JP2008121923A - Heat pump water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain reduction in thermal loss (=improvement in defrosting efficiency) in defrosting operation while avoiding increase in complication or cost of a system. <P>SOLUTION: In the heat pump water heater, the temperature of water within a hot water passage 22 of a hot water supply heat exchanger 2 is raised prior to starting of defrosting operation. According to this, the thermal loss during distribution of refrigerant discharged from a compressor 1 in a refrigerant passage 21 of the heat exchanger 2. Consequently, the refrigerant discharged from the compressor 1 reaches an air heat exchanger 4 without large drop of temperature, and the time of defrosting the air heat exchanger 4 can be shortened. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat pump type hot water heater that stores water boiled by a heat pump in a hot water storage tank.

  In the conventional heat pump type hot water heater, when the outlet side refrigerant temperature of the air heat exchanger is lowered to a predetermined temperature, the defrosting operation is performed to defrost the air heat exchanger. The defrosting operation is an operation of removing frost from the air heat exchanger using a high-temperature refrigerant discharged from the compressor, but a hot water supply heat exchanger exists between the compressor and the air heat exchanger. For this reason, a reduction in defrosting efficiency due to heat loss in the heat exchanger for hot water supply has been a problem.

Therefore, the refrigerant discharged from the compressor bypasses the hot water heat exchanger during the defrosting operation and flows to the air heat exchanger (see, for example, Patent Document 1), or stops the water circulation pump during the defrosting operation. In addition, by setting the expansion valve on the open side compared to the normal operation, a method (for example, see Patent Document 2) for reducing the heat loss between the compressor and the air heat exchanger as much as possible has been devised. .
JP 2001-108256 A JP 2001-82802 A

  However, the former has a problem in that the system is complicated and the cost is increased by adding functional parts (refrigerant piping and bypass valve) for bypassing the hot water heat exchanger. Moreover, the latter had the subject by which the loss by the low temperature water which has accumulated in the heat exchanger for hot water supply is not improved.

  In view of the above points, an object of the present invention is to reduce heat loss during defrosting operation (= improvement of defrosting efficiency) while avoiding complication and cost increase of the system.

  The present invention is characterized in that, in the heat pump type hot water heater, before the defrosting operation is started, a defrost preparation operation for increasing the temperature of water in the hot water supply heat exchanger (2) is performed.

  In this way, since the water temperature in the hot water supply heat exchanger (2) rises at the start of the defrosting operation, the refrigerant discharged from the compressor (1) flows through the hot water supply heat exchanger (2). The heat loss at the time of doing is reduced. Moreover, the functional component for bypassing the heat exchanger for hot water supply (2) is unnecessary, and the complexity and cost increase of the system can be avoided.

  In this case, a bypass pipe (130) and a water circulation pump (8) for returning the water flowing out from the hot water supply heat exchanger (2) to the hot water supply heat exchanger (2) by bypassing the hot water storage tank (6) are provided. During the frost preparation operation, the water exchanged with the refrigerant in the hot water supply heat exchanger (2) can be returned to the hot water supply heat exchanger (2) through the bypass pipe (130).

  If it does in this way, the water temperature in the hot water supply heat exchanger (2) can be raised more rapidly than the case where the hot water storage tank (6) is not bypassed.

  In addition, a water circulation pump (8) for circulating water between the hot water storage tank (6) and the hot water supply heat exchanger (2) is provided, and the water circulation pump (8) is stopped during the defrost preparation operation. Then, heat exchange between the water staying in the hot water supply heat exchanger (2) and the refrigerant can be performed.

  If it does in this way, the water temperature in the heat exchanger for hot water supply (2) can be raised more rapidly than the case where water is circulated.

  The defrosting operation can be started when the temperature of the water flowing into the hot water supply heat exchanger (2) reaches a predetermined temperature.

  In this way, at the start of the defrosting operation, it can be confirmed that the water temperature in the hot water supply heat exchanger (2) has risen reliably, and the loss of unnecessary heating of the water in the piping other than the heat exchanger is reduced. Therefore, the heat loss when the refrigerant discharged from the compressor (1) flows through the hot water supply heat exchanger (2) is reliably reduced.

  In addition, the code | symbol in the bracket | parenthesis of each means described in a claim and this column shows the correspondence with the specific means as described in embodiment mentioned later.

  An embodiment of the present invention will be described. FIG. 1 is a diagram illustrating an overall configuration of a heat pump type hot water heater according to the present embodiment.

  The heat pump type hot water heater includes a heat pump H, a hot water circuit W, a control device E, and the like.

