JP2014052123A - Engine driven heat pump chiller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide constitution for a heat pump chiller having a plurality of chiller units connected in parallel in a water circuit, the constitution enabling water temperature reduction in the water circuit during defrosting operation to be suppressed without placing a load onto the chiller units.SOLUTION: In a heat pump chiller 1000, when a plurality of chiller units 100 perform hot water operation, any chiller units do not perform defrosting operation in the same period, but the chiller units 100 perform defrosting operation alternately at least one by one while at least one chiller unit 100 continues hot water operation. The defrosting operation is such that an operation changeover mechanism is controlled to change over the hot water operation into no hot water operation, a first expansion valve is closed to prevent cooling medium from flowing in a water heat exchanger, and the openings of a second expansion valve and a flow control valve are controlled to permit the cooling medium and exhaust heat medium to flow in engine exhaust heat recovery equipment.

Description

  The present invention relates to an engine-driven heat pump chiller in which a compressor for compressing a refrigerant is driven by an engine and the temperature of water as a heat medium is adjusted by the condensation heat or evaporation heat of the refrigerant.

  When heating operation is continuously performed in a low temperature environment, frost adheres to the outdoor heat exchanger. Conventionally, a heat pump chiller that performs a defrosting operation for removing frost is known.

  Patent Document 1 discloses performing a defrosting operation in a heat pump chiller in which a plurality of chiller units are connected in parallel to a water circuit (paragraphs 0140 to 0147). The number (predetermined number) of chiller units that perform the defrosting operation is set by the number of connected chiller units connected to the water circuit (paragraph 0140). For example, when the number of connected units is four, the predetermined number is set to one, and when the number of connected units is 5 to 8, the predetermined number is set to two (paragraph 0141) so that the water temperature of the water circuit does not decrease. However, Patent Document 1 does not indicate the presence of other evaporators used in place of the water heat exchanger during the defrosting operation, and the water temperature generated by the defrosting operation (cooling operation) of a predetermined number of chiller units. The decrease in power must be offset by heating operation of other chiller units.

  Patent Document 2 discloses performing a defrosting operation in a heat pump chiller connected to a water circuit (paragraph 0034). This heat pump chiller includes an engine exhaust heat recovery unit that uses engine exhaust heat as a heat absorption source as an evaporator used instead of the water heat exchanger. In this heat pump chiller, the refrigerant discharged from the compressor is caused to flow to the outdoor heat exchanger during the defrosting operation as in the cooling operation, and then returned to the compressor via the engine exhaust heat recovery device. That is, in the defrosting operation, the refrigerant does not flow through the water heat exchanger that adjusts the temperature of the water.

Japanese Patent No. 3731095 Japanese Patent No. 4549205

  Patent Document 1 discloses a heat pump chiller in which a plurality of chiller units are connected in parallel to a water circuit. However, in order to suppress a decrease in the water temperature of the water circuit during a defrosting operation, a load is applied to another chiller unit. Patent Document 2 does not disclose a heat pump chiller in which a plurality of chiller units are connected in parallel to a water circuit.

  Therefore, the present invention provides a configuration that can suppress a decrease in the water temperature of the water circuit during the defrosting operation without applying a load to the chiller unit other than the defrosting operation in the heat pump chiller that connects the plurality of chiller units to the water circuit in parallel To do.

