Refrigeration cycle device

Abstract

A refrigeration cycle device (100) comprises a radiation cooling unit (12) that is disposed outdoors and functions as a condenser by radiating electromagnetic waves, a first heat exchanger (21) that is disposed at a lower position than the radiation cooling unit (12) and functions as an evaporator by heat exchange with a heat medium, liquid piping (31), gas piping (32), a compressor (11), a bypass valve (13) that switches between a first path (30a) in which the refrigerant passes through the compressor (11) and a second path (30b) in which the refrigerant bypasses the compressor (11) and does not pass therethrough, and a control device (60). The control device (60) switches between the first path (30a) and the second path (30b) on the basis of a determination as to whether a predetermined condition is satisfied.

Description

Refrigeration Cycle Equipment

[0001] The present disclosure relates to a refrigeration cycle device.

[0002] Energy-saving refrigeration cycle devices that utilize natural energy have been known for some time. Patent Document 1 (JP 2003-254686 A) discloses an ice-making system in which a condenser is installed at a higher position than an evaporator, and the condenser exchanges heat with air through natural convection and dissipates heat through infrared radiation, circulating a refrigerant without power.

[0003] Japanese Patent Application Laid-Open No. 2003-254686

[0004] The ice-making system in Patent Document 1 (JP 2003-254686 A) discloses switching to a circulation path using a compressor during the summer when temperatures are so high that the refrigerant does not circulate naturally. However, Patent Document 1 (JP 2003-254686 A) simply discloses switching to a circulation path using a compressor depending on the season, but does not disclose how the switching is controlled.

[0005] An object of the present disclosure is to provide a natural energy type refrigeration cycle device that can suitably switch between a circulation path using a compressor and a natural circulation path.

[0006] The refrigeration cycle device according to the present disclosure includes a radiative cooling unit that is disposed outdoors and functions as a condenser by radiating electromagnetic waves, a first heat exchanger that is disposed lower than the radiative cooling unit and functions as an evaporator by exchanging heat with a heat medium, a first pipe connecting an outlet of the radiative cooling unit to an inlet of the first heat exchanger, a second pipe connecting the outlet of the first heat exchanger to an inlet of the radiative cooling unit, a compressor, a switching valve that switches between a first path in which the refrigerant passes through the compressor and a second path in which the refrigerant bypasses the compressor, and a control device. The control device switches between the first path and the second path based on whether a predetermined condition is met.

[0007] According to the refrigeration cycle device of the present disclosure, the control device can suitably switch between a first path, which is a circulation path using a compressor, and a second path, which is a natural circulation path, based on a determination of whether a predetermined condition is met.

[0008] Fig. 1 is a diagram showing a configuration example of a refrigeration cycle device in embodiment 1. Fig. 2 is a flowchart showing control of a circulation path in embodiment 1. Fig. 3 is a diagram showing a configuration example of a refrigeration cycle device in embodiment 2. Fig. 4 is a flowchart showing control of a circulation path in embodiment 2. Fig. 5 is a diagram showing a configuration example of a refrigeration cycle device in embodiment 3.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments described below, when numbers, quantities, etc. are mentioned, the scope of the present disclosure is not necessarily limited to those numbers, quantities, etc., unless otherwise specified. The same reference numerals are used for the same or equivalent parts, and redundant descriptions may not be repeated. It is intended from the beginning that the configurations in the embodiments may be used in appropriate combinations.

[0010] Embodiment 1. Fig. 1 is a diagram showing an example of the configuration of a refrigeration cycle apparatus 100 in Embodiment 1. The refrigeration cycle apparatus 100 includes an outdoor unit 10, an indoor unit 20, and a control device 60. The control device 60 may be disposed in at least one of the outdoor unit 10 or the indoor unit 20. In the refrigeration cycle apparatus 100, the outdoor unit 10 and the indoor unit 20 are connected by a liquid pipe 31 and a gas pipe 32 to form a refrigerant circuit 30.

[0011] The outdoor unit 10 includes a compressor 11, a radiative cooling unit 12, a bypass valve 13, and a pressure sensor 14. The compressor 11 draws in a refrigerant, compresses it, and discharges it. The radiative cooling unit 12 functions as a condenser by radiating electromagnetic waves. Radiative heat radiation is a phenomenon in which thermal energy is radiated as electromagnetic waves into space, taking advantage of the fact that the Earth's atmosphere transmits infrared rays of specific wavelengths without absorbing them. The radiative cooling unit 12 is placed facing skyward, for example, on the roof of a building.

