Heat storage air conditioning system and control method

Abstract

The present invention provides an air conditioning system of the heat storage type in which the power consumption required for air conditioning can be reduced. The heat storage air conditioning system comprises: a compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the compressor; a heat exchanger for heat storage provided on the downstream side of the condenser; an expansion valve provided on the downstream side of the heat exchanger for heat storage; an evaporator that vaporizes the refrigerant depressurized by the expansion value; main piping which connects the compressor, the condenser, the heat exchanger for heat storage, the expansion valve, and the evaporator and through which the refrigerant passes; a heat storage tank storing a heat storage material; a pump that delivers the heat storage material to the heat exchanger for heat storage; and a heat storage material channel which connects the heat storage tank, the pump, and the heat exchanger for heat storage and through which the heat storage material passes.

Description

Heat storage air conditioning system and control method

[0001] This disclosure claims priority to Japanese Patent Application No. 2024-004335, filed on January 16, 2024, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses an air conditioning system for a subway car, including a heat source tank provided in the subway car that accommodates a coolant source so that it can be supplied and discharged, an indoor unit that cools the interior of the car by heat exchange using the coolant source in the heat source tank, an air conditioner that circulates the coolant source between the heat source tank and the indoor unit, and a heat source supply and discharge device that exchanges the coolant source in the heat source tank, which has been heated by heat exchange in the indoor unit, with a coolant source that is lower in temperature than the coolant source. In the air conditioning system of Patent Document 1, a heat source supply and discharge base is provided outside the car along the subway tracks. In moving objects such as cars, the power supply capacity of the air conditioning system is often limited, making it necessary to reduce the power consumption required for air conditioning.

[0003] JP 2009-184621 A

[0004] A heat storage type air conditioning system that can reduce the power consumption required for air conditioning is provided.

[0005] The present disclosure provides a heat storage air conditioning system and a control method that can solve the above-mentioned problems.

[0006] According to one aspect of the present disclosure, a heat storage air conditioning system includes a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, a heat storage heat exchanger provided downstream of the condenser in the refrigerant flow direction, an expansion valve provided downstream of the heat storage heat exchanger, an evaporator that vaporizes the refrigerant decompressed by the expansion valve, a main pipe through which the refrigerant passes that connects the compressor, the condenser, the heat storage heat exchanger, the expansion valve, and the evaporator, a heat storage tank that stores a heat storage material, a pump that sends the heat storage material to the heat storage heat exchanger, and a heat storage material flow path through which the heat storage material passes that connects the heat storage tank, the pump, and the heat storage heat exchanger.

[0007] According to one aspect of the present disclosure, a control method is provided for a heat storage air conditioning system including a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, a heat storage heat exchanger provided downstream of the condenser in a refrigerant flow direction, an expansion valve provided downstream of the heat storage heat exchanger, an evaporator that vaporizes the refrigerant decompressed by the expansion valve, a main pipe through which the refrigerant passes that connects the compressor, the condenser, the heat storage heat exchanger, the expansion valve, and the evaporator, a heat storage tank that stores a heat storage material, a pump that sends the heat storage material to the heat storage heat exchanger, and a heat storage material flow path through which the heat storage material passes that connects the heat storage tank, the pump, and the heat storage heat exchanger, wherein the control method operates the compressor at a rotation speed that is different from a minimum rotation speed within a predetermined range, and operates the pump at a predetermined rotation speed that is less than an upper limit value.

[0008] According to the above-described heat storage air conditioning system and control method, it is possible to reduce the power consumption required for air conditioning.

[0009] FIG. 1 is a diagram showing an example of a heat storage air conditioning system according to an embodiment. FIG. 1 is a first diagram showing a state of a heat storage air conditioning system according to an embodiment during cooling operation. FIG. 2 is a second diagram showing a state of a heat storage air conditioning system according to an embodiment during cooling operation. FIG. 1 is a diagram showing an example of a Mollier diagram according to an embodiment. FIG. 2 is a diagram showing an example of power consumption in cooling operation according to an embodiment. FIG. 3 is a diagram showing a state of a heat storage air conditioning system according to an embodiment during cooling operation. FIG. 4 is a diagram showing a state of a heat storage air conditioning system according to an embodiment during cooling operation. FIG. 1 is a diagram showing an example of the configuration of a heat storage tank according to an embodiment. FIG. 2 is a diagram showing an example of control of a heat storage air conditioning system according to an embodiment.

