JP2008039335A - Heat pump defrosting circuit, heat pump water heater, and defrosting method for heat pump water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To implement an efficient and short defrosting operation by opening and closing a defrosting valve appropriately during the defrosting operation. <P>SOLUTION: A heat pump defrosting circuit connects a compressor 2, a gas cooler 3, an expansion valve 6 and an evaporator 7 in series with refrigerant piping 10 and 11, and connects a refrigerant piping point between the compressor and the gas cooler and a refrigerant piping point between the expansion valve and the evaporator with defrosting piping 23 having the defrosting valve 22. In a defrosting operation, the opening/closing of the defrosting valve is controlled in accordance with the discharge pressure and discharge refrigerant temperature of the compressor without an operation stop of the compressor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a defrost circuit for a heat pump, a heat pump type water heater provided with the circuit, and a defrost method in the heat pump type water heater.

  The heat pump type hot water heater includes a refrigerant cycle and a hot water supply cycle. In the refrigerant cycle, a compressor, a gas cooler, an expansion valve, and an evaporator are sequentially connected by a refrigerant pipe. A defrost valve is provided in the middle of the refrigerant pipe between the compressor and the gas cooler and in the refrigerant pipe between the expansion valve and the evaporator. It is the structure which defrosts by connecting with the defrost piping which has, and letting the refrigerant | coolant discharged from the said compressor pass through the said evaporator via defrost piping.

  The hot water supply cycle includes a hot water storage tank (hot water supply tank) and a circulation path, and a water circulation pump and a heat exchange path are interposed in the circulation path.

When the outside air temperature is low, the evaporator may be frosted and the capacity may be reduced. For this reason, in this kind of heat pump type hot water heater, a defrosting operation that removes frost formation is enabled. That is, the defrost operation which supplies the high-temperature discharge gas from a compressor directly to an evaporator is enabled (for example, refer patent document 1).
JP 2002-310519 A

  In the defrost operation, the high-temperature discharge gas from the compressor is supplied directly to the evaporator via the defrost pipe without passing through the refrigerant pipe having the expansion valve. The pressure and temperature of the refrigerant will decrease. For this reason, there was a problem that the defrost effect was lowered and it took a long time to operate the defrost.

  It is an object of the present invention to provide a heat pump defrost circuit and a heat pump type hot water heater that can perform defrost operation efficiently and in a short time by controlling opening and closing of the defrost valve during the defrost operation.

  In order to solve the above-described problems, the present invention was made as a defrost circuit for a heat pump, a heat pump hot water heater, and a defrost method in a heat pump hot water heater. The defrost circuit for a heat pump of the present invention includes a compressor, a gas cooler, an expansion A valve and an evaporator are sequentially connected by a refrigerant pipe, and the refrigerant pipe halfway between the compressor and the gas cooler and the refrigerant pipe halfway between the expansion valve and the evaporator have a defrost valve and the compression A defrost circuit for a heat pump, which is connected by a defrost pipe through which the refrigerant discharged from the machine passes through the evaporator and performs a defrost operation without stopping the operation of the compressor even when the defrost valve is closed, During operation, at least the discharge pressure of the compressor and the discharge side refrigerant temperature On the other hand in that the control device is provided for opening and closing the defrost valve based on.

  The defrost circuit for heat pump of the present invention can control the opening and closing of the defrost valve during the defrost operation, and can supply a predetermined pressure and temperature of refrigerant to the evaporator, so that the defrost operation can be performed efficiently and in a short time. It should be noted that at least one of the discharge pressure and the discharge side refrigerant temperature of the compressor is meant to include either the discharge pressure or the discharge side refrigerant temperature, or both the discharge pressure and the discharge side refrigerant temperature.

  In the heat pump defrost circuit of the present invention, the defrost valve is not opened, the expansion valve is opened at a set opening, and the refrigerant is circulated by the compressor within the time set from the start of the defrost.

