JP2008039360A - Heat pump type water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump type water heater capable of shortening a defrosting time. <P>SOLUTION: As this heat pump type water heater is provided with a heat pump circuit constituted by circularly connecting a compressor 11, a water-refrigerant heat exchanger 12, pressure reducing devices 13A, 13B and an evaporator 14 by refrigerant piping, a hot water supply circuit constituted by circularly connecting a hot water storage tank 20 for storing hot water, a pump 23 for circulating hot water in the hot water storage tank 20, and the water-refrigerant heat exchanger 12 by piping, and a defrost preliminary interval for performing an operation in a state of reducing a flow rate of the pump 23 by a specific flow rate for a specific time before starting a defrosting operation to defrost the evaporator 14, a flow rate of the water flowing into the water-refrigerant heat exchanger 12 before starting the defrosting can be lowered, heat radiation of the refrigerant in the water-refrigerant heat exchanger can be reduced, and the heat of high temperature of the refrigerant can be used in the defrosting operation of the evaporator 14, thus the defrosting time can be shortened. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention has a heat pump circuit in which a compressor, a water-refrigerant heat exchanger, a decompressor, and an evaporator are connected by refrigerant piping, and a hot water supply circuit in which a hot water storage tank, a pump, and a water-refrigerant heat exchanger are connected by piping. The present invention relates to a heat pump water heater.

Conventionally, during the defrosting operation, the pump flow rate is reduced to a position close to the lower limit value, or the pump is stopped, and the defrosting is performed using the heat stored in the water-refrigerant heat exchanger (for example, Patent Document 1).
JP-A-2005-147609

  However, in the conventional defrosting method, in general, before starting the defrosting operation from the viewpoint of suppression of high pressure and countermeasures against refrigerant noise, the frequency of the compressor is reduced or the expansion valve opening is set to be lower than that during normal operation. Since it opens, high temperature heat cannot be stored in a water-refrigerant heat exchanger, and it had the subject that defrost time will become long.

  This invention solves the said conventional subject, and it aims at providing the heat pump type water heater which can shorten defrost time.

  In order to solve the above-mentioned conventional problems, the heat pump type hot water heater of the present invention includes a heat pump circuit configured by connecting a compressor, a water-refrigerant heat exchanger, a decompression device, and an evaporator in an annular shape by a refrigerant pipe, Hot water storage tank that stores hot water, a pump that circulates the hot water in the hot water storage tank, a hot water supply circuit that is formed by connecting water-refrigerant heat exchangers in a ring shape, and a defrosting operation that starts defrosting the evaporator Before, the flow rate of the water flowing into the water-refrigerant heat exchanger can be lowered before the start of the defrosting by providing a defrost preparation section that operates by reducing the flow rate of the pump for a certain time. Since the heat quantity of the refrigerant in the water-refrigerant heat exchanger is suppressed and the high-temperature heat of the refrigerant can be used for the defrosting operation of the evaporator, the defrosting time can be shortened.

  The heat pump water heater of the present invention can provide a heat pump water heater that can shorten the defrosting time.

  A heat pump type hot water supply apparatus according to a first aspect of the present invention includes a compressor, a water-refrigerant heat exchanger, a decompression device, a heat pump circuit configured by connecting an evaporator in a ring shape with a refrigerant pipe, a hot water storage tank for storing hot water, and the hot water storage Before starting the defrosting operation for defrosting the evaporator, the pump for circulating hot water in the tank, the hot water supply circuit configured by connecting the water-refrigerant heat exchanger in a ring shape with piping, and the flow rate of the pump By providing a defrost preparation section that operates with a constant flow decrease for a certain period of time, the flow rate of water flowing into the water-refrigerant heat exchanger can be reduced before the start of defrosting. The amount of heat of the refrigerant can be suppressed, and the high-temperature heat of the refrigerant can be used for the defrosting operation of the evaporator, so the defrosting time can be shortened.