[0010] <Embodiments> Planning systems according to each embodiment will be described below with reference to Figs. 1 to 9. (Configuration) Fig. 1 is a diagram showing an example of a heat storage air conditioning system according to an embodiment. The heat storage air conditioning system 100 is a heat storage type cooling system suitable for mobile objects such as vehicles that have restrictions on installation space and power supply capacity. The vehicle may be an EV (Electric Vehicle) or a battery-powered AGT (Automated Guideway Transit) that does not have a pantograph power supply. As shown in FIG. 1 , the heat storage air conditioning system 100 includes a compressor 1, a condenser 2, a three-way valve 8a, a three-way valve 8b, a third expansion valve 6, a heat accumulator / radiator 11, a three-way valve 8c, a first expansion valve 3, an evaporator 4, a pipe P1 connecting them, a pipe P2, a second expansion valve 5 provided on the pipe P2, a heat storage tank 12, a pump 13, pipes P3 and P4, a pipe P5 connecting the heat storage tank 12, the pump 13, and the heat accumulator / radiator 11, and a control device 10. A refrigerant flows through the pipes P1 to P4. A liquid heat storage material flows through the pipe P5. The configuration shown in FIG. 1 is a schematic representation of the basic configuration of the heat storage air conditioning system 100, and other components may also be included.

[0011] One end of the pipe P2 is connected to the pipe P1 downstream of the condenser 2 and upstream of the third expansion valve 6, and the other end is connected to the pipe P1 downstream of the first expansion valve 3 and upstream of the evaporator 4, so as to form a refrigerant flow path that bypasses the third expansion valve 6, the heat accumulator / radiator 11, and the first expansion valve 3. The terms "upstream" and "downstream" refer to the upstream and downstream sides of the refrigerant flow direction. A three-way valve 8a is provided at the connection point between the pipe P2 and the pipe P1 on the upstream side. The flow rates of the refrigerant flowing through the pipes P1 and P2 can be adjusted by controlling the three-way valve 8a.

[0012] One end of the pipe P3 is connected to the pipe P1 downstream of the three-way valve 8a and upstream of the third expansion valve 6, and the other end is connected to the pipe P1 downstream of the third expansion valve 6 and upstream of the heat accumulator / radiator 11, so as to form a flow path for refrigerant that bypasses the third expansion valve 6. A three-way valve 8b is provided at the connection point between the pipe P3 and the pipe P1 on the upstream side. By controlling the three-way valve 8b, the flow rates of the refrigerant flowing through the third expansion valve 6 and the pipe P3 can be adjusted.

[0013] One end of the pipe P4 is connected to the pipe P1 downstream of the heat accumulator / radiator 11 and upstream of the first expansion valve 3, and the other end is connected to the pipe P1 downstream of the first expansion valve 3 and upstream of the evaporator 4, so as to form a flow path for refrigerant that bypasses the first expansion valve 3. A three-way valve 8c is provided at the connection point between the pipe P4 and the pipe P1 on the upstream side. By controlling the three-way valve 8c, the flow rates of the refrigerant flowing through the first expansion valve 3 and the pipe P4 can be adjusted.

[0014] Compressor 1 compresses refrigerant and discharges high-pressure refrigerant. This high-pressure refrigerant is supplied to condenser 2. The high-pressure refrigerant supplied to condenser 2 exchanges heat with outside air or the like, releasing heat, and is condensed and liquefied. First expansion valve 3, second expansion valve 5, and third expansion valve 6 all reduce the pressure of the condensed refrigerant. These expansion valves are used or not used depending on the purpose, as the flow of refrigerant is switched by three-way valves 8a to 8c. Switching between first expansion valve 3 to third expansion valve 6 will be described later.

[0015] The heat accumulator / radiator 11 exchanges heat between the refrigerant flowing through the pipe P1 and the heat storage material flowing through the pipe P5. The heat accumulator / radiator 11 is, for example, a plate-type heat exchanger. When the heat accumulator / radiator 11 cools the refrigerant using the heat storage material, the heat storage material absorbs heat from the refrigerant and stores it, so it functions as a heat accumulator. Conversely, when the heat storage material is cooled using the refrigerant, the heat storage material radiates heat, so it functions as a heat radiator. When the heat accumulator / radiator 11 functions as a heat accumulator, the refrigerant flows into the heat accumulator / radiator 11 via the pipe P3 without passing through the third expansion valve 6. The refrigerant that flows into the heat accumulator / radiator 11 is cooled by heat exchange with the heat storage material in the heat accumulator / radiator 11, and is decompressed by the first expansion valve 3 to become a low-pressure, low-temperature refrigerant, which is then sent to the evaporator 4.

