JP6119895B1 - Heat pump equipment - Google Patents

Abstract

To provide a heat pump device capable of reliably avoiding a liquid back state at the time of starting of a compressor and shortening the starting time of the compressor. A heat pump device having a heat pump cycle using a refrigerant, wherein a bypass pipe connecting a discharge side of a compressor and a suction side of the compressor via a bypass valve, and a heat pump device. At startup, the refrigerant pressure Pin on the suction side of the compressor 20, the heat source hot water temperature Tw, the refrigerant superheat degree ΔTin on the suction side of the compressor 20, the refrigerant superheat degree ΔTout on the discharge side of the compressor 20, and the suction side of the compressor 20 And a control unit 18 that controls opening and closing of the bypass valve 71 based on at least one of the refrigerant temperatures Tin. [Selection] Figure 1

Description

  The present invention relates to a heat pump apparatus that can reliably avoid a liquid back state at the time of starting a compressor and shorten the starting time of the compressor.

  In a heat pump device using a low-pressure refrigerant used in a high temperature region, in order to avoid damage to the compressor due to liquid compression, control is performed so that both the suction side and the discharge side of the compressor are overheated. As a control means related to this, for example, the one shown in Patent Document 1 is known. In the heat pump device of Patent Document 1, more stable start-up can be performed by controlling the degree of refrigerant superheat on the compressor suction side during start-up and on the compressor discharge side during normal operation.

International Publication No. 2015/056648

  However, in the heat pump cycle as described above, if the temperature of the hot water serving as the heat source is near the lower limit temperature at which operation is possible, the degree of superheat of the refrigerant sucked into the compressor will not sufficiently increase, and it will take a long time before switching to normal operation. May be required.

  The present invention has been made in view of the above, and an object of the present invention is to provide a heat pump device that can reliably avoid the liquid back state at the time of starting the compressor and shorten the starting time of the compressor. To do.

  In order to solve the above-described problems and achieve the object, a heat pump device according to the present invention includes a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, and a condenser that is condensed by the condenser. A heat pump device having an expansion mechanism for decompressing the refrigerant and a heat pump cycle in which an evaporator for recovering heat from the heat source hot water and evaporating the refrigerant is connected in an annular shape, the discharge side of the compressor and the suction side of the compressor And a bypass line connecting the two through a bypass valve, and at the time of starting the heat pump device, the refrigerant pressure on the suction side of the compressor, the amount of heat of the heat source hot water, the degree of refrigerant superheat on the suction side of the compressor, the compression A controller that controls opening and closing of the bypass valve based on at least one of a refrigerant superheat degree on the discharge side of the compressor and a refrigerant temperature on the suction side of the compressor. Characterized in that was.

  The heat pump device according to the present invention is characterized in that, in the above invention, the compressor suction side connection point of the bypass line is between the evaporator and the expansion mechanism.

  Moreover, the heat pump device according to the present invention is characterized in that, in the above invention, the compressor suction side connection point of the bypass line is between the compressor and the evaporator.

  In the heat pump device according to the present invention, in the above invention, the compressor suction side connection point of the bypass line is upstream of a temperature detection unit that detects a refrigerant temperature on the compressor suction side. Features.

  Moreover, the heat pump device according to the present invention is characterized in that, in the above invention, a check valve is provided between the compressor and the condenser, and a compressor discharge side connection point of the bypass line is the compressor and the compressor. It is between check valves.

  Moreover, the heat pump device according to the present invention is characterized in that, in the above invention, a flexible pipe is interposed between the compressor and the compressor discharge side connection point of the bypass pipeline.

  Moreover, the heat pump device according to the present invention is characterized in that, in the above invention, the flexible pipe is arranged to be bendable in response to vibration of the compressor.

  Further, in the heat pump device according to the present invention, in the above invention, the control unit is configured such that the refrigerant pressure on the suction side of the compressor is less than a lower limit value, the amount of heat of the heat source hot water is less than a lower limit value, and the suction side of the compressor When the refrigerant superheat degree is less than the lower limit value, the refrigerant superheat degree on the discharge side of the compressor is less than the lower limit value, and the refrigerant temperature on the suction side of the compressor is less than the lower limit value, the bypass is satisfied The valve is controlled to open.