  An engine-driven heat pump chiller according to the present invention includes a plurality of engine-driven heat pump chiller units that drive a compressor that compresses a refrigerant by an engine and adjust the temperature of water as a heat medium by the condensation heat or evaporation heat of the refrigerant. The chiller unit includes an air heat exchanger that functions as a condenser that liquefies refrigerant using air as a heat radiation source or an evaporator that vaporizes refrigerant using air as a heat absorption source, and a water inlet pipe for introducing the water. A water discharge pipe for discharging the water, as a cooler for cooling the water using a gas-liquid two-phase refrigerant as a heat radiation source, or as a heater for heating water using the refrigerant discharged from the compressor as a heat absorption source Switching between a functioning water heat exchanger, a hot water operation in which the air heat exchanger functions as an evaporator, and a non-warm water operation in which the air heat exchanger functions as a condenser. An operation switching mechanism for switching, an engine exhaust heat recovery device that functions as a refrigerant evaporator using the exhaust heat of the engine as a heat absorption source via a waste heat medium, and a liquid state toward the air heat exchanger during the hot water operation Adjusting the flow rate of the refrigerant, and adjusting the flow rate of the refrigerant in the liquid state toward the water heat exchanger during the non-warm water operation, and the liquid state in the liquid state toward the engine exhaust heat recovery device A second expansion valve that adjusts the flow rate of the refrigerant, and a flow rate adjustment valve that adjusts the flow rate of the exhaust heat medium flowing through the engine exhaust heat recovery device, and each of the inlet pipe and the outlet pipe includes: Each of the chiller units is connected in parallel, and the defrosting control is performed by removing at least one chiller unit from the chiller unit at a time without performing the defrosting operation at the same time while the plurality of chiller units are in hot water operation. Frost operation The chiller unit that performs the defrosting operation switches the hot water operation to the non-warm water operation by controlling the operation switching mechanism, so that the refrigerant does not flow through the water heat exchanger. The first expansion valve is closed, and the opening degrees of the second expansion valve and the flow rate adjustment valve are controlled so that the refrigerant and the exhaust heat medium flow through the engine exhaust heat recovery device.

  The heat pump chiller which concerns on this invention can suppress the water temperature fall of the water circuit at the time of a defrost operation, without applying load to chiller units other than a defrost operation.

It is a lineblock diagram of the heat pump chiller concerning this embodiment. It is a block diagram of the chiller unit which concerns on this embodiment. It is a block diagram of the chiller unit in cold water operation. It is a block diagram of the chiller unit in a warm water operation. It is a block diagram of the chiller unit in a defrost operation. It is a block diagram of the heat pump chiller in defrost control.

(Configuration of this embodiment)
An engine-driven heat pump chiller 1000 according to this embodiment will be described with reference to FIG. FIG. 1 is a configuration diagram of a heat pump chiller 1000 according to the present embodiment.

  In FIG. 1, the heat pump chiller 1000 includes four chiller units 100 </ b> A, 100 </ b> B, 100 </ b> C, 100 </ b> D and a water circuit 200. The chiller units 100A, 100B, 100C, and 100D have the same configuration, and different reference numerals are provided for the convenience of identification. Hereinafter, when it is not necessary to distinguish the four chiller units, reference numeral 100 is used for the chiller unit.

  The heat pump chiller 1000 adjusts the temperature of the water flowing through the water circuit 200. The water circuit 200 includes an incoming water main pipe 210, an outgoing water main pipe 220, and the water circuit 40 of each chiller unit 100. The water circuit 40 includes a water inlet branch pipe (water inlet pipe) 41 and a water outlet branch pipe (water outlet pipe) 42. The incoming water branch pipe 41 of each chiller unit 100 is connected in parallel to the incoming water main pipe 210, and the outgoing water branch pipe 42 of each chiller unit 100 is connected in parallel to the outgoing water main pipe 220. Water is distributed from the incoming water main pipe 210 to each chiller unit 100 via each incoming water branch pipe 41, and the temperature is adjusted in each chiller unit 100. The water whose temperature has been adjusted merges from each chiller unit 100 to each water discharge main pipe 220 via each water discharge branch pipe 42 and is discharged from the heat pump chiller 1000. The water circuit 200 may be a part of either a closed circuit or an open circuit. In the case of a closed circuit, the incoming water main pipe 210 and the outgoing water main pipe 220 are connected via a heat exchanger on the load side.

  The chiller unit 100 can perform any one of hot water operation, cold water operation, and defrosting operation. Below, the structure of the chiller unit 100 is demonstrated first, and a hot water operation, a cold water operation, and a defrost operation are demonstrated on it.

  The chiller unit 100 according to the present embodiment will be described with reference to FIG. FIG. 2 is a configuration diagram of the chiller unit 100 according to the present embodiment.