[0016] When the heat accumulator / radiator 11 functions as a radiator, the refrigerant is decompressed by the third expansion valve 6 to become a low-pressure, low-temperature refrigerant, and flows into the heat accumulator / radiator 11. The refrigerant that flows into the heat accumulator / radiator 11 exchanges heat with a heat storage material in the heat accumulator / radiator 11 and absorbs heat from the heat storage material. The refrigerant that has passed through the heat accumulator / radiator 11 is sent to the evaporator 4 via the pipe P4 without passing through the first expansion valve 3. Alternatively, when the heat accumulator / radiator 11 is not used, the refrigerant passes through the pipe P5, is decompressed by the second expansion valve 5, and then flows into the evaporator 4.

[0017] The low-pressure refrigerant that has been decompressed and expanded by any of the first expansion valve 3 to third expansion valve 6 is supplied to the evaporator 4. The low-pressure refrigerant supplied to the evaporator 4 absorbs heat from the air in the vehicle that is supplied by the fan 7 and vaporizes, and the vaporized refrigerant is drawn into the compressor 1. The refrigerant is converted back into high-pressure refrigerant by the compressor 1 and circulates through the above-mentioned path. The air cooled by the evaporator 4 is supplied to the vehicle interior.

[0018] The heat storage material supplied to the heat accumulator / radiator 11, which exchanges heat with the refrigerant, is stored in a heat storage tank 12. By driving a pump 13, the heat storage material is supplied from the heat storage tank 12 to the heat accumulator / radiator 11. The heat storage tank 12, the pump 13, and the heat accumulator / radiator 11 are connected by a pipe P5. By driving the pump 13, the heat storage material circulates through the heat storage tank 12, the pump 13, and the heat accumulator / radiator 11 via the pipe P5. The heat storage material is, for example, a long life coolant (LLC) that is initially cooled to about 5°C. For example, the heat storage tank 12 is provided with a temperature sensor 14 that measures the temperature of the heat storage material. The temperature of the heat storage material measured by the temperature sensor 14 is transmitted to the control device 10.

[0019] The control device 10 is a computer such as a microcomputer. The control device 10 controls the opening and closing and the opening degrees of the three-way valves 8a to 8c, the opening degrees of the first expansion valve 3, the second expansion valve 5, and the third expansion valve 6, the start / stop and rotation speed control of the compressor 1, the start / stop and rotation speed control of the pump 13, and the start / stop and rotation speed control of the fan 7. For example, the control device 10 switches the three-way valves 8a to 8c or changes the rotation speed of the compressor 1 and the pump 13 according to the temperature of the heat storage material measured by the temperature sensor 14, thereby controlling the heat storage air conditioning system 100 so that the room can be cooled to the desired set temperature.

[0020] (Cooling Operation 1: Cooling Operation Using a Thermal Storage System) Next, with reference to FIGS. 2 to 7, the control of the thermal storage air conditioning system 100 during cooling operation will be described. FIG. 2 shows the flow of refrigerant in the thermal storage air conditioning system 100 at the start of cooling operation. When cooling operation is started, the control device 10 controls the three-way valve 8a to prevent the refrigerant from flowing through pipe P2, controls the three-way valve 8b to prevent the refrigerant from flowing through the third expansion valve 6, and controls the three-way valve 8c to prevent the refrigerant from flowing through pipe P4 and to flow through the first expansion valve 3. The control device 10 operates the compressor 1 at a predetermined rotation speed or less, for example, at a minimum rotation speed. The control device 10 operates the pump 12 at a predetermined rotation speed that is lower than the maximum rotation speed. With this control, the refrigerant and the thermal storage material flow in the direction of the arrows through the thick-line flow paths in FIG. 2. This operation is called cooling operation using a thermal storage system (or cooling operation 1). Even when the compressor 1 is operated at a low speed, the refrigerant is cooled by the heat storage material in the heat accumulator / radiator 11, so that sufficient cooling performance can be obtained. For example, the control device 10 controls the rotation speed of the pump 12 in accordance with the set temperature of the cooling system and the room temperature, and adjusts the flow rate of the heat storage material, thereby controlling the temperature of the vehicle's room to the set temperature. From the viewpoint of power saving, it is preferable to operate the compressor 1 at as low a speed as possible, but the rotation speed of not only the pump 12 but also the compressor 1 may be adjusted in accordance with the difference between the set temperature of the cooling system and the room temperature.

