CN204301351U - Heat pump-type hot-water supply device - Google Patents

Abstract

A highly reliable heat pump water heater capable of preventing fatigue damage to the air heat exchanger even when the water temperature raising operation and the air heat exchanger defrosting operation are repeated. The heat pump hot water heater is configured to be able to switch at least between the heating operation and the defrosting operation, and includes: a main circuit, during the heating operation, a compressor, a flow switching valve, and a water circuit for exchanging heat between the water and the refrigerant. a heat exchanger, a first flow regulating valve, and an air heat exchanger for exchanging heat between air and refrigerant are connected in sequence; Or the bypass pipe through which the two-phase refrigerant flows to the suction side of the compressor, and the second flow rate adjustment valve provided in the bypass pipe detect the water temperature of the water supplied to the water heat exchanger during the warm-up operation, During the defrosting operation, when the water temperature is equal to or higher than the reference water temperature, the opening degree of the second flow rate adjustment valve is increased from the reference opening degree.

Description

Heat pump hot water supply

technical field

The utility model relates to a heat pump type hot water supplier using reverse cycle operation for defrosting operation.

Background technique

Existing heat pump hot water suppliers use a water heat exchanger as a condenser and an air heat exchanger as an evaporator. Since the water temperature rise operation is performed when the outside air temperature is low, if the refrigerant flowing through the air heat exchanger serving as the evaporator falls below 0°C, frost will be formed on the surface of the air heat exchanger, and the evaporation performance will deteriorate. Unable to perform. In order to maintain the temperature raising capability, it is necessary to perform a defrosting operation at a timing corresponding to the frosting amount.

As a general method of performing the defrosting operation, there is a method of reverse cycle operation. Reverse cycle operation is to switch the flow of refrigerant relative to the air heat exchanger so that the air heat exchanger becomes a condenser, thereby allowing high-temperature and high-pressure refrigerant to flow into the air heat exchanger, and the air heat exchanger The surface temperature rises to melt the frost generated in the air heat exchanger (see Patent Document 1).

This reverse cycle operation is not limited to the defrosting operation for the heat pump water heater, but is also a common defrosting operation for other heat pump circuits such as heat pump air conditioners.

Patent Document 1: Japanese Patent Laid-Open No. 2002-243276 (see paragraph [0077], etc.)

In the case of a heat pump water heater, although the water heat exchanger functions as an evaporator during the defrosting operation, the heat of the hot water in the hot water storage tank is used as a heat source for the evaporator.

The hot water is usually supplied to the water heat exchanger at a temperature in the range of 10°C to 60°C. On the other hand, during the defrosting operation, the refrigerant supplied to the water heat exchanger is below 0°C. As the air temperature falls below -20°C, the temperature difference between the water and the refrigerant increases, and the refrigerant may pass through the water heat exchanger as a gaseous refrigerant having a degree of superheat of 20°C or higher.

The high-superheated gaseous refrigerant discharged from the water heat exchanger is sucked into the compressor and compressed to become a high-pressure, high-temperature gaseous refrigerant. However, when it is sucked into the compressor, due to its large superheated Therefore, the temperature of the gaseous refrigerant discharged from the compressor becomes high and is supplied to the air heat exchanger.

In this way, since the refrigerant receives a large heat supply from the hot water by passing through the water heat exchanger, it has the advantage of shortening the defrosting time by about several minutes compared with the heat pump circuit of the air heat source.

However, when the reverse cycle operation method is used in the defrosting operation of the heat pump water heater, there are the following problems.

For the air heat exchanger that becomes low temperature during the water temperature raising operation, if the heat pump water heater switches to the defrosting operation, the high-temperature gaseous refrigerant will flow into the air heat exchanger, and the temperature of the heat exchanger will greatly increase. rise. For example, when the defrosting operation is performed when the temperature of the outside air is 2°C, a temperature difference of 40°C or more occurs in the air heat exchanger.

When such a large temperature change occurs in the air heat exchanger, there is a problem that thermal stress is repeatedly applied to metal connection parts and the like, eventually leading to fatigue failure.

Therefore, by switching between the warm-up operation and the defrosting operation, the temperature variation of the refrigerant circuit components is reduced, thereby improving the reliability of the heat exchanger.

Utility model content

This utility model was produced in response to the above-mentioned problems, and its purpose is to provide a heat pump water heater with high reliability. Frost operation can also prevent fatigue damage of the air heat exchanger.