In the heat pump hot water heater of the second invention, particularly in the first invention, in the defrost preparation section, by providing a lower limit value for the flow rate of the pump, it is possible to prevent an abnormal increase in the refrigerant pressure discharged from the compressor. . This is because when the flow rate of the pump during normal operation is extremely low and the pump flow rate is reduced by a fixed flow rate when entering the defrost preparation section, the flow rate becomes zero and the high pressure rises abnormally. To prevent this.

  In the heat pump type hot water heater of the third invention, particularly in the first or second invention, the lower limit value of the pump flow rate is set to be equal to or higher than the lower limit value of boiling set during the heating operation in the defrost preparation section. Thus, simple control can be realized. Usually, at the time of boiling operation, a boiling lower limit value is set for the pump flow rate, and control is performed so as to operate at a pump flow rate higher than that. When the pump flow rate is controlled at the boiling lower limit value or more during the boiling operation, the discharge refrigerant pressure of the compressor does not rise abnormally. However, when the defrosting operation is started, the outside air temperature is low and the pump flow rate is often lowered. Therefore, when the constant flow pump flow rate is decreased, the boiling lower limit value, that is, the lower limit value that can be operated without problems is lower. As a result, the discharged refrigerant pressure rises abnormally. Therefore, by setting the lower limit value of the defrosting operation preparation section higher than the lower limit value during the boiling operation, even if the pump flow rate is reduced by a constant flow rate after entering the defrosting operation preparation section from the normal boiling operation, The discharged refrigerant pressure can be operated without any problem. Originally, in order to prevent an abnormal increase in high pressure, it is necessary to appropriately determine and control (decrease) the flow rate based on the discharge refrigerant pressure state (high pressure state) of the compressor before entering the defrosting operation preparation section. However, since the control is complicated and the cost is increased, simple control can be realized by performing the control as in the present invention.

  In the heat pump type hot water heater of the fourth invention, in particular in the first to third inventions, even if the refrigerant pressure on the high pressure side is equal to or higher than the critical pressure, water is deprived of heat and the refrigerant temperature decreases. Since it does not condense, it becomes easy to form a temperature difference between the refrigerant and water in the entire water-refrigerant heat exchanger, so that hot water can be obtained and the heat exchange rate can be increased.

  In the heat pump type hot water heater of the fifth invention, particularly in the fourth invention, since the refrigerant to be used is carbon dioxide, the use of carbon dioxide which is relatively inexpensive and stable is used as the refrigerant, thereby suppressing the product cost. At the same time, reliability can be improved. In addition, carbon dioxide has an ozone depletion coefficient of zero and a global warming coefficient of about 1/700 of the alternative refrigerant HFC-407C, which is very small.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a heat pump type water heater in the present embodiment. In FIG. 1, the heat pump circuit 10 of the heat pump type water heater in this embodiment includes an inverter type compressor 11, a water-refrigerant heat exchanger 12, a main expansion valve 13A, a capillary tube 13B, and an evaporator 14 in order by refrigerant piping. It is configured to be connected in a ring shape. A blower 15 for sending air to the evaporator 14 is installed on the leeward side of the evaporator 14, and the blower 15 operates by being controlled by a blower control means (not shown) such as a microcomputer. Allow air to circulate. Further, the heat pump circuit 10 includes a thermistor 10A that detects the temperature of the compressor 11, a thermistor 10B that detects the temperature of the refrigerant discharged from the compressor 11, a pressure sensor 10C that detects the pressure of the refrigerant discharged from the compressor 11, A thermistor (outside air temperature detecting means) 10D for detecting the temperature of the air flowing through the evaporator 14 (outside air temperature) and a thermistor (evaporator temperature detecting means) 10E for detecting the temperature of the evaporator 14 are provided. The thermistor 10 </ b> A is provided for detecting cold start, and the pressure sensor 10 </ b> C is provided mainly for detecting abnormality of the compressor 11 or the heat pump circuit 10. Note that, if the inverter compressor 11 is configured without an accumulator, the heat pump water heater can be reduced in size and weight, but the present invention is not limited to this, and the compressor with the accumulator is compressed. There is no problem even if the machine is used. In addition, since the refrigerant flowing through the heat pump circuit uses carbon dioxide whose high pressure side exceeds the critical pressure, it is condensed even if the temperature drops due to heat deprived from the water flowing through the water-refrigerant heat exchanger 12. Therefore, a water-refrigerant heat exchanger can easily form a temperature difference between the refrigerant and water, high-temperature hot water can be obtained, and heat exchange efficiency can be increased.