[0021] If such operation continues, the temperature of the heat storage material gradually rises due to heat exchange with the refrigerant, and the ability of the heat storage material to cool the refrigerant decreases. Then, the control device 10 increases the rotation speed of the pump 12 to increase the flow rate of the heat storage material. For example, the control device 10 may store a table that associates the temperature of the heat storage material with the rotation speed of the pump 12, and control the rotation speed of the pump 12 based on the temperature of the heat storage material measured by the temperature sensor 14 and this table. By increasing the flow rate of the heat storage material, the ability of the heat storage material to cool the refrigerant is maintained, allowing for continued air conditioning operation using the heat storage system and achieving power savings.

[0022] (Cooling operation 2: cooling operation using a refrigeration cycle) When the temperature of the heat storage material rises and it becomes impossible to cool the refrigerant even by increasing the rotation speed of the pump 12, the control device 10 controls the three-way valve 8a so that the refrigerant flows through the pipe P2 and does not flow through the heat accumulator / radiator 11. The control device 10 operates the compressor 1 at a rotation speed that allows the cooling set temperature to be achieved and stops the pump 12. With this control, the refrigerant flows in the direction of the arrows through the thick-line flow path in Figure 3. This makes it possible to continue cooling operation without using a heat storage material. This operation is called cooling operation using a refrigeration cycle (or cooling operation 2).

[0023] The Mollier diagram in Figure 4 shows the changes in the state of the refrigerant when cooling operations 1 and 2 are performed. In Figure 4, each symbol represents the following state: A1 represents the state (gas phase) of the high-temperature, high-pressure refrigerant discharged from compressor 1 when the heat accumulator / radiator 11 shown in Figure 3 is not used (cooling operation 2); A2 represents the state (liquid phase) of the refrigerant at the outlet side of condenser 2 in that case; A5 represents the state (liquid phase) of the refrigerant at the inlet side of evaporator 4; and A6 represents the state (gas phase) of the refrigerant at the outlet side of evaporator 4. In contrast, A3 represents the state (gas phase) of the refrigerant discharged from compressor 1 during cooling operation 1 shown in Figure 2; A4 represents the state (liquid phase) of the refrigerant at the outlet side of condenser 2 during cooling operation 1 shown in Figure 2; A5 represents the state (liquid phase) of the refrigerant at the inlet side of evaporator 4; and A6 represents the state (gas phase) of the refrigerant at the outlet side of evaporator 4. Cooling operation 1 allows for a reduction in the work required by compressor 1 to increase enthalpy by the amount of L1 - L2 compared to cooling operation 2.

[0024] FIG. 5 shows the power consumption in cooling operations 1 and 2. The vertical axis of FIG. 5 represents power consumption (W), and the horizontal axis represents operating time. T1 is the time when cooling operation 1 is switched to cooling operation 2. The dashed line graph represents the overall power consumption of the thermal storage air conditioning system 100, and the solid line graph represents the trend in power consumption of compressor 1. As shown in the figure, power consumption can be reduced by performing cooling operation 1, which uses thermal storage material to suppress the rotation speed of compressor 1. For example, in a mobile object powered solely by a battery, the battery power must be used to travel to the destination, prioritizing air conditioning. With the thermal storage air conditioning system 100, cooling operation 1 can reduce the power consumption required for air conditioning, allowing more power to be used for travel.

[0025] (Cooling Operation 3: Cooling Operation by Refrigeration Cycle with Cooling of Heat Storage Material) When the temperature of the heat storage material rises, it is possible to continue cooling using Cooling Operation 2, but continuing Cooling Operation 2 increases power consumption. Therefore, while performing cooling operation, the heat storage / radiator 11 is used as a heat radiator to cool the heat storage material. For example, the control device 10 controls the three-way valves 8a to 8c so that the refrigerant flows through the third expansion valve 6 but does not flow through the first expansion valve 3 and the second expansion valve 5. The control device 10 operates the compressor 1 at a rotation speed that achieves the set cooling temperature. The control device 10 operates the pump 12 at a predetermined rotation speed. Through this control, the refrigerant and the heat storage material flow in the direction of the arrows through the thick-line flow path in Figure 6. The refrigerant that passes through the condenser 2 is decompressed by the third expansion valve 6 to become a low-temperature refrigerant. In the heat storage / radiator 11, the low-temperature refrigerant and the heat storage material are cooled by heat exchange between them. The refrigerant that absorbs heat in the heat storage / radiator 11 exchanges heat with the indoor air in the evaporator 4, cooling the room. This makes it possible to cool the heat storage material whose temperature has risen due to the cooling operation 1. This operation is called the cooling operation by the refrigeration cycle that involves cooling the heat storage material (or cooling operation 3).