  The chiller unit 100 includes a refrigerant circuit 10 through which refrigerant circulates, a cooling water circuit 30 through which engine cooling water circulates, a water circuit 40 through which water flows, a control device 50, and an input device 60. The user commands the operation of the heat pump chiller 100 by operating the input device 60. The control device 50 controls driving of the refrigerant circuit 10, the cooling water circuit 30, and the water circuit 40 based on the input command. By this operation, the chiller unit 100 adjusts the temperature of the water flowing through the water circuit 40.

  The refrigerant circuit 10 includes a compressor 1, a four-way valve 2, an air heat exchanger 3, a water heat exchanger 4, an engine exhaust heat recovery device 5, a first expansion valve 6, a second expansion valve 7, and a bridge circuit 8. ing.

  The refrigerant circuit 10 includes a discharge path 11, a suction path 12, a gas path 13, a liquid path 14, a high pressure liquid path 15, a low pressure liquid path 16, a liquid path 17, a gas path 18, a high pressure liquid path 19, and a low pressure liquid path 20. , And a low-pressure gas path 21. The discharge path 11 connects the compressor 1 and the four-way valve 2. The suction path 12 connects the four-way valve 2 and the compressor 1. The gas path 13 connects the four-way valve 2 and the air heat exchanger 3. The liquid path 14 connects the air heat exchanger 3 and the bridge circuit 8. The high pressure liquid path 15 connects the bridge circuit 8 and the first expansion valve 6. The low-pressure liquid path 16 connects the first expansion valve 6 and the bridge circuit 8. The liquid path 17 connects the bridge circuit 8 and the water heat exchanger 4. The gas path 18 connects the water heat exchanger 4 and the four-way valve 2. The high-pressure liquid path 19 branches from the high-pressure liquid path 15 at the connection point P1, and connects the high-pressure liquid path 15 and the second expansion valve 7. The low-pressure liquid path 20 connects the second expansion valve 7 and the engine exhaust heat recovery device 5. The low-pressure gas path 21 connects the engine exhaust heat recovery device 5 and the suction path 12 and joins the suction path 12 at the connection point P2. The merging path 12a points to the downstream side (compressor 1 side) of the connection point P2 in the suction path 12.

  The compressor 1 sucks the refrigerant from the suction path 12, compresses the refrigerant, and discharges the refrigerant from the discharge path 11. The four-way valve 2 connects the discharge path 11 to the gas path 13 and the suction path 12 to the gas path 18 during cold water operation, and connects the discharge path 11 to the gas path 18 and the suction path 12 to the gas path 13 during hot water operation. . The cold water operation refers to an operation state in which water in the water circuit 40 is cooled, and the hot water operation refers to an operation state in which water in the water circuit 40 is heated. The air heat exchanger 3 functions as a condenser that liquefies refrigerant using air as a heat radiation source during cold water operation, and functions as an evaporator that vaporizes refrigerant using air as a heat absorption source during hot water operation. The water heat exchanger 4 functions as a cooler that cools water using a gas-liquid two-phase refrigerant as a heat radiation source during cold water operation, and functions as a heater that heats water using the refrigerant in the discharge path 11 as a heat absorption source during hot water operation. . The engine exhaust heat recovery unit 5 functions as an evaporator that evaporates the refrigerant using the exhaust heat of the engine 31 as a heat absorption source via engine cooling water, as will be described later. The first expansion valve 6 adjusts the flow rate of the liquid refrigerant toward the air heat exchanger 3 during the hot water operation, and adjusts the flow rate of the liquid refrigerant toward the water heat exchanger 4 during the cold water operation. The second expansion valve 7 adjusts the flow rate of the refrigerant in the liquid state toward the engine exhaust heat recovery unit 5. A first expansion valve 6 and a second expansion valve 7 are arranged in parallel downstream of the bridge circuit 8. As a result, the water heat exchanger 4 and the engine exhaust heat recovery device 5 are arranged in parallel in the refrigerant flow direction during cold water operation, and the air heat exchanger 3 and the engine exhaust heat recovery device in the refrigerant flow direction during hot water operation. 5 are arranged in parallel. Next, the configuration of the bridge circuit 8 will be described.

