JP2020046158A - Refrigeration circuit - Google Patents

Abstract

To provide a refrigeration circuit in which cold heat of drain water generated in an evaporator can be effectively used.SOLUTION: A refrigeration circuit (1) comprises: an evaporator (EV), a compressor (CP), a condenser (CD) and an expansion device (EX) each on a refrigerant circulation duct (RC); a drain water tank (DT) storing drain water generated in the evaporator during operation; and a drain water circuit (DC). The drain water circuit includes a drain water circulating circuit (DCC) and a drain water discharging circuit (DDC), and both circuits shares in the upstream part, a drain water pump (PD) pressure-feeding drain water of the drain water tank, and circuit switching means (TV) switching a flow direction of pressure-fed drain water. The drain water circulating circuit includes, at a position downstream of the circuit switching means, cooling medium cooling devices (GC,LC) cooling media by drain water, and causes drain water to return to the drain water tank, and the drain water discharging circuit scatters drain water to the condenser by a spray nozzle (SN) provided in a downstream end.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigeration circuit, and more particularly to a refrigeration circuit configured to be able to effectively utilize the cold heat of drain water (condensed water) generated in an evaporator.

  2. Description of the Related Art A refrigeration circuit built in an air conditioner (air conditioner) and the like has an evaporator, a compressor, a condenser, and an expansion device arranged on a pipe in which a refrigerant circulates in the direction in which the refrigerant flows.

  During operation of the refrigeration circuit, the low-temperature and low-pressure liquid-phase refrigerant absorbs heat from air (in a case of an air conditioner, indoor air) introduced by an evaporator fan and evaporates (vaporizes) under a constant pressure. At that time, the air is cooled. The low-pressure gas-phase refrigerant flowing out of the evaporator flows into the compressor, is compressed, and is sent out to the condenser as a high-temperature, high-pressure gas-phase refrigerant. The high-temperature and high-pressure gas-phase refrigerant radiates heat to air (outside air in the case of an air conditioner) introduced by the condenser fan in the condenser and condenses (liquefies) under a constant pressure. The high-pressure liquid-phase refrigerant flowing out of the condenser expands isenthalpy in an expansion device (capillary, electronic expansion valve, etc.), becomes a low-temperature, low-pressure liquid-phase refrigerant, and returns to the evaporator.

  During operation of the refrigeration circuit, the surface temperature of the evaporator is low because a low-temperature refrigerant flows inside the evaporator. Therefore, moisture contained in the air introduced into the evaporator is cooled and condensed on the surface of the evaporator, and drain water (condensed water) is generated.

  For this reason, in the conventional refrigeration circuit, a drain pan (drain water tray) is disposed below the evaporator to collect the drain water and guide it to the outside with a hose or the like to discharge the drain water, or temporarily store the drain water in a tank to periodically store the drain water. It was manually drained.

  However, the drain water generated in the evaporator has a low temperature and therefore retains cold. Therefore, the conventional refrigeration circuit is discarded without using this cold energy, and there is room for improvement from the viewpoint of effective use of energy.

  The present invention has been made in view of the above problems, and provides a refrigeration circuit configured to be able to effectively use cold energy held by drain water generated in an evaporator. With the goal.

  In order to solve the above problems, a refrigeration circuit of the present invention includes an evaporator, a compressor, a condenser, and an expansion device that are sequentially arranged in a flow direction of the refrigerant on a pipe in which the refrigerant circulates, and further includes a refrigeration circuit. A drain water tank that stores drain water generated in the evaporator during operation of the circuit; and a drain water circuit through which the drain water stored in the drain water tank circulates. A drain water pump that pumps the drain water stored in the drain water tank upstream of the drain water pump and the drain water pump. The drain water circulation circuit shares a circuit switching means for switching a flow direction of the drain water pumped by a water pump. A refrigerant cooler that cools the refrigerant is provided downstream of the circuit switching means, and the drain water that has passed through the refrigerant cooler is configured to be returned to the drain water tank. A spray nozzle is provided at a downstream end thereof, and the drain water is sprayed to the condenser by the spray nozzle.

  Preferably, the drain water circulation circuit includes a liquid-phase refrigerant cooling circuit and a gas-phase refrigerant cooling circuit arranged in parallel with each other downstream of the circuit switching means, and the liquid-phase refrigerant cooling circuit flows out of the condenser. And a liquid-phase refrigerant cooler for cooling the liquid-phase refrigerant on the way to the expansion device, wherein the gas-phase refrigerant cooling circuit cools the gas-phase refrigerant discharged from the compressor and on the way to the condenser. A gas-phase refrigerant cooler is provided.

  Preferably, the drain water pump is operated when the level of the drain water in the drain water tank is equal to or higher than a first level, and when the level is equal to or higher than a first level and lower than a second level, the drain water pump is operated. Flows only through the drain water circulation circuit, and when the water level is equal to or higher than the second water level and lower than the third water level, the drain water flows only through the drain water discharge circuit, and when the water level is equal to or higher than the third water level Then, the drain water is forcibly drained from the drain water tank.

  Preferably, the drain water pump is operated when the level of the drain water in the drain water tank is equal to or higher than a first water level, and the temperature of the refrigerant immediately upstream of the expansion device and the temperature of the refrigerant in the drain water tank. The difference between the temperature of the drain water is a first temperature difference, the lower limit of the first temperature difference is a first lower limit, the temperature of the refrigerant immediately downstream of the compressor, and the temperature of the drain water in the drain water tank. When the water level is equal to or higher than the first water level and lower than the third water level, the first temperature difference is equal to the second temperature difference. When it exceeds the lower limit, the drain water flows only through the liquid-phase refrigerant cooling circuit, the first temperature difference is equal to or less than the first lower limit, and the second temperature difference is the second temperature difference. 2 If it exceeds the lower limit, the drain water It flows only refrigerant cooling circuit.