[0026] Another mode of cooling operation by a refrigeration cycle accompanied by cooling of the heat storage material is shown in Figure 7. That is, the control device 10 controls the three-way valves 8a to 8c so that the refrigerant flows through the third expansion valve 6 and the second expansion valve 5, but does not flow through the first expansion valve 3. This type of control also makes it possible to cool the heat storage material. This operation is called cooling operation 4.

[0027] The control device 10 cools the heat storage material while continuing the cooling operation using the refrigeration cycle shown in Fig. 6 or 7. Then, when the temperature measured by the temperature sensor 14 reaches a predetermined temperature (for example, 5°C), the control device 10 switches back to cooling operation 1 in Fig. 2 and continues the cooling operation. This makes it possible to reduce the power consumption of the heat storage air conditioning system 100.

[0028] (Improvements to the Heat Storage Tank) As an improvement to increase the heat storage capacity of the heat storage material, the heat storage tank 12 may be equipped with a latent heat storage material. FIG. 8 shows a cross section of the heat storage tank 12 equipped with a latent heat storage material. The oval-shaped member in FIG. 8 is the latent heat storage material 15. The latent heat storage material 15 is, for example, a tubular container filled with a latent heat storage material having a larger heat capacity than the heat storage material. A large number of latent heat storage materials 15 are installed inside the heat storage tank 12, and liquid heat storage material flows between the latent heat storage materials 15. Heat exchange occurs between the heat storage material in the heat storage tank 12 and the latent heat storage material 15, allowing the temperature of the heat storage tank 12 to be kept low for a long period of time, and allowing cooling operation 1 (cooling operation using a heat storage system) to be performed for a long period of time. This reduces the power consumption of the heat storage air conditioning system 100. By installing the latent heat storage material 15 in the heat storage tank 12, the cooling capacity of the heat storage material can be maintained for a long time, eliminating the need for a large amount of heat storage material and allowing the heat storage tank 12 to be made lighter and more compact. This is expected to improve the fuel efficiency of the vehicle and reduce the power consumption required for movement. The compactness of the heat storage tank 12 increases the flexibility of installation and eliminates the need to reinforce the vehicle side to install the heat storage tank 12.

[0029] (Operation) Next, an example of control of the heat storage air conditioning system 100 according to the embodiment will be described with reference to FIG. 9 . When the cooling operation is started, the control device 10 performs the cooling operation using the heat storage system (step S1). That is, the control device 10 performs the cooling operation in the cooling operation mode 1 illustrated in FIG. 2 . The control device 10 operates the compressor 1, for example, at a rotation speed that is different from the minimum rotation speed within a predetermined range, and operates the pump 12 at a rotation speed below the upper limit. The control device 10 monitors the temperature of the heat storage material measured by the temperature sensor 14. When the temperature of the heat storage material is equal to or higher than a predetermined first threshold (step S2; Yes), the control device 10 increases the rotation speed of the pump 12 and increases the flow rate of the heat storage material supplied to the heat accumulator / radiator 11 (step S3). When the temperature of the heat storage material is lower than the first threshold (step S2; No), the control device 10 continues the cooling operation 1. The first threshold is a value lower than the upper limit of the heat storage material temperature that can be increased by heat exchange with the refrigerant.