The heat pump hot water supplier of the present invention is configured to be able to switch at least between the heating operation and the defrosting operation, and is provided with: , a water heat exchanger for exchanging heat between water and refrigerant, a first flow regulating valve, and an air heat exchanger for exchanging heat between air and refrigerant to connect these components in sequence; and a bypass circuit, the bypass The circuit is configured to include a bypass pipe and a second flow rate adjustment valve, wherein the bypass pipe is connected to the suction side of the compressor and diverts the liquid refrigerant or the two-phase refrigerant to the suction side of the compressor, and the second flow rate The adjustment valve is provided in the bypass pipe, and the heat pump water heater is characterized in that it detects the water temperature of the water supplied to the water heat exchanger during the warm-up operation, and detects the temperature of the water supplied to the water heat exchanger during the defrosting operation. When the water temperature is equal to or higher than the reference water temperature, the opening degree of the second flow rate adjustment valve is increased from the reference opening degree.

According to the heat pump water heater of the present invention, even if the operation of raising the temperature of water and the operation of defrosting the air heat exchanger are repeated, fatigue damage of the air heat exchanger can be prevented, and a highly reliable water heater can be provided. Heat pump hot water supply.

Preferably, the heat pump water heater is configured to maintain the opening degree of the second flow rate adjustment valve at the reference opening degree when the water temperature is lower than a reference water temperature during the defrosting operation.

Preferably, the heat pump water heater is configured to detect the evaporation temperature of the refrigerant in the air heat exchanger during the heating operation, and detect the evaporation temperature of the refrigerant in the air heat exchanger during the defrosting operation. When the temperature is equal to or lower than the reference evaporation temperature, the opening degree of the second flow rate adjustment valve is increased from the reference opening degree.

Preferably, the heat pump water heater is configured to detect the evaporation temperature of the refrigerant in the air heat exchanger during the heating operation, and detect the evaporation temperature of the refrigerant in the air heat exchanger during the defrosting operation. When the temperature is higher than the reference evaporation temperature, the opening degree of the second flow adjustment valve is maintained at the reference opening degree.

Preferably, the heat pump water heater is configured such that during the defrosting operation, the opening degree of the first flow rate adjustment valve is fully opened.

Preferably, the bypass pipe connects between the first flow rate adjustment valve and the air heat exchanger, and a suction side of the compressor.

Preferably, a receiver is provided between the first flow adjustment valve and the air heat exchanger, and a third flow adjustment valve is provided between the receiver and the air heat exchanger, so The bypass pipe connects between the first flow rate adjustment valve and the receiver, and to a suction side of the compressor.

Preferably, an accumulator is provided between the flow path switching valve and the compressor, and the bypass piping connects between the first flow rate adjustment valve and the air heat exchanger, and the accumulator. suction side connection.

Description of drawings

FIG. 1 is a refrigerant circuit diagram of a heat pump water heater according to Embodiment 1. FIG.

FIG. 2 is a diagram showing the flow of refrigerant when the air heat exchanger 5 according to Embodiment 1 performs a temperature raising operation.

FIG. 3 is a diagram showing the flow of refrigerant when the air heat exchanger 5 according to Embodiment 1 performs a defrosting operation.

4 is a Mollier diagram when the second electronic expansion valve is closed during the defrosting operation according to Embodiment 1. FIG.

5 is a Mollier diagram when the second electronic expansion valve is opened during the defrosting operation according to Embodiment 1. FIG.

FIG. 6 is a diagram showing the air heat exchanger (header portion) when the second electronic expansion valve is opened and when the second electronic expansion valve is closed during the defrosting operation according to Embodiment 1. FIG. Comparison graph of temperature changes.

7 is a control flowchart of the first electronic expansion valve and the second electronic expansion valve during the defrosting operation according to the first embodiment.

8 is a diagram showing correction of the opening degree of the second electronic expansion valve during the defrosting operation according to Embodiment 1. FIG.

9 is a flow chart of controlling the second electronic expansion valve based on the evaporation temperature of the air heat exchanger 5 during warm-up operation according to the second embodiment.

10 is a diagram showing correction of the opening degree of the second electronic expansion valve during the defrosting operation according to the second embodiment.

11 is a refrigerant circuit diagram showing another example of the refrigerant circuit of the heat pump water heater according to Embodiment 1. FIG.

12 is a refrigerant circuit diagram showing another example of the refrigerant circuit of the heat pump water heater according to Embodiment 1. FIG.

