JP5558937B2 - Heat pump type water heater - Google Patents

Description

  The present invention relates to a heat pump hot water supply apparatus for heating hot water in a hot water storage tank with a heat pump.

  In this type of conventional heat pump hot water supply apparatus, a hot water storage tank having a water supply pipe connected to the lower part and a hot water discharge pipe connected to the upper part, a water refrigerant heat exchanger as a compressor, a condenser, and an electron as a pressure reducer Heat pump type heating means having a heat pump cycle in which an air heat exchanger as an expansion valve and an evaporator is connected in an annular shape with refrigerant piping, and hot water taken out from the lower part of the hot water storage tank is circulated to the water side of the water refrigerant heat exchanger to store hot water And a heating circulation circuit having a circulation pump for returning to the upper part of the tank, and the hot water in the hot water storage tank is circulated to the heat pump heating means to be boiled up.

  Here, the heat pump heating means is controlled so as to operate in a state in which the operation efficiency is high. As a control method, the discharge temperature of the refrigerant discharged from the compressor is set in advance. Some control the opening of the electronic expansion valve so that the target discharge temperature is reached (see, for example, Patent Document 1).

JP 2002-188860 A

  By the way, in the conventional heat pump water heater, when the boiling of hot water in the hot water storage tank proceeds and the boiling end (at the end of boiling) approaches, the incoming temperature of the hot water flowing into the water-refrigerant heat exchanger increases. come. If it does so, the state of a heat pump cycle will be in the state at the time of the end of boiling shown with the continuous line from the state of the stable time shown with the chain line of FIG. At the end of boiling, the incoming temperature of hot water flowing into the water-refrigerant heat exchanger increases, and the temperature of refrigerant flowing out of the water-refrigerant heat exchanger also increases. In this state, if the opening of the electronic expansion valve is controlled so that the discharge temperature of the refrigerant discharged from the compressor is maintained at a preset target discharge temperature, the discharge temperature of the compressor and the water refrigerant heat exchanger will flow out. The temperature difference from the refrigerant temperature to be reduced is unnecessarily small, the specific enthalpy difference that maximizes the operation efficiency cannot be maintained, and the operation is inefficient.

Accordingly, in order to solve the above-mentioned problems, the present invention is particularly configured as claimed in claim 1, a heat pump heating system including a hot water storage tank for storing hot water, a compressor, a water refrigerant heat exchanger, a decompressor, and an evaporator. Means, a heating circulation circuit for annularly connecting the water side of the water-refrigerant heat exchanger of the heat pump heating means and the hot water storage tank, and the heat pump for heating the hot water in the hot water storage tank to a target boiling temperature In the heat pump type hot water supply apparatus comprising a control means for controlling the heating means, the control means is configured to calculate a discharge temperature of the refrigerant discharged from the compressor and an outflow temperature of the refrigerant flowing out of the water refrigerant heat exchanger. hot water temperature difference, and controlling the opening of said decompressor so that a predetermined target temperature difference, the predetermined target temperature difference flowing into the water-refrigerant heat exchanger and the target boiling temperature and outside air temperature And it shall be calculated on the basis of the water inlet temperature.

Further, in claim 2, a hot water storage tank for storing hot water, a heat pump type heating means including a compressor, a water refrigerant heat exchanger, a decompressor, and an evaporator, and the water refrigerant heat exchanger of the heat pump type heating means A heat pump hot water supply comprising: a heating circuit that annularly connects the water side of the hot water storage tank and the hot water storage tank; and a control means that controls the heat pump heating means to heat the hot water in the hot water storage tank to a target boiling temperature In the apparatus, the control means reduces the pressure so that a temperature difference between a discharge temperature of the refrigerant discharged from the compressor and an outflow temperature of the refrigerant flowing out of the water refrigerant heat exchanger becomes a predetermined target temperature difference. The predetermined target temperature difference is such that the higher the outside air temperature is, the higher the outside air temperature is based on the target boiling temperature, the outside air temperature, and the incoming water temperature flowing into the water-refrigerant heat exchanger. , The value of the predetermined target temperature difference decreases, the higher the incoming water temperature, the smaller the predetermined target temperature difference value, and the higher the target boiling temperature, the lower the predetermined target temperature difference. The value was calculated so as to increase .

