Multi-heat-source heat pump device

Abstract

To provide an open loop type and direct expansion type heat pump device having low cost and furthermore having improved heat exchange efficiency compared to a closed loop type heat pump device.SOLUTION: A multi heat source-heat pump device includes a freezing cycle in which a compressor 110 compressing refrigerant, a four-way valve 120, an outdoor heat exchanger 130, an expansion valve 140 and an indoor heat exchanger 210 are connected via a refrigerant piping 2, 3. By switching the four-way valve 120, the outdoor heat exchanger 130 functions as a condenser and the indoor heat exchanger 210 functions as an evaporator during cooling operation, and the indoor heat exchanger 210 functions as a condenser and the outdoor heat exchanger 130 functions as an evaporator during heating operation. The multi heat source-heat pump device comprises as the outdoor heat exchanger 130, two heat exchangers i.e. a water refrigerant heat exchanger 131 that is immersed into water in a water reservoir in which water such as groundwater is stored, and an air refrigerant heat exchanger 132 having an air blowing fan.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a multi-source heat pump device that uses water such as air and groundwater as a heat source for heat collection and heat release. More specifically, it relates to a multi-source heat pump device suitable for protected horticulture.

[0002] In recent years, as the reserves of fossil fuels decrease, the price of fuel oil has tended to rise. In such a situation, the introduction of air-source heat pumps as an alternative technology to oil-fired heaters has been promoted, but the actual situation is that the introduction has not advanced very much.

[0003] One of the reasons is that when heating operation is performed at low outdoor temperatures, frosting occurs on the heat exchanger of the outdoor unit, resulting in a decrease in heat collection efficiency or COP (Coefficient Of Performance). In particular, the heating load of horticultural facilities is maximum from night to dawn when the outdoor temperature is the lowest, so the COP is lower than that of air-source heat pumps for homes / buildings and industries.

[0004] In addition, when frosting occurs on the outdoor heat exchanger, a defrost operation is performed with the outdoor heat exchanger as the condenser and the indoor heat exchanger as the evaporator. During defrosting, the heat supply to the room is stopped, and only electricity is consumed without contributing to heating. Also, there are few dedicated devices developed for protected horticulture, and the high initial installation cost is also an obstacle to popularization.

[0005] On the other hand, a ground-source heat pump, which is one of the water-source heat pumps, can efficiently collect heat from the ground or groundwater even in severe cold (see, for example, Patent Documents 1 and 2).

[0006] However, excavation and boring are required to bury the heat exchanger, and the construction cost for the burial is high. Also, the cost varies depending on the soil quality and groundwater conditions in the area, which is a negative factor when considering equipment investment and has not led to technical popularization and social implementation.

[0007] In addition, a conventional ground source heat pump needs to drive a pump for circulating brine that transfers heat between a heat source such as the ground or groundwater and the heat pump, which is one of the reasons for reducing the system COP of the entire heat pump.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] Therefore, an object of the present invention is to provide a multi-source heat pump device that uses water such as air and groundwater as a heat source for heat collection and heat release, and can optimize the operation according to the outside air temperature, water temperature, etc., and is particularly suitable for facility horticulture.