Explanation of reference signs:

1...Compressor; 2...Four-way valve (flow switching valve); 3...Water heat exchanger; 3a...Temperature detector; 4...First electronic expansion valve (first flow adjustment valve); 5...Air heat exchange 5a...header; 5b...branch; 5c...splitter; 5d...temperature detector; 6...bypass circuit; 7...second electronic expansion valve (second flow adjustment valve); 10...receiver; 11 ...the third electronic expansion valve; 12...accumulator.

Detailed ways

Hereinafter, the heat pump type water heater which concerns on this invention is demonstrated using drawing.

In addition, the structure etc. which are demonstrated below are an example, and the heat pump type water heater which concerns on this invention is not limited to such a structure etc.

In addition, repeated or similar descriptions will be appropriately simplified or omitted.

Implementation mode 1.

FIG. 1 is a refrigerant circuit diagram of a heat pump water heater according to Embodiment 1. FIG.

FIG. 2 is a diagram showing the flow of refrigerant when the air heat exchanger 5 according to Embodiment 1 performs a temperature raising operation.

FIG. 3 is a diagram showing the flow of refrigerant when the air heat exchanger 5 according to Embodiment 1 performs a defrosting operation.

As shown in Figure 1, the heat pump hot water supplier in Embodiment 1 is mainly composed of: compressor 1, which compresses the refrigerant; During the defrosting operation and the heating operation of the water, the flow direction of the refrigerant in the refrigeration cycle is switched; the water heat exchanger 3 enables heat exchange between the water and the refrigerant; the first electronic expansion valve 4 (equivalent to the utility model The first flow rate adjustment valve), which depressurizes by adjusting the flow rate of the refrigerant; the air heat exchanger 5, which exchanges heat between the external air and the refrigerant; and the bypass circuit 6, by means of which the During the defrosting operation of the air heat exchanger 5 , the refrigerant piping on the upstream side of the first electronic expansion valve 4 is connected to the suction side of the compressor 1 to divide the refrigerant. In addition, the bypass circuit 6 is provided with a second electronic expansion valve 7 (corresponding to the second flow rate adjustment valve of the present invention) for adjusting the flow rate of the flowing refrigerant.

In FIG. 1 , the flow of the refrigerant in the refrigeration cycle during warm-up operation is described by solid lines.

The refrigerant that has become a high-pressure and high-temperature gas in the compressor 1 is discharged from the discharge port of the compressor 1 and sent to the four-way valve 2 . The four-way valve 2 is a valve for switching the refrigerant circuit, and is fixed in such a way that when the heat pump water heater operates as a water heater (water temperature raising operation), 1 The discharged refrigerant is sent to the water heat exchanger 3 for exchanging heat between water and refrigerant.

The refrigerant sent into the water heat exchanger 3 exchanges heat with water in the water heat exchanger 3 . The high-pressure, high-temperature gaseous refrigerant heats the water, thereby condensing and becoming a high-pressure, medium-temperature liquid refrigerant. At the same time, the water flowing into the water heat exchanger 3 receives heat from the refrigerant to raise the temperature of the water. The water heat exchanger 3 functions as a condenser of the refrigeration cycle.

The first electronic expansion valve 4 is controlled so that the subcooling degree of the refrigerant at the outlet of the condensation of the water heat exchanger 3 functioning as a condenser is constant.

When the degree of subcooling is small, the flow rate of the refrigerant is reduced by reducing the opening degree of the first electronic expansion valve 4 , thereby increasing the degree of subcooling. When the degree of subcooling is high, the flow rate of the refrigerant is increased by increasing the opening degree of the first electronic expansion valve 4 , thereby reducing the degree of supercooling.

The refrigerant discharged from the water heat exchanger 3 is decompressed by the first electronic expansion valve 4 that adjusts the flow rate of the refrigerant to reduce the pressure, and the refrigerant becomes a low-pressure, low-temperature liquid refrigerant. The refrigerant flows from the first electronic expansion valve 4 into the air heat exchanger 5 , and the external air and the refrigerant exchange heat in the air heat exchanger 5 . Although the bypass circuit 6 is connected between the first electronic expansion valve 4 and the air heat exchanger 5, in the case of the warm-up operation, since the second electronic expansion valve 7 is closed, the refrigerant does not Flow to bypass circuit 6.

Since the temperature of the refrigerant flowing into the air heat exchanger 5 is low, it receives heat from the outside air, evaporates, and becomes a low-pressure, low-temperature gaseous refrigerant. At the same time, the outside air is cooled to a lower temperature, and this air passes through the air heat exchanger 5 . The air heat exchanger 5 functions as an evaporator of the refrigeration cycle.