  In the heat pump device according to the present invention, in the above invention, when the bypass valve is in an open state, the control unit is configured such that the refrigerant pressure on the suction side of the compressor is equal to or higher than an upper limit value, and the heat amount of the heat source hot water is an upper limit value. The refrigerant superheat degree on the suction side of the compressor is higher than the upper limit value, the refrigerant superheat degree on the discharge side of the compressor is higher than the upper limit value, the refrigerant temperature on the suction side of the compressor is higher than the upper limit value, The bypass valve is controlled to be closed when at least one of the conditions that the refrigerant pressure on the suction side is equal to or higher than the first set value and the refrigerant superheat degree is equal to or higher than the second set value is satisfied.

  The heat pump device according to the present invention is characterized in that, in the above invention, the control unit performs the opening / closing control by controlling an opening degree of the bypass valve.

  In the heat pump device according to the present invention, in the above invention, the control unit has at least two operation modes of a start operation mode and a normal operation mode, and the start operation mode is a mode for controlling opening and closing of the bypass valve. In the start-up of the heat pump device, the start-up operation mode is set.

  In the heat pump device according to the present invention, in the above invention, the control unit shifts to the normal operation mode when the refrigerant superheat degree on the suction side of the compressor is equal to or higher than an upper limit value in the start-up operation mode. It is characterized by.

  The heat pump device according to the present invention is the heat pump device according to the above invention, wherein the control unit is in a startup operation mode when the heat pump device is started, and the refrigerant superheat degree on the discharge side of the compressor is the upper limit value in the startup operation mode. It shifts to normal operation mode in the above case, It is characterized by the above-mentioned.

  According to the present invention, the bypass pipe that connects the discharge side of the compressor and the suction side of the compressor via the bypass valve is provided, and the control unit is configured to provide the refrigerant on the suction side of the compressor when the heat pump device is activated. The bypass valve based on at least one of pressure, heat quantity of heat source hot water, refrigerant superheat on the suction side of the compressor, refrigerant superheat on the discharge side of the compressor, and refrigerant temperature on the suction side of the compressor. Since the opening / closing control is performed, it is possible to reliably avoid the liquid back state at the time of starting the compressor and shorten the starting time of the compressor.

1 is an overall configuration diagram of an exhaust heat recovery heat pump device according to an embodiment of the present invention. It is a Ph diagram of R245fa including a saturated gas line and an isentropic line. It is a perspective view which shows the structure of the heat pump part shown in FIG. It is an expansion perspective view of the heat pump part containing the bypass pipe line shown in FIG. It is a flowchart which shows an example of the control processing of the control part containing the starting operation mode control process by a starting operation mode control part. It is a figure which shows an example which provided the refrigerant | coolant return destination of the bypass line in the exhaust heat recovery heat pump apparatus shown in FIG. 1 between the evaporator and the expansion mechanism.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

(overall structure)
FIG. 1 is an overall configuration diagram of an exhaust heat recovery heat pump apparatus 10 according to an embodiment of the present invention. The exhaust heat recovery heat pump device 10 is a system that recovers exhaust heat from warm water such as factory waste water and generates steam using the recovered exhaust heat. The generated steam is external steam such as a drying device or a sterilizer. Sent to the use facility.

  As shown in FIG. 1, the exhaust heat recovery heat pump device 10 generates heat by evaporating water to generate water vapor, and heat is generated from the hot water (heat source hot water) supplied by the hot water supply unit 14 and the hot water supply unit 14. And a heat pump unit 16 that supplies this heat as a heat source for generating steam in the steam generation unit 12 and a control unit 18.

  The heat pump unit 16 includes a compressor 20 that compresses the refrigerant, a condenser 22 that condenses the refrigerant compressed by the compressor 20, an expansion mechanism 24 that decompresses the refrigerant that has exited the condenser 22, and heat from the heat source hot water. This is a heat pump device having a heat pump cycle in which an evaporator 26 that recovers and evaporates the refrigerant is connected in an annular shape. In the present embodiment, a heater 28 is connected between the outlet side of the condenser 22 and the inlet side of the expansion mechanism 24. The expansion mechanism 24 is, for example, an electronic expansion valve.