Means for Solving the Problems

[0010] In order to solve the above problems, the present invention includes a refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, and an accumulator are connected via refrigerant piping. By switching the four-way valve, during the cooling operation, the outdoor heat exchanger acts as a condenser, and the indoor heat exchanger acts as an evaporator. During the heating operation, the indoor heat exchanger acts as a condenser, and the outdoor heat exchanger acts as an evaporator. In the multi-source heat pump device, As the outdoor heat exchanger, it has two heat exchangers, a first outdoor heat exchanger and a second outdoor heat exchanger. The indoor heat exchanger is arranged in a cultivation house for agriculture or the like, and has an open-loop type water storage tank in which water selected from river water, industrial wastewater, and agricultural water is stored. The first outdoor heat exchanger is immersed in the water in the water storage tank, and is an open-loop type and direct expansion type water-refrigerant heat exchanger in which heat exchange is performed between the water and the refrigerant. The second outdoor heat exchanger is an air-refrigerant heat exchanger having a blower fan. The first outdoor heat exchanger and the second outdoor heat exchanger are connected in parallel to the refrigerant pipe, and are provided with a switching valve for flowing the refrigerant to either one or both of the first outdoor heat exchanger and the second outdoor heat exchanger. During the cooling operation, by switching the four-way valve, the high-temperature and high-pressure gas refrigerant generated by the compressor is sent to the outdoor heat exchanger side, and Secretary's Office it is condensed by heat exchange with the water in the water storage tank or the outside air in the outdoor heat exchanger. After being depressurized to a predetermined pressure by the expansion valve, it evaporates by heat exchange with the air in the cultivation house in the indoor heat exchanger, becomes a low-temperature and low-pressure gas refrigerant, reaches the accumulator via the four-way valve, and is inhaled into the compressor again. During the heating operation, by switching the four-way valve, the high-temperature and high-pressure gas refrigerant generated by the compressor is sent to the indoor heat exchanger side, is condensed by heat exchange with the air in the cultivation house in the indoor heat exchanger, and evaporates by heat exchange with the water in the water storage tank or the outside air in the outdoor heat exchanger after passing through the expansion valve, becomes a low-temperature and low-pressure gas refrigerant, reaches the accumulator via the four-way valve, and is inhaled into the compressor again, which is a feature.

Effect of the Invention

[0016] According to the present invention, since it is an open-loop type in which the water-refrigerant heat exchanger (first outdoor heat exchanger) is immersed in the water storage tank, the construction cost is lower than that of the closed-loop type, and by making the water in the water storage tank flowing water, the heat exchange efficiency can be improved.

[0017] In addition to the water-refrigerant heat exchanger (the first outdoor heat exchanger), an air-refrigerant heat exchanger (the second outdoor heat exchanger) having a blower fan is further provided, and since these heat exchangers can be selectively used, it is possible to optimize the operation according to the water temperature, the outside air temperature, etc.

[0018] Also, according to the above defrosting means, it is possible to defrost the frost adhering to the air-refrigerant heat exchanger (the second outdoor heat exchanger) while continuing the heating operation.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0020] Next, referring to FIGS. 1 and 2, embodiments of the present invention will be described, but the present invention is not limited thereto.

[0021] As shown in FIG. 1, the multi-source heat pump apparatus 1 according to this embodiment includes an outdoor unit 10 on the heat source side and an indoor unit 20 on the utilization side. In this embodiment, although it is assumed that the indoor unit 20 is installed in a cultivation house of a horticultural facility such as agriculture, it may be installed in a normal residential house, building, or industrial factory facility, etc.

[0022] The outdoor unit 10 basically includes a compressor 110 that compresses the refrigerant, a four-way valve 120, an outdoor heat exchanger 130, an expansion valve 140, and an accumulator 150. As the refrigerant, for example, an HFO mixed refrigerant such as R410A, R32, or R452B may be used.

[0023] The indoor unit 20 is basically provided with an indoor heat exchanger 210 and an indoor blower 211. When floor heating or the like is performed, the indoor heat exchanger 210 is placed in a hot water tank (not shown). The outdoor unit 10 and the indoor unit 20 are connected via a liquid-side pipe 2 and a gas-side pipe 3.

[0024] During the cooling operation, the four-way valve 120 is switched to the state shown by the solid line in the figure, and the high-temperature and high-pressure gas refrigerant generated by the compressor 110 is sent to the outdoor heat exchanger 130. In the outdoor heat exchanger 130, it exchanges heat with, for example, the outside air and is condensed. After being depressurized to a predetermined pressure by the expansion valve 140, it exchanges heat with the indoor air in the indoor heat exchanger 210 and evaporates, becoming a low-temperature and low-pressure gas refrigerant. Then, it reaches the accumulator 150 via the four-way valve 120 and is inhaled into the compressor 110 again.

[0025] During the heating operation, the four-way valve 120 is switched to the state shown by the dashed line in the figure, and the high-temperature and high-pressure gas refrigerant generated by the compressor 110 is sent to the indoor heat exchanger 210. In the indoor heat exchanger 210, it exchanges heat with the indoor air and is condensed. After passing through the expansion valve 140, it exchanges heat with, for example, the outside air in the outdoor heat exchanger 130 and evaporates, becoming a low-temperature and low-pressure gas refrigerant. Then, it reaches the accumulator 150 via the four-way valve 120 and is inhaled into the compressor 110 again.