  On the other hand, the hot water supply circuit of the heat pump type water heater in the present embodiment includes a hot water storage tank 20 for storing hot water, a pump 23 for causing hot water in the hot water storage tank 20 to flow into the water-refrigerant heat exchanger 12 and circulating in the hot water supply circuit. The water-refrigerant heat exchanger 12 is sequentially connected in an annular shape by a liquid pipe. The bottom pipe 21 for supplying water to the hot water storage tank 20 is connected to a water supply pipe 32 to which water is supplied via a pressure reducing valve 31. A hot water supply pipe 33 is connected to the upper part of the hot water storage tank 20, and hot water is mixed and mixed in the water supply pipe 35 through which the water is supplied from the water supply pipe 32 through the pressure reducing valve 31 and the mixing valve 34. Hot water is supplied to the hot water supply terminal 36. The hot water storage tank 20 is provided with a plurality of thermistors 20A, 20B, 20C for detecting the amount of hot water in the hot water storage tank 20, and the hot water supply circuit is provided with the temperature of the hot water flowing into the water-refrigerant heat exchanger 12. A thermistor (incoming water temperature detecting means) 20D for detecting and a thermistor (outlet temperature detecting means) 20E for detecting the temperature of hot water flowing out from the water-refrigerant heat exchanger 12 are provided. Between the mixing valve 34 and the hot water supply terminal 36, a flow rate sensor 30A for detecting the flow rate and a thermistor 30B for detecting the hot water temperature are provided. The hot water storage tank 20 in the present embodiment is a stacked hot water storage tank, and is configured so that stirring in the tank is prevented and high temperature water is accumulated at the top and low temperature water is accumulated at the bottom.

  The operation of the heat pump type hot water supply apparatus configured as described above will be described below. When the time reaches a predetermined time or when the plurality of thermistors 20A, 20B, and 20C for detecting the amount of hot water in the hot water storage tank 20 detects that the amount of hot water in the hot water storage tank 20 has become a predetermined amount or less, the heat pump circuit 10 is operated to start the hot water storage operation.

  In the heat pump circuit 10, after the refrigerant compressed by the inverter compressor 11 and discharged from the inverter compressor 11 radiates heat by the water-refrigerant heat exchanger 12 and is depressurized by the main expansion valve 13A and the capillary tube 13B. Then, heat is absorbed from the air sent by operating the blower 15 in the evaporator 14 and is sucked into the inverter compressor 11 again in a gas state. The capacity control of the inverter type compressor 11 and the opening degree control of the expansion valve 13A are controlled such that the temperature of the refrigerant discharged from the compressor 11 detected by the thermistor 10B maintains a preset temperature.

  On the other hand, in the hot water supply circuit, hot water in the hot water storage tank 20 is circulated to the hot water supply circuit by the operation of the pump 23, heat exchange with the refrigerant is performed in the water-refrigerant heat exchanger 12, and returned to the hot water storage tank 20 again in a stacked state. Hot water is stored at the top. Further, the value of the thermistor (hot water temperature detecting means) 20E becomes a target hot water temperature determined by the incoming water temperature detected by the thermistor (incoming water temperature detecting means) 20D and the desired boiling temperature determined by the hot water storage tank 20. Thus, the pump 23 is controlled. Hereinafter, the defrosting operation of the heat pump type water heater configured as described above will be described.

  FIG. 2 is a control block diagram in the present embodiment. First, the configuration of the pump flow rate control means 40 that controls the flow rate of the pump will be described. The determination of the flow rate of the pump flow rate control means 40 is different in three sections during the normal boiling operation, the defrost preparation section, and the defrost operation.