The low-pressure and low-temperature gaseous refrigerant discharged from the air heat exchanger 5 flows into the four-way valve 2 for switching the refrigerant circuit again, and is sent to the suction port of the compressor 1 via the four-way valve 2 . The low-pressure and low-temperature gaseous refrigerant fed into the suction port of the compressor 1 is compressed in the compressor 1 to become a high-pressure and high-temperature gaseous refrigerant, and is discharged from the discharge port.

When the refrigeration cycle is operated to raise the temperature, the above cycle is repeated to form a hot water dispenser that generates hot water by a heat pump action that transfers heat from outside air to water.

As the refrigerant, if a refrigerant used in an air conditioner such as R410A is used, the refrigeration cycle system can be configured at low cost, and the efficiency at the time of operation is also good. In addition, for example, when a refrigerant such as CO ₂ is used, it becomes a hot water supplier capable of supplying higher temperature hot water.

In such a heat pump water heater, heat exchange is performed to extract heat from outside air so that the saturation temperature of the refrigerant is lower than the outside air temperature. Therefore, when the temperature of the outside air is low, the saturation temperature of the refrigerant becomes lower than the dew point temperature, and moisture in the outside air condenses on the surface of the air heat exchanger 5 to form frost.

If the ventilation performance of the air heat exchanger 5 decreases due to frost, sufficient heat of evaporation cannot be obtained from the outside air. Therefore, the evaporation pressure of the refrigerant decreases, the density of the refrigerant sucked into the compressor 1 decreases, and the circulation of the refrigerant decreases. amount decreased. Accompanied by the decrease in the amount of circulation, the performance as a hot water supplier also decreases.

Therefore, in order to ensure the performance of the hot water supplier when the outside air temperature is low, it is necessary to perform a defrosting operation for removing frost adhering to the surface of the air heat exchanger 5 .

In the hot water supplier according to Embodiment 1 of the present invention employing the reverse defrosting system, the four-way valve 2 switches the refrigeration cycle to perform the defrosting operation.

In FIG. 1 , the flow of the refrigerant in the refrigeration cycle during the defrosting operation is described by dotted lines.

During the defrosting operation, the four-way valve 2 is switched to supply the high-pressure, high-temperature gaseous refrigerant discharged from the compressor 1 to the air heat exchanger 5 .

The high-pressure, high-temperature gaseous refrigerant sent to the air heat exchanger 5 applies heat to the frost adhering to the air heat exchanger 5 to condense. The frost adhering to the air heat exchanger 5 is melted by heat, becomes a liquid, and flows down from the air heat exchanger 5 . In this way, the air heat exchanger 5 functions as a condenser.

The condensed high-pressure and medium-temperature liquid refrigerant is decompressed by the first electronic expansion valve 4 , and the liquid refrigerant becomes a low-pressure and low-temperature liquid refrigerant and flows into the water heat exchanger 3 . In the water heat exchanger 3, the water and the refrigerant exchange heat to cool the water, and the refrigerant acquires heat and evaporates to become a low-pressure and low-temperature gaseous refrigerant. That is, water heat exchanger 3 functions as an evaporator.

The low-pressure and low-temperature gaseous refrigerant discharged from the water heat exchanger 3 is sent to the suction port of the compressor 1 again through the four-way valve 2 . The low-pressure and low-temperature gaseous refrigerant fed into the suction port of the compressor 1 is compressed in the compressor 1 to become high-pressure and high-temperature gaseous refrigerant, which is then discharged from the discharge port. During the defrosting operation, the above cycle is repeated, and the frost adhering to the air heat exchanger 5 is melted and liquefied by heat, thereby removing the frost from the air heat exchanger 5 .

Here, when switching from the warming operation to the defrosting operation, a large temperature difference occurs in the air heat exchanger 5 in a short time. That is, a phenomenon occurs in which the low-temperature state functioning as the evaporator during the warm-up operation is switched to the high-temperature state functioning as the condenser during the defrosting operation in a short period of time.

The main reason for the occurrence of the above phenomenon is that in the case of the heat pump hot water supplier, the heat of the hot water in the hot water storage tank is used as a heat source for the evaporator during the defrosting operation.

FIG. 4 is a Mollier diagram when the second electronic expansion valve 7 is closed during the defrosting operation according to the first embodiment.

