JP2004340535A - Heat pump water heater - Google Patents

Abstract

An object of the present invention is to provide a heat pump hot water supply apparatus that controls the discharge temperature of refrigerant from a compressor to a target value quickly and stably, and has high durability and high operating efficiency.
A heat pump hot water supply apparatus of the present invention controls a pressure reducing means according to at least one of an operating frequency of a compressor, a discharge temperature, an outside air temperature, a set hot water supply temperature, and a water input temperature of a radiator. Then, the discharge temperature of the refrigerant of the compressor 10 is set to a predetermined temperature. According to the above invention, it is possible to provide a heat pump hot water supply apparatus capable of quickly and stably controlling the discharge temperature to a target value even if the incoming water temperature or the outside air temperature fluctuates.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat pump water heater.
[0002]
[Prior art]
As a conventional heat pump hot water supply device, a heat pump hot water supply device as described in Patent Document 1 has been proposed. As shown in FIG. 3, this heat pump hot water supply apparatus includes a refrigerant circulation circuit 5 including a compressor 1, a radiator 2, a pressure reducing means 3, and a heat absorber 4, a hot water tank 6, a radiator 2, and a flow rate adjusting means 7. Pressure reducing means such that the temperature difference between the incoming water temperature of the hot water supply circuit 8 flowing into the radiator 2 and the outlet temperature of the high-pressure refrigerant in the refrigerant circulation circuit 5 flowing out of the radiator 8 has a target value. 3 was provided with a control means 9 for controlling the control unit 3. When the discharge temperature of the refrigerant discharged from the compressor 1 is equal to or higher than a specified value, the control means 9 increases the target value of the temperature difference. As a result, the discharge temperature of the refrigerant is controlled within the operating temperature range of the compressor 1.
[0003]
However, in this configuration, the discharge temperature cannot be directly controlled. For example, when the operating frequency of the compressor 1, the discharge temperature, the outside air temperature, the set hot water supply temperature, the incoming water temperature, and the like change, the discharge temperature changes, and stable discharge is performed. Does not reach temperature. In addition, since the outlet temperature of the refrigerant is a temperature after heat exchange in the radiator 8, it takes time to stabilize, and it takes a long time to obtain an appropriate discharge temperature and a temperature difference. was there.
[0004]
[Patent Document 1]
JP-A-2002-188859
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned conventional problems, and to provide a heat pump hot water supply device that controls the discharge temperature of refrigerant from a compressor to a target value quickly and stably, and has high durability and high operation efficiency. I do.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a heat pump hot water supply apparatus, comprising: a pressure reducing means including an operating frequency of a compressor, a discharge temperature, an outside air temperature, a set hot water supply temperature, and an inlet temperature of a radiator of a hot water supply circuit. The discharge temperature of the refrigerant of the compressor is controlled to a predetermined temperature by performing control in accordance with at least one value.
[0007]
According to the present invention, the discharge temperature can be quickly and stably controlled to the target value.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The heat pump hot water supply apparatus according to the first aspect of the present invention includes a refrigerant circulation circuit including a compressor, a radiator, a pressure reducing unit, and a heat absorber, a hot water supply circuit including a hot water tank, the radiator, and a flow rate adjusting unit. Discharge temperature control means for adjusting the discharge temperature of the refrigerant of the compressor by controlling the pressure reducing means, wherein the discharge temperature control means comprises an operating frequency of the compressor, a discharge temperature, an outside air temperature, and a set hot water supply temperature. And at least one of the inlet temperatures of the radiator of the hot water supply circuit.
[0009]
According to the present invention, even if at least one of the operating frequency of the compressor, the discharge temperature, the outside air temperature, the set hot water supply temperature, and the inlet temperature of the radiator of the hot water supply circuit changes, the predetermined discharge temperature is maintained. By controlling the pressure reducing means, a desired discharge temperature can be obtained.
[0010]
According to a second aspect of the present invention, there is provided a heat pump hot water supply apparatus, wherein the discharge temperature control means according to the first aspect controls closed loop control for controlling the pressure reducing means in accordance with the discharge temperature, the operating frequency of the compressor, the outside air temperature, and the set hot water supply. An open loop control for controlling the pressure reducing means in accordance with at least one of the temperature and the inlet temperature is provided, and the closed loop control and the open loop control are controlled in combination.
