JP2013249966A - Heat pump type water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump type water heater capable of using a heating object fluid that has a viscosity variable with temperature.SOLUTION: A heat pump type water heater includes: a heat pump cycle 13 having a heat exchanger 18 for exchanging heat between a high temperature refrigerant discharged from a compressor 15 and a hot water supply fluid; a hot water supply fluid circulation circuit 12 having a hot water storage tank 11 for storing the hot water supply fluid heated in the heat exchanger 18 and a pressure-feeding means 14 for feeding the hot water supply fluid to the heat exchanger 18; temperature detecting means 21, 22 for detecting temperatures of the hot water supply fluid; and a control means 20 for controlling actuation of the pressure-feeding means 14 and of the compressor 15 on the basis of the temperature of the hot water supply fluid detected by the temperature detecting means 21. A fluid having a viscosity higher than a viscosity of water at a prescribed temperature or lower is used as the hot water supply fluid. The control means 20 starts actuation of the pressure feeding means 14 prior to the compressor 15, and when the temperature of the hot water supply fluid exceeds the prescribed temperature, the control means starts actuation of the compressor 15.

Description

  The present invention relates to a heat pump type water heater that heats a hot water supply fluid by a heat pump cycle.

  Conventionally, a heat pump cycle is known in which heat is exchanged between a high-temperature and high-pressure refrigerant discharged from a compressor and a fluid to be heated in a heat exchanger to heat the fluid to be heated. For example, Patent Literature 1 discloses a heat pump type hot water heater that heats hot water as a fluid to be heated using a heat pump cycle.

Japanese Patent No. 3227651

  In addition, as a dedicated heating application, it is considered to use an antifreeze liquid as a heating target fluid of a heat pump water heater. Since the antifreeze has a low melting point, it can be used in a temperature range of 0 ° C. or lower, but the viscosity tends to increase as the temperature decreases. For this reason, when using antifreeze as a fluid to be heated in a heat pump type hot water heater, the viscosity increases at the time of start-up in a low-temperature environment, and thus the flow rate required for the heat exchanger cannot be secured. When the heat pump cycle compressor is started in this state, when the high-temperature and high-pressure refrigerant flows into the heat exchanger, there is not a sufficient amount of fluid to be heated in the heat exchanger. May rise suddenly and damage the equipment.

  On the other hand, it is possible to change the pump for circulating the fluid to be heated to one having a high head and to perform control in consideration of the viscosity change of the fluid to be heated depending on the temperature. There is a problem that a large specification change is required for the heat pump type water heater.

  In view of the above points, an object of the present invention is to provide a heat pump type water heater that can use a fluid to be heated whose viscosity changes depending on temperature.

In order to achieve the above object, according to the first aspect of the present invention, a heat exchanger that exchanges heat between the high-temperature refrigerant discharged from the compressor (15) that compresses and discharges the refrigerant and the hot water supply fluid ( 18), a hot water storage tank (11) for storing hot water supply fluid heated by the heat exchanger (18), and a hot water supply fluid flowing out of the hot water storage tank (11). A hot water supply fluid circulation circuit (12) having a pumping means (14) for pumping to the heat exchanger (18), a temperature detection means (21, 22) for detecting the temperature of the hot water supply fluid, and the temperature detection means ( Control means (20) for controlling the operation of the pressure feeding means (14) and the compressor (15) based on the temperature of the hot water supply fluid detected in 21, 22),
The hot water supply fluid is a fluid having a higher viscosity than water at a predetermined temperature or less, and the control means (20) starts the operation of the pressure feeding means (14) before the compressor (15), When the temperature of the hot water supply fluid exceeds the predetermined temperature, the operation of the compressor (15) is started.

  Thus, by starting the operation of the pumping means (14) prior to the compressor (15) at the time of low temperature startup, the temperature of the hot water supply fluid can be raised, and the viscosity of the hot water supply fluid can be lowered accordingly. Then, by starting the operation of the compressor (15) when the temperature of the hot water supply fluid exceeds the predetermined temperature A, a sufficient flow rate of hot water supply fluid can be secured in the heat exchanger (16), and the high temperature refrigerant The amount of heat it has can be reliably radiated to the hot water supply fluid by the heat exchanger (16). Thereby, the malfunction that the flow rate of the hot water supply fluid is insufficient in the heat exchanger (16) and the temperature and pressure of the refrigerant rapidly increase can be prevented. As a result, it is possible to use a fluid to be heated whose viscosity changes depending on the temperature without changing the pumping means of a conventional heat pump type water heater using water as a hot water supply fluid.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