  ADVANTAGE OF THE INVENTION According to the refrigeration circuit of this invention, the outstanding effect that the energy of the cold heat which the drain water which generate | occur | produces in an evaporator possesses can be used effectively can be acquired.

It is a schematic explanatory view showing a refrigeration circuit of a first embodiment of the present invention. It is a flowchart which shows the 1st aspect of switching control of the drain water circuit in the refrigeration circuit of 1st Embodiment of this invention. FIGS. 3A and 3B are schematic explanatory diagrams illustrating a flow of drain water realized by the switching control of the first embodiment illustrated in FIG. 2, wherein FIG. 2A illustrates a state in which the drain water flows only through a drain water circulation circuit, and FIG. The state in which drain water flows only through the discharge circuit is shown. It is a flowchart which shows the 2nd aspect of the switching control of the drain water circuit in the refrigeration circuit of 1st Embodiment of this invention. It is a schematic explanatory view showing the flow of drain water realized by the switching control of the second mode shown in FIG. 4, (A) shows a state where drain water flows only through the liquid-phase refrigerant cooling circuit LCC, and (B) Shows a state in which drain water flows only through the gas-phase refrigerant cooling circuit GCC, and FIG. 2C shows a state in which drain water flows only through the drain water discharge circuit DDC. It is a flowchart which shows the 3rd aspect of the switching control of the drain water circuit in the refrigeration circuit of 1st Embodiment of this invention. It is a schematic explanatory view showing the flow of drain water realized by the switching control of the third mode shown in FIG. 6, (A) shows a state in which drain water flows only through the liquid refrigerant cooling circuit LCC, and (B) Shows a state in which drain water flows only through the gas-phase refrigerant cooling circuit GCC, and FIG. 2C shows a state in which drain water flows only through the drain water discharge circuit DDC. It is a schematic explanatory view showing a refrigeration circuit of a second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic explanatory view showing a refrigeration circuit 1 according to a first embodiment of the present invention. Here, a case where the refrigeration circuit is applied to an air conditioner will be described as an example.

  The refrigeration circuit 1 is configured such that an evaporator EV, a compressor CP, a condenser CD, and an expansion device EX are arranged on a pipeline RC in which the refrigerant circulates in the direction in which the refrigerant flows.

  During the operation of the refrigeration circuit 1, the low-temperature and low-pressure liquid-phase refrigerant absorbs heat from room air introduced into the evaporator EV by, for example, an evaporator fan EVF configured as a sirocco fan and evaporates (vaporizes) under a constant pressure. At this time, the air is cooled. The low-pressure gas-phase refrigerant flowing out of the evaporator EV flows into the compressor CP and is compressed, and is sent out to the condenser CD as a high-temperature and high-pressure gas-phase refrigerant. The high-temperature and high-pressure gas-phase refrigerant radiates heat to outdoor air introduced by the condenser fan CDF in the condenser CD and condenses (liquefies) under a constant pressure. The high-pressure liquid-phase refrigerant flowing out of the condenser CD expands in an isenthalpy manner in the expansion device EX (capillary, electronic expansion valve, etc.), becomes a low-temperature, low-pressure liquid-phase refrigerant, and returns to the evaporator EV (FIG. (See the circuit with the arrow in 1).

  During the operation of the refrigeration circuit 1, the surface temperature of the evaporator EV becomes low because a low-temperature refrigerant flows inside the evaporator EV. Therefore, moisture contained in the indoor air introduced into the evaporator EV is cooled and condensed on the surface of the evaporator EV, and drain water (condensed water) is generated.

  Therefore, the refrigeration circuit 1 arranges a drain pan (drain water receiving tray) DP below the evaporator EV to collect the drain water, and transfers the collected drain water to a drain water tank DT arranged below the drain pan DP. It is configured to store. The refrigeration circuit 1 is provided with a drain water circuit DC which will be described in detail below, so that the cold energy held by the stored drain water can be effectively used.

  The drain water circuit DC includes a drain water circulation circuit DCC and a drain water discharge circuit DDC. Both circuits are provided with a drain water pump PD for pumping drain water stored in a drain water tank DT and a drain water pump at its upstream part. The three-way valve TV (circuit switching means) configured as an electromagnetic valve that switches the flow direction of the drain water pumped by the PD and a pipe connecting these components to each other are shared (the above-described common part is replaced by the drain). Water supply circuit DSC). Then, by switching the direction of the three-way valve TV (A direction or B direction indicated by an arrow in the figure), a state in which drain water flows through the drain water circulation circuit DCC or a state in which drain water flows through the drain water discharge circuit DDC Is realized.

  The drain water circulation circuit DCC cools the refrigerant circulating in the pipeline RC of the refrigeration circuit 1 by using the cool heat (mainly sensible heat) of the drain water supplied via the drain water supply circuit DSC, and is used for cooling. Is drained to the drain water tank DT.

  Specifically, the drain water circulation circuit DCC includes a liquid-phase refrigerant cooling circuit LCC configured to cool the liquid-phase refrigerant flowing into the expansion device EX, downstream of the three-way valve TV (in the direction A), and a compressor. A gas-phase refrigerant cooling circuit GCC configured to cool the gas-phase refrigerant discharged from the CP.

  The liquid-phase refrigerant cooling circuit LCC and the gas-phase refrigerant cooling circuit GCC are arranged in parallel with each other, branch off from each other at a branch point PB immediately downstream of the three-way valve TV, and at a junction PM immediately upstream of the drain water tank DT. Join.