[0011]
According to the present invention, since the discharge temperature is directly controlled by the closed loop control, a predetermined discharge temperature can be accurately obtained. Also, by combining the closed loop control and the open loop control, it is possible to quickly respond to changes in the operating frequency of the compressor, the outside air temperature, the set hot water supply temperature, and the inlet temperature.
[0012]
According to a third aspect of the present invention, in the heat pump hot water supply apparatus according to the second aspect, only open loop control is performed at the time of starting operation.
[0013]
According to the present invention, the effect of the discharge temperature that fluctuates at the start of operation or at the start of operation such as when switching from defrosting operation to normal operation is stopped by performing closed loop operation and performing only open loop control, thereby achieving stable pressure reduction. The means can be controlled.
[0014]
According to a fourth aspect of the present invention, in the heat pump water heater according to the second aspect, the open loop control value is fixed after a predetermined time from the start of the operation.
[0015]
According to the present invention, since the open loop control value is maintained until the predetermined time, it is possible to cope with a sudden change in the operating frequency of the compressor, the outside air temperature, the set hot water supply temperature, the inlet temperature and the like while the temperature state of the device is stabilized. Then, by fixing the open loop control value after a predetermined time to control only the closed loop, it is possible to accurately control the temperature to a predetermined temperature without interference between both the open loop control and the closed loop control.
[0016]
The heat pump water heater of the invention according to claim 5 is a supercritical heat pump cycle in which the refrigerant pressure is equal to or higher than the critical pressure in the refrigerant circulation circuit. It is configured to heat.
[0017]
According to the present invention, since the refrigerant that exchanges heat with the water in the hot water storage tank is pressurized to a critical pressure or higher, the refrigerant is not condensed even if the temperature is reduced by the heat of the water in the hot water storage tank. Therefore, it is easy to form a temperature difference between the refrigerant and the water in the entire heat exchange area, so that high-temperature hot water can be obtained and the heat exchange efficiency can be increased.
[0018]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
(Example 1)
FIG. 1 shows a configuration diagram of a heat pump water heater according to a first embodiment of the present invention. The present embodiment is a general household heat pump hot water supply apparatus for storing hot water mainly by using inexpensive midnight power, and includes a compressor 10, a radiator 11, a pressure reducing means 12, and a heat absorber 13 connected in series. And a hot-water supply circuit 17 having a hot water storage tank 15, a radiator 11, and a flow rate adjusting means 16, and a control means 18. The refrigerant circulation circuit 14 uses, for example, a supercritical heat pump cycle in which carbon dioxide gas (CO2) is used as a refrigerant and the refrigerant pressure on the high pressure side is equal to or higher than the critical pressure of the refrigerant. The compressor 10 is driven by a built-in electric motor (not shown), compresses the sucked refrigerant to a pressure exceeding a critical pressure, and discharges the compressed refrigerant. The radiator 11 performs heat exchange between the refrigerant in the refrigerant circuit 14 and the water in the hot water supply circuit 17. For example, a refrigerant passage through which the refrigerant flows and a flowing water passage through which the water flows are provided in a double pipe structure. And a counter-flow heat exchanger configured such that the flow direction of the refrigerant and the flow direction of the flowing water face each other. The pressure reducing means 12 changes the degree of pressure reduction of the refrigerant by driving a built-in stepping motor (not shown) to change the degree of opening of the flow path. The heat absorber 13 acts to absorb atmospheric heat by a fan (not shown).
[0020]
The hot water supply circuit 14 controls the flow rate adjusting means 16 so that the water in the hot water tank 15 is filled with a predetermined amount, that is, the hot water tank 15 is filled with hot water. This is a circulation configuration in which water is supplied from the bottom of the hot water storage tank 15 and returned to the upper part of the hot water storage tank 15, and the boiling in the hot water storage tank 15 is performed by heating the water in the hot water supply circuit 14 to a predetermined temperature by the radiator 11. The flow rate adjusting means 16 varies the flow rate by voltage control using a DC pump.
[0021]
19 is a tap water temperature setting means for setting a set hot water supply temperature which is a boiling temperature of the hot water storage tank 15. The set hot water supply temperature is determined by the amount of hot water used in hot water frost 5 per day, the water temperature, and the like. 20 is a discharge temperature detecting means for detecting the discharge temperature of the refrigerant of the compressor 10, 21 is an incoming water temperature detecting means for detecting an incoming water temperature of the hot water circuit 14 into the radiator 11, and 22 is a radiator 11 of the hot water circuit 14. A tapping temperature detecting means for detecting a tapping temperature from the outside, and 23 is an outside temperature detecting means for detecting an outside temperature. Reference numeral 24 denotes a water supply pipe to the hot water storage tank 15, and reference numeral 25 denotes a hot water supply pipe connecting the faucet 26 to the hot water storage tank 15.