  The heat pump H is configured by connecting the compressor 1, the refrigerant flow path 21 of the hot water supply heat exchanger 2, the expansion valve 3, the air heat exchanger 4, and the accumulator 5 in a ring shape with the refrigerant pipe 100, and the air heat The exchanger 4 is provided with an outdoor fan 41 that blows outside air.

The compressor 1 is driven by an electric motor (not shown), and compresses and discharges the gas-phase refrigerant sucked from the accumulator 5. The hot water supply heat exchanger 2 exchanges heat between the refrigerant discharged from the compressor 1 flowing through the refrigerant flow path 21 and the water flowing through the hot water flow path 22. Thereby, the water which flows through the hot water flow path 22 of the heat exchanger 2 for hot water supply is heated. The hot water supply heat exchanger 2 is configured such that the flow direction of the refrigerant and the flow direction of the liquid face each other. The expansion valve 3 allows the refrigerant flowing out from the refrigerant flow path 21 of the hot water supply heat exchanger 2 to flow. The valve body is driven by a motor (not shown) to control the valve opening degree. The air heat exchanger 4 evaporates the refrigerant that has passed through the expansion valve 3 by exchanging heat with the outside air blown by the outdoor fan 41. The accumulator 5 separates the refrigerant that has passed through the air heat exchanger 4 into gas-phase refrigerant and liquid refrigerant.

  The hot water circuit W includes a hot water storage tank 6 that stores water (hot water) heated by the hot water supply heat exchanger 2 and a hot water flow path 22 of the hot water supply heat exchanger 2. A hot water outlet 61 and a hot water flow path 22 provided at the lower part of the hot water storage tank 6 are connected by a first hot water pipe 110, and a hot water inlet 62 and a hot water flow path 22 provided at the upper part of the hot water storage tank 6 are connected by a second hot water pipe. Connected at 120.

  The first hot water pipe 110 and the second hot water pipe 120 are connected by a bypass pipe 130. An electric bypass valve 7 for switching the flow path is disposed at a connection portion between the first hot water pipe 110 and the bypass pipe 130. A water circulation pump 8 that is driven by an electric motor (not shown) to generate a flow of water is disposed between the hot water flow path 22 and the bypass valve 7 in the first hot water pipe 110.

  At the first switching position of the bypass valve 7, water circulates between the hot water storage tank 6 and the hot water flow path 22 with the operation of the water circulation pump 8. More specifically, the water in the hot water storage tank 6 flows into the hot water passage 22 from the hot water outlet 61 via the first hot water pipe 110, passes through the hot water passage 22, and then passes through the second hot water pipe 120. The water is returned from the inlet 62 into the hot water storage tank 6.

  At the second switching position of the bypass valve 7, the water that has flowed out of the hot water flow path 22 along with the operation of the water circulation pump 8 flows into the bypass pipe 130 via the second hot water pipe 120, and further the first hot water pipe 110. Is returned to the hot water flow path 22. In other words, the water that has flowed out of the hot water flow path 22 bypasses the hot water storage tank 6 and is returned to the hot water flow path 22.

  The control device E as the control means is composed of a microcomputer, a memory (storage means), a counter, and peripheral circuits. The control device E receives an output signal from the water temperature sensor 91 that detects the water temperature on the inlet side of the hot water flow path 22, an output signal from the refrigerant temperature sensor 92 that detects the refrigerant temperature on the outlet side of the air heat exchanger 4, and the like. Then, the control device E controls the compressor 1, the expansion valve 3, the outdoor fan 41, the bypass valve 7, the water circulation pump 8, and the like based on the output signals and the like.

  Next, the operation of the water heater of this embodiment will be described. FIG. 2 is a time chart showing an operation example of the water heater of the present embodiment.

  As shown in FIG. 2, during the heating operation, the compressor 1, the outdoor fan 41, and the water circulation pump 8 are operated. Further, the bypass valve 7 is controlled to the first switching position, and water circulates between the hot water storage tank 6 and the hot water passage 22. The boiling operation is well known and will not be described in detail.

  If the refrigerant temperature at the outlet side of the air heat exchanger 4 detected by the refrigerant temperature sensor 92 decreases to the first predetermined temperature (for example, −5 ° C.) during the boiling operation, the defrosting preparation is started from the boiling operation. Switch to driving.

  In this defrost preparation operation, the compressor 1 and the water circulation pump 8 are operated, and the outdoor fan 41 is stopped. In this connection, the refrigerant flow rate is increased by increasing the rotational speed of the compressor 1 compared to that during the boiling operation.