As shown in FIG. 2, the refrigerant flowing in the heat pump cycle has an isentropic line L1 on the Ph diagram in the superheated region on the low pressure side, and a saturated gas line L2 and an isentropic line L1 on the high pressure side. It is a refrigerant having the characteristic of having intersections or contact points greater than or equal to a point. This refrigerant is, for example, 1,1,1,3,3-pentafluoropropane (structural formula: CHF ₂ CH ₂ CF ₃ , R245fa). FIG. 2 shows a Ph diagram of R245fa, where the saturated gas line L2 and the isentropic line L1 intersect at two points PP1 and PP2.

  The refrigerant that has been compressed by the compressor 20 to a high temperature and high pressure is cooled and condensed by exchanging heat with the water circulating in the steam generation unit 12 in the condenser 22. The refrigerant that has exited the condenser 22 is preheated with water flowing through the water supply path 30 by the heater 28 and further cooled, and then adiabatic expansion is performed by the expansion mechanism 24, and the hot water path 32 of the hot water supply unit 14 is expanded by the evaporator 26. It absorbs heat from the flowing heat source hot water, evaporates and returns to the compressor 20.

  The refrigerant path of the heat pump unit 16 includes a suction pressure sensor 34 and a suction temperature sensor 35 that respectively detect a refrigerant pressure Pin and a refrigerant temperature Tin on the suction side of the compressor 20, and a refrigerant pressure Pout and a refrigerant on the discharge side of the compressor 20. The discharge pressure sensor 36 and the discharge temperature sensor 37 for detecting the temperature Tout, the inlet temperature sensor 38 for detecting the refrigerant temperature Ta on the inlet side of the expansion mechanism 24, and the heat quantity of the heat source hot water flowing into the evaporator 26 are detected. As a means, a heat source hot water temperature sensor 29 is installed to measure the temperature Tw of the heat source hot water. In this embodiment, the heat source hot water temperature Tw is used as the heat quantity reference as the heat quantity of the heat source hot water. However, when the temperature fluctuation of the heat source hot water is small, a heat source hot water flow rate sensor is provided instead of the heat source hot water temperature sensor 29, and the heat source It is good also considering the flow volume of warm water as a reference | standard of calorie | heat amount. Further, both the heat source hot water temperature sensor 29 and the heat source hot water flow rate sensor may be provided, and the heat flow calculated from the flow rate and temperature of the heat source hot water may be used as a reference for the heat amount. Hereinafter, in the present embodiment, the control when the temperature Tw of the heat source hot water is used as a reference for the amount of heat will be described as a representative example.

  A bypass line 70 connected via a bypass valve 71 is provided between the discharge side and the suction side of the compressor 20. The bypass valve 71 is controlled to be opened and closed by the control unit 18 when the heat pump device is activated. When the bypass valve 71 is open, the refrigerant on the discharge side of the compressor 20 flows into the suction side. The control of the bypass valve 71 will be described later.

  The steam generation unit 12 uses a refrigerant circulating in the heat pump unit 16 as a heat source to evaporate water to generate steam, and a vapor-liquid two-phase flow including water and steam generated by the condenser 22 A water vapor separator 42 that separates into water, a steam supply path 44 that supplies the steam separated by the water vapor separator 42 to an external steam utilization facility, and water that is separated by the water vapor separator 42 is supplied from the water supply path 30. And a water circulation path 46 that joins the water to be led from the condenser 22 to the water vapor separator 42.

  The water vapor separator 42 is formed of a cylindrical container along the vertical direction, and stores water inside the container by supplying water from the water supply path 30 connected to the water circulation path 46 connected to the lower end wall. . In the water supply path 30, water (water supply) from a water pipe or a water tank (not shown) is introduced to the water circulation path 46 through the heater 28 by the water supply pump 48. Under the control of the control unit 18, the feed water pump 48 is operated at its rotational speed via an inverter (INV) 52 based on a detection value (water level) of a water level sensor 50 that measures the water level of water stored in the water vapor separator 42. Is controlled. Connected to the water vapor separator 42 is a pressure relief valve 54 that is opened when the internal vapor pressure exceeds a predetermined pressure.