[0012] The radiative cooling unit 12 will now be described in detail. The radiative cooling unit 12 is configured, for example, by laminating a polymer layer and a metal reflective layer from the surface. The radiative cooling unit 12 is arranged so as to be in contact with the gas pipe 32, and radiates the thermal energy received from the refrigerant into space as electromagnetic waves in a specific wavelength range (for example, 8 to 13 μm).

[0013] The bypass valve 13 is arranged in parallel with the compressor 11 and functions as a switching valve that switches between passing the refrigerant through the compressor 11 and bypassing the compressor 11. The bypass valve 13 switches between a refrigerant passing state and a blocked state, thereby switching the flow path of the refrigerant flowing through the refrigerant circuit 30 between a first path 30a that passes through the compressor 11 and a second path 30b that passes through the bypass valve 13. The bypass valve 13 may not be arranged in parallel with the compressor 11, but may be a flow path switching valve that is arranged at the branch point between the first path 30a and the second path 30b. The pressure sensor 14 is arranged on the inlet side of the radiative cooling unit 12 and detects the pressure of the refrigerant before it passes through the radiative cooling unit 12. The detected value of the pressure sensor 14 is sent to the control device 60.

[0014] The indoor unit 20 includes a first heat exchanger 21. The first heat exchanger 21 is disposed at a lower position than the radiative cooling section 12 and functions as an evaporator by exchanging heat with a heat medium (e.g., air, water, etc.). A liquid pipe 31 connects the outlet of the radiative cooling section 12 to the inlet of the first heat exchanger 21. A gas pipe 32 connects the outlet of the first heat exchanger 21 to the inlet of the radiative cooling section 12.

[0015] The control device 60 includes a control unit 61 and a storage unit 62. The control device 60 can communicate with the compressor 11 and the bypass valve 13 of the refrigerant circuit 30 to control the compressor 11 and the bypass valve 13. The control unit 61 is a computing entity that controls each actuator of the refrigerant circuit 30 by executing various programs. The control unit 61 is configured as a computer such as a processor. The processor may be configured, for example, as a microcontroller, a central processing unit (CPU), or a micro-processing unit (MPU). Note that the processor has the function of executing various processes by executing programs, but some or all of these functions may be implemented using dedicated hardware circuits such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). The term "processor" is not limited to a processor in the narrow sense that executes processes using a stored program, such as a CPU or MPU, but may also include hardwired circuits such as an ASIC or FPGA. Therefore, a processor may be interpreted as a processing circuitry whose operations are predefined by computer-readable code and / or hardwired circuitry. The processor may be configured on a single chip or multiple chips. Furthermore, the processor and associated processing circuitry may be configured on multiple computers interconnected by wire or wirelessly via a local area network or a wireless network. The processor and associated processing circuitry may be configured as a cloud computer that performs remote calculations based on input data and outputs the calculation results to another device in a remote location.

[0016] The memory unit 62 provides a storage area for storing program code, work memory, etc., when the processor of the control unit 61 executes various programs. The memory unit 62 may be one or more non-transitory computer-readable media. Examples of the memory unit 62 include volatile memories such as dynamic random access memory (DRAM) and static random access memory (SRAM), and non-volatile memories such as read-only memory (ROM) and flash memory. The memory unit 62 may also be one or more computer-readable storage media. Examples of the memory unit 62 include storage devices such as hard disk drives (HDDs) and solid-state drives (SSDs). The control unit 61 controls each actuator of the refrigerant circuit 30 by executing the programs stored in the memory unit 62.

[0017] In the refrigeration cycle apparatus 100, the vapor refrigerant condenses in the radiative cooling unit 12 by radiative heat radiation, becoming a liquid refrigerant and flowing down to the first heat exchanger 21 by its own weight. The liquid refrigerant absorbs heat of vaporization from the surrounding heating medium in the first heat exchanger 21 and evaporates. When the value of the pressure sensor 14 is a sufficiently low pressure below the threshold, the bypass valve 13 is in a passing state, allowing the refrigerant to pass through the second path 30b. The vapor refrigerant evaporated in the first heat exchanger 21 is naturally drawn into the radiative cooling unit 12 through the second path 30b. On the other hand, when the value of the pressure sensor 14 is equal to or greater than the threshold and not a sufficiently low pressure, the bypass valve 13 is in a closed state, allowing the refrigerant to pass through the first path 30a. The vapor refrigerant evaporated in the first heat exchanger 21 is guided to the radiative cooling unit 12 through the first path 30a by the operation of the compressor 11.