[0030] Even after the rotation speed of the pump 12 increases, the control device 10 monitors the temperature of the heat storage material measured by the temperature sensor 14. If the temperature of the heat storage material is below a predetermined second threshold (step S4; No), the control device 10 continues the control of step S3. The second threshold is a temperature higher than the first threshold at which the heat storage material can no longer cool the refrigerant (a predetermined temperature at which the refrigerant can no longer absorb heat). If the temperature of the heat storage material reaches or exceeds the second threshold (step S4; Yes), the cooling operation using the heat storage system is switched to cooling operation using the refrigeration cycle (step S5). That is, the control device 10 performs the cooling operation in one of the cooling operations 2 to 4 illustrated in FIGS. 3, 6, and 7. The cooling operation to be performed using any of the cooling operations 2 to 4 can be selected arbitrarily. It may be possible to arbitrarily switch between the cooling operations 2 to 4 during the cooling operation using the refrigeration cycle. For example, cooling operation 2 may be performed until the indoor temperature reaches the set temperature, and once the indoor temperature reaches the set temperature and enters the phase of maintaining the indoor temperature at the set temperature, cooling of the heat storage material may be performed by cooling operation 3 or cooling operation 4. The switching between cooling operations 2 to 4 may be performed by the control device 10 or by a user instruction. Even during cooling operation using the refrigeration cycle, the control device 10 monitors the temperature of the heat storage material measured by the temperature sensor 14. If the temperature of the heat storage material is higher than a predetermined third threshold (step S6; No), the control device 10 continues the control of step S5. The third threshold may be set, for example, to the initial temperature of the heat storage material (e.g., 5°C) or a value close to it. When the temperature of the heat storage material falls below the third threshold (step S6; Yes), the control device 10 switches from cooling operation using the refrigeration cycle to cooling operation using the heat storage system (step S1). During cooling operation, the control device 10 repeatedly executes the control of steps S1 to S6. In this way, the heat storage air conditioning system 100 can reduce power consumption by performing cooling operation (cooling operation 1) using the heat storage system. Even after the heat storage temperature rises, cooling operation can be continued by performing cooling operation (cooling operations 2 to 4) using the refrigeration cycle, and the heat storage material can be cooled by using the heat storage / radiator 11 as a radiator (cooling operations 3 to 4), and cooling operation (cooling operation 1) using the heat storage system can be performed again.

[0031] (Effects) As described above, according to this embodiment, the heat accumulator / radiator 11 and the heat storage tank 12 are provided separately and connected by the pipe P5, and when necessary, the heat storage material is supplied to the heat accumulator / radiator 11 by driving the pump 13. As a result, even if a large heat storage tank 12 is required to store the heat storage material required for air conditioning, it is possible to perform air conditioning operation using the heat storage system by arranging the heat storage tank 12 in a location where it can be stored. Air conditioning systems mounted on vehicles, etc., are generally limited by the amount of space available for installation. If only a small-capacity heat storage tank can be installed due to this limitation, there is a possibility that the heat storage capacity of the heat storage tank will be insufficient and air conditioning will not be possible when the cooling load is high. In contrast, the heat storage air conditioning system 100 of this embodiment, which is configured so that the heat storage / radiator 11 and the heat storage tank 12 can be located in separate locations, is easy to install even in mobile vehicles with many spatial constraints, and by storing a sufficient amount of heat storage material in the heat storage tank 12, cooling operation using the heat storage system can be performed for a longer period of time. Electric vehicles and battery-powered AGTs without pantograph power supply are becoming more common, and in these mobile vehicles, remaining battery capacity is an issue. However, the heat storage air conditioning system 100 of this embodiment can be expected to have a significant power saving effect by reducing the power consumption of the compressor 1 through the use of heat storage material. The heat exchange performance of the heat storage / radiator 11 can be controlled by adjusting the output of the pump 12. For example, by increasing the output of the pump 12 even after the temperature of the heat storage material has risen above a certain level, cooling operation using the heat storage system can be continued.

[0032] By using a plate-type heat exchanger as the heat accumulator / radiator 11, it is possible to obtain the same performance as a fan coil-type heat exchanger while keeping the size more compact, which makes it easier to install in a mobile body with many spatial constraints.

[0033] In cooling operation 1, the heat storage material cools the high-temperature refrigerant discharged from the compressor 1. Because the refrigerant can be cooled by the low-temperature heat storage material, the compressor 1 can be operated at, for example, the minimum rotation speed, and the amount of power consumed by the compressor 1 and the refrigeration cycle can be reduced.

[0034] In cooling operations 3 and 4, the heat storage material is cooled by heat exchange with the low-temperature refrigerant that has passed through the third expansion valve 6. Since the heat storage material can be cooled by the refrigeration cycle within the heat storage air conditioning system 100, there is no need to provide external equipment such as a heat source supply and exhaust device.

[0035] By installing the latent heat storage material 15 in the heat storage tank 12, it is possible to improve the cooling capacity of the heat storage material and reduce the weight and size of the heat storage tank 12. This makes it possible to further reduce power consumption and introduce the heat storage air conditioning system 100 without worrying about spatial constraints.