[0022]
Next, the configuration and operation of the control means 18 will be described with reference to the operation system diagram of the control means shown in FIG. 27 is a discharge temperature control means for controlling the pressure reducing means 12 according to the discharge temperature, the outside air temperature, the incoming water temperature, the set hot water supply temperature and the target frequency. An open loop control means 28, a target discharge temperature setting means 29, a closed loop control means 30, and an adding section 31 are provided. The open loop control means 28 sets the basic opening of the pressure reducing means 12, and the closed loop control means The control amount of the feedback control is set so that the discharge temperature becomes the target value by 30, and the set value of the open-loop control means 28 and the set value of the closed-loop control means 30 are added by the adding unit 31 to control the pressure reducing means 12.
[0023]
The open loop control means 28 sets the optimal opening of the pressure reducing means 12 based on a combination of the three temperatures of the outside air temperature detecting means 23, the incoming water temperature detecting temperature 21, and the tap water temperature setting means 19. The values to be set here are obtained by calculating in advance the optimum values in the combination of the above three, digitizing the values, and storing them in a memory (not shown) for use. This open loop control is set so as to be fixed at a value after a lapse of a predetermined time (for example, 5 minutes) from the start of the operation when the operation is started, or when the operation is restarted such as when the operation is switched from the defrosting operation to the normal operation. are doing. This is because when the detection values of the outside air temperature detecting means 23 and the incoming water temperature detecting means 21 are suddenly changed due to the ambient temperature at the time of stopping or defrosting, control is performed using open-loop control in order to cope with this change. Then, when it is time for the outside air temperature and the incoming water temperature to settle down to their original values, the value of the open loop control is fixed, thereby acting to prevent interference with the closed loop control. In addition, if the error in the open loop control is small, it is possible to quickly control the disturbance without interference with the closed loop.
[0024]
The target discharge temperature setting means 29 sets the hot water supply temperature set by the tapping temperature setting means 19 by adding a predetermined temperature difference. This predetermined temperature difference is changed by respective values of the outside air temperature detecting means 23, the incoming water temperature detecting means 19, and the target frequency setting means 32. Conditions to be changed are set so that the discharge temperature falls within an appropriate temperature range, and an efficient operation is performed without causing abnormal discharge pressure or motor overcurrent of the compressor. For this predetermined temperature difference, an optimum value in a combination of the outside air temperature, the incoming water temperature, and the frequency is obtained in advance, converted into a numerical value, stored in a memory (not shown), and used.
[0025]
The closed loop control means 30 performs feedback control so that the detection value of the discharge temperature detection means 20 becomes the target value set by the target discharge temperature setting means 29. That is, if the detected value is lower than the target value, the opening of the pressure reducing means 12 is set to be reduced, and if the detected value is higher, the opening is set to be open. As the control method, known P control, PI control, PID control, fuzzy control, or the like may be used. This closed-loop control is performed for a predetermined time (for example, a time until the discharge temperature reaches a predetermined value) from the start of the operation when the operation is started or when the operation is restarted such as when the operation is switched from the defrosting operation to the normal operation. The operation is performed only by the open loop control without performing the operation. This is because if the feedback control is performed when the discharge temperature is significantly lower than the target value, the opening of the pressure reducing means 12 may be excessively narrowed and the discharge pressure may rise abnormally. This has the effect of preventing this.
[0026]
The target frequency setting means 32 sets an optimum operating frequency of the compressor 10 based on a combination of the three temperatures of the outside air temperature detecting means 23, the incoming water temperature detecting temperature 21, and the hot water temperature setting means 19. The values to be set here are obtained in advance by obtaining an optimum value in the combination of the three necessary to obtain a required hot water supply capacity, quantified, stored in a memory (not shown), and used. The optimum value is determined by judging not only the hot water supply capacity but also the overall operating condition such as the operating efficiency and the compressor discharge pressure, suction pressure, discharge temperature, compressor motor current, and the like.