  In FIG. 2, the bridge circuit 8 includes a closed path 80 and four check valves 81, 82, 83, 84. The four check valves 81, 82, 83, 84 are arranged on the closed path 80. In the closed path 80, the inlets of the two check valves 81 and 82 are disposed on the opposite side to the inlets of the other two check valves 83 and 84. Connection points P3, P4, P5, and P6 are provided between two adjacent check valves 81, 82, 83, and 84, respectively. The liquid path 14 is connected to the connection point P3, the high pressure liquid path 15 is connected to the connection point P4, the liquid path 17 is connected to the connection point P4, and the low pressure liquid path 16 is connected to the connection point P5. Has been. The operation of the bridge circuit 8 will be described in the description of the cold water operation and the hot water operation described later.

  The coolant circuit 30 includes an engine 31, a thermostat valve 32, a three-way valve 33, a radiator 34, and the engine exhaust heat recovery unit 5 described above. The engine 31 drives the compressor 1. The engine exhaust heat recovery device 5 belongs to both the refrigerant circuit 10 and the cooling water circuit 30.

  The cooling water circuit 30 includes a main path 35, a return path 36, and an exhaust heat recovery path 37. The main path 35 returns cooling water from the engine 31 to the engine 31 via the thermostat valve 32, the three-way valve 33, and the radiator 34. The return path 36 branches from the main path 35 at the thermostat valve 32 and joins the main path 35 on the downstream side of the radiator 34. The exhaust heat recovery path 37 branches from the main path 35 at the three-way valve 33 and joins the main path 35 on the downstream side of the radiator 34 via the engine exhaust heat recovery unit 5.

  The thermostat valve 32 opens one of the main path 35 and the return path 36 and closes the other based on the temperature of the cooling water in the main path 35 or the engine 31. When the temperature of the cooling water is lower than a predetermined temperature (for example, 60 ° C.), the thermostat valve 32 closes the main path 35 and opens the return path 36. In this case, the cooling water circulates only through the engine 31 and the thermostat valve 32. That is, the low-temperature cooling water is not supplied to the radiator 34 and the engine exhaust heat recovery unit 5. When the temperature of the cooling water is equal to or higher than a predetermined temperature, the thermostat valve 32 opens the main path 35 and closes the return path 36. The three-way valve (flow control valve) 33 adjusts the opening degree of the main path 35 and the exhaust heat recovery path 37 based on a command from the control device 50, and the cooling water flowing through the main path 35 and the exhaust heat recovery path 37. Change the flow rate. The three-way valve 33 can also completely close one of the main path 35 and the exhaust heat recovery path 37. When the three-way valve 33 opens the main path 35, the cooling water returns to the engine 31 via the radiator 34. When the three-way valve 33 opens the exhaust heat recovery path 37, the cooling water returns to the engine 31 via the engine exhaust heat recovery device 5. In this case, since the cooling water is supplied to the engine exhaust heat recovery device 5, the engine exhaust heat recovery device 5 can function as a refrigerant evaporator using the exhaust heat of the engine 31 as a heat absorption source via the engine cooling water.

  The water circuit 40 includes a water heat exchanger 40, a water inlet path 41, and a water outlet path 42. The water heat exchanger 40 belongs to both the refrigerant circuit 10 and the water circuit 40.

  The chiller unit 100 includes various sensors. The refrigerant circuit 10 includes a first pressure sensor 61, a first temperature sensor 71, a second pressure sensor 62, and a second temperature sensor 72. The first pressure sensor 61 and the first temperature sensor 71 respectively detect the pressure and temperature of the refrigerant in the merge path 12a. The second pressure sensor 62 and the second temperature sensor 72 detect the pressure and temperature of the refrigerant in the low-pressure gas path 21, respectively. The coolant circuit 30 includes a rotation speed sensor 38 that detects the rotation speed of the engine 31. The water circuit 40 includes an incoming water temperature sensor 43 and an outgoing water temperature sensor 44. The incoming water temperature sensor 43 detects the temperature of water in the incoming water path 41, and the outgoing water temperature sensor 44 detects the temperature of water in the outgoing water path 41.