The pump flow rate control means 40 is a pump flow rate determining means 48 for determining the pump flow rate during the normal boiling operation, and a target hot water temperature setting means 42 for setting the target temperature of the hot water discharged from the water-refrigerant heat exchanger. The pump has a pump flow lower limit setting means 43 for setting the lower limit value (boiling lower limit value) of the pump flow rate during the boiling operation, and the thermistor (the hot water temperature detection means) 20E is used during the boiling operation. The flow rate of the pump 23 is determined so that the detected hot water temperature becomes the target hot water temperature set by the target hot water temperature setting means 42. However, even if the hot water temperature does not reach the target hot water temperature, the flow rate of the pump is controlled so as not to fall below the boiling lower limit value set by the pump flow rate lower limit setting means 43 during the boiling operation.

  Further, the pump flow rate control means 40 is a pump flow rate determining means 49 for determining the pump flow rate at the time of the defrost preparation section, and a pump flow rate storage at the time of boiling operation for storing the pump flow rate at the time of normal boiling operation. Means 44, defrost preparation section operation pump lowering flow setting means 45 for setting a constant flow rate to be reduced from the pump flow rate during the defrost preparation section, defrost preparation section pump for setting a lower limit value of the pump flow rate during the defrost preparation section The flow rate lower limit setting means 46 is provided, and during the defrost preparation section, when the defrost start is detected by the defrost start detection means 41 due to the outside air temperature, the evaporator temperature, etc., the pump flow rate memory during the boiling operation is stored. The pump lowering amount set by the pump lowering flow rate setting means 45 during the defrost preparation section operation is subtracted from the pump flow rate during the boiling operation stored in the means 44, and the result is If it is not less than the lower limit value set by the defrost preparation section pump flow rate lower limit setting means 46, the value is determined as the flow rate of the pump 23, and if it is less than the lower limit value, the lower limit value is determined as the flow rate of the pump 23. .

  The pump flow rate control means 40 includes a defrosting operation pump flow rate setting means 47 for setting the pump flow rate during the defrosting operation, and a defrosting operation pump flow rate determination means 50 for determining the pump flow rate during the defrosting operation. And when the defrosting start detecting means 41 detects that the defrosting is started, the defrosting operation pump flow rate determining means is set to the pump flow rate set by the defrosting operation pump flow rate setting means 47 after the completion of the defrost preparation section. 50 determines the flow rate of the pump.

  The pump flow rate control means 40 has a pump flow rate variable means 51 for controlling the flow rate of the pump. The pump flow rate determination means 48 at the time of boiling operation, the pump flow rate determination means 49 at the time of defrost preparation section operation, and the time at the time of defrost operation. The pump 23 is controlled so that the pump flow rate determined by the pump flow rate determining means 50 is obtained.

  FIG. 3 is a flow chart of pump flow rate control in the present embodiment. The flow for determining the flow rate of the pump will be described with reference to FIG.

(Step 1)
Proceed to step 2 after starting the boiling operation.

(Step 2)
The thermistor (hot water temperature detection means) 20E detects the hot water temperature and proceeds to step 3.

(Step 3)
It is determined whether or not it is immediately after the start of the boiling operation. If it is immediately after the start, the process proceeds to step 4; otherwise, the process proceeds to step 5.

(Step 4)
Determine the initial flow rate of the pump and proceed to step 19.

(Step 5)
It is determined whether or not the defrosting operation start condition is satisfied. If not satisfied, the process proceeds to step 6, and if satisfied, the process proceeds to step 13.

(Step 6)
The hot water temperature detected by the thermistor (hot water temperature detecting means) 20E is compared with the target hot water temperature, and if the target hot water temperature has not been reached, the process proceeds to step 9, and if the target hot water temperature has been reached, the process proceeds to step 7.

(Step 7)
Control is performed to decrease the flow rate of the pump (to increase the temperature of the hot water), and the process proceeds to step 8.

(Step 8)
If the flow rate of the pump after the reduction is lower than the lower limit value (boiling lower limit value) during the boiling operation, the boiling lower limit value is set as the pump flow rate, and the process proceeds to step 12.