  The heat pump type hot water supply apparatus of the present invention is provided with a defrost circuit for heat pump.

  In the defrost method in the heat pump type hot water heater of the present invention, the refrigerant pipe halfway between the compressor and the gas cooler and the refrigerant pipe halfway between the expansion valve and the evaporator have a defrost valve and are discharged from the compressor. A defrost method in a heat pump in which a refrigerant is connected to the evaporator through a defrost pipe and the defrost operation is performed without stopping the operation of the compressor even when the defrost valve is closed, the discharge pressure of the compressor and The defrost valve is closed based on the discharge side refrigerant temperature, and the defrost valve is opened based on the discharge pressure of the compressor or the discharge side refrigerant temperature.

  The present invention controls the opening and closing of the defrost valve during the defrost operation, so that the defrost operation can be performed efficiently and in a short time.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 to 3 show an embodiment of a heat pump type water heater according to the present invention. FIG. 1 is a refrigeration cycle diagram of a heat pump water heater. In the figure, the refrigerant cycle 1 includes a compressor 2, a gas cooler 3, a refrigerant heat exchanger 5, an expansion valve 6, and an evaporator (air heat exchanger). 7 and an accumulator 8.

  The compressor 2, the gas cooler 3, the refrigerant heat exchanger 5, the expansion valve 6, and the evaporator 7 are sequentially connected by refrigerant pipes 10, 11, 12, and 13. In the refrigerant heat exchanger 5, the high pressure side refrigerant pipe 11 and the low pressure are connected. A basic series of refrigerant cycles is configured by exchanging counter-current heat in the side refrigerant pipe 12 and arranging the accumulator 8 in the low-pressure side refrigerant pipes 12 and 13. The evaporator 7 is provided with an evaporator fan 15 for adjusting the capacity of the evaporator 7.

  The gas cooler 3 is a heat exchanger (counter flow type gas cooler) in which a water supply pipe 19 extending from a water inlet 17 to a hot water supply outlet 18 is inserted. And the hot water supply circuit is comprised by installing the water pump 20 and the proportional valve (water control valve) 21 which send the water supply water for heat exchange in the water supply piping 19 at the water inlet side.

  The middle of the refrigerant pipe 10 between the compressor 2 and the gas cooler 3 and the middle of the refrigerant pipe 11 between the expansion valve 6 and the evaporator 7 are connected by a defrost pipe 23 having a defrost valve 22. The defrost valve 22 is a valve that opens when frost is melted by the high-temperature discharge gas (high-pressure high-temperature refrigerant) from the compressor 2 when frost adheres to the evaporator 7. By opening the defrost valve 22, the refrigerant from the compressor 2 can be directly supplied to the evaporator 7, thereby enabling a defrost operation for removing the frost of the evaporator 7. The refrigerant cycle 1 can perform a normal hot water heating operation and a defrost operation.

  In FIG. 1, reference numeral 25 denotes an outside air temperature detection thermistor (outside air temperature detection temperature sensor) for detecting the outside air temperature (equipment atmosphere temperature). An evaporator thermistor (evaporator inlet temperature sensor) 26 for detecting the refrigerant temperature on the inlet side of the evaporator is provided in the vicinity of the evaporator 7 of the refrigerant pipe 11. A compressor inlet thermistor (compressor inlet temperature sensor) 27 for detecting the temperature of the refrigerant sucked into the compressor 2 is provided near the compressor 2 in the refrigerant pipe 13.

  In the vicinity of the compressor 2 of the refrigerant pipe 10, a compressor discharge port thermistor (compressor discharge port temperature sensor) 28 for detecting the temperature of the refrigerant discharged from the compressor 2, and the compressor 2 discharges. And a compressor discharge pressure sensor 29 for detecting the pressure of the refrigerant.