[0036] As described above, several embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as defined in the claims, as well as in the scope and spirit of the invention.

[0037] <Additional Notes> The heat storage air conditioning system and control method described in each embodiment can be understood, for example, as follows.

[0038] (1) A heat storage air conditioning system 100 according to a first aspect includes a compressor 1 that compresses a refrigerant, a condenser 2 that condenses the refrigerant compressed by the compressor 1, a heat storage heat exchanger 11 provided downstream of the condenser 2 in the refrigerant flow direction, an expansion valve 3 provided downstream of the heat storage heat exchanger 11, an evaporator 4 that vaporizes the refrigerant decompressed by the expansion valve 3, a main pipe P1 through which the refrigerant flows that connects the compressor 1, the condenser 2, the heat storage heat exchanger 11, the expansion valve 3, and the evaporator 4, a heat storage tank 12 that stores a heat storage material, a pump 13 that sends the heat storage material to the heat storage heat exchanger 11, and a heat storage material pipe P5 through which the heat storage material flows that connects the heat storage tank 12, the pump 13, and the heat storage heat exchanger 11. This makes it possible to realize a heat storage type air conditioning system that can be mounted on a mobile object without requiring external equipment for exhausting heat.

[0039] (2) The heat-storage air-conditioning system 100 according to a second aspect is the heat-storage air-conditioning system 100 of (1), further comprising a bypass pipe P2 provided downstream of the condenser to bypass the heat-storage heat exchanger 11 and the expansion valve 3, a second expansion valve 5 provided in the bypass pipe, and a first valve 8a provided at a branch point of the bypass pipe and the main pipe to adjust the flow rate of the refrigerant flowing through the bypass pipe and the flow rate of the refrigerant flowing through the main pipe. This enables cooling operation (cooling operation 2) using a refrigeration cycle.

[0040] (3) The heat-storage air conditioning system 100 according to a third aspect is the heat-storage air conditioning system 100 of (1) to (2), and further includes a second bypass pipe P4 that bypasses the expansion valve 3, a third expansion valve 6 provided between the condenser 2 and the heat-storage heat exchanger 11, and a second valve 8c provided at a branch point of the second bypass pipe P4 and the main pipe P1 that adjusts the flow rate of the refrigerant flowing through the second bypass pipe and the flow rate of the refrigerant flowing through the main pipe. This enables cooling operations (cooling operations 3 and 4) using a refrigeration cycle that involves cooling the heat storage material.

[0041] (4) The heat-storage air-conditioning system 100 according to a fourth aspect is the heat-storage air-conditioning system 100 of any one of (1) to (3), in which a latent heat storage material 15 is mounted in the heat storage tank 12. This improves the cooling capacity of the heat storage material and makes it possible to make the heat storage tank 12 more compact.

[0042] (5) The heat-storage air-conditioning system 100 according to a fifth aspect is the heat-storage air-conditioning system 100 of any one of (1) to (4), further comprising a control device 10 that operates the compressor at a rotation speed that is within a predetermined range of the difference from the minimum rotation speed, and operates the pump at a predetermined rotation speed that is less than the upper limit value. This makes it possible to reduce the power consumption of the compressor 1.

[0043] (6) A sixth aspect of the heat storage air conditioning system 100 is the heat storage air conditioning system 100 of (5), in which the control device increases the rotation speed of the pump when the temperature of the heat storage material becomes equal to or higher than a predetermined first threshold. This increases the duration of the cooling operation in cooling operation 1, and reduces the power consumption of the compressor 1.

[0044] (7) A heat-storage air-conditioning system 100 according to a seventh aspect is the heat-storage air-conditioning system 100 of any one of (1) to (6), further comprising a control device 10 that controls the first valve so that, when the temperature of the heat storage material rises to a predetermined temperature at which the refrigerant can no longer absorb heat, the refrigerant flows through the bypass pipe P2 instead of through the main pipe P1. This allows the cooling operation to continue even after the temperature of the heat storage material has risen.

[0045] (8) The heat storage air conditioning system 100 according to an eighth aspect is the heat storage air conditioning system 100 according to any one of (1) to (7), further comprising a control device 10 that controls the second valve 8c so that the refrigerant flows through the second bypass pipe P4 without flowing through the main pipe P1. This allows the heat storage material to be cooled.