[0026] As described above, during the cooling operation, the outdoor heat exchanger 130 acts as a condenser (heat radiator), and the indoor heat exchanger 210 acts as an evaporator (heat absorber). On the contrary, during the heating operation, the outdoor heat exchanger 130 acts as an evaporator (heat absorber), and the indoor heat exchanger 210 acts as a condenser (heat radiator).

[0027] According to this embodiment, the outdoor heat exchanger 130 includes two outdoor heat exchangers, a first outdoor heat exchanger 131 and a second outdoor heat exchanger 132.

[0028] The first outdoor heat exchanger 131 is an open-loop water-refrigerant direct expansion type heat exchanger and is immersed in the water storage tank 160 as shown in FIG. 2. The second outdoor heat exchanger 132 is a normal air-refrigerant heat exchanger having a blower fan 133.

[0029] The first outdoor heat exchanger 131 and the second outdoor heat exchanger 132 are connected in parallel to the liquid side pipe (refrigerant pipe on the liquid side) 2, and a solenoid valve 135 as an on-off valve is attached to the branch flow path 2a on the first outdoor heat exchanger 131 side, and a solenoid valve 136 as an on-off valve is attached to the branch flow path 2b on the second outdoor heat exchanger 132 side.

[0030] In this embodiment, the water storage tank 160 is a water storage tank installed on the ground surface, and groundwater (well water) is pumped up from a water supply pipe 161 having a pumping pump P1. In the water storage tank 160, in order to make the stored water flow from bottom to top, it is preferable that the tip of the water supply pipe 161 is drawn into the bottom of the water storage tank 160, but the water supply pipe 161 may be drawn from the bottom of the water storage tank 160. Further, the water storage tank 160 is provided with a drain pipe 162 for draining overflow water.

[0031] The first outdoor heat exchanger 131 acts as a water-refrigerant heat exchanger by immersing its refrigerant pipe (copper pipe also called a path) 131a in the water storage tank 160. Fins may be attached to the immersed refrigerant pipe 131a. Instead of a zigzag shape, for example, it may be immersed in a state of being wound around a spiral strip.

[0032] A pipe made of a material other than copper may be used for the refrigerant pipe 131a, but in any case, the refrigerant pipe 131a is preferably a pipe made of a corrosion-resistant metal material, a pipe coated with a corrosion-resistant paint (for example, an epoxy resin paint used for lining the inner and outer surfaces of a general metal pipe), or a pipe coated with a corrosion-resistant material such as polyethylene resin.

[0033] As shown in Fig. 2, it is preferable to dispose an air supply pipe 165 having a plurality of air ejection holes 166 in the pipe wall on the end side in the water storage tank 160, send air into the air supply pipe 165 from the blower P2, and eject the air from the air ejection holes 166 to promote the convection of the stored water. In this case, the end side of the air supply pipe 165 where the air ejection holes 166 are provided may be arranged along the bottom of the water storage tank 160.

[0034] Instead of the air supply pipe 165 or together with the air supply pipe 165, for example, propeller-shaped stirring blades may be provided in the water storage tank 160.

[0035] As another aspect, as shown in Fig. 3 (plan view of the water storage tank 160), a zigzag water channel is formed in the water storage tank 160 by partition plates 167 (three partition plates in this example), and the refrigerant pipe 131a of the first outdoor heat exchanger 131 is piped in a zigzag shape along the water channel, and the flow direction of the water in the water channel (solid line arrow) and the flow direction of the refrigerant in the refrigerant pipe 131a (dashed line arrow) are made to be countercurrent in opposite directions, whereby the heat exchange efficiency between water and refrigerant can also be increased.

[0036] Also, a water temperature sensor may be provided to drive the pumping pump P1 so that the water temperature is within a predetermined temperature range. The water storage tank 160 may be a reservoir formed by excavation or the like, and the water for heat exchange may be well water, or may also be river water, industrial wastewater, agricultural water, or the like.

[0037] The compressor 110 is preferably a variable speed type compressor with inverter control, and its rotation speed is preferably controlled according to the heat exchange amount of the first outdoor heat exchanger (water-refrigerant heat exchanger) 131 in the water storage tank 160.