  A first on-off valve V1 configured as an electromagnetic valve is disposed immediately downstream of the branch point PB in the liquid-phase refrigerant cooling circuit LCC, and an electromagnetic valve immediately downstream of the branch point PB in the gas-phase refrigerant cooling circuit GCC. The configured second on-off valve V2 is arranged. This allows the drain water to flow through one or both of the liquid-phase refrigerant cooling circuit LCC and the gas-phase refrigerant cooling circuit GCC through the opening / closing operation of the first opening / closing valve V1 and the second opening / closing valve V2, and to utilize the cold heat. Can be.

  The liquid-phase refrigerant cooling circuit LCC includes a liquid-phase refrigerant cooler LC (refrigerant cooler) downstream of the first on-off valve V1 and upstream of the junction PM in the direction of drain water flow. In the LC, the liquid-phase refrigerant flowing out of the condenser CD toward the expansion device EX is cooled through heat exchange with drain water.

  The gas-phase refrigerant cooling circuit GCC includes a gas-phase refrigerant cooler GC (refrigerant cooler) downstream of the second on-off valve V2 and upstream of the junction PM in the direction of drain water flow. In the GC, the gas-phase refrigerant discharged from the compressor CP to the condenser CD is cooled through heat exchange with drain water.

  The drain water discharge circuit DDC is configured to cool the condenser CD of the refrigeration circuit 1 using cold heat (mainly latent heat) of the drain water supplied via the drain water supply circuit DSC.

  Specifically, the drain water discharge circuit DDC is provided with a spray nozzle SN at the downstream end thereof (in the direction B) downstream of the three-way valve TV, and the drain water is supplied to the heat transfer surface of the condenser CD by the spray nozzle SN. Sprayed on. As a result, the drain water evaporates (vaporizes) on the heat transfer surface of the condenser CD, and flows through the heat transfer surface of the condenser CD, and thus inside the condenser CD, by the heat of evaporation (latent heat) absorbed at that time. The refrigerant can be cooled.

  In the refrigeration circuit 1 configured as described above, the level of the drain water in the drain water tank DT (the drain water stored in the drain water tank DT) is used so that the cooling heat of the drain water can be used as efficiently as possible. The three-way valve TV and the first and second on-off valves V1 and V2 are controlled based on one or both of the amount and the temperature.

  For this purpose, the drain water tank DT is provided with first to third water level sensors LS1 to LS3 and a drain water temperature sensor TSD.

  The first to third water level sensors LS1 to LS3 are installed to detect whether or not the levels of the drain water in the drain water tank DT have reached first to third water levels L1 to L3 described later.

  Here, the first water level sensor LS1 is installed below the drain water suction port PDI by the drain water pump PD, and the third water level sensor LS3 is installed near the upper end in the drain water tank DT.

  Further, the drain water temperature sensor TSD is installed at the bottom of the drain water tank DT so as to measure the temperature of the drain water regardless of the level of the drain water in the drain water tank DT.

  Further, refrigerant temperature sensors TSR1 and TSR2 are installed in a portion of the pipeline RC of the refrigeration circuit 1 immediately upstream of the expansion device EX and a portion immediately downstream of the compressor CP, respectively.

  A mode of switching control of the drain water circuit DC in the refrigeration circuit 1 configured as described above will be described below.

  FIG. 2 is a flowchart illustrating a first mode of switching control of the drain water circuit DC in the refrigeration circuit 1. FIG. 3 is a schematic explanatory view showing the flow of drain water realized by the switching control of the first embodiment shown in FIG. 2, and FIG. 3A shows a state in which drain water flows only in the drain water circulation circuit DCC. And (B) show the state in which drain water flows only through the drain water discharge circuit DDC.

  In the first embodiment, the direction of the three-way valve TV (the A direction or the B direction) and the third direction are determined based on the levels of the drain water in the drain water tank DT detected by the first to third water level sensors LS1 to LS3. Opening / closing of the first on-off valve V1 and the second on-off valve V2 is controlled.

  After the operation of the air conditioner (refrigeration circuit 1) is started in step S100 of the flowchart shown in FIG. 2, in step S110, the level L of the drain water in the drain water tank DT is set to the first level using the first level sensor LS1. It is determined whether or not the water level is less than L1 (L <L1).

  If the determination result in step S110 is Yes (that is, the level L of the drain water in the drain water tank DT is less than the first level L1), the level of the drain water in the drain water tank DT is equal to the level of the drain water pump PD. Since the drain water is lower than the suction port PDI and the drain water cannot be pumped by the drain water pump PD, the operation proceeds in the Yes direction, and the operation of the drain water pump PD is stopped in step S115.

  If the determination result in step S110 is No (that is, the level L of the drain water in the drain water tank DT is equal to or higher than the first level L1), the drain water pump PD pumps the drain water in the drain water tank DT. Therefore, in the No direction, the three-way valve TV is switched to the A direction in step S120, the first on-off valve V1 and the second on-off valve V2 are opened in step S130, and the drain water pump PD is turned on in step S140. Is activated.

  In this state, as shown in FIG. 3A, the drain water stored in the drain water tank DT is pumped by the drain water pump PD, reaches the three-way valve TV, and then flows in the direction A. Then, a part of the drain water flows into the liquid-phase refrigerant cooling circuit LCC via the first on-off valve V1, and cools the liquid-phase refrigerant flowing into the expansion device EX in the liquid-phase refrigerant cooler LC. On the other hand, the remainder of the drain water flows into the gas-phase refrigerant cooling circuit GCC via the second on-off valve V2, and cools the gas-phase refrigerant discharged from the compressor CP in the gas-phase refrigerant cooler GC. After that, the drain water that has passed through each of the liquid-phase refrigerant cooling circuit LCC and the gas-phase refrigerant cooling circuit GCC merges at the junction PM, and then returns to the drain water tank DT.