  The water circulation path 46 includes a liquid pipe 46 a that communicates from the lower end wall of the water vapor separator 42 to the condenser 22, and a vapor pipe 46 b that communicates from the condenser 22 to the upper side wall of the water vapor separator 42. Water flows through the liquid pipe 46a, and a gas-liquid two-phase flow containing water and steam flows through the steam pipe 46b. A circulation pump 56 is provided in the liquid pipe 46a. The operation speed of the circulation pump 56 is controlled through an inverter (INV) 58 under the control of the control unit 18.

  The steam supply path 44 is a path that is connected to the upper end wall of the water vapor separator 42 and is supplied into the water vapor separator 42 from the steam pipe 46b, where the steam after the water is separated is sent out to the outside. The steam supply path 44 is provided with a pressure adjustment valve (steam pressure adjusting means) 60 for adjusting the pressure of the flowing steam. The pressure adjustment valve 60 is adjusted in opening degree based on the vapor pressure in the water vapor separator 42 measured by the pressure sensor 62 under the control of the control unit 18. By appropriately adjusting the opening degree of the pressure regulating valve 60, the flow rate and pressure of the steam sent out from the exhaust heat recovery heat pump device 10 can be controlled. As the steam pressure adjusting means for adjusting the pressure of the steam flowing through the steam supply path 44, a steam compressor that compresses steam instead of or together with the pressure adjusting valve 60 may be used.

  The control unit 18 controls the operating rotational speed of the compressor 20 via the inverter (INV) 40. The control unit 18 enters the start-up operation mode when the heat pump device is started, and causes the start-up operation mode control unit 18a to perform start-up operation mode control. Further, the control unit 18 enters the normal operation mode when the startup operation mode control ends, and causes the normal operation mode control unit 18b to perform the normal operation mode control.

  The startup operation mode control unit 18a performs startup operation mode control when the heat pump device is started up. The start-up operation mode control includes the refrigerant pressure Pin on the suction side of the compressor 20, the heat source hot water temperature Tw, the refrigerant superheat degree ΔTin on the suction side of the compressor 20, the refrigerant superheat degree ΔTout on the discharge side of the compressor 20, and the compressor 20 The bypass valve 71 is controlled to open and close based on at least one of the refrigerant temperatures Tin on the suction side, and the operating rotational speed of the compressor 20 is controlled via the inverter 40 based on the detection values of the sensors 34 to 38. To do.

  The normal operation mode control unit 18b performs the operation control of the compressor 20 based on the detection values of the sensors 34 to 38 from the time when the bypass operation 71 is closed and the start-up operation mode control is finished, so that the heat pump unit 16 Control the heating output. That is, the normal operation mode control unit 18b determines the refrigerant enthalpy difference from the discharge side of the compressor 20 to the inlet side of the expansion mechanism 24 based on the detection values of the sensors 34 to 38, and the refrigerant circulation amount of the heat pump cycle. And the operation rotational speed of the compressor 20 is controlled so that the calculated heat pump heating output becomes the target heating output. Note that the bypass valve 71 is closed during control by the normal operation mode control unit 18b.

  The control unit 18 may further control the water supply pump 48, the circulation pump 56, and the pressure regulating valve 60, but the steam generation unit 12 side may be controlled by another control unit (not shown). Good.

  Here, as shown in FIGS. 1, 3, and 4, the connection point PT <b> 2 on the compressor suction side of the bypass pipe 70 is provided on the pipe LN <b> 1 between the evaporator 26 and the compressor 20. The connection point PT2 is provided on the upstream side of the suction temperature sensor 35 that detects the refrigerant temperature on the compressor suction side. As a result, the suction temperature sensor 35 can detect the temperature of the refrigerant including the refrigerant from the bypass pipe line 70, so that the temperature can be detected with high accuracy even when the bypass valve 71 is opened. Can do.