[0038] When using the first outdoor heat exchanger 131 during the cooling operation or the heating operation, the solenoid valve 135 is opened and the solenoid valve 136 is closed. On the contrary, when using the second outdoor heat exchanger 132, the solenoid valve 136 is opened and the solenoid valve 135 is closed.

[0039] Whether to use the first outdoor heat exchanger 131 or the second outdoor heat exchanger 132 is determined by the outside air temperature, the water temperature, and the heating or cooling capacity required from the user side. In some cases, the valve openings of the solenoid valves 135 and 136 can be adjusted to use the first outdoor heat exchanger 131 and the second outdoor heat exchanger 132 together.

[0040] Next, according to the second embodiment, in an aspect having the first outdoor heat exchanger (water-refrigerant heat exchanger) 131 and the second outdoor heat exchanger (air-refrigerant heat exchanger) 132, when frosting occurs on the second outdoor heat exchanger 132 during the heating operation, defrosting can be performed without stopping the heating operation.

[0041] Therefore, as shown in FIG. 4, in addition to the above configuration (the configuration of FIG. 1), two branch pipes 4 and 5 and three solenoid valves 137, 138, and 139 are used. In the following description, the upstream and downstream are based on the flow direction of the refrigerant during the heating operation.

[0042] First, one end of the first branch pipe 4 is connected to the gas side pipe 3. The other end of the first branch pipe 4 is connected to the upstream end 132a side of the second outdoor heat exchanger 132 in the branch flow path 2b on the second outdoor heat exchanger 132 side. Let the connection point be P. A solenoid valve 137 is provided in the first branch pipe 4.

[0043] Next, one end of the second branch pipe 5 is connected between the other end 132b on the downstream side of the second outdoor heat exchanger 132 and the solenoid valve 136 in the branch flow path 2b on the second outdoor heat exchanger 132 side. Let the connection point be Q. The other end of the second branch pipe 5 is connected to the pipe portion on the upstream side of the expansion valve 140 in the liquid side pipe 2. Let the connection point be R. A solenoid valve 138 is provided in the first branch pipe 5.

[0044] Also, a solenoid valve 139 is provided between the connection point P and the expansion valve 140 in the branch flow path 2b on the second outdoor heat exchanger 132 side.

[0045] During the heating operation using the second outdoor heat exchanger (air-refrigerant heat exchanger) 132, the four-way valve 120 is switched to the state shown by the chain line in the figure, and the solenoid valves 136 and 139 are opened while the solenoid valves 135, 137, and 138 are closed.

[0046] During this heating operation, as described above, the indoor heat exchanger 210 becomes a condenser (radiator), and the second outdoor heat exchanger 132 becomes an evaporator (heater). Therefore, especially at low outside air temperatures, frosting (frost formation) is likely to occur on the second outdoor heat exchanger 132. As the frosting increases, the heat exchange efficiency between air and refrigerant decreases.

[0047] Therefore, defrosting will be performed. In this embodiment, among the solenoid valves 135 to 139, the solenoid valves 135, 137, and 138 are opened, and the remaining solenoid valves 136 and 139 are closed.

[0048] As a result, a part of the high-temperature and high-pressure gas refrigerant generated by the compressor 110 and flowing toward the indoor heat exchanger 210 flows through the first branch pipe 4 to the second outdoor heat exchanger 132, and thus defrosting is performed.

[0049] The refrigerant condensed (released heat) and liquefied in the second outdoor heat exchanger 132 reaches the above connection point R on the upstream side of the expansion valve 140 through the second branch pipe 5, where it merges with the refrigerant condensed (released heat) and liquefied in the indoor heat exchanger 210. After the pressure is reduced by the expansion valve 140, it evaporates in the first outdoor heat exchanger (water-refrigerant heat exchanger) 131 to become a low-pressure gas refrigerant, and then returns to the compressor 110 through the accumulator 150.

[0050] Thus, according to the embodiment shown in FIG. 4, although the amount of the high-temperature and high-pressure gas refrigerant supplied to the indoor heat exchanger 210 decreases by the amount supplied to the second outdoor heat exchanger 132 through the first branch pipe 4, it is possible to defrost the frost adhering to the second outdoor heat exchanger 132 without interrupting the heating operation.