  In the state described above, in the following step S150, it is determined using the second water level sensor LS2 whether or not the water level L of the drain water in the drain water tank DT is less than the second water level L2 (L <L2). .

  When the determination result in step S150 is Yes (that is, the level L of the drain water in the drain water tank DT is less than the second level L2), the process proceeds in the Yes direction, and the determination in step S150 is repeated.

  If the determination result in step S150 is No (that is, the water level L of the drain water in the drain water tank DT is equal to or higher than the second water level L2), a large amount of drain water has already been stored in the drain water tank DT. Since the margin for storing further drain water is becoming scarce, the flow proceeds in the No direction, the three-way valve TV is switched to the B direction in step S160, and the first on-off valve V1 and the second on-off valve are opened in step S170. Valve V2 is closed.

  In this state, as shown in FIG. 3 (B), the drain water which is pressure-fed by the drain water pump PD and reaches the three-way valve TV flows in the direction B, flows into the drain water discharge circuit DDC, and finally flows. Is sprayed on the heat transfer surface of the condenser CD by the spray nozzle SN. This cools the heat transfer surface of the condenser CD, and thus the refrigerant flowing inside the condenser CD.

  In the state described above, in the following step S180, it is determined whether or not the water level L of the drain water in the drain water tank DT is equal to or higher than the third water level L3 (L3 ≦ L) using the third water level sensor LS3. .

  If the determination result in step S180 is No (that is, the level L of the drain water in the drain water tank DT is less than the third level L3), the process proceeds in the No direction, and the determination in step S180 is repeated.

  If the result of the determination in step S180 is Yes (that is, the level L of the drain water in the drain water tank DT is equal to or higher than the third level L3), there is a possibility that the drain water overflows from the drain water tank DT. Therefore, the process proceeds in the Yes direction, an abnormality alarm is issued in step S190, and the drain water in the drain water tank DT is automatically forcibly drained.

  Thereafter, the control flow returns to step S110, and the control in the above-described mode is repeated.

  As described above, in the switching control of the first embodiment of the drain water circuit DC, when the water level L of the drain water in the drain water tank DT rises to the first water level L1 or higher that can be pumped by the drain water pump PD. The refrigerant in the refrigeration circuit 1 is cooled by circulating the drain water in the drain water circulation circuit DCC (the liquid-phase refrigerant cooling circuit LCC and the gas-phase refrigerant cooling circuit GCC). Further, when the water level L of the drain water in the drain water tank DT reaches the second water level L2 indicating that the room for storing further drain water in the drain water tank DT is becoming scarce, the drain water discharging circuit DDC passes. The discharge of the drain water is started. At this time, the refrigerant in the refrigeration circuit 1 flowing inside the condenser CD is simultaneously cooled. Then, when the water level L of the drain water in the drain water tank DT reaches the third water level L3 indicating that there is a possibility that the drain water overflows from the drain water tank DT, the drain water in the drain water tank DT is forced. Drained.

  That is, in the switching control of the first aspect of the drain water circuit DC, when the amount of drain water is small, the refrigerant in the refrigeration circuit 1 is cooled while circulating the drain water, and when the amount of drain water increases, The refrigerant in the refrigeration circuit 1 is cooled by discharging the heat and cooling the heat transfer surface of the condenser CD. Thus, in the control, the cold heat of the drain water can be effectively used.

  FIG. 4 is a flowchart illustrating a second mode of the switching control of the drain water circuit DC in the refrigeration circuit 1. FIG. 5 is a schematic explanatory view showing the flow of the drain water realized by the switching control of the second mode shown in FIG. 4, and FIG. 5 (A) shows the drain water flowing only through the liquid-phase refrigerant cooling circuit LCC. (B) shows a state where drain water flows only through the gas-phase refrigerant cooling circuit GCC, and (C) shows a state where drain water flows only through the drain water discharge circuit DDC.

  In the second aspect, based on the temperature of the drain water in the drain water tank DT detected by the drain water temperature sensor TSD, the direction of the three-way valve TV (A direction or B direction) and the first on-off valve V1 The opening and closing of the second on-off valve V2 is controlled.

  After the operation of the air conditioner (refrigeration circuit 1) is started in step S200 of the flowchart shown in FIG. 4, the three-way valve TV is switched to the direction A in step S210, and the first on-off valve V1 is opened in step S215. At this time, the second on-off valve V2 is closed.

  In this state, in the following step S220, it is determined using the first water level sensor LS1 whether or not the water level L of the drain water in the drain water tank DT is less than the first water level L1 (L <L1).

  If the determination result in step S220 is Yes (that is, the level L of the drain water in the drain water tank DT is less than the first level L1), the level of the drain water in the drain water tank DT is equal to the level of the drain water pump PD. Since it is lower than the suction port PDI and the drain water cannot be pumped by the drain water pump PD, the process proceeds in the Yes direction and the determination in step S220 is repeated.

  When the determination result in step S220 is No (that is, the level L of the drain water in the drain water tank DT is equal to or higher than the first level L1), the drain water pump PD pumps the drain water in the drain water tank DT. Therefore, the process proceeds in the No direction, and in step S230, the drain water pump PD is started.