  According to the first aspect of the present invention, when boiling the hot water in the hot water storage tank, the control means uses the discharge temperature of the refrigerant discharged from the compressor and the outflow temperature of the refrigerant flowing out of the water refrigerant heat exchanger. By controlling the opening of the decompressor so that the temperature difference becomes a predetermined target temperature difference, the heat pump heating means can be operated while maintaining the specific enthalpy difference that makes the operating efficiency high during boiling. It can be done.

Furthermore, by controlling the opening of the decompressor, both the discharge temperature of the refrigerant discharged from the compressor and the outflow temperature of the refrigerant flowing out of the water-refrigerant heat exchanger change. The temperature change amount of the temperature difference between the discharge temperature and the outflow temperature is large, the control speed is high until the temperature difference between the discharge temperature and the outflow temperature becomes the predetermined target temperature difference, and it can be operated quickly and efficiently . In addition, since the predetermined target temperature difference is calculated based on the target boiling temperature, outside air temperature, and incoming water temperature, when the boiling temperature changes constantly, such as the outside air temperature and the incoming water temperature, the operating efficiency is high at that time. Thus, the predetermined target temperature difference can be obtained with certainty, and the heat pump heating means can be operated with high efficiency .

According to claim 2, when boiling the hot water in the hot water storage tank, the control means is a temperature between a discharge temperature of the refrigerant discharged from the compressor and an outflow temperature of the refrigerant flowing out of the water refrigerant heat exchanger. By controlling the opening of the decompressor so that the difference becomes a predetermined target temperature difference, the heat pump heating means can be operated while maintaining the specific enthalpy difference that makes the operating efficiency high during boiling. Furthermore, by controlling the opening of the decompressor, both the discharge temperature of the refrigerant discharged from the compressor and the outflow temperature of the refrigerant flowing out of the water-refrigerant heat exchanger change. The temperature change amount of the temperature difference between the discharge temperature and the outflow temperature is large, the control speed is high until the temperature difference between the discharge temperature and the outflow temperature becomes the predetermined target temperature difference, and it can be operated quickly and efficiently. a given target temperature Based difference target boiling temperature, outside air temperature, the incoming water temperature, as the outside air temperature is high, the value of the predetermined target temperature difference becomes smaller, as the incoming water temperature is high, the value of the predetermined target temperature difference is small The higher the target boiling temperature is, the larger the value of the predetermined target temperature difference is calculated.Therefore, when boiling is performed when conditions such as the outside air temperature and the incoming water temperature are constantly changing, the operating efficiency at that time is A predetermined target temperature difference with high efficiency can be obtained reliably, and the heat pump heating means can be operated with high efficiency.

The schematic block diagram of one Embodiment of the heat pump type hot water supply apparatus of this invention. The figure which showed the relationship between the opening degree of the electronic expansion valve of the same embodiment, and a control parameter. The figure which compared the state of the heat pump cycle at the time of the end of boiling of the same embodiment, and the state of the heat pump cycle at the time of the end of the conventional boiling. The schematic block diagram of other embodiment of the heat pump type hot-water supply apparatus of this invention. The figure which showed the state of the heat pump cycle at the time of the boiling operation of the conventional heat pump type hot-water supply apparatus.

Next, an embodiment of the present invention will be described with reference to the drawings.
1 is a hot water storage tank unit having a hot water storage tank 2 for storing hot water, 3 is a heat pump heating means for heating the hot water in the hot water storage tank 2, 4 is a heating forward pipe 5 connected to the lower part of the hot water storage tank 2, and A heating circulation circuit comprising a heating return pipe 6 connected to the upper part of the hot water storage tank 2 and connecting the hot water storage tank 2 and the heat pump type heating means 3 in an annular shape so that hot water circulates, and 7 is connected to the lower part of the hot water storage tank 2 A hot water supply pipe 8 for supplying water to the hot water storage tank 2 and a hot water discharge pipe 8 connected to the upper part of the hot water storage tank 2 for discharging hot water stored therein.