  As shown in FIG. 2, the control unit of the heat pump type hot water heater includes the temperature sensors 25, 26, 27, and 28, a compressor discharge pressure sensor 29, a control device 30, and the like. Then, data of the temperature sensors 25, 26, 27, 28 and the compressor discharge pressure sensor 29 are input to the control device 30. The control device 30 transmits control signals to the defrost valve 22, the compressor 2, the evaporator fan 15, the water pump 20, the water control valve 21, and the like based on the input data and the like, and the defrost valve 22 and the like. Are to be activated respectively.

  According to the heat pump type water heater configured as described above, when the compressor 2 and the water pump 20 are operated with the defrost valve 22 closed, the refrigerant from the compressor 2 is indicated by an arrow A in FIG. As described above, the refrigerant pipes 10, 11, and 12 flow. The feed water flowing through the feed water pipe 19 is heated by the gas cooler 3 and stored in a hot water storage tank (not shown).

  Next, the case where defrost operation is performed will be described. This defrosting operation is started by supplying the refrigerant to the evaporator 7 with the water pump 20 stopped. In the defrost operation, the refrigerant from the compressor 2 flows through the refrigerant pipe 10, the defrost pipe 23, the refrigerant pipe 12, and the refrigerant pipe 13 as shown by an arrow B in FIG. Defrost operation control will be described with reference to the flowchart of FIG.

  First, it is determined whether or not the condition of defrosting operation (defrosting operation = ON) is satisfied (S1). If defrost operation = ON is not established, it is determined whether or not each value of ta, te, and ta-te has reached the defrost operation set value (S2). Here, ta represents the outside air temperature (° C.) detected by the outside air temperature detection temperature sensor 25, te represents the evaporator inlet side refrigerant temperature (° C.) detected by the evaporator inlet temperature sensor 26, and ta-te represents the outside air temperature. And the difference between the refrigerant temperature on the inlet side of the evaporator.

  When the control device 30 determines that the defrost operation is to be performed based on the data ta, te, and ta-te, the defrost timer count is started (S3), the water pump 20 is turned off, and the water control valve is turned off. 21 is closed (S4). Furthermore, it transfers to S5 and defrost driving | operation is performed. At the initial operation of the defrost operation, the evaporator fan 15 is stopped and the opening of the expansion valve 6 is reduced to a predetermined opening. Here, the opening degree of the expansion valve 6 is reduced to a predetermined opening degree so that the refrigerant flows slightly from the expansion valve 6 through the refrigerant pipe 11 and the high-pressure and high-temperature refrigerant suddenly passes through the defrost pipe 23. This is to prevent being supplied to the evaporator 7. Then, after a predetermined time has elapsed, the defrost valve 22 is opened and the expansion valve 6 is closed, and the process proceeds to step S1. In step S2, if the condition is not satisfied, the defrost operation is not performed.

  If it is determined in step S1 that the defrost operation = ON condition is satisfied, the process proceeds to step S6, where the condition of SUC> frost melting set temperature is satisfied, or the maximum defrost operation time has elapsed. It is determined whether or not (S6). Here, SUC is the compressor inlet temperature (° C.) detected by the compressor inlet temperature sensor 27.

  If at least one of the conditions is satisfied, the defrost operation is stopped (defrost operation = OFF), and the defrost timer is reset (S7). Further, the water pump 20 and the evaporator fan 15 are turned on, the defrost valve 22 is closed and the expansion valve 7 is opened (S8), and the water control valve 21 is controlled and opened to perform a hot water supply operation (S9).

  If it is determined in step S6 that none of the conditions is satisfied, the process proceeds to step S10, and it is determined whether or not the condition of high pressure> abnormal high pressure set value is satisfied. The high pressure means the compressor discharge pressure (MPa) detected by the compressor discharge pressure sensor 29. The abnormal high pressure set value refers to a set high pressure at which the compressor discharge pressure refrigerant is determined to be abnormal.