[0018] Next, a description will be given of the control executed by the control device 60. Fig. 2 is a flowchart showing the control of the circulation path in embodiment 1. The processing of the flowchart in Fig. 2 is repeatedly called and executed as a subroutine from the main routine in the control of the control device 60.

[0019] The control device 60 first detects the value of the pressure sensor 14 in step S (hereinafter simply referred to as "S") 11. Next, the control device 60 determines whether the value of the pressure sensor 14 is equal to or greater than a predetermined threshold (S12). If the control device 60 determines that the value of the pressure sensor 14 is equal to or greater than the predetermined threshold (YES in S12), it changes the bypass valve 13 to a closed state (S13). This causes the refrigerant to flow through the first path 30a.

[0020] Next, the control device 60 starts the compressor 11 (S14). By operating the compressor 11, the refrigerant can be guided to the radiative cooling unit 12 even when the refrigerant pressure is high in the radiative cooling unit 12. Next, the control device 60 determines whether a predetermined fixed time has elapsed since the compressor 11 was started (S15). If the control device 60 determines that the fixed time has elapsed since the compressor 11 was started (YES in S15), it stops the compressor 11 (S16) and returns the process from the subroutine to the main routine. If the control device 60 determines that the fixed time has not elapsed since the compressor 11 was started (NO in S15), it returns the process from the subroutine to the main routine without stopping the compressor 11.

[0021] When the control device 60 determines in S12 that the value of the pressure sensor 14 is less than the predetermined threshold value (NO in S12), the control device 60 changes the bypass valve 13 to the passing state (S17) and returns the process from the subroutine to the main routine, whereby the refrigerant flows through the second path 30b.

[0022] The refrigeration cycle apparatus 100 of the first embodiment switches between the first path 30a through which the refrigerant passes through the compressor 11 and the second path 30b through which the refrigerant passes through the bypass valve 13, based on the value of the pressure sensor 14. This allows for appropriate switching between the first path 30a, which is a path for circulation using the compressor 11, and the second path 30b, which is a path for natural circulation.

[0023] Embodiment 2. A refrigeration cycle apparatus 100A of embodiment 2 differs from embodiment 1 in that a control device 60A includes a communication unit 63 instead of the pressure sensor 14. The following description will focus on differences from embodiment 1, and will omit a description of the same configuration as embodiment 1. Figure 3 is a diagram showing an example of the configuration of the refrigeration cycle apparatus 100A of embodiment 2.

[0024] As shown in Fig. 3, the control device 60A includes a control unit 61, a memory unit 62, and a communication unit 63. The communication unit 63 communicates with a weather data providing system 70. The weather data providing system 70 is a system that records and transmits weather data acquired in advance. The weather data includes, for example, data on the amount of clouds, data on humidity, data on rainfall, and data on the amount of dust. The control device 60 receives the weather data provided by the weather data providing system 70 via the communication unit 63.

[0025] Fig. 4 is a flowchart showing the control of the circulation path in embodiment 2. The process of the flowchart in Fig. 4 is repeatedly called and executed as a subroutine from a main routine in the control of control device 60A.

[0026] First, in step S21, the control device 60A determines whether or not the communication unit 63 has received weather data provided by the weather data providing system 70. If the control device 60A determines that weather data has not been received (NO in S21), the control device 60A returns the process from the subroutine to the main routine. If the control device 60A determines that weather data has been received by the communication unit 63 (YES in S21), the control device 60A determines whether, for example, the amount of cloud cover is equal to or greater than a predetermined threshold value in the weather data (S22).

[0027] In S22, the control device 60A may execute, as data other than the amount of clouds, determination of whether humidity is equal to or greater than a predetermined threshold, determination of whether rainfall is equal to or greater than a predetermined threshold, determination of whether dust amount is equal to or greater than a predetermined threshold, etc. When the control device 60A determines that the amount of clouds (humidity, rainfall, dust amount) is equal to or greater than a predetermined threshold (YES in S22), the control device 60A changes the bypass valve 13 to a closed state (S23). As a result, the refrigerant flows through the first path 30a.

[0028] Next, the control device 60A starts the compressor 11 (S24). By operating the compressor 11, the refrigerant can be guided to the radiative cooling unit 12 even when the refrigerant pressure is high in the radiative cooling unit 12 and natural circulation is difficult. Next, the control device 60A determines whether the amount of clouds (humidity, rainfall, and dust amount) is less than a predetermined threshold (S25). If the control device 60A determines that the amount of clouds (humidity, rainfall, and dust amount) is less than a predetermined threshold (YES in S25), it stops the compressor 11 (S26) and returns the process from the subroutine to the main routine. If the control device 60A determines that the amount of clouds (humidity, rainfall, and dust amount) is equal to or greater than a predetermined threshold (NO in S25), it returns the process from the subroutine to the main routine without stopping the compressor 11.