  9 is a water supply bypass pipe branched from the water supply pipe 7, 10 is a mixing valve that mixes hot water from the hot water discharge pipe 8 and water from the water supply bypass pipe 9 to make hot water at a hot water supply set temperature, and 11 is mixed by the mixing valve 10 A plurality of hot water supply temperature sensors 12 for detecting a hot water supply temperature later, a plurality of hot water storage temperature sensors 12 for detecting the temperature of hot water in the hot water storage tank 2, and a plurality of sensors 12 in the hot water storage tank unit 1. Is a hot water storage control means for controlling the operation of each device.

  The heat pump type heating means 3 includes a compressor 14 for compressing refrigerant, a refrigerant-side flow path for circulating the refrigerant discharged from the compressor 14, and water for circulating hot water from the heating forward pipe 5 to the heating return pipe 6. A water refrigerant heat exchanger 15 that exchanges heat between the high-temperature and high-pressure refrigerant and the hot water in the hot water storage tank 2, and a decompressor that depressurizes the refrigerant after passing through the water refrigerant heat exchanger 15. A heat pump cycle 18 in which an electronic expansion valve 16 and an air heat exchanger 17 as an evaporator for evaporating the low-temperature and low-pressure refrigerant from the electronic expansion valve 16 are connected in an annular shape by a refrigerant pipe, and water in the water-refrigerant heat exchanger 15 And a heating circulation pump 19 that circulates the hot water in the hot water storage tank 2 provided in the middle of the heating circulation circuit 4 on the side. Carbon dioxide is used as a refrigerant in the heat pump cycle 18 so that it is a supercritical heat pump cycle. Those that make up the.

  A discharge temperature sensor 20 is provided between the compressor 14 and the water refrigerant heat exchanger 15 to detect the discharge temperature of the refrigerant discharged from the compressor 14, and 21 is a water refrigerant heat exchanger 15 and an electronic expansion valve 16. And an outflow temperature sensor 22 for detecting the temperature of the refrigerant flowing out from the refrigerant side of the water refrigerant heat exchanger 15 toward the electronic expansion valve 16, 22 is provided on the air inlet side of the air heat exchanger 17, An outside air temperature sensor that detects the outside air temperature, 23 is an incoming water temperature sensor that detects the incoming water temperature that flows into the water side of the water refrigerant heat exchanger 15, and 24 is a water side from the water refrigerant heat exchanger 15 toward the hot water storage tank 2. It is a boiling temperature sensor which detects the boiling temperature which flows out.

  Reference numeral 25 denotes a heating control means as a control means for receiving the output of each sensor in the heat pump type heating means 3 to control the operation of each device. The heating control means 25 is communicably connected to the hot water storage control means 13 and cooperates with the hot water storage control means 13 It operates as follows.

Next, the operation of this embodiment will be described.
In the midnight time zone, the hot water storage control means 13 instructs the heating control means 25 to start a boiling operation so as to start the boiling operation so that the hot water in the hot water storage tank 2 reaches a predetermined target boiling temperature. The heating control means 25 controls the compressor 14 to operate at the operation frequency set according to the target boiling temperature and the outside air temperature detected by the outside air temperature sensor 22 in the boiling operation, and discharge The opening degree of the electronic expansion valve 16 is feedback-controlled at a predetermined cycle so that the temperature difference ΔH between the refrigerant temperature detected by the temperature sensor 20 and the refrigerant temperature detected by the outflow temperature sensor 21 becomes a predetermined target temperature difference ΔHm. At the same time, the heating control means 25 feedback-controls the rotational speed of the heating circulation pump 19 so that the hot water heated by the water refrigerant heat exchanger 15 detected by the boiling temperature sensor 24 reaches the target boiling temperature.

  The predetermined target boiling temperature is calculated by the hot water storage control means 13 so as to ensure the predicted amount of the hot water supply amount on the next day from the hot water supply results such as the maximum value and the average value of the past hot water supply amount. It is determined in the range from 0C to 90C.

The heating control means 25 determines the predetermined target temperature difference ΔHm based on the target boiling temperature, the outside air temperature detected by the outside air temperature sensor 22, and the incoming water temperature detected by the incoming water temperature sensor 23. Calculated by
ΔHm = Outside air temperature × A + Incoming water temperature × B + Target boiling temperature × C + D
(Here, A and B are negative coefficients, C is a positive coefficient, and D is a fixed value.)