[0046] (9) A control method according to a ninth aspect is a heat storage air conditioning system including a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, a heat storage heat exchanger provided downstream of the condenser in the refrigerant flow direction, an expansion valve provided downstream of the heat storage heat exchanger, an evaporator that vaporizes the refrigerant decompressed by the expansion valve, a main pipe through which the refrigerant passes that connects the compressor, the condenser, the heat storage heat exchanger, the expansion valve, and the evaporator, a heat storage tank that stores a heat storage material, a pump that sends the heat storage material to the heat storage heat exchanger, and a heat storage material flow path through which the heat storage material passes that connects the heat storage tank, the pump, and the heat storage heat exchanger, wherein the control method operates the compressor at a rotation speed whose difference from a minimum rotation speed is within a predetermined range, and the pump at a predetermined rotation speed that is less than an upper limit value.

[0047] According to the above-described heat storage air conditioning system and control method, it is possible to reduce the power consumption required for air conditioning.

[0048] 100... Heat storage air conditioning system 1... Compressor 2... Condenser 3... First expansion valve 4... Evaporator 5... Second expansion valve 6... Third expansion valve 7... Fan 8a, 8b, 8c... Three-way valves 10... Control device 11... Heat accumulator / radiator 12... Heat storage tank 13... Pump 14... Temperature sensor P1, P2, P3, P4... Piping P5... Pipe

Claims

1. A heat storage air-conditioning system comprising: a compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the compressor; a heat storage heat exchanger provided downstream in the flow direction of the refrigerant in the condenser; an expansion valve provided downstream of the heat storage heat exchanger; an evaporator that vaporizes the refrigerant decompressed by the expansion valve; a main pipe through which the refrigerant passes and that connects the compressor, the condenser, the heat storage heat exchanger, the expansion valve, and the evaporator; a heat storage tank that stores a heat storage material; a pump that sends the heat storage material to the heat storage heat exchanger; and a heat storage material flow path through which the heat storage material passes and that connects the heat storage tank, the pump, and the heat storage heat exchanger.

2. The heat storage air-conditioning system according to claim 1, further comprising: a bypass pipe provided downstream of the condenser and bypassing the heat storage heat exchanger and the expansion valve; a second expansion valve provided in the bypass pipe; and a first valve provided at a branch point between the bypass pipe and the main pipe and that adjusts the flow rate of the refrigerant flowing through the bypass pipe and the flow rate of the refrigerant flowing through the main pipe.

3. The heat storage air-conditioning system according to claim 1 or 2, further comprising: a second bypass pipe that bypasses the expansion valve; a third expansion valve provided between the condenser and the heat storage heat exchanger; and a second valve provided at a branch point between the second bypass pipe and the main pipe and that adjusts the flow rate of the refrigerant flowing through the second bypass pipe and the flow rate of the refrigerant flowing through the main pipe.

4. The heat storage air-conditioning system according to claim 1 or 2, further comprising a latent heat storage material mounted in the heat storage tank.

5. The heat storage air-conditioning system according to claim 1, further comprising a control device that operates the compressor at a rotation speed such that the difference from the minimum rotation speed is within a predetermined range and operates the pump at a predetermined rotation speed less than the upper limit.

6. The heat storage air-conditioning system according to claim 5, wherein the control device increases the rotation speed of the pump when the temperature of the heat storage material becomes equal to or higher than a predetermined first threshold value.

7. The heat storage air-conditioning system according to claim 2, further comprising a control device that controls the first valve such that when the temperature of the heat storage material rises to a predetermined temperature at which heat absorption from the refrigerant becomes impossible, the refrigerant flows through the bypass pipe instead of through the main pipe.

8. The heat storage air conditioning system according to claim 3, further comprising a control device that controls the second valve so that the refrigerant flows through the second bypass pipe without flowing through the main pipe.

9. In a heat storage air conditioning system comprising a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, a heat storage heat exchanger provided on the downstream side in the flow direction of the refrigerant in the condenser, an expansion valve provided on the downstream side of the heat storage heat exchanger, an evaporator that vaporizes the refrigerant decompressed by the expansion valve, a main pipe through which the refrigerant passes and connects the compressor, the condenser, the heat storage heat exchanger, the expansion valve, and the evaporator, a heat storage tank that stores a heat storage material, a pump that sends the heat storage material to the heat storage heat exchanger, and a heat storage material flow path through which the heat storage material passes and connects the heat storage tank, the pump, and the heat storage heat exchanger, a control method of operating the compressor at a rotation speed such that a difference from the minimum rotation speed is within a predetermined range and operating the pump at a predetermined rotation speed less than an upper limit value.

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