  In this state, as shown in FIG. 5A, the drain water stored in the drain water tank DT is pressure-fed by the drain water pump PD, reaches the three-way valve TV, flows in the direction A, and opens and closes in the first direction. It flows into the liquid-phase refrigerant cooling circuit LCC via the valve V1. After that, the drain water cools the liquid refrigerant flowing into the expansion device EX in the liquid refrigerant cooler LC, and then returns to the drain water tank DT.

  In the above state, in the following step S240, a determination regarding the temperature of the drain water in the drain water tank DT is performed.

  Here, the temperature difference between the temperature Td of the drain water in the drain water tank DT detected by the drain water temperature sensor TSD and the temperature Tr1 of the refrigerant immediately upstream of the expansion device EX detected by the refrigerant temperature sensor TSR1 (the The first temperature difference is ΔT1 (= Tr1−Td), and the lower limit (first lower limit) set in advance for the temperature difference is ΔT1L.

  In step S240, it is determined whether or not the above-described temperature difference ΔT1 exceeds a lower limit value ΔT1L (ΔT1> ΔT1L).

  When the determination result in step S240 is Yes (that is, when the temperature difference ΔT1 exceeds the lower limit value ΔT1L), the process proceeds in the Yes direction, and the determination in step S240 is repeated. As described above, when the temperature difference ΔT1 is higher than the lower limit ΔT1L, the temperature Td of the drain water in the drain water tank DT is sufficiently lower than the temperature Tr1 of the refrigerant immediately upstream of the expansion device EX, and In the phase refrigerant cooler LC, the refrigerant can be effectively cooled by the drain water. Therefore, in this case, the state described above is maintained, and the cooling of the refrigerant is continued by flowing the drain water only to the liquid-phase refrigerant cooling circuit LCC.

  If the determination result in step S240 is No (that is, the temperature difference ΔT1 is equal to or less than the lower limit ΔT1L), the refrigerant immediately upstream of the expansion device EX due to the temporal rise in the temperature Td of the drain water in the drain water tank DT. The temperature difference from the temperature Tr1 becomes small, and the cooling of the refrigerant by the drain water in the liquid-phase refrigerant cooler LC cannot be performed effectively. Therefore, in this case, the flow proceeds in the No direction, and the flow of the drain water is switched.

  That is, the second on-off valve V2 is opened in step S250, and the first on-off valve V1 is closed in step S255.

  In this state, as shown in FIG. 5B, the drain water stored in the drain water tank DT is pressure-fed by the drain water pump PD and reaches the three-way valve TV, and then flows in the direction A, and the second opening / closing operation is performed. It flows into the gas-phase refrigerant cooling circuit GCC via the valve V2. After that, the drain water returns to the drain water tank DT after cooling the vapor refrigerant discharged from the compressor CP in the vapor refrigerant cooler GC.

  In the state described above, in the following step S260, a determination regarding the temperature of the drain water in the drain water tank DT is performed.

  Here, the temperature difference between the temperature Td of the drain water in the drain water tank DT detected by the drain water temperature sensor TSD and the temperature Tr2 of the refrigerant immediately downstream of the compressor CP detected by the refrigerant temperature sensor TSR2 (the The second temperature difference) is ΔT2 (= Tr2−Td), and the lower limit (second lower limit) preset for the temperature difference is ΔT2L.

  In step S260, it is determined whether or not the above-mentioned temperature difference ΔT2 exceeds a lower limit value ΔT2L (ΔT2> ΔT2L).

  If the determination result in step S260 is Yes (that is, the temperature difference ΔT2 is larger than the lower limit value ΔT2L), the process proceeds in the Yes direction, and the determination in step S260 is repeated. As described above, when the temperature difference ΔT2 is higher than the lower limit ΔT2L, the temperature Td of the drain water in the drain water tank DT is sufficiently lower than the temperature Tr2 of the refrigerant immediately downstream of the compressor CP, and In the phase refrigerant cooler GC, the cooling of the refrigerant by the drain water can be effectively performed. Therefore, in this case, the state described above is maintained, and the cooling of the refrigerant is continued by flowing the drain water only to the gas-phase refrigerant cooling circuit LCC.

  If the determination result in step S260 is No (that is, the temperature difference ΔT2 is equal to or less than the lower limit ΔT2L), the refrigerant immediately downstream of the compressor CP due to the temporal rise of the temperature Td of the drain water in the drain water tank DT. The temperature difference from the temperature Tr2 becomes small, and the refrigerant in the gas-phase refrigerant cooler GC cannot be effectively cooled by the drain water. Further, the drain water whose temperature has increased in this manner is in a state where it can be easily evaporated. Therefore, in this case, the flow proceeds in the No direction, and the flow of the drain water is switched.

  That is, the three-way valve TV is switched to the direction B in step S270, and the second on-off valve V2 is closed in step S275.

  In this state, as shown in FIG. 5C, the drain water stored in the drain water tank DT is pumped by the drain water pump PD and reaches the three-way valve TV, and then flows in the direction B to discharge the drain water. It flows into the circuit DDC and is finally sprayed on the heat transfer surface of the condenser CD by the spray nozzle SN. At this time, since the temperature Td of the drain water in the drain water tank DT has risen to near the temperature Tr2 of the gas-phase refrigerant discharged from the compressor CP, when the temperature Td is sprayed on the heat transfer surface of the condenser CD. Evaporates (evaporates) easily. As a result, the heat transfer surface of the condenser CD, that is, the refrigerant flowing inside the condenser CD is effectively cooled by the evaporation heat (latent heat) of the drain water.

  In the state described above, in the following step S280, the drain water level L in the drain water tank DT is lower than the first water level L1 (L <L1) or the first water level sensor LS1 and the third water level sensor LS3. It is determined whether or not the water level is equal to or higher than the third water level L3 (L3 ≦ L).