  The predetermined target temperature difference ΔHm becomes smaller as the outside air temperature becomes higher than the above formula, and the value becomes smaller as the incoming water temperature becomes higher, and the value becomes higher as the target boiling temperature becomes higher. During the boiling operation in which conditions such as the outside air temperature and the incoming water temperature change every moment, the predetermined target temperature difference ΔHm at which the operating efficiency of the heat pump type heating means 3 becomes the maximum efficiency at that time can be ensured. The heat pump heating means 3 can be operated with high efficiency. The calculation of the predetermined target temperature difference ΔHm may be performed constantly during the boiling operation, or may be performed in accordance with a predetermined cycle for feedback control of the opening degree of the electronic expansion valve 16. .

  As described above, during the boiling operation, the heating control unit 25 determines that the temperature difference ΔH between the refrigerant temperature detected by the discharge temperature sensor 20 and the refrigerant temperature detected by the outflow temperature sensor 21 is a predetermined target temperature calculated. The opening degree of the electronic expansion valve 16 is controlled so as to be the difference ΔHm. Specifically, when ΔH <ΔHm, the opening degree of the electronic expansion valve 16 is controlled in the closing direction so that ΔH> ΔHm. In this case, the opening degree of the electronic expansion valve 16 is controlled in the opening direction.

  Here, the relationship of the control parameter with respect to the opening degree of the electronic expansion valve 16 under a certain condition during the boiling operation will be described with reference to FIG. Is a control parameter controlled by opening degree control of the electronic expansion valve 16. Here, the refrigerant discharge temperature discharged from the compressor 14 and detected by the discharge temperature sensor 20 and the outflow temperature flowing out of the water refrigerant heat exchanger 15 A temperature difference from the refrigerant outflow temperature detected by the sensor 21 is used.

  As shown in FIG. 2, in this case, when the opening degree of the electronic expansion valve 16 is changed, both the discharge temperature of the refrigerant discharged from the compressor 14 and the outflow temperature of the refrigerant flowing out of the water refrigerant heat exchanger 15 are obtained. 2, the temperature change amount per pulse of the opening change of the electronic expansion valve 16 is large as shown by a thick solid line in FIG. 2, and the temperature difference between the discharge temperature and the outflow temperature is set as a predetermined target temperature difference. The control speed is fast, the controllability is good, and the heat pump heating means 3 can be operated quickly and with maximum efficiency.

  As described above, when the boiling operation proceeds while the control by the heating control means 25 as described above is performed, the water in the lower part of the hot water storage tank 2 is circulated to the heat pump heating means 3, and Hot water heated to the target boiling temperature from above is stored in a stacked state. The hot water storage temperature sensor 12 detects that the required amount of hot water has been boiled in the hot water storage tank 2, or the incoming water temperature detected by the incoming water temperature sensor 23 of the heat pump type heating means 3 exceeds a predetermined high temperature that is difficult to boil up. When the detection is completed or the midnight time period when the power unit price is low is over, the hot water storage control means 13 issues a stop instruction to the heating control means 25 to stop the boiling operation, and the heating control means 25 is connected to the compressor 14. The operation of the heating circulation pump 19 is stopped and the boiling operation is finished.

  At the end of boiling just before the end of the boiling operation, the hot water in the mixed layer between the hot water layer and the water layer in the hot water storage tank 2 flows into the heat pump type heating means 3, and at this time, water / refrigerant heat exchange is performed. The incoming temperature of the hot water flowing into the water side of the vessel 15 gradually rises.