  On the other hand, the connecting point PT1 on the compressor discharge side of the bypass line 70 is provided on the line LN2 between the compressor 20 and the condenser 22. A check valve 80 is disposed on the pipe line LN2 between the connection point PT1 and the condenser 22. By providing this check valve 80, it is possible to prevent the refrigerant from flowing back through the bypass line 70 from the condenser 22 side.

  Further, a flexible pipe 81 is interposed in a part of the pipe line LN2 between the connection point PT1 and the compressor 20. The flexible pipe 81 is arranged to be bendable with respect to the vibration of the compressor 20. 3 and 4, the downstream end portion of the flexible pipe 81 is fixed by a bracket 100 attached to a housing or the like. The upstream end portion of the flexible pipe 81, that is, the end portion in the -Z direction can be bent in the XY plane direction (horizontal direction). On the other hand, the compressor 20 uses a reciprocating engine and is a V-type engine. However, because the paired cylinders move up and down alternately, the vibration in the Z direction is canceled between the cylinders and mainly vibrates in the X direction. Here, since the flexible pipe 81 can absorb the vibration in the X direction, the vibration to the connection point PT1 disposed downstream is reduced. A small bypass pipe 70 is connected to the connection point PT1, and this connection has a structure in which stress concentration tends to occur because the bypass pipe 70 has a smaller diameter than the pipe LN2. However, vibration is not transmitted, and since it is fixed by the bracket 100, stress concentration is less likely to occur. As shown in FIGS. 3 and 4, the check valve 80 is also fixed by the bracket 100.

(Example of startup operation mode control processing)
Here, an example of the control process of the control unit 18 including the startup operation mode control process by the startup operation mode control unit 18a will be described with reference to the flowchart shown in FIG. As shown in FIG. 5, first, the control unit 18 determines whether or not an activation instruction has been received (step S101). When the control unit 18 does not receive the activation instruction (No at Step S101), the determination process at Step S101 is repeated. On the other hand, when receiving the start instruction (Yes in step S101), the control unit 18 starts up the compressor 20 (step S102) and causes the start-up operation mode control unit 18a to perform start-up operation mode control. The starting operation mode control unit 18a first determines whether or not the refrigerant pressure Pin on the suction side of the compressor 20 is less than the lower limit value Pinlow (step S103). When the refrigerant pressure Pin is less than the lower limit value Pinlow (step S103, Yes), the bypass valve 71 is opened (step S104), and the compressor 20 is operated.

  Thereafter, the startup operation mode control unit 18a determines whether or not the refrigerant pressure Pin is equal to or higher than the upper limit value Pinhigh (> lower limit value Pinlow) (step S106). When the refrigerant pressure Pin is not equal to or higher than the upper limit value Pinhigh (No at Step S106), the determination process at Step S106 is repeated with the bypass valve 71 opened. On the other hand, when the refrigerant pressure Pin is equal to or higher than the upper limit value Pinhigh (step S106, Yes), the bypass valve 71 is closed (step S107), and the compressor 20 is operated.

  Thereafter, the start-up operation mode control unit 18a determines whether or not the refrigerant superheat degree on the discharge side of the compressor 20 is equal to or more than a specified value set in advance as a normal operation transition condition (step S108). If it is equal to or greater than the specified value (step S108, Yes), the control unit 18 switches from the control by the startup operation mode control unit 18a to the control by the normal operation mode control unit 18b. If it is less than the specified value (No at Step S108), the determination of the refrigerant pressure on the suction side of the compressor 20 (Step S103) is repeated again. In addition, you may prescribe | regulate other transition conditions (for example, temperature conditions of heat source warm water, timer conditions after starting a compressor, etc.) as normal operation transition conditions. Further, an AND condition or an OR condition obtained by combining one or more of these conditions may be used, and when the AND condition or the OR condition is satisfied, the process may be shifted to the normal operation mode control.