  If the determination result in step S280 is No (that is, the level L of the drain water in the drain water tank DT is equal to or higher than the first level L1 and lower than the third level L3 (L1 ≦ L <L3)), the process proceeds to the No direction. The determination in step S280 is repeated while continuing the cooling of the refrigerant through the supply of the drain water to the drain water discharge circuit DDC.

  If the determination result in step S280 is Yes, the drain water cannot be pumped by the drain water pump PD (when the water level L of the drain water in the drain water tank DT is less than the first water level L1 (L <L1)). In some cases, the drain water may overflow from the drain water tank DT, and forced drainage of the drain water is required (the level L of the drain water in the drain water tank DT is equal to or higher than the third water level L3 (L3 ≦ L)), the operation proceeds in the Yes direction, the operation of the drain water pump PD is stopped in step S290, and the drain water in the drain water tank DT is automatically forcibly drained. .

  As described above, in the switching control of the second aspect of the drain water circuit DC, the temperature difference between the temperature Td of the drain water in the drain water tank DT and the temperature Tr1 of the refrigerant immediately upstream of the expansion device EX is sufficiently high. If the temperature difference is large, the liquid refrigerant flowing into the expansion device EX is cooled by flowing drain water into the liquid refrigerant cooling circuit LCC, and if the temperature difference cannot be secured sufficiently, the liquid refrigerant cooling circuit LCC Is switched to the gas-phase refrigerant cooling circuit GCC. When the temperature difference between the temperature Td of the drain water in the drain water tank DT and the temperature Tr2 of the gas-phase refrigerant discharged from the compressor CP is sufficiently large, the drain water flows through the gas-phase refrigerant cooling circuit GCC. When the gaseous refrigerant discharged from the compressor CP is cooled by the above method and the temperature difference cannot be sufficiently secured, switching from the gaseous refrigerant cooling circuit GCC to the drain water discharge circuit DDC is performed. At this time, the temperature Td of the drain water in the drain water tank DT has risen to near the temperature Tr2 of the gas-phase refrigerant discharged from the compressor CP, and when the water is sprayed on the heat transfer surface of the condenser CD. Since the refrigerant is easily evaporated (vaporized), the refrigerant flowing inside the condenser CD is effectively cooled.

  That is, in the switching control of the second aspect of the drain water circuit, the refrigerant in the portion that can be effectively cooled according to the temperature of the drain water (the temperature difference from the refrigerant) is cooled, and the temperature of the drain water rises. When it becomes easy to evaporate, it is sprayed on the heat transfer surface of the condenser to cool the refrigerant flowing therein. Thus, in the control, the cold heat of the drain water can be effectively used.

  FIG. 6 is a flowchart showing a third mode of the switching control of the drain water circuit DC in the refrigeration circuit 1. FIG. 7 is a schematic explanatory view showing a flow of drain water realized by the switching control of the third mode shown in FIG. 6, and FIG. 7A shows a state in which drain water flows only through the liquid-phase refrigerant cooling circuit LCC. (B) shows a state where drain water flows only through the gas-phase refrigerant cooling circuit GCC, and (C) shows a state where drain water flows only through the drain water discharge circuit DDC.

  In the third embodiment, the drain water level in the drain water tank DT detected by the first to third water level sensors LS1 to LS3, and the drain water in the drain water tank DT detected by the drain water temperature sensor TSD , The direction of the three-way valve TV (the direction A or the direction B) and the opening and closing of the first on-off valve V1 and the second on-off valve V2 are controlled.

  After the operation of the air conditioner (refrigeration circuit 1) is started in step S300 of the flowchart shown in FIG. 6, in step S310, the first water level sensor LS1 is used to set the drain water level L in the drain water tank DT to the first level. It is determined whether or not the water level is less than L1 (L <L1).

  When the determination result in step S310 is Yes (that is, the level L of the drain water in the drain water tank DT is less than the first level L1), the level of the drain water in the drain water tank DT is equal to the level of the drain water pump PD. Since it is lower than the suction port PDI and the drain water cannot be pumped by the drain water pump PD, the operation proceeds in the Yes direction, and the operation of the drain water pump PD is stopped in step S315.

  When the determination result in step S310 is No (that is, the level L of the drain water in the drain water tank DT is equal to or higher than the first level L1), the drain water pump PD pumps the drain water in the drain water tank DT. Since it is possible to proceed in the No direction, the three-way valve TV is switched to the A direction in step S320, the first on-off valve V1 is opened in step S325, and the drain water pump PD is started in step S330. At this time, the second on-off valve V2 is closed.

  In this state, as shown in FIG. 7A, the drain water stored in the drain water tank DT is pressure-fed by the drain water pump PD, reaches the three-way valve TV, flows in the direction A, and opens and closes in the first direction. It flows into the liquid-phase refrigerant cooling circuit LCC via the valve V1. After that, the drain water cools the liquid refrigerant flowing into the expansion device EX in the liquid refrigerant cooler LC, and then returns to the drain water tank DT.

  In the above state, in the following step S340, the temperature Td of the drain water in the drain water tank DT detected by the drain water temperature sensor TSD and the temperature of the refrigerant immediately upstream of the expansion device EX detected by the refrigerant temperature sensor TSR1 It is determined whether or not the temperature difference ΔT1 from Tr1 exceeds the lower limit value ΔT1L (ΔT1> ΔT1L).