The hot water is supplied to the water heat exchanger 3 at a temperature in the range of 10° C. to 60° C. On the other hand, the temperature of the refrigerant supplied to the water heat exchanger 3 during the defrosting operation is lower than the temperature of the outside air. Therefore, the temperature of the refrigerant is usually 0°C or lower, and sometimes falls below -20°C as the outside air temperature decreases. Therefore, the temperature difference between the water and the refrigerant increases, and the refrigerant sometimes passes through the water heat exchanger 3 as a gaseous refrigerant having a degree of superheat of 20° C. or higher as shown in the Mollier diagram of FIG. 4 .

The high-superheated gas refrigerant discharged from the water heat exchanger 3 with hot water as a heat source is sucked into the compressor 1 and compressed to become a high-pressure and high-temperature gas refrigerant. Since it has a high degree of superheat at the time of suction, the temperature of the gaseous refrigerant discharged from the compressor 1 becomes high, and is supplied to the air heat exchanger 5 .

When the temperature raising operation is switched to the defrosting operation, the high-temperature gas refrigerant with a high degree of superheat flows into the low-temperature air heat exchanger 5 , and the temperature of the air heat exchanger 5 suddenly rises. For example, when the defrosting operation is performed when the outside air temperature is 2°C, a temperature difference of 40°C or more occurs. Due to this temperature difference, a large thermal stress is generated in the components constituting the air heat exchanger 5 .

The air heat exchanger 5 is, for example, a fin-tube heat exchanger and has a plurality of paths. For the plurality of tubes arranged horizontally, a path is formed by connecting a constant number of tubes, and one end side of each path is connected to a header (header) 5a via a branch pipe 5b to merge, and further connected to a refrigerant circuit. That is, each branch pipe 5b is attached to the header pipe 5a substantially at right angles by brazing or the like, and is connected to each path. In addition, the other end side of each path is joined by the flow divider 5c, and is connected to a refrigerant circuit similarly.

In the temperature raising operation shown in FIG. 2 , the temperature of the air heat exchanger 5 is low, so the header 5 a shrinks in the longitudinal direction. And when the temperature becomes high by the defrosting operation shown in FIG. 3, the header 5a will expand in the longitudinal direction. If the header pipe 5a repeatedly shrinks and expands due to the temperature difference between the warm-up operation and the defrosting operation, for example, stress is generated at the connecting portion between the branch pipes 5b and the header pipe 5a, resulting in fatigue failure. In addition, the same fatigue failure may also occur in other parts connected by brazing, that is, the joint parts of heat transfer tubes in each path, branch tubes 5b, fins, and flow dividers 5c.

5 is a Mollier diagram when the second electronic expansion valve is opened during the defrosting operation according to Embodiment 1. FIG.

Fig. 6 is a diagram showing changes in temperature of the air heat exchanger (manifold) when the second electronic expansion valve is opened and when the second electronic expansion valve is closed during the defrosting operation according to Embodiment 1. Compare chart.

In the heat pump water heater according to Embodiment 1, the second electronic expansion valve 7 is opened during the defrosting operation so that the refrigerant flows into the bypass circuit 6 and the refrigerant flows into the water. The amount of refrigerant in the heat exchanger 3 is relatively reduced. As a result, the refrigerant flowing in the bypass circuit 6 and the refrigerant flowing in the water heat exchanger 3 merge before being sucked into the compressor 1, and as shown in the Mollier diagram shown in FIG. The degree of superheat of the refrigerant in the compressor 1 is suppressed. Therefore, the discharge temperature of the refrigerant discharged from the compressor 1 is lowered, and thermal stress can be reduced by suppressing the temperature change of the air heat exchanger 5 as shown in FIG. 6 .

The degree of superheat of the refrigerant sucked into the compressor 1 changes according to the opening degree of the second electronic expansion valve 7 . If the second electronic expansion valve 7 is largely opened, the flow rate of the diverted refrigerant increases, so that the degree of superheat sucked into the compressor 1 decreases. When the balance between the flow rates of the refrigerants is broken, the degree of superheat becomes 0° C., and the liquid refrigerant is sucked into the compressor 1 , which causes malfunctions in the compressor 1 . Therefore, it is preferable to set the suction superheat degree of the compressor 1 to about several degrees (for example, 1 degreeC).

Here, a method of controlling the first electronic expansion valve 4 and the second electronic expansion valve 7 according to Embodiment 1 will be described.

7 is a control flowchart of the first electronic expansion valve and the second electronic expansion valve during the defrosting operation according to the first embodiment.