[0029] When the control device 60A determines in S22 that the amount of cloud cover (humidity, rainfall, and dust amount) is less than a predetermined threshold (NO in S22), the control device 60A changes the bypass valve 13 to the passing state (S27) and returns the process from the subroutine to the main routine, whereby the refrigerant flows through the second path 30b.

[0030] The refrigeration cycle apparatus 100A of the second embodiment switches between the first path 30a through which the refrigerant passes through the compressor 11 and the second path 30b through which the refrigerant passes through the bypass valve 13, based on the values ​​of the amount of cloud cover (humidity, rainfall, and dust amount) that are meteorological data. This allows for appropriate switching between the first path 30a, which is a circulation path using the compressor 11, and the second path 30b, which is a natural circulation path.

[0031] Embodiment 3. A refrigeration cycle apparatus 100B of embodiment 3 differs from embodiment 1 in that the outdoor unit 10A includes a second heat exchanger 15, a camera 71, and a humidity sensor 72, but is not provided with a pressure sensor 14. The following description will focus on differences from embodiment 1, and will omit a description of the same configuration as embodiment 1. Figure 5 is a diagram showing an example of the configuration of the refrigeration cycle apparatus 100B of embodiment 3.

[0032] As shown in FIG. 5 , a second heat exchanger 15 that functions as a condenser by exchanging heat with air is disposed between the outlet side of the radiative cooling unit 12 and the inlet side of the first heat exchanger 21. The second heat exchanger 15 is included in the outdoor unit 10A and is installed, for example, on the roof of a building, similar to the radiative cooling unit 12. A fan (not shown) is provided near the second heat exchanger 15 to blow air toward the second heat exchanger 15. The provision of the second heat exchanger 15 allows the refrigerant to condense even when the amount of radiant heat released in the radiative cooling unit 12 is small. The second heat exchanger 15 may be provided in the refrigeration cycle apparatus 100 of the first embodiment and the refrigeration cycle apparatus 100A of the second embodiment.

[0033] The camera 71 is disposed in a position where it can capture images of clouds in the sky. The images captured by the camera 71 are transmitted to the control device 60. The control device 60 detects the amount of clouds from the captured images. The processing after the amount of clouds is detected is the same as the processing from S22 onwards in FIG. 4. The humidity sensor 72 measures the humidity of the outside air. The value measured by the humidity sensor 72 is transmitted to the control device 60. The control device 60 detects the humidity from the measurement value of the humidity sensor 72. The processing after the humidity is detected is the same as the processing from S22 onwards in FIG. 4. Either the camera 71 or the humidity sensor 72 may be disposed in the refrigeration cycle apparatus 100B.

[0034] Summary The refrigeration cycle apparatus 100 (100A, 100B) of the present disclosure includes a radiative cooling unit 12 that is placed outdoors and functions as a condenser by radiating electromagnetic waves, a first heat exchanger 21 that is placed lower than the radiative cooling unit 12 and functions as an evaporator by exchanging heat with a heat medium, a liquid pipe 31 that connects an outlet of the radiative cooling unit 12 to an inlet of the first heat exchanger 21, a gas pipe 32 that connects the outlet of the first heat exchanger 21 to an inlet of the radiative cooling unit 12, a compressor 11, a bypass valve 13 that switches between a first path 30a through which the refrigerant passes through the compressor 11 and a second path 30b through which the refrigerant bypasses the compressor 11, and a control device 60 (60A). The control device 60 (60A) switches between the first path 30a and the second path 30b based on a determination of whether a predetermined condition is met.

[0035] Preferably, the refrigeration cycle apparatus 100 further includes a pressure sensor 14 arranged on the inlet side of the radiative cooling unit 12 and measuring the pressure of the refrigerant. The control device 60 switches the bypass valve 13 so that the refrigerant passes through the first path 30a when the value of the pressure sensor 14 is equal to or greater than a threshold, and passes through the second path 30b when the value of the pressure sensor 14 is less than the threshold.

[0036] Preferably, the refrigeration cycle apparatus 100A further includes a communication unit 63 that receives weather data. The control device 60A switches the bypass valve 13 based on the weather data so that the refrigerant passes through either the first path 30a or the second path 30b.

[0037] Preferably, the control device 60A detects the amount of clouds using meteorological data, and switches the bypass valve 13 so that the refrigerant circulates through the first path 30a when the amount of clouds is equal to or greater than a threshold, and so that the refrigerant circulates through the second path 30b when the amount of clouds is less than the threshold.