  The cold water operation will be described with reference to FIG. FIG. 3 is a configuration diagram of the chiller unit 100 in the cold water operation.

  In the cold water operation, the four-way valve 2 connects the discharge path 11 to the gas path 13 and connects the suction path 12 to the gas path 18. For this reason, the refrigerant in the high-pressure gas state discharged from the compressor 1 flows to the air heat exchanger 3.

  Since the temperature of the refrigerant flowing through the air heat exchanger 3 is higher than the temperature of the air flowing through the air heat exchanger 3, heat is transferred from the refrigerant to the air. As a result, the refrigerant loses heat of condensation and liquefies, and becomes a high-pressure liquid refrigerant. That is, the air heat exchanger 3 functions as a refrigerant condenser using air as a heat radiation source.

  The refrigerant in the high-pressure liquid state flows from the air heat exchanger 3 through the liquid path 14 to the connection point P3 of the bridge circuit 8. The connection point P3 is located on the outlet side of the check valves 81 and 83 and is located on the inlet side of the check valve 82. Therefore, the refrigerant flows from the connection point P3 to the high-pressure liquid path 15 via the check valve 82 and the connection point P4. In the cold water operation, the three-way valve 33 is controlled so that the cooling water does not flow through the engine exhaust heat recovery device 5, and the second expansion valve 7 is closed. For this reason, the refrigerant passes only through the first expansion valve 6. In the first expansion valve 6, the high-pressure liquid refrigerant expands to become a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant flows from the low-pressure liquid path 16 to the connection point P6 of the bridge circuit 8. Although the connection point P6 is on the inlet side of the four check valves 81, 82, 83, and 84, the high-pressure liquid refrigerant described above flows through the connection points P3 and P4. Due to the pressure difference, the refrigerant at the connection point P6 can pass only through the check valve 84 and cannot pass through the check valves 81 and 83. For this reason, the low-pressure gas-liquid two-phase refrigerant flows from the connection point P6 to the water heat exchanger 4 via the check valve 84, the connection point P5, and the liquid path 17.

  Since the temperature of the refrigerant flowing through the water heat exchanger 4 is lower than the temperature of the water flowing through the water heat exchanger 4, heat moves from water to the refrigerant. As a result, the refrigerant is vaporized by obtaining the heat of evaporation, and becomes a refrigerant in a low-pressure gas state. Moreover, water is cooled by the heat radiation to the refrigerant. That is, the water heat exchanger 4 functions as a cooler of the water circuit 40 using the gas-liquid two-phase refrigerant as a heat radiation source.

  The refrigerant in the low-pressure gas state flows from the water heat exchanger 4 to the gas path 18. Since the suction path 12 is connected to the gas path 18, the refrigerant is sucked into the compressor 1.

  While the cold water operation is being performed, the refrigerant circulates in the refrigerant circuit 10 along the above-described path.

  The hot water operation will be described with reference to FIG. FIG. 4 is a configuration diagram of the chiller unit 100 in the hot water operation.

  In the hot water operation, the four-way valve 2 connects the discharge path 11 to the gas path 18 and connects the suction path 12 to the gas path 13. For this reason, the refrigerant in the high-pressure gas state discharged from the compressor 1 flows to the water heat exchanger 4.

  Since the temperature of the refrigerant flowing through the water heat exchanger 4 is higher than the temperature of the water flowing through the water heat exchanger 4, heat moves from the refrigerant to the water. As a result, the refrigerant loses heat of condensation and liquefies, and becomes a high-pressure liquid refrigerant. Moreover, water is heated by the endothermic heat from the refrigerant. That is, the water heat exchanger 4 functions as a heater of the water circuit 40 that uses the refrigerant in the discharge path 11 as a heat absorption source.