8 is a diagram showing correction of the opening degree of the second electronic expansion valve during the defrosting operation according to Embodiment 1. FIG.

First, in step 1, it is judged whether or not a defrosting operation is necessary during the temperature raising operation. This judgment is as follows: for example, the evaporation temperature is measured by the temperature detector 5d, and when the temperature is lower than a predetermined temperature for a predetermined time or longer, it is judged that frost is attached to the air heat exchanger 5.

If it is determined that the defrosting operation is necessary, then in step 2, the first electronic expansion valve 4 of the two electronic expansion valves, the first electronic expansion valve 4 and the second electronic expansion valve 7, is fully opened.

This is to prevent the responsiveness of the control from being slowed down due to the control of the two electronic expansion valves during the defrosting operation. In addition, it is also intended to prevent an operation in which the pressure loss of the refrigerant increases due to throttling of the first electronic expansion valve 4 , thereby causing insufficient refrigerant.

Next, the control of the second electronic expansion valve 7 in steps 3 to 5 will be described.

The temperature of hot water flowing into the water heat exchanger 3 during warm-up operation is an important parameter for controlling the opening degree of the second electronic expansion valve 7 in order to suppress the degree of suction superheat of the compressor 1 . If the temperature of the water flowing into the water heat exchanger 3 is high, the amount of heat exchange with the refrigerant increases, so the degree of superheat increases. Therefore, it is necessary to increase the opening degree of the second electronic expansion valve 7 to divert the liquid or the two-phase refrigerant with low dryness to the suction side of the compressor 1 . Conversely, if the temperature of the water flowing into the water heat exchanger 3 is low, the amount of heat exchange with the refrigerant decreases, so the degree of superheat of the refrigerant decreases. Therefore, it is necessary to reduce the opening degree of the second electronic expansion valve 7 to reduce the flow rate of the low-dryness refrigerant diverted to the suction side of the compressor 1 .

Therefore, when the transition to the defrosting operation is determined, the temperature Tw of the hot water flowing into the water heat exchanger 3 during the warm-up operation is measured by the temperature detector 3 a and stored in the memory in advance.

This water temperature Tw is read in step 3.

Then, in step 4, it is determined whether the water temperature Tw is equal to or higher than the reference water temperature Twstd. If the water temperature Tw is equal to or higher than the reference water temperature Twstd, the process proceeds to step 5, and the opening of the second electronic expansion valve 7 during the defrosting operation is corrected in the direction of increasing from the reference opening during the defrosting operation.

If the water temperature Tw is lower than the reference water temperature Twstd, the process proceeds to step 6, and the opening degree of the second electronic expansion valve 7 during the defrosting operation is maintained at the reference opening degree during the defrosting operation.

That is, as shown in FIG. 8 , if the water temperature Tw is equal to or higher than the reference water temperature Twstd, the defrosting operation is performed in a direction in which, for example, the reference opening in the defrosting operation is increased in proportion to the deviation between the water temperature Tw and the reference water temperature Twstd. The opening degree of the second electronic expansion valve 7 is corrected.

In this way, the water temperature Tw at the time of the warm-up operation is stored in advance, and the water temperature Tw is read at the transition to the defrosting operation to calculate the opening degree of the second electronic expansion valve 7. Therefore, the first electronic expansion valve 7 can be set at the start of the defrosting operation. The opening degree of the second electronic expansion valve 7 can be quickly controlled when switching from the warm-up operation to the defrosting operation.

Since the temperature of the water flowing into the water heat exchanger 3 is equal to the temperature of the hot water in the hot water storage tank of the heat pump water heater, and does not change between the warm-up operation and the defrost operation, the defrost operation can Initially, the opening degree of the second electronic expansion valve 7 is determined, so that the second electronic expansion valve 7 can be controlled to an optimum opening degree. Therefore, it is not necessary to adjust the opening degree of the second electronic expansion valve 7 while measuring the degree of superheat of the refrigerant during the defrosting operation, and it is possible to cope with the defrosting operation in a short time.

The opening degree of the second electronic expansion valve 7 is calculated by the following formula 1.

Cv2＝Cv1×α+β×(Tw－Twstd) (Formula 1)

Here, each variable is as follows.

Cv1: Cv value when the first electronic expansion valve 4 is fully opened

Cv2: A Cv value corresponding to the opening degree of the second electronic expansion valve 7

Tw: Water temperature of hot water flowing into the water heat exchanger 3 before defrosting starts

Twstd: reference water temperature

α: Coefficient

β: Correction value for the deviation between the water temperature (Tw) and the reference water temperature (Twstd)

The opening degree of the second electronic expansion valve 7 is an equivalent opening degree of the electronic expansion valve obtained from Cv2 calculated by Equation 1.