[0051] After defrosting, the solenoid valves 135, 137, and 138 are closed, and the solenoid valves 136 and 139 are opened to return to the original heating operation state before the start of defrosting with the second outdoor heat exchanger 132 as the evaporator. However, in some cases, only the solenoid valve 135 may be opened, and the remaining solenoid valves 136, 137, 138, and 139 may be closed to continue the heating operation with the first outdoor heat exchanger 131 as the evaporator.

[0052] During the cooling operation, the solenoid valves 137 and 138 are closed, the solenoid valve 139 is opened, and the solenoid valves 135 and 136 are controlled to open and close according to whether the first outdoor heat exchanger 131 or the second outdoor heat exchanger 132 is used. The opening and closing of these solenoid valves are controlled by a control unit (not shown).

[0053] From the above description, in horticultural facilities such as greenhouses and solar energy utilization type plant factories, by introducing the multi-source heat pump device of the present invention, while taking advantage of the advantages of the air source heat pump, the disadvantage of frosting on the outdoor heat exchanger that occurs when the outside air temperature drops can be switched to an open loop direct expansion type heat pump, enabling stable heat collection.

[0054] In addition, it is possible to significantly reduce the equipment and operation costs of the water source heat pump and maximize the COP. Further, it can be expected to be popularized not only in the agricultural field but also in households, buildings, industrial fields, etc.

Explanation of Signs

[0055] 1 Multi-source heat pump device 2 Liquid side pipe 2a, 2b Branch flow path 3 Gas side pipe 10 Outdoor unit 110 Compressor 120 Four-way valve 130 Outdoor heat exchanger 131 First outdoor heat exchanger (water-refrigerant direct expansion type heat exchanger) 132 Second outdoor heat exchanger (air-refrigerant heat exchanger) 135, 136, 137, 138, 139 Solenoid valve 140 Expansion valve 150 Accumulator 160 Water storage tank 20 Indoor unit 210 Indoor heat exchanger

Claims

【Claim 1】 A multi-source heat pump apparatus including a refrigeration cycle in which a compressor for compressing a refrigerant, a four-way valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, and an accumulator are connected via refrigerant pipes, and by switching the four-way valve, during cooling operation, the outdoor heat exchanger acts as a condenser and the indoor heat exchanger acts as an evaporator, and during heating operation, the indoor heat exchanger acts as a condenser and the outdoor heat exchanger acts as an evaporator, wherein as the outdoor heat exchanger, there are two heat exchangers, a first outdoor heat exchanger and a second outdoor heat exchanger, the indoor heat exchanger is disposed in a cultivation house for agriculture or the like, and there is an open-loop type water storage tank in which water selected from river water, industrial wastewater, and agricultural water is stored, the first outdoor heat exchanger is immersed in the water in the water storage tank, and it is an open-loop type and direct expansion type water-refrigerant heat exchanger in which heat exchange is performed between the water and the refrigerant, and the second outdoor heat exchanger is an air-refrigerant heat exchanger having a blower fan, the first outdoor heat exchanger and the second outdoor heat exchanger are connected in parallel to the refrigerant pipes, and a switching valve for flowing the refrigerant is provided in either one or both of the first outdoor heat exchanger and the second outdoor heat exchanger, during cooling operation, by switching the four-way valve, the high-temperature and high-pressure gas refrigerant generated by the compressor is sent to the outdoor heat exchanger side, heat-exchanged with the water in the water storage tank or the outside air in the outdoor heat exchanger and condensed, after being depressurized to a predetermined pressure by the expansion valve, heat-exchanged with the air in the cultivation house in the indoor heat exchanger and evaporated, becomes a low-temperature and low-pressure gas refrigerant, reaches the accumulator via the four-way valve, and is inhaled into the compressor again, during heating operation, by switching the four-way valve, the high-temperature and high-pressure gas refrigerant generated by the compressor is sent to the indoor heat exchanger side, heat-exchanged with the air in the cultivation house in the indoor heat exchanger and condensed, heat-exchanged with the water in the water storage tank or the outside air in the outdoor heat exchanger via the expansion valve and evaporated, becomes a low-temperature and low-pressure gas refrigerant, reaches the accumulator via the four-way valve, and is inhaled into the compressor again.

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