It is a whole lineblock diagram of the heat pump type hot water heater of a 1st embodiment. It is a flowchart which shows the control process of the boiling operation of 1st Embodiment. It is explanatory drawing which shows the action | operation of the fluid pump at the time of starting, and a compressor, (a) shows the case where the fluid temperature for hot water supply at the time of starting exceeds predetermined temperature, (b) shows the fluid temperature for hot water supply at the time of starting Shows a case where the temperature does not exceed the predetermined temperature. It is a whole block diagram of the heat pump type water heater of 2nd Embodiment. It is a flowchart which shows the control processing of the boiling operation of 2nd Embodiment.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a heat pump type hot water heater 10 is a heat pump cycle for heating a hot water supply fluid circulation circuit 12 that circulates a hot water supply fluid in a hot water storage tank 11 and a hot water supply fluid as a fluid to be heated. A heat pump cycle 13 is provided. In this embodiment, antifreeze is used as the hot water supply fluid. The antifreeze is a liquid containing propylene glycol as a main component and can be used even in a low temperature environment of 0 ° C. or lower, but has a characteristic that the viscosity increases as the temperature decreases.

  The hot water storage tank 11 for storing hot water supply fluid is a tank that is formed of a metal (for example, stainless steel) having excellent corrosion resistance, has a heat insulating structure, and can retain a high temperature hot water supply fluid for a long time. The hot water supply fluid stored in the hot water storage tank 11 is discharged from an outlet provided in the upper part of the hot water storage tank 11 and used for heating applications such as floor heating. A hot water supply fluid used for heating is recirculated from an inflow port provided at a lower portion in the hot water storage tank 11.

  The hot water supply fluid circulation circuit 12 is provided with a hot water supply fluid pump 14 as pressure feeding means for circulating the hot water supply fluid. The hot water supply fluid pump 14 is configured to be able to change the flow rate of the hot water supply fluid to be pumped by changing the rotation speed, and its operation is controlled by a control signal output from the control device 20. The When the control device 20 operates the hot water supply fluid pump 14, the hot water supply fluid is supplied from the hot water supply fluid outlet 11 a provided on the lower side of the hot water storage tank 11 → the hot water supply fluid pump 14 → the heat exchanger 16 described later. The hot water supply fluid passage 16 a circulates in the order of the hot water supply fluid inlet 11 b on the upper side of the hot water storage tank 11.

  The heat pump cycle 13 is a refrigeration cycle in which a compressor 15, a heat exchanger 16, an expansion valve 17, an evaporator 18 and the like are sequentially connected by piping. The heat pump cycle 13 employs carbon dioxide as a refrigerant, and constitutes a supercritical refrigeration cycle in which the pressure of the high-pressure refrigerant discharged from the compressor 15 is equal to or higher than the critical pressure of the refrigerant.

  The compressor 15 sucks the refrigerant in the heat pump cycle 13 and compresses and discharges the refrigerant until it reaches a critical pressure or higher. As the compressor 15, for example, a fixed capacity type electric compressor can be used.

  The refrigerant discharge port of the compressor 15 is connected to the refrigerant passage 16 b inlet side of the heat exchanger 16. The heat exchanger 16 is a heat exchanger configured to include a hot water supply fluid passage 16a through which hot water supply fluid passes and a refrigerant passage 16b through which high-temperature and high-pressure refrigerant discharged from the compressor 15 passes. The heat exchanger for heating heats the hot water supply fluid by dissipating the amount of heat of the high-temperature and high-pressure refrigerant discharged from the machine 15 to the hot water supply fluid. In the heat pump cycle 13 of the present embodiment, as described above, the supercritical refrigeration cycle is configured. Therefore, the refrigerant passing through the refrigerant passage 16b of the heat exchanger 16 dissipates heat in the supercritical state without being condensed. To do.

  The inlet side of the expansion valve 17 is connected to the outlet side of the refrigerant passage 16 b of the heat exchanger 16. The expansion valve 17 is a variable throttle mechanism that decompresses and expands the high-pressure refrigerant that has flowed out of the refrigerant passage 16 b of the heat exchanger 16.

  An evaporator 18 is connected to the outlet side of the expansion valve 17. The evaporator 18 performs heat exchange between the low-pressure refrigerant decompressed by the expansion valve 17 and the outside air (outdoor air) blown by a blower fan (not shown), thereby evaporating the low-pressure refrigerant and exerting an endothermic effect. It is a heat exchanger.