  If the refrigerant pressure Pin is not less than the lower limit value Pinlow (No at Step S103), the start-up operation mode control unit 18a further determines whether or not the elapsed time after the start of the compressor is within a preset specified value (Step S103). S105). When the elapsed time after the start of the compressor exceeds a preset specified value (No at Step S105), the process proceeds to Step S104 and the bypass valve 71 is opened. On the other hand, when the elapsed time after starting up the compressor is within the preset specified value (step S105, Yes), the process proceeds to step S108. When this control is performed, the elapsed time after starting the compressor exceeds a preset specified value (No in Step S105), and the refrigerant pressure on the suction side of the compressor 20 is equal to or higher than the upper limit (Step S106, Yes). In this case, in order to prevent chattering of the bypass valve 71 from occurring, the bypass valve 71 is provided with a dead time of 10 seconds, for example. This time can be appropriately set depending on the configuration of the equipment and the operating conditions.

  If the refrigerant superheating degree on the discharge side of the compressor 20 is not equal to or greater than the specified value (No at Step S108), the activation operation mode control unit 18a proceeds to Step S103 and repeats the activation operation mode control described above. On the other hand, when the refrigerant superheat degree on the discharge side of the compressor 20 is equal to or higher than the specified value (step S108, Yes), the startup operation mode control unit 18a ends the startup operation mode control, and the control unit 18 starts up. The operation mode is shifted to the normal operation mode, the normal operation mode control is performed by the normal operation mode control unit 18b (step S109), and this process is terminated.

  In the startup operation mode control process shown in FIG. 5, the bypass valve 71 is opened when the refrigerant pressure Pin on the suction side of the compressor 20 is less than the lower limit value Pinlow. The bypass valve 71 may be opened when the heat source hot water temperature Tw is lower than the lower limit value Twlow. Further, the bypass valve 71 may be opened when the refrigerant superheating degree ΔTin on the suction side of the compressor 20 is less than the lower limit value ΔTinlow. Further, the bypass valve 71 may be opened when the refrigerant superheat degree ΔTout on the discharge side of the compressor 20 is less than the lower limit value ΔToutlow. Further, the bypass valve 71 may be opened when the refrigerant temperature Tin on the suction side of the compressor 20 is lower than the lower limit value Tinlow. Further, in the startup operation mode control process, an AND condition or an OR condition obtained by combining one or more of these conditions may be used, and the bypass valve 71 may be opened when the AND condition or the OR condition is satisfied.

  Furthermore, although the bypass valve 71 based on the above-described startup operation mode control processing is open / close control that opens or closes, the present invention is not limited thereto, and the startup operation mode control unit 18a adjusts the opening degree of the bypass valve 71 by PID control. May be performed. For example, when the refrigerant pressure Pin is less than the lower limit value Pinlow, the activation operation mode control unit 18a opens the bypass valve 71 according to the refrigerant pressure Pin, and the refrigerant pressure Pin quickly approaches the upper limit value Pinhigh (target value). Thus, the opening degree of the bypass valve 71 is adjusted. And the starting operation mode control part 18a closes the bypass valve 71, when the refrigerant | coolant pressure Pin becomes more than upper limit Pinhigh for a fixed time.

  In the start-up operation mode control process shown in FIG. 5, the bypass valve 71 is closed when the refrigerant pressure Pin on the suction side of the compressor 20 is equal to or higher than the upper limit value Pinhigh. The bypass valve 71 may be closed when the heat source hot water temperature Tw is equal to or higher than the upper limit value Thigh. Further, the bypass valve 71 may be closed when the refrigerant superheating degree ΔTin on the suction side of the compressor 20 is equal to or higher than the upper limit value ΔTinhigh. Further, the bypass valve 71 may be closed when the refrigerant superheating degree ΔTout on the discharge side of the compressor 20 is equal to or higher than the upper limit value ΔTouthigh. Further, the bypass valve 71 may be closed when the refrigerant temperature Tin on the suction side of the compressor 20 is equal to or higher than the upper limit value Tinhigh. Further, in the startup operation mode control process, an AND condition or an OR condition obtained by combining one or more of these conditions may be set, and the bypass valve 71 may be closed when the AND condition or the OR condition is satisfied.