  The refrigerant in the high-pressure liquid state flows from the water heat exchanger 4 via the liquid path 17 to the connection point P5 of the bridge circuit 8. The connection point P5 is located on the inlet side of the check valve 83 and on the outlet side of the check valves 82 and 84. Therefore, the refrigerant flows from the connection point P5 to the high-pressure liquid path 15 via the check valve 83 and the connection point P4. The refrigerant flows from the high pressure liquid path 15 to the first expansion valve 6 and flows from the connection point P1 of the high pressure liquid path 15 to the second expansion valve 7 via the high pressure liquid path 19. In the hot water operation, the refrigerant passes through the first expansion valve 6 and the second expansion valve 7. In the first expansion valve 6, the high-pressure liquid refrigerant expands to become a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant flows from the low-pressure liquid path 16 to the connection point P6 of the bridge circuit 8. The connection point P6 is on the inlet side of the four check valves 81, 82, 83, and 84, but the above-described high-pressure liquid refrigerant flows through the connection points P4 and P5. Due to the pressure difference, the refrigerant at the connection point P6 can pass only through the check valve 81 and cannot pass through the check valves 82 and 84. Therefore, the low-pressure gas-liquid two-phase refrigerant flows from the connection point P6 to the air heat exchanger 3 via the check valve 81, the connection point P3, and the liquid path 14. The flow of the refrigerant passing through the second expansion valve 7 will be described later.

  Since the temperature of the refrigerant flowing through the air heat exchanger 3 is lower than the temperature of the air flowing through the air heat exchanger 3, heat is transferred from the air to the refrigerant. As a result, the refrigerant is vaporized by obtaining the heat of evaporation, and becomes a refrigerant in a low-pressure gas state. That is, the air heat exchanger 3 functions as a refrigerant evaporator using air as a heat absorption source.

  The refrigerant in the low-pressure gas state flows from the air heat exchanger 3 to the gas path 13. Since the suction path 12 is connected to the gas path 13, the refrigerant is sucked into the compressor 1.

  On the other hand, the refrigerant passing through the second expansion valve 7 expands in the second expansion valve 7 and becomes a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant flows to the engine exhaust heat recovery device 5 via the low-pressure liquid path 20.

  Since the temperature of the refrigerant flowing through the engine exhaust heat recovery unit 5 is lower than the temperature of the cooling water flowing through the engine exhaust heat recovery unit 5, heat moves from the cooling water to the refrigerant. As a result, the refrigerant is vaporized by obtaining the heat of evaporation, and becomes a refrigerant in a low-pressure gas state. That is, the engine exhaust heat recovery device 5 functions as a refrigerant evaporator using cooling water as a heat absorption source.

  The refrigerant in the low pressure gas state flows from the engine exhaust heat recovery device 5 to the suction path 12 via the low pressure gas path 21. At the connection point P2, the refrigerant from the engine exhaust heat recovery device 5 merges with the refrigerant from the air heat exchanger 3. The merged refrigerant flows through the merge path 12a and is sucked into the compressor 1.

  While the hot water operation is being performed, the refrigerant circulates in the refrigerant circuit 10 along the above-described path.

  The defrosting operation will be described with reference to FIG. FIG. 5 is a configuration diagram of the chiller unit 100 in the defrosting operation.

  The hot water operation, cooling operation, and defrosting operation have the following relationship. The four-way valve (operation switching mechanism) 2 switches between the hot water operation and the non-warm water operation by switching the flow path in the refrigerant circuit 10. Here, the non-warm water operation indicates a cooling operation and a defrosting operation. In the defrosting operation, the four-way valve 2 is switched to the non-warm water operation, the first expansion valve 6 is closed so that the refrigerant does not flow through the water heat exchanger 4, and the refrigerant and cooling water flow through the engine exhaust heat recovery device 5. In this operation, the opening degree of the second expansion valve 7 and the flow rate adjustment valve 33 is controlled. Since the first expansion valve 6 is closed, the entire amount of refrigerant flows through the engine exhaust heat recovery device 5. On the other hand, the three-way valve 33 has a small opening so that a part of the cooling water flows through the engine exhaust heat recovery device 5 even if the main path 35 is closed so that the entire amount of cooling water flows through the engine exhaust heat recovery device 5. However, the main path 35 may be opened.

