system comprising at least the following elements: Multiple evaporators (41a-41c) having outlets and inlets for normal steam flow; a condenser having an outlet and an inlet; a compressor having an outlet and an inlet, and a pipe for carrying compressed heated gas connecting the outlet of the compressor and the inlet of the condenser; an expansion device (61) having an outlet and an inlet; a pipe (73) for carrying liquid forward, connecting the outlet of the condenser and the inlet of the expansion device, the pipe having a pipe valve (110) for carrying liquid forward; multiple pipes (74a-74c) for carrying refrigerant, each connecting the outlet of the expansion device (61) to the inlet of each of the evaporators (41a-41c) and having a check valve; an intake manifold (77) having one outlet and multiple inlets corresponding to the number of evaporators (41a-41c); each of the evaporators (41a-41c) A closed-loop steam cycle cooling system comprising: a plurality of pipes (76a-76c) for carrying cooling gas, each having a pipe valve (102a-102c) for carrying cooling gas, connecting the intake port of the intake manifold (77) to one intake port of the intake manifold (77); an intake pipe connecting the outlet of the intake manifold (77) to the intake port of the compressor; a pipe for carrying liquid in the reverse direction, connecting the outlet of the condenser to the outlet of one evaporator selected from the plurality of evaporators (41a-41c), and having a pipe valve (101a-101c) for carrying liquid in the reverse direction; and an additional pipe (78a-78c) for carrying liquid in the reverse direction, connecting the intake port of the selected evaporator (41a-41c) to the low-pressure side of a pipe valve (110) for carrying liquid in the forward direction, wherein the additional pipe (78a-78c) for carrying liquid in the reverse direction has a check valve.

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