  Here, the state of the heat pump cycle 18 at the end of boiling will be described with reference to FIG. 3, but the state of the heat pump cycle 18 in the boiling operation in the present embodiment is the state at the time of stability shown by the chain line in FIG. To the state at the end of boiling shown by the solid line. In addition, what is drawn with a dotted line in FIG. 3 is the state of the heat pump cycle 18 at the end of boiling shown in FIG. 5, and the state of the heat pump cycle 18 at the end of boiling in this embodiment. For comparison. In the present embodiment, the opening degree of the electronic expansion valve 16 is controlled so that the temperature difference ΔH between the refrigerant temperature detected by the discharge temperature sensor 20 and the refrigerant temperature detected by the outflow temperature sensor 21 becomes a predetermined target temperature difference ΔHm. Therefore, even if the incoming temperature of the hot water flowing into the water side of the water-refrigerant heat exchanger 15 increases, the optimum target temperature difference ΔHm can be calculated accordingly, and the optimum target temperature calculated from the temperature difference ΔH can be calculated. Since the difference ΔHm is maintained, the heat pump maintains the specific enthalpy difference that maximizes the operation efficiency even during boiling operation, particularly at the end of boiling when the incoming water temperature flowing into the water side of the water refrigerant heat exchanger 15 becomes high. The type heating means 3 can be operated.

  The present invention is not limited to the embodiment described so far, and can be applied without changing the gist thereof. For example, the heat pump cycle 18 may be an ejector cycle using an ejector as a decompressor. Is.

  In addition, as shown in FIG. 4, the heat pump cycle 18 includes an internal heat exchanger 26 that performs heat exchange between the high-pressure refrigerant after passing through the water-refrigerant heat exchanger 15 and the low-pressure refrigerant on the suction side of the compressor 14. In this case, the outflow temperature sensor 21 detects the refrigerant temperature downstream of the water refrigerant heat exchanger 15 and upstream of the internal heat exchanger 26 through which the high-pressure refrigerant passes. The opening of the electronic expansion valve 16 is controlled so that the temperature difference ΔH between the refrigerant temperature detected by the discharge temperature sensor 20 and the refrigerant temperature detected by the outflow temperature sensor 21 becomes a predetermined target temperature difference ΔHm. By doing so, the heat pump heating means 3 can be operated while maintaining the specific enthalpy difference that maximizes the operating efficiency, as in the embodiment described above.

2 Hot water storage tank 3 Heat pump type heating means 4 Heating circulation circuit 14 Compressor 15 Water refrigerant heat exchanger 16 Electronic expansion valve (pressure reducer)
17 Air heat exchanger (evaporator)
20 Discharge temperature sensor 21 Outflow temperature sensor 22 Outside air temperature sensor 23 Incoming water temperature sensor 25 Heating control means (control means)

Claims (2)

A hot water storage tank for storing hot water, a heat pump heating means including a compressor, a water refrigerant heat exchanger, a decompressor, and an evaporator, a water side of the water refrigerant heat exchanger of the heat pump heating means, and the hot water storage tank In the heat pump type hot water supply apparatus, the control means includes: a heating circulation circuit that connects the ring shape and a control means for controlling the heat pump heating means to heat the hot water in the hot water storage tank to a target boiling temperature. , the temperature difference between the outlet temperature of the refrigerant flowing out from the water refrigerant heat exchanger and the discharge temperature of the refrigerant discharged from the compressor, and controlling the opening of said decompressor so that a predetermined target temperature difference , the predetermined target temperature difference, heat pump, characterized in that to calculate on the basis of the hot water in the incoming water temperature flowing into the water-refrigerant heat exchanger and the target boiling temperature and outside air temperature Hot water system. A hot water storage tank for storing hot water, a heat pump heating means including a compressor, a water refrigerant heat exchanger, a decompressor, and an evaporator, a water side of the water refrigerant heat exchanger of the heat pump heating means, and the hot water storage tank In the heat pump type hot water supply apparatus, the control means includes: a heating circulation circuit that connects the ring shape and a control means for controlling the heat pump heating means to heat the hot water in the hot water storage tank to a target boiling temperature. The opening degree of the decompressor is controlled so that the temperature difference between the discharge temperature of the refrigerant discharged from the compressor and the outflow temperature of the refrigerant flowing out of the water refrigerant heat exchanger becomes a predetermined target temperature difference. , the predetermined target temperature difference, based on the hot water of the incoming water temperature flowing into the water-refrigerant heat exchanger and the target boiling temperature and the outside air temperature, the higher the outside air temperature is high, the predetermined target temperature difference Value decreases, as the entering-water temperature increases, the value of the predetermined target temperature difference becomes smaller, the larger the target boiling temperature is higher, calculated as the value of the predetermined target temperature difference increases A heat pump type hot water supply device characterized in that it is configured to do so.

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