The water temperature generally used in the heat pump water heater is set as the reference water temperature Twstd, and the coefficient α is determined such that the suction superheat of the compressor 1 is 1° C. during the defrosting operation at the reference water temperature Twstd. The opening degree of the second electronic expansion valve 7 at this time is the reference opening degree during the defrosting operation.

In addition, the correction value β when the water temperature Tw of the water flowing into the water heat exchanger 3 changes from the reference water temperature Twstd is determined. The relationship between the above three parameters (Tw, α, β) is determined through experiments in advance.

Implementation mode 2.

In the defrosting operation according to the second embodiment, in addition to the control of the opening degree of the second electronic expansion valve 7 based on the water temperature of the water flowing into the water heat exchanger 3 during the warming operation according to the first embodiment, The opening degree of the second electronic expansion valve 7 is controlled based on the evaporation temperature of the air heat exchanger 5 during the warm-up operation.

9 is a flowchart of the control of the second electronic expansion valve 7 based on the evaporation temperature of the air heat exchanger 5 during the warm-up operation according to the second embodiment.

FIG. 10 is a diagram showing correction of the opening degree of the second electronic expansion valve 7 during the defrosting operation according to the second embodiment.

A control flow added to Embodiment 1 will be described.

When the evaporating temperature of the air heat exchanger 5 during the warm-up operation is low, the change in temperature rise of the air heat exchanger 5 during switching to the defrosting operation increases. Therefore, in step 3, the evaporation temperature Te of the air heat exchanger 5 during the warm-up operation at the time of transition to the defrosting operation is read, and in step 7, it is judged whether the evaporation temperature Te is equal to or lower than the reference evaporation temperature Testd. . When the evaporating temperature Te is equal to or lower than the reference evaporating temperature Testd, the temperature of the gaseous refrigerant supplied from the compressor 1 during the defrosting operation is lowered. Therefore, in step 8, the opening degree of the second electronic expansion valve 7 is adjusted to Correction to increase from the reference opening during defrosting operation. Conversely, when the evaporation temperature Te of the air heat exchanger 5 during the warm-up operation is higher than the reference evaporation temperature Testd, in step 9, the opening degree of the second electronic expansion valve 7 is maintained at the reference opening degree during the defrosting operation. .

That is, as shown in FIG. 10 , when the evaporation temperature Te during the warm-up operation is equal to or lower than the reference evaporation temperature Testd, the opening is proportional to, for example, the reference opening during the defrosting operation according to the deviation between the evaporation temperature Te and the reference evaporation temperature Testd. In the direction of increase, the opening degree of the second electronic expansion valve 7 during the defrosting operation is corrected.

In this way, the evaporating temperature Te at the time of warm-up operation is stored in advance, and the evaporating temperature Te is read at the time of transition to the defrosting operation to calculate the opening degree of the second electronic expansion valve 7. Therefore, it is possible to set By setting the opening degree of the second electronic expansion valve 7, the opening degree control of the second electronic expansion valve 7 can be quickly performed when switching from the warm-up operation to the defrosting operation.

In addition, instead of correcting the opening degree of the second electronic expansion valve 7 based on the evaporation temperature Te of the air heat exchanger 5 during the warm-up operation described above, the following correction may be added to the control, that is, the temperature of the outside air is measured, and the external When the air temperature is low, it is determined that the temperature of the air heat exchanger 5 has decreased, and the temperature of the gaseous refrigerant supplied from the compressor 1 during the defrosting operation is decreased, thereby increasing the opening degree of the second electronic expansion valve 7 .

At this time, when the evaporating temperature during warm-up operation is low or the outside air temperature is low, if the temperature of the refrigerant on the low-pressure side is 0°C or lower, the low-temperature refrigerant may be decomposed at the beginning. After the defrosting operation, the hot water flowing into the water heat exchanger 3 may freeze as a heat exchange medium. Therefore, by controlling the opening degree of the second electronic expansion valve 7 based on the evaporation temperature of the air heat exchanger 5 or the outside air temperature during warm-up operation as described above, it is also possible to achieve the following effect: When the temperature is low, the low-temperature refrigerant can be diverted to the water heat exchanger 3 to prevent the hot water from freezing.