[0027]
The hot water temperature control means 33 controls the flow rate adjusting means 16 in accordance with the values of the incoming water temperature detecting means 21, the hot water temperature detecting means 22 and the hot water temperature setting means 19 so that the hot water temperature becomes the set hot water supply temperature. That is, if the tapping temperature is low, the flow rate of the flow rate adjusting means 16 is decreased, and if the temperature is high, the flow rate is increased. Specifically, feedback control is performed by known PI control based on a temperature deviation between the set hot water supply temperature and the hot water supply temperature. In addition, the flow rate adjusting means 16 is controlled by multiplying by a coefficient inversely proportional to the difference between the set hot water supply temperature and the incoming water temperature and adding the result to the feedback value as a basic control amount. That is, in the case of the same hot water supply capacity, if the deviation between the set hot water supply temperature and the incoming water temperature is large, the required flow rate is small, and if the deviation is large, the required flow rate is large. The basic control amount is set in consideration of this point. The feedback control is PI control, but may be P control, PID control, or fuzzy control.
[0028]
According to the configuration of the first embodiment described above, using a supercritical heat pump cycle in which the refrigerant pressure on the high pressure side is equal to or higher than the critical pressure of the refrigerant, the counterflow type in which the flow direction of the refrigerant and the flow direction of the flowing water are opposed to the radiator Since a heat exchanger is used, hot water can be supplied efficiently at high temperature.
[0029]
Further, as the target value of the discharge temperature, an optimum value is set from the outside air temperature, the incoming water temperature, the set hot water supply temperature, and the target frequency, and the pressure reducing means is controlled by the closed loop control means so that the discharge temperature becomes the target value. The temperature can be reliably controlled to the target value. Further, the open loop control means sets the optimal opening of the pressure reducing means according to the outside air temperature, the incoming water temperature, and the set hot water supply temperature. Therefore, since an appropriate refrigerant always circulates through the refrigerant circuit, there is no abnormal temperature rise or abnormal pressure rise, and therefore, the durability is high and the operation efficiency can be improved.
[0030]
In the embodiment, the supercritical heat pump cycle is used as the heating means, but a normal heat pump cycle may be used.
[0031]
In this case, as the refrigerant, Freon gas, ammonia, and a hydrocarbon refrigerant (propane, butane, etc.) are useful.
[0032]
【The invention's effect】
As described above, according to the present invention, the present invention provides a heat pump hot water supply apparatus that can quickly and stably control the discharge temperature of refrigerant from a compressor to a target value, and has high durability and high operating efficiency. Can be.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a heat pump water heater according to a first embodiment of the present invention; FIG. 2 is an operation system diagram of control means of the heat pump water heater in the first embodiment; FIG. 3 is a configuration diagram of a conventional heat pump water heater; Description]
DESCRIPTION OF SYMBOLS 10 Compressor 11 Radiator 12 Decompression means 13 Heat sink 14 Refrigerant circulation circuit 15 Hot water tank 16 Flow rate adjustment means 17 Hot water supply circuit 19 Outlet water temperature setting means 20 Discharge temperature detection means 21 Incoming water temperature detection means 23 Outside air temperature detection means 27 Discharge temperature Control means 28 Open loop control means 30 Closed loop control means 32 Target frequency setting means

Claims (5)

A refrigerant circulation circuit including a compressor, a radiator, a pressure reducing means, and a heat absorber, a hot water supply circuit having a hot water tank, the radiator, and a flow rate adjusting means, and a discharge temperature of refrigerant of the compressor, the pressure reducing means. Discharge temperature control means for adjusting by controlling the discharge temperature control means, at least the operating frequency of the compressor, the discharge temperature, the outside air temperature, the set hot water supply temperature and the inlet temperature of the radiator of the hot water supply circuit. A heat pump water heater that controls according to one value. The discharge temperature control means includes a closed loop control for controlling the pressure reducing means in accordance with the discharge temperature, and an open control for controlling the pressure reducing means in accordance with at least one of the operating frequency of the compressor, the outside air temperature, the set hot water supply temperature, and the inlet temperature. The heat pump hot water supply apparatus according to claim 1, further comprising a loop control, wherein the control is performed by combining the closed loop control and the open loop control. 3. The heat pump water heater according to claim 2, wherein only the open loop control is performed when the operation is started. 3. The heat pump water heater according to claim 2, wherein the open loop control value is fixed after a predetermined time from the start of operation. The refrigerant circulation circuit is a supercritical heat pump cycle in which the pressure of the refrigerant is equal to or higher than the critical pressure, and heats the water in the hot water storage tank with the refrigerant pressurized to the critical pressure or higher. The heat pump water heater according to the above.

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