(Step 9)
If the tapping temperature is higher than the target tapping temperature, the process proceeds to step 10, and if the tapping temperature is substantially equal to the target tapping temperature, the process proceeds to step 11.

(Step 10)
Maintain the current flow rate of the pump and proceed to Step 12.

(Step 11)
Increase the pump flow rate and proceed to Step 12.

(Step 12)
Determine the pump flow rate and proceed to step 19.

(Step 13)
The flow rate Q of the pump during the boiling operation is stored, and the process proceeds to step 14.

(Step 14)
It is determined whether it is a defrost preparation section. If it is a defrost preparation section, the process proceeds to step 15, and if it is not a defrost preparation section (that is, during the defrost operation), the process proceeds to step 18.

(Step 15)
The pump flow rate during the defrost preparation section is set to a value obtained by subtracting the decrease amount set by the pump decrease flow rate setting means 45 during the defrost preparation section operation, and the process proceeds to step 16.

(Step 16)
If the pump flow rate in the defrost preparation section obtained in step 15 is lower than the lower limit value set by the defrost preparation section pump flow rate lower limit setting means 46, the pump flow rate is set to the lower limit value, and the lower limit value is set. If it becomes lower, the pump flow rate is obtained and the process proceeds to step 17.

(Step 17)
The pump flow rate in the defrost preparation section is determined, and the process proceeds to step 19.

(Step 18)
The pump flow rate during the defrosting operation is determined, and the process proceeds to step 19.

(Step 19)
The pump is controlled so that the determined pump flow rate is obtained.

  As described above, the defrosting time can be shortened by providing the defrosting preparation section in which the flow rate of the pump is decreased for a certain period of time before starting the defrosting operation.

  As described above, the boiling control in the heat pump type hot water heater according to the present invention includes the integrated heat pump type hot water heater in which the hot water storage tank and the heat pump cycle are integrated, and the hot water heated by the water-refrigerant heat exchanger is directly discharged. It can also be applied to instantaneous water heating operation.

Configuration diagram of heat pump water heater in Embodiment 1 Block diagram of operation control in the first embodiment Control flowchart in Embodiment 1

Explanation of symbols

10A thermistor (compressor temperature detection means)
10B thermistor (discharge temperature detection means)
10C Pressure sensor (Discharge pressure detection means)
10D thermistor (outside temperature detection means)
10E thermistor (evaporator temperature detection means)
DESCRIPTION OF SYMBOLS 11 Inverter type compressor 12 Water-refrigerant heat exchanger 13 Pressure reducing device 14 Evaporator 20 Hot water storage tank 20A Thermistor (hot water amount detection means)
20B thermistor (hot water detection means)
20C thermistor (hot water detection means)
20D thermistor (incoming water temperature detection means)
20E Thermistor (Tapping temperature detection means)
23 Pump

Claims (5)

Compressor, water-refrigerant heat exchanger, decompression device, heat pump circuit constructed by connecting the evaporators in an annular shape through refrigerant piping, a hot water storage tank for storing hot water, a pump for circulating hot water in the hot water storage tank, water Before the start of the defrosting operation for defrosting the evaporator, and the hot water supply circuit configured by connecting the refrigerant heat exchangers in a ring shape, the pump is operated by reducing the flow rate of the pump for a certain period of time. A heat pump type hot water heater characterized by providing a frost operation preparation section. The heat pump type hot water heater according to claim 1, wherein a lower limit value is provided for a flow rate of the pump in the defrosting operation preparation section. The heat pump type hot water heater according to claim 2, wherein the lower limit value of the flow rate of the pump is set to be equal to or higher than the lower limit value of the boiling set during the normal heating operation in the defrosting operation preparation section. The heat pump type hot water heater according to any one of claims 1 to 3, wherein the refrigerant pressure on the high pressure side is equal to or higher than the critical pressure. The heat pump type hot water heater according to claim 4, wherein the refrigerant to be used is carbon dioxide.

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