  Further, the bypass valve 7 is controlled to the second switching position, and the hot water heated by heat exchange with the refrigerant in the hot water supply heat exchanger 2 flows out of the hot water flow path 22, and the second hot water pipe 120, bypass It is returned to the hot water flow path 22 via the pipe 130 and the first hot water pipe 110. Thereby, all the water in the warm water flow path 22 is made high temperature. As described above, by bypassing the hot water storage tank 6 and circulating the water, the water temperature in the hot water passage 22 can be increased more quickly than when the hot water storage tank 6 is not bypassed.

  Then, when the water temperature on the inlet side of the hot water passage 22 detected by the water temperature sensor 91 reaches the second predetermined temperature, the defrost preparation operation is switched to the defrost operation.

  In this defrosting operation, the rotational speed of the compressor 1 is made higher than that during the defrosting preparation operation, and the refrigerant flow rate is further increased. Further, the water circulation pump 8 and the outdoor fan 41 are stopped. Thereby, the frost adhering to the air heat exchanger 4 is melted by the heat of the refrigerant.

  Here, at the start of the defrosting operation, the water temperature in the hot water passage 22 is increased by the defrosting preparation operation, so that the refrigerant discharged from the compressor 1 flows through the refrigerant passage 21 of the hot water supply heat exchanger 2. The heat loss at the time of doing is reduced. Therefore, the refrigerant discharged from the compressor 1 reaches the air heat exchanger 4 without greatly reducing the temperature, and the defrosting time of the air heat exchanger 4 is shortened.

(Other embodiments)
In the above embodiment, the water circulation pump 8 is operated and water is circulated during the defrost preparation operation. However, the water circulation pump 8 is stopped during the defrost preparation operation and stays in the hot water flow path 22. Heat exchange between the water and the refrigerant may be performed.

  In addition, when the hot water boiled during the defrost preparation operation is reintroduced into the hot water passage 22 via the bypass pipe 130, the water that was near the outlet of the hot water passage 22 just before the start of the defrost preparation operation is just bypassed. The operation time for raising the water temperature in the hot water channel 22 can be shortened by stopping the water circulation pump 8 at a timing when the circuit including the pipe 130 goes around and is introduced into the hot water channel 22 again. it can. For detection of this timing, the water temperature on the inlet side of the hot water flow path 22 detected by the water temperature sensor 91 is used.

It is a figure which shows the whole structure of the heat pump type hot water heater which concerns on one Embodiment of this invention. It is a time chart which shows the operation example of the water heater of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Heat exchanger for hot water supply, 4 ... Air heat exchanger, 6 ... Hot water storage tank,
E ... Control device (control means).

Claims (4)

A compressor (1) that compresses the refrigerant, a heat exchanger (2) for hot water supply that heats water by performing heat exchange between the refrigerant discharged from the compressor (1) and water, and the heat exchange for hot water supply A hot water storage tank (6) for storing water heated in the vessel (2), an air heat exchanger (4) for exchanging heat between the refrigerant and air that has passed through the hot water supply heat exchanger (2), In a heat pump type water heater provided with a control means (E) for performing a defrosting operation for melting frost adhering to the air heat exchanger (4) by the heat of the refrigerant,
The said control means (E) performs the defrost preparation operation which raises the temperature of the water in the said hot water supply heat exchanger (2), before starting the said defrost operation, The heat pump type water heater characterized by the above-mentioned . A bypass pipe (130) and a water circulation pump (8) for returning the water flowing out from the hot water supply heat exchanger (2) to the hot water supply heat exchanger (2) by bypassing the hot water storage tank (6), In the defrosting preparation operation, the control means (E) exchanges water that has exchanged heat with the refrigerant in the hot water supply heat exchanger (2) via the bypass pipe (130). It returns to 2), The heat pump type hot water heater of Claim 1 characterized by the above-mentioned. A water circulation pump (8) for circulating water between the hot water storage tank (6) and the hot water supply heat exchanger (2) is provided, and the control means (E) performs the water circulation during the defrost preparation operation. The heat pump type hot water supply device according to claim 1, wherein heat exchange between water and refrigerant staying in the hot water supply heat exchanger (2) is performed in a state where the pump (8) is stopped. A water temperature sensor (91) for detecting the temperature of water flowing into the hot water supply heat exchanger (2) is provided, and the control means (E) is a temperature detected by the water temperature sensor (91) during the defrost preparation operation. The heat pump hot water heater according to any one of claims 1 to 3, wherein the defrosting operation is started when the temperature reaches a predetermined temperature.

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