  When the condition of step S10 is satisfied, the expansion valve 6 is opened by a predetermined opening and depressurized to a predetermined pressure (S11). If the condition of step S10 is not satisfied, it is determined whether the conditions of high pressure <valve closing set pressure and HG <valve operation set temperature are satisfied without opening the expansion valve 7 (S12). HG is the compressor discharge port temperature (compressor discharge refrigerant temperature ° C.) detected by the compressor discharge port temperature sensor 28. If the condition of step S12 is satisfied, the defrost valve 22 is closed and the defrost timer is reset (S13).

  If the condition of step S12 is not satisfied, it is determined whether one of the conditions of high pressure> valve opening set pressure or HG> valve operation set temperature is satisfied (S14). If this condition is satisfied, the defrost valve 22 is opened and the process proceeds to step S1 (S15). If not established, the process proceeds to step S1 with the defrost valve 22 closed.

  During the defrosting operation, the processing procedure from step S1 to step S15 is repeated, and when the pressure and temperature of the refrigerant sent from the compressor 2 during the defrosting operation are reduced, the defrosting valve is operated by a signal from the control device 30. 22 is closed for a predetermined time.

  At this time, the refrigerant in the refrigerant pipe 10 between the compressor 2 and the expansion valve 6 and the defrost pipe 23 between the refrigerant pipe 10 and the defrost valve 22 can be raised to a predetermined pressure and a predetermined temperature. When the refrigerant reaches a predetermined pressure or a predetermined temperature, the control device 30 opens the defrost valve 22, so that the refrigerant having a high temperature flows into the evaporator 7.

  As described above, during the defrost operation, the defrost valve 22 is opened and closed to control the pressure and temperature of the refrigerant supplied to the evaporator 7, so that the refrigerant having the optimum temperature can be supplied to the evaporator 7. Moreover, the refrigerant pipe between the compressor 2 and the expansion valve 6 includes the pipe of the gas cooler 3 and the refrigerant in the refrigerant pipe is also supplied to the evaporator 7, so that the defrosting operation can be performed quickly and efficiently.

It is the schematic of the refrigerant cycle in the heat pump type water heater of this invention. It is a simplified block diagram of the same refrigerant cycle. It is a flowchart which shows the defrost driving | operation in the heat pump type water heater of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerant cycle 2 Compressor 3 Gas cooler 6 Expansion valve 7 Evaporator 10 Refrigerant pipe 11 Refrigerant pipe 12 Refrigerant pipe 13 Refrigerant pipe 20 Water pump 21 Water control valve 22 Defrost valve 23 Defrost pipe 30 Controller

Claims (4)

A compressor, a gas cooler, an expansion valve, and an evaporator are sequentially connected by a refrigerant pipe, and the refrigerant pipe halfway between the compressor and the gas cooler and the refrigerant pipe halfway between the expansion valve and the evaporator are defrost valves. And a defrost circuit for a heat pump that is defrosted without stopping the operation of the compressor even when the defrost valve is closed, connected by a defrost pipe that passes the refrigerant discharged from the compressor through the evaporator Because
A defrost circuit for a heat pump, comprising a control device that opens and closes the defrost valve based on at least one of a discharge pressure of the compressor and a discharge side refrigerant temperature during the defrost operation.   2. The defrost circuit for a heat pump according to claim 1, wherein the defrost valve is not opened, the expansion valve is opened at a set opening, and the refrigerant is circulated by a compressor within a time set from the start of defrost.   A heat pump type hot water heater comprising the heat pump defrost circuit according to claim 1 or 2. The refrigerant pipe halfway between the compressor and the gas cooler and the refrigerant pipe halfway between the expansion valve and the evaporator are connected by a defrost pipe having a defrost valve and passing the refrigerant discharged from the compressor through the evaporator. And in the state where the defrost valve is closed, it is a defrost method in a heat pump that performs defrost operation without stopping operation of the compressor,
A defrost in a heat pump type hot water heater, wherein the defrost valve is closed based on a discharge pressure and a discharge side refrigerant temperature of the compressor, and the defrost valve is opened based on a discharge pressure or a discharge side refrigerant temperature of the compressor. Method.

Images