  In the defrosting operation, the air heat exchanger 3 functions as a condenser as in the cooling operation, and the engine exhaust heat recovery device 5 functions as an evaporator instead of the water heat exchanger 4 that functions as an evaporator in the cooling operation. To do. In the defrosting operation, the refrigerant in the high-pressure gas state is supplied to the air heat exchanger 3 as in the cooling operation, so that the piping in the air heat exchanger 3 is heated. As a result, the frost attached to the air heat exchanger 3 in the hot water operation is removed. In the defrosting operation, since the refrigerant does not flow through the water heat exchanger 4, the water temperature does not decrease due to the evaporation of the refrigerant.

  In the defrosting operation, the chiller unit 100 controls the opening degree of the second expansion valve 7 based on the degree of superheat of the refrigerant flowing through the merge path 12a or the degree of superheat of the refrigerant flowing in the low-pressure gas path 21. In the defrosting operation, since the first expansion valve 6 is closed, the entire amount of the refrigerant flowing through the low-pressure gas path 21 flows through the merge path 12a. For this reason, the superheat degree of the refrigerant in the junction path 12a is substantially equal to the superheat degree of the refrigerant in the low-pressure gas path 21.

  The degree of superheat of the refrigerant can be specified by detecting the pressure of the refrigerant and the temperature of the refrigerant. Specifically, the saturated vapor temperature corresponding to the refrigerant pressure is identified based on the saturated vapor line of the refrigerant, and the degree of superheat is identified as the temperature difference between the refrigerant temperature and the saturated vapor temperature. For this reason, the superheat degree of the refrigerant flowing through the merging path 12 a is specified based on the detection value by the first pressure sensor 61 and the detection value by the first temperature sensor 71. Similarly, the degree of superheat of the refrigerant flowing through the low-pressure gas path 21 is specified based on the detection value by the second pressure sensor 62 and the detection value by the second temperature sensor 72.

  With reference to FIG. 6, defrost control is demonstrated. FIG. 6 is a configuration diagram of the heat pump chiller 1000 in the defrost control.

  Each chiller unit 100 performs defrost control in order to remove frost attached to the air heat exchanger 3. For example, the chiller unit 100 determines that the defrosting operation is necessary when the continuous execution time of the hot water operation exceeds a predetermined time. In order to cope with the case where the need for the defrosting operation occurs in the plurality of chiller units 100, the defrosting control is prepared. The defrosting control is a control for causing the chiller units 100 to perform the defrosting operation alternately at least one unit without performing the defrosting operation at the same time while all the chiller units 100 are operating in the hot water operation. .

  The heat pump chiller 1000 includes a control mechanism for executing defrost control. In the present embodiment, the control mechanism is an aggregate of the control devices 50 of all the chiller units 100, and the control devices 50 are connected so as to communicate with each other. Of all the chiller units 100, one chiller unit 100 is designated as a parent device, and the control device 50 of the parent device causes each chiller unit 100 to perform a snow removal operation. Note that the control mechanism may be a device that is arranged outside each chiller unit 100 and that controls each chiller unit 100 in an integrated manner.

  In FIG. 6, three chiller units 100A, 100B, and 100C are in operation, and one chiller unit 100D is at rest. The three chiller units 100A, 100B, and 100C that are in operation are all performing hot water operation. When the three chiller units 100A, 100B, and 100C determine that the defrosting operation is necessary, the master unit (for example, the chiller unit 100A) designates one chiller unit 100A and performs the defrosting operation on the chiller unit 100A. Let The master unit causes the other two chiller units 100B and 100C to continue the hot water operation. The defrosting operation is executed for a predetermined time, for example. When the defrosting operation of the designated chiller unit 100A is completed, the master unit designates another chiller unit 100B and causes the chiller unit 100B to perform the defrosting operation. In this manner, the master unit designates the chiller unit 100 that performs the defrosting operation in turn, and causes the other chiller units 100 to continue the hot water operation. In this way, while all the chiller units 100 are performing hot water operation while all the chiller units 100 are performing defrost operation at the same time, at least one chiller unit 100 is performing hot water operation, 100 defrosting operations are performed alternately. In addition, when only one chiller unit 100 is performing the hot water operation and it is determined that the defrosting operation is necessary, the process proceeds to the defrosting operation. In this case, another chiller unit 100 is appropriately activated for the hot water operation according to the target water temperature.