  For example, the bypass valve 71 is closed when the refrigerant pressure Pin is equal to or higher than the upper limit value (first set value) Pinhigh and the refrigerant superheat degree ΔTin is equal to or higher than the upper limit value (second set value) ΔTinhigh.

  Furthermore, the condition for performing the startup operation mode control with the bypass valve 71 opened may be combined with the condition for shifting to the normal operation mode control with the bypass valve 71 closed under different category conditions. For example, the control may be performed such that the bypass valve 71 is opened when the refrigerant pressure Pin is less than the lower limit value Pinlow and the bypass valve 71 is closed when the refrigerant superheat degree ΔTout is equal to or higher than the upper limit value ΔThigh.

  In FIG. 5, when the refrigerant pressure Pin is not lower than the lower limit value Pinlow in Step S103 (No in Step S103), whether or not the elapsed time after starting the compressor is within a preset specified value in Step S105. When the elapsed time after starting the compressor exceeds a preset value (step S105, No), the bypass valve 71 is opened (step S104), and the elapsed time after starting the compressor is set in advance. If it is within the specified value (step S105, Yes), it is determined whether or not the refrigerant superheat degree on the discharge side of the compressor 20 is equal to or more than the specified value set in advance as the normal operation transition condition (step S108). It was. However, the present invention is not limited to this, and the determination process in step S105 is deleted, and when the refrigerant pressure Pin is not lower than the lower limit Pinlow (No in step S103), the refrigerant superheat degree on the discharge side of the compressor 20 immediately becomes normal operation in advance. It may be determined whether or not the value is equal to or greater than a specified value set as the transition condition (step S108). In this process, if the refrigerant pressure on the suction side of the compressor 20 is equal to or higher than the lower limit value, it is presumed that liquid back does not occur. Therefore, the closed state of the bypass valve 71 is maintained and the discharge side of the compressor 20 is maintained. Switching to the normal operation mode control is performed based only on the refrigerant superheat condition.

  The temperature Tw of the heat source hot water described above may be the temperature on the upstream side of the evaporator 26 or the temperature on the downstream side of the evaporator 26. Furthermore, it is good also considering the temperature of an evaporator main body instead of the temperature Tw of heat source warm water. Further, a temperature difference between the heat source hot water temperature on the upstream side of the evaporator 26 and the heat source hot water temperature on the downstream side may be used as a condition for opening and closing the bypass valve 71 described above.

  In the above-described embodiment, the suction side (refrigerant return destination) of the compressor 20 in the bypass pipe line 70 is connected to the connection point PT2 between the compressor 20 and the evaporator 26. However, the present invention is not limited to this. Instead, as shown in FIG. 6, the suction side of the compressor 20 in the bypass pipe line 70 may be connected to a connection point PT3 on the pipe line LN3 between the evaporator 26 and the expansion mechanism 24. The arrangement of the bypass line 70 shown in FIG. 6 has an advantage that evaporation of the evaporator 26 can be promoted by the returned refrigerant. On the other hand, the arrangement of the bypass pipe line 70 shown in FIG. 1 has an advantage that the response speed when the bypass valve 71 is opened can be increased.

  In the present embodiment, when the heat pump device is started, the refrigerant pressure Pin, the heat source hot water temperature Tw on the suction side of the compressor 20, the refrigerant superheat degree ΔTin on the suction side of the compressor 20, and the refrigerant superheat degree on the discharge side of the compressor 20 The bypass valve 71 is controlled to open and close based on at least one of ΔTout and the refrigerant temperature Tin on the suction side of the compressor 20. As a result, it is possible to reliably avoid the liquid back state at the start of the compressor 20 and shorten the start time of the compressor 20.

  Conventionally, there is a bypass line (hot gas bypass) that bypasses the refrigerant from the discharge side to the suction side of the compressor. This bypass line is subject to sudden load fluctuations during normal operation. It has a function to perform capacity control to cope with, and in this embodiment, the bypass pipe line used for reliably avoiding the liquid back state at the time of starting the compressor and shortening the starting time of the compressor It has different functions. Note that, during normal operation, capacity control over a long period of time using a conventional bypass pipe causes a problem that the degree of refrigerant superheating on the compressor suction side increases excessively.