  If the determination result in step S340 is Yes (that is, the temperature difference ΔT1 is greater than the lower limit value ΔT1L), the process proceeds in the Yes direction, and the determination in step S340 is repeated. As described above, when the temperature difference ΔT1 is higher than the lower limit ΔT1L, the temperature Td of the drain water in the drain water tank DT is sufficiently lower than the temperature Tr1 of the refrigerant immediately upstream of the expansion device EX, and In the phase refrigerant cooler LC, the refrigerant can be effectively cooled by the drain water. Therefore, in this case, the state described above is maintained, and the cooling of the refrigerant is continued by flowing the drain water only to the liquid-phase refrigerant cooling circuit LCC.

  If the determination result in step S340 is No (that is, the temperature difference ΔT1 is equal to or less than the lower limit ΔT1L), the refrigerant immediately upstream of the expansion device EX due to the temporal rise of the temperature Td of the drain water in the drain water tank DT. The temperature difference from the temperature Tr1 becomes small, and the cooling of the refrigerant by the drain water in the liquid-phase refrigerant cooler LC cannot be performed effectively. Therefore, in this case, the flow proceeds in the No direction, and the flow of the drain water is switched.

  That is, the second on-off valve V2 is opened in step S350, and the first on-off valve V1 is closed in step S355.

  In this state, as shown in FIG. 7B, the drain water stored in the drain water tank DT is pressure-fed by the drain water pump PD and reaches the three-way valve TV, and then flows in the direction A, and the second opening / closing operation is performed. It flows into the gas-phase refrigerant cooling circuit GCC via the valve V2. After that, the drain water returns to the drain water tank DT after cooling the vapor refrigerant discharged from the compressor CP in the vapor refrigerant cooler GC.

  In the state described above, in the following step S360, it is determined whether or not the water level L of the drain water in the drain water tank DT is lower than the second water level L2 (L <L2) using the second water level sensor LS2. .

  If the determination result in step S360 is Yes (that is, the level L of the drain water in the drain water tank DT is less than the second level L2), the process proceeds in the Yes direction, and the determination in step S360 is repeated.

  If the determination result in step S360 is No (that is, the level L of the drain water in the drain water tank DT is equal to or higher than the second level L2), a large amount of drain water has already been stored in the drain water tank DT. Since the margin for storing further drain water is becoming scarce, the flow proceeds in the No direction and the flow of drain water is switched.

  That is, the three-way valve TV is switched to the direction B in step S370, and the second on-off valve V2 is closed in step S375.

  In this state, as shown in FIG. 7 (C), the drain water which is pressure-fed by the drain water pump PD and reaches the three-way valve TV flows in the direction B, flows into the drain water discharge circuit DDC, and finally flows. Is sprayed on the heat transfer surface of the condenser CD by the spray nozzle SN. This cools the heat transfer surface of the condenser CD, and thus the refrigerant flowing inside the condenser CD.

  In the state described above, in the following step S380, the level L of the drain water in the drain water tank DT is equal to or more than the second level L2 and less than the third level L3 using the second level sensor LS2 and the third level sensor LS3 (L2 ≦ It is determined whether or not L <L3).

  If the determination result in step S380 is Yes, the flow proceeds in the Yes direction, and the determination in step S380 is repeated while continuing to cool the refrigerant through the supply of the drain water to the drain water discharge circuit DDC.

  If the determination result in step S380 is No (that is, the level L of the drain water in the drain water tank DT is lower than the second level L2 or higher than the third level L3), the process proceeds in the No direction, and in step S390, Using the second water level sensor LS2, it is determined whether or not the water level L of the drain water in the drain water tank DT is lower than the second water level L2 (L <L2).

  If the determination result in step S390 is No, the water level L of the drain water in the drain water tank DT is equal to or higher than the third water level L3, and there is a possibility that the drain water overflows from the drain water tank DT. Since the forced drainage of water is required, the process proceeds in the direction of No. In step S315, the operation of the drain water pump PD is stopped, and the drain water in the drain water tank DT is automatically drained. Is done.

  If the determination result in step S390 is Yes, the process proceeds in the Yes direction and returns to step S310, and the control in the above-described mode is repeated.

  As described above, the switching control in the third mode of the drain water circuit DC is performed by switching from the gas-phase refrigerant cooling circuit GCC to the drain water discharging circuit DDC in the switching control in the second mode. This is performed based on the level L of the drain water in the drain water tank DT instead of the temperature difference with the gas-phase refrigerant discharged from the tank. In the switching control, when the operation of the drain water pump PD does not need to be stopped when returning from step S390 to step S310, the drain water pump PD can be continuously operated, and thus the cooling heat of the drain water can be effectively used.

  In the refrigeration circuit 1 of the first embodiment described above, when the drain water flows into the drain water discharge circuit DDC and is finally sprayed on the heat transfer surface of the condenser CD by the spray nozzle SN, most of the drain water Is considered to evaporate on the heat transfer surface, but there is a possibility that part of the drain water will flow down on the heat transfer surface of the condenser CD without evaporating and drop below the condenser CD. The refrigeration circuit according to the second embodiment described below is configured such that the drain water dropped without evaporating on the heat transfer surface of the condenser CD can be reused.

  FIG. 8 is a schematic explanatory view showing a refrigeration circuit 2 according to the second embodiment of the present invention.

  In the refrigeration circuit 2, a condenser drain pan DPC is provided below the condenser CD, so that the drain water dropped without evaporating on the heat transfer surface of the condenser CD is stored. The condenser drain pan DPC is provided with a fourth water level sensor LS4 for detecting whether or not the level of the stored drain water has reached an upper limit water level.

  On the other hand, a branch circuit BC is provided in parallel with an intermediate portion of the drain water discharge circuit DDC (a portion between the three-way valve TV and the condenser CD). On the branch circuit BC, a third on-off valve V3 and an aspirator AR, which are configured as solenoid valves, are installed in order in the direction in which the drain water flows.