11 is a refrigerant circuit diagram showing another example of the refrigerant circuit of the heat pump water heater according to Embodiment 1. FIG.

The refrigerant circuit of the heat pump water heater shown in FIG. 11 is as follows. In Embodiment 1 shown in FIG. Receiver (Receiver) 10, and a third electronic expansion valve 11 is arranged between the receiver 10 and the air heat exchanger 5, and the bypass circuit 6 and the The suction side of compressor 1 is connected.

Also in the heat pump water heater including such a refrigerant circuit, the opening degree control of the second electronic expansion valve 7 described in the first and second embodiments described above can be performed, and the same effect can be obtained.

In addition, FIG. 12 is a refrigerant circuit diagram showing another example of the refrigerant circuit of the heat pump water heater according to the first embodiment.

The refrigerant circuit of the heat pump water heater shown in FIG. 12 is configured as follows. A storage device for pre-storing excess refrigerant is provided between the compressor 1 and the four-way valve 2 in Embodiment 1 shown in FIG. 1 . An accumulator 12, and a bypass circuit 6 is connected between the four-way valve 2 and the accumulator 12.

Also in the heat pump water heater including such a refrigerant circuit, the opening degree control of the second electronic expansion valve 7 described in the first and second embodiments described above can be performed, and the same effect can be obtained.

As mentioned above, although Embodiment 1, 2 was demonstrated, this invention is not limited to the description of each embodiment as mentioned above. For example, it is also possible to combine all or part of the respective embodiments.

Claims (8)

1. a heat pump-type hot-water supply device, consists of and at least can switch between intensification running and defrosting operate, and possess:

Major loop, when described intensification running, this major loop according to compressor, flow channel switching valve, make water and cold-producing medium carry out the water heat exchanger of heat exchange, first flow regulating valve and these parts are connected by the order that makes air and cold-producing medium carry out the air heat exchanger of heat exchange; And

Bypass circulation, this bypass circulation is configured to comprise bypass pipe arrangement and the second flow rate regulating valve, wherein, this bypass pipe arrangement is connected with the suction side of described compressor, and liquid refrigerant or two-phase system cryogen are shunted to the suction side of described compressor, this second flow rate regulating valve is located at described bypass pipe arrangement

The feature of described heat pump-type hot-water supply device is, is configured to:

When described intensification running, the water temperature of the water being supplied to described water heat exchanger is detected,

When described defrosting running, when described water temperature is more than benchmark water temperature, the aperture of described second flow rate regulating valve is increased from reference opening amount.

2. heat pump-type hot-water supply device according to claim 1, is characterized in that,

Be configured to: when described defrosting running, when the not enough benchmark water temperature of described water temperature, the aperture of described second flow rate regulating valve be maintained described reference opening amount.

3. heat pump-type hot-water supply device according to claim 1, is characterized in that,

Be configured to: when described intensification running, the refrigerant evaporating temperature of described air heat exchanger is detected,

When described defrosting running, when described refrigerant evaporating temperature is below benchmark evaporating temperature, the aperture of described second flow rate regulating valve is increased from reference opening amount.

4. the heat pump-type hot-water supply device according to any one of claims 1 to 3, is characterized in that,

Be configured to: when described intensification running, the refrigerant evaporating temperature of described air heat exchanger is detected,

When described defrosting running, when described refrigerant evaporating temperature is greater than benchmark evaporating temperature, the aperture of described second flow rate regulating valve is maintained reference opening amount.

5. the heat pump-type hot-water supply device according to any one of claims 1 to 3, is characterized in that,

Be configured to: when described defrosting running, make the aperture of described first flow regulating valve be formed as the aperture opened completely.

6. the heat pump-type hot-water supply device according to any one of claims 1 to 3, is characterized in that,

Described bypass pipe arrangement is by between described first flow regulating valve and described air heat exchanger, be connected with the suction side of described compressor.

7. the heat pump-type hot-water supply device according to any one of claims 1 to 3, is characterized in that,

Receiver is provided with between described first flow regulating valve and described air heat exchanger, and, between described receiver and described air heat exchanger, be provided with the 3rd flow rate regulating valve,

Described bypass pipe arrangement is by between described first flow regulating valve and described receiver, be connected with the suction side of described compressor.

8. the heat pump-type hot-water supply device according to any one of claims 1 to 3, is characterized in that,

Accumulator is provided with between described flow channel switching valve and described compressor,

Described bypass pipe arrangement is by between described first flow regulating valve and described air heat exchanger, be connected with the suction side of described accumulator.