[0038] Preferably, the control device 60A detects the humidity of the outside air from weather data, and switches the bypass valve 13 so that the refrigerant passes through the first path 30a when the humidity is above a threshold, and passes through the second path 30b when the humidity is below the threshold.

[0039] Preferably, the control device 60A detects the amount of rainfall from weather data, and switches the bypass valve 13 so that the refrigerant passes through the first path 30a when the amount of rainfall is equal to or greater than a threshold, and passes through the second path 30b when the amount of rainfall is less than the threshold.

[0040] Preferably, the control device 60A detects the amount of dust from weather data, and switches the bypass valve 13 so that the refrigerant passes through the first path 30a when the amount of dust is above a threshold, and passes through the second path 30b when the amount of dust is below the threshold.

[0041] Preferably, the refrigeration cycle apparatus 100B further includes a second heat exchanger 15 that functions as a condenser by exchanging heat with air between the radiative cooling unit 12 and the first heat exchanger 21.

[0042] According to the above configuration, the control device 60 (60a) switches between the first path 30a through which the refrigerant passes through the compressor 11 and the second path 30b through which the refrigerant passes through the bypass valve 13, based on a determination as to whether a predetermined condition is met. This allows for suitable switching between the first path 30a, which is a path for circulation using the compressor 11, and the second path 30b, which is a path for natural circulation.

[0043] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0044] 10, 10A Outdoor unit, 11 Compressor, 12 Radiation cooling section, 13 Bypass valve, 14 Pressure sensor, 15 Second heat exchanger, 20 Indoor unit, 21 First heat exchanger, 30 Refrigerant circuit, 30a First path, 30b Second path, 31 Liquid piping, 32 Gas piping, 60, 60A Control device, 61 Control unit, 62 Memory unit, 63 Communication unit, 70 Weather data providing system, 71 Camera, 72 Humidity sensor, 100, 100A, 100B Refrigeration cycle device.

Claims

1. A refrigeration cycle device comprising: a radiative cooling unit that is placed outdoors and functions as a condenser by radiating electromagnetic waves; a first heat exchanger that is placed at a lower position than the radiative cooling unit and functions as an evaporator by heat exchange with a heat medium; a first piping that connects an outlet of the radiative cooling unit and an inlet of the first heat exchanger; a second piping that connects the outlet of the first heat exchanger and an inlet of the radiative cooling unit; a compressor; a switching valve that switches between a first path in which a refrigerant passes through the compressor and a second path in which the refrigerant bypasses the compressor; and a control device, wherein the control device switches between the first path and the second path based on a determination of whether a predetermined condition is met.

2. The refrigeration cycle device of claim 1, further comprising a pressure sensor arranged on the inlet side of the radiative cooling section for measuring the pressure of the refrigerant, wherein the control device switches the switching valve so that the refrigerant passes through the first path when the value of the pressure sensor is equal to or greater than a threshold value, and so that the refrigerant passes through the second path when the value of the pressure sensor is less than the threshold value.

3. A refrigeration cycle device as described in claim 1, further comprising a communication unit that receives weather data, and the control device switches the switching valve so that the refrigerant passes through either the first path or the second path based on the weather data.

4. The refrigeration cycle device of claim 3, wherein the control device detects the amount of clouds from the weather data, and switches the switching valve so that the refrigerant passes through the first path when the amount of clouds is equal to or greater than a threshold, and passes through the second path when the amount of clouds is less than the threshold.

5. The refrigeration cycle device of claim 3, wherein the control device detects the humidity of the outside air from the weather data, and switches the switching valve so that the refrigerant passes through the first path when the humidity is equal to or greater than a threshold value, and passes through the second path when the humidity is less than the threshold value.

6. The refrigeration cycle device of claim 3, wherein the control device detects the amount of rainfall from the weather data, and switches the switching valve so that the refrigerant passes through the first path when the amount of rainfall is equal to or greater than a threshold, and passes through the second path when the amount of rainfall is less than the threshold.

7. The refrigeration cycle device of claim 3, wherein the control device detects the amount of sand and dust from the weather data, and switches the switching valve so that the refrigerant passes through the first path when the amount of sand and dust is equal to or greater than a threshold, and so that the refrigerant passes through the second path when the amount of sand and dust is less than the threshold.

8. A refrigeration cycle device as described in any one of claims 1 to 7, further comprising a second heat exchanger that functions as a condenser by heat exchange with air between the radiative cooling section and the first heat exchanger.

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