  The aspirator AR is configured to create a decompressed state using the Venturi effect, and to be able to suck the drain water from a suction port ARS provided at a portion where the depressurized state is established. Here, the suction port ARS and the bottom of the condenser drain pan DPC are connected by a suction pipe SC.

  In the refrigeration circuit 2 configured as described above, drain water flows into the drain water discharge circuit DDC, and is sprayed on the heat transfer surface of the condenser CD by the spray nozzle SN to cool the refrigerant flowing in the condenser CD. In this case, the drain water dropped without evaporating on the heat transfer surface of the condenser CD is stored in the condenser drain pan DPC.

  When the fourth water level sensor LS4 detects that the level of the drain water in the condenser drain pan DPC has risen and has reached the upper limit level, the third on-off valve V3 is opened. As a result, part of the drain water flowing through the drain water discharge circuit DDC flows into the branch circuit BC, and passes through the aspirator AR. At this time, since a reduced pressure state is created in the aspirator AR, the drain water in the condenser drain pan DPC is sucked into the aspirator AR from the suction port ARS through the suction pipe SC. The suctioned drain water merges with the drain water flowing into the aspirator AR after passing through the third on-off valve V3, and then flows out of the aspirator AR and flows into the drain water discharge circuit DDC via the branch circuit BC.

  As a result, the drain water dropped without evaporating on the heat transfer surface of the condenser CD flows into the drain water discharge circuit DDC again, and can be reused for cooling the refrigerant flowing in the condenser CD. Further, it is possible to prevent the drain water dropped from the heat transfer surface of the condenser CD from flowing out to the floor near the condenser CD.

1 Refrigeration circuit CP Compressor CD Condenser DC Drain water circuit DCC Drain water circulation circuit DDC Drain water discharge circuit DT Drain water tank EV Evaporator EX Expansion device GC Gas-phase refrigerant cooler (refrigerant cooler)
GCC Gas-phase refrigerant cooling circuit L1 First water level L2 Second water level L3 Third water level LC Liquid-phase refrigerant cooler (refrigerant cooler)
LCC Liquid-phase refrigerant cooling circuit PD Drain water pump RC Line SN Spray nozzle TV Three-way valve (circuit switching means)
ΔT1 First temperature difference (temperature difference between the temperature of the drain water in the drain water tank and the temperature of the refrigerant immediately upstream of the expansion device)
ΔT2 Second temperature difference (temperature difference between the temperature of the drain water in the drain water tank and the temperature of the refrigerant immediately downstream of the compressor)
ΔT1L Lower limit of first temperature difference ΔT2L Lower limit of second temperature difference

Claims (4)

A refrigeration circuit including an evaporator, a compressor, a condenser, and an expansion device which are sequentially arranged in a flowing direction of the refrigerant on a pipe in which the refrigerant circulates,
The refrigeration circuit further includes:
A drain water tank for storing drain water generated in the evaporator during operation of the refrigeration circuit,
A drain water circuit through which the drain water stored in the drain water tank flows,
With
The drain water circuit includes a drain water circulation circuit and a drain water discharge circuit,
The drain water circulation circuit and the drain water discharge circuit are provided with a drain water pump for pumping the drain water stored in the drain water tank and a flow direction of the drain water pumped by the drain water pump in an upstream portion thereof. It shares the circuit switching means to switch,
The drain water circulation circuit includes a refrigerant cooler that cools the refrigerant through heat exchange with the drain water downstream of the circuit switching unit, and returns the drain water that has passed through the refrigerant cooler to the drain water tank. Is configured to
The refrigeration circuit, wherein the drain water discharge circuit includes a spray nozzle at a downstream end thereof, and is configured to spray the drain water to the condenser by the spray nozzle. The drain water circulation circuit includes a liquid-phase refrigerant cooling circuit and a gas-phase refrigerant cooling circuit arranged in parallel with each other downstream of the circuit switching means,
The liquid-phase refrigerant cooling circuit includes a liquid-phase refrigerant cooler that cools a liquid-phase refrigerant flowing out of the condenser toward the expansion device,
The refrigeration circuit according to claim 1, wherein the gas-phase refrigerant cooling circuit includes a gas-phase refrigerant cooler that cools a gas-phase refrigerant discharged from the compressor and on the way to the condenser. The drain water pump is operated when the level of the drain water in the drain water tank is equal to or higher than a first level,
When the water level is equal to or higher than the first water level and lower than the second water level, the drain water flows only through the drain water circulation circuit,
When the water level is equal to or higher than the second water level and lower than the third water level, the drain water flows only through the drain water discharge circuit,
The refrigeration circuit according to claim 1, wherein the drain water is forcibly drained from the drain water tank when the water level is equal to or higher than a third water level. The drain water pump is operated when the level of the drain water in the drain water tank is equal to or higher than a first level,
The difference between the temperature of the refrigerant immediately upstream of the expansion device and the temperature of the drain water in the drain water tank is a first temperature difference, the lower limit of the first temperature difference is a first lower limit, When the difference between the temperature of the refrigerant immediately downstream and the temperature of the drain water in the drain water tank is a second temperature difference, and the lower limit of the second temperature difference is a second lower limit,
When the water level is equal to or higher than the first water level and lower than the third water level,
When the first temperature difference is higher than the first lower limit, the drain water flows only through the liquid-phase refrigerant cooling circuit,
When the first temperature difference is equal to or less than the first lower limit, and the second temperature difference is higher than the second lower limit, the drain water flows only through the gas-phase refrigerant cooling circuit, The refrigeration circuit according to claim 2, wherein:

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