(Effect of this embodiment)
The heat pump chiller 1000 according to the present embodiment has the following effects due to the above-described configuration.

  In the heat pump chiller 1000 according to the present embodiment, when a plurality of chiller units 100 are performing hot water operation, all the chiller units 100 perform hot water operation on at least one chiller unit 100 without performing defrosting operation at the same time. The defrosting operation is performed on at least one chiller unit 100 in turn while continuing. In the defrosting operation, the operation switching mechanism (four-way valve 2) is switched to the non-warm water operation, the first expansion valve 6 is closed so that the refrigerant does not flow through the water heat exchanger 4, and the refrigerant and the exhaust heat medium (cooling water) are supplied. In this operation, the opening degree of the second expansion valve 7 and the flow rate adjusting valve (three-way valve 33) is controlled so as to flow through the engine exhaust heat recovery device 5.

  In the defrosting operation, the engine exhaust heat recovery device 5 functions as an evaporator instead of the water heat exchanger 4 when the refrigerant is flown so that the air heat exchanger 3 becomes a condenser as in the cooling operation. For this reason, in the chiller unit 100 in which the defrosting operation is performed, the water temperature in the water heat exchanger 4 is not reduced due to the evaporation of the refrigerant. Therefore, the heat pump chiller 1000 according to the present embodiment can suppress a decrease in the water temperature of the water circuit 200 during the defrosting operation without imposing a load on the chiller unit 100.

1 Compressor 2 Four-way valve (Operation switching mechanism)
DESCRIPTION OF SYMBOLS 3 Air heat exchanger 4 Water heat exchanger 5 Engine exhaust heat recovery device 6 1st expansion valve 7 2nd expansion valve 8 Position switching mechanism 31 Engine 33 Three-way valve (flow control valve)
41 Inlet branch pipe (inlet pipe)
42 Drainage branch pipe (Drainage pipe)
100, 100A, 100B, 100C, 100D Chiller unit 1000 Engine heat pump chiller

Claims (1)

A compressor for compressing the refrigerant is driven by the engine, and a plurality of engine-driven heat pump chiller units that adjust the temperature of water as a heat medium by heat of condensation or evaporation of the refrigerant are provided,
The chiller unit is
An air heat exchanger that functions as a condenser that liquefies refrigerant using air as a heat radiation source or an evaporator that vaporizes refrigerant using air as a heat absorption source;
A water inlet pipe for introducing the water and a water outlet pipe for discharging the water, the gas-liquid two-phase refrigerant as a heat radiation source as a cooler for cooling the water or the refrigerant discharged from the compressor A water heat exchanger that functions as a heater for heating water as an endothermic source;
An operation switching mechanism for switching between a hot water operation in which the air heat exchanger functions as an evaporator and a non-warm water operation in which the air heat exchanger functions as a condenser;
An engine exhaust heat recovery device functioning as an evaporator of a refrigerant using the exhaust heat of the engine as a heat absorption source through an exhaust heat medium;
A first expansion valve that adjusts the flow rate of the refrigerant in the liquid state toward the air heat exchanger during the hot water operation and adjusts the flow rate of the refrigerant in the liquid state toward the water heat exchanger during the non-warm water operation. When,
A second expansion valve for adjusting a flow rate of the refrigerant in a liquid state toward the engine exhaust heat recovery device;
A flow rate adjustment valve that adjusts the flow rate of the exhaust heat medium flowing through the engine exhaust heat recovery device,
Each of the inlet pipe and the outlet pipe is connected in parallel,
The defrosting control is a control for causing the chiller units to perform the defrosting operation alternately at least one unit without performing the defrosting operation at the same time while all the chiller units are operating in the hot water operation. The chiller unit that performs the defrosting operation switches the warm water operation to the non-warm water operation by controlling the operation switching mechanism, and the first expansion valve is controlled so that the refrigerant does not flow through the water heat exchanger. An engine-driven heat pump chiller that is closed and controls the opening of the second expansion valve and the flow rate adjustment valve so that the refrigerant and the exhaust heat medium flow through the engine exhaust heat recovery device.

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