DESCRIPTION OF SYMBOLS 10 Waste heat recovery heat pump apparatus 12 Steam generation part 14 Hot water supply part 16 Heat pump part 18 Control part 18a Start-up operation mode control part 18b Normal operation mode control part 20 Compressor 22 Condenser 24 Expansion mechanism 26 Evaporator 28 Heater 29 Heat source hot water Temperature sensor 30 Water supply path 32 Hot water path 34 Suction pressure sensor 35 Suction temperature sensor 36 Discharge pressure sensor 37 Discharge temperature sensor 38 Inlet temperature sensor 40, 52, 58 Inverter 42 Steam separator 44 Steam supply path 46 Water circulation path 70 Bypass pipe 71 Bypass valve 80 Check valve 81 Flexible piping 100 Bracket LN1, LN2, LN3 Pipe line PT1, PT2, PT3 Connection point

Claims (9)

A compressor that compresses the refrigerant, a condenser that condenses the refrigerant compressed by the compressor, an expansion mechanism that decompresses the refrigerant condensed by the condenser, and an evaporator that recovers heat from the heat source hot water and evaporates the refrigerant A heat pump device having a heat pump cycle in which the two are connected in an annular shape,
The refrigerant has two or more intersections or contact points on the high-pressure side with a saturated gas line and an isentropic line,
A bypass line connecting the discharge side of the compressor and the suction side of the compressor via a bypass valve;
A controller that switches between a start-up operation mode for opening and closing the bypass valve and a normal operation mode for performing a normal operation by closing the bypass valve;
With
The control unit, in the startup operation mode,
The refrigerant pressure on the suction side of the compressor is equal to or higher than the upper limit value, the amount of heat of the heat source hot water is equal to or higher than the upper limit value, the degree of refrigerant superheat on the suction side of the compressor is equal to or higher than the upper limit value, and the refrigerant temperature on the suction side of the compressor is upper limit value Or more, a refrigerant superheat degree on the suction side of the compressor being at least a second set value lower than an upper limit value of the refrigerant superheat degree and a refrigerant pressure being at least a first set value lower than the upper limit value of the refrigerant pressure. When the condition is satisfied, the bypass valve is closed and controlled,
The heat pump device according to claim 1, wherein the normal operation mode is entered when the bypass valve is in a closed state and the refrigerant superheating degree on the discharge side of the compressor is equal to or higher than an upper limit value.   The control unit is configured such that the refrigerant pressure on the suction side of the compressor is less than a lower limit value, the amount of heat of the heat source hot water is less than a lower limit value, the degree of refrigerant superheat on the suction side of the compressor is less than a lower limit value, and the discharge side of the compressor 2. The bypass valve is controlled to open when at least one of the following conditions is satisfied: the refrigerant superheat degree is less than a lower limit value and the refrigerant temperature on the suction side of the compressor is less than a lower limit value. Heat pump device.   The heat pump device according to claim 1, wherein the control unit performs the opening / closing control by controlling an opening degree of the bypass valve. The diameter of the bypass line is smaller than the diameter of the pipe between the compressor and the condenser,
Interposing flexible piping in the piping between the compressor and the compressor discharge side connection point of the bypass line,
The heat pump device according to any one of claims 1 to 3, wherein a downstream end portion of the flexible pipe is fixed by a bracket. A check valve is provided between the compressor discharge side connection point and the condenser,
The heat pump device according to claim 4, wherein the check valve is fixed by a bracket.   The heat pump apparatus according to claim 4 or 5, wherein the flexible pipe is arranged to be bendable corresponding to a vibration direction of the compressor. The heat pump device according to any one of claims 1 to 6, wherein a compressor suction side connection point of the bypass pipe is between the evaporator and the expansion mechanism. The heat pump device according to any one of claims 1 to 6, wherein a compressor suction side connection point of the bypass pipe is between the compressor and the evaporator. The heat pump device according to claim 8, wherein the compressor suction side connection point of the bypass pipe is upstream of a temperature detection unit that detects a refrigerant temperature on the compressor suction side .

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