  Of the components of the hot water supply fluid circulation circuit 12, the hot water storage tank 11 is configured as a tank unit 200 and is disposed indoors. Further, the hot water supply fluid pump 14 of the hot water supply fluid circulation circuit 12, the components 15 to 18 of the heat pump cycle 13, etc. are integrally configured as a heat pump unit 300 and are disposed outdoors. For this reason, the temperature of the hot water supply fluid pumped by the hot water supply fluid pump 14 is affected by the outside air temperature.

  Next, the control device 20 of the present embodiment will be described. The control device 20 includes a known microcomputer including a CPU, a ROM, a RAM, and the like and peripheral circuits thereof. On the output side of the control device 20, a hot water supply fluid pump 14, a compressor 15 and the like are connected to control the operation thereof. Further, on the input side of the control device 20, a first temperature sensor 21 that detects the temperature of the hot water supply fluid flowing into the hot water supply fluid pump 14 in the hot water supply fluid circulation circuit 12 (hereinafter referred to as “hot water supply fluid temperature”). A second temperature sensor 22 for detecting the temperature of the hot water supply fluid flowing out from the heat exchanger 16 is connected. The first temperature sensor 21 is provided downstream of the hot water storage tank 11 in the hot water supply fluid circulation circuit 12 and upstream of the hot water supply fluid pump 14, and the second temperature sensor 22 is provided in the heat exchanger 16 in the hot water supply fluid circulation circuit 12. It is provided on the downstream side. These temperature sensors 21 and 22 are configured to detect a hot water supply fluid temperature that changes according to the ambient temperature (outside air temperature).

  Next, the operation of the heat pump type water heater 10 of the present embodiment having the above configuration will be described with reference to FIGS. The control process shown in FIG. 2 starts when a heating operation start request signal is output from an operation panel (not shown) in a state where power is supplied to the heat pump type hot water heater 10 from the outside.

  When the boiling operation is started, the hot water supply fluid temperature is detected based on the sensor signals of the temperature sensors 21 and 22 (S10), and it is determined whether or not the hot water supply fluid temperature exceeds a predetermined temperature A (S11). Here, the predetermined temperature A will be described. As described above, when an antifreeze liquid is used as the hot water supply fluid, the viscosity increases in a low temperature environment. Therefore, even if the hot water supply fluid pump 14 is operated, the flow rate of the hot water supply fluid flowing into the heat exchanger 16 is high. Less. For this reason, the predetermined temperature A is a temperature at which the viscosity of the hot water supply fluid decreases to such an extent that the flow rate of the hot water supply fluid necessary for the heat exchanger 16 can be secured when the hot water supply fluid pump 14 circulates the hot water supply fluid. Set as The predetermined temperature A may be set based on the type and concentration of the antifreeze used as the hot water supply fluid, and is set to 0 ° C. in this embodiment.

  As a result of the determination process of S11, when it is determined that the hot water supply fluid temperature is higher than the predetermined temperature A (S11: YES), heat exchange is performed when the hot water supply fluid is circulated by the hot water supply fluid pump 14. Since the flow rate of the hot water supply fluid required for the water heater 16 can be secured, the operation of the hot water supply fluid pump 14 is started at the normal rotation (first rotation speed) (S12), and the operation of the compressor 15 is started (S13). .

  As a result, as shown in FIG. 3 (a), when the hot water supply fluid temperature at the time of activation exceeds a predetermined temperature A, the hot water supply fluid pump 14 and the compressor 15 start operating simultaneously. Immediately after the start-up, the hot water supply fluid pump 14 is operated in a start-up operation having a higher rotational speed than the steady operation in order to circulate hot water supply fluid through the hot water supply fluid circulation circuit 12 at an early stage. Thereafter, the hot water supply fluid pump 14 shifts to a steady operation having a lower rotational speed than the start operation.

  On the other hand, as a result of the determination process of S11, when it is determined that the hot water supply fluid temperature does not exceed the predetermined temperature A (S11: NO), when the hot water supply fluid pump 14 circulates the hot water supply fluid, Since the flow rate of the hot water supply fluid necessary for the heat exchanger 16 cannot be secured, the operation of the hot water supply fluid pump 14 is started at a high speed (second rotation speed) (S14). Thereby, as shown in FIG.3 (b), when the hot water supply fluid temperature at the time of starting is below the predetermined temperature A, only the hot water supply fluid pump 14 will start operation. When the temperature of the hot water supply fluid at the time of startup is equal to or lower than the predetermined temperature A, the viscosity of the hot water supply fluid (antifreeze) is high. The hot water supply fluid temperature at the start-up shown is higher than that when the temperature is higher than the predetermined temperature A.

  By starting the operation of the hot water supply fluid pump 14 in the process of S14, the hot hot water supply fluid kept in the hot water storage tank 11 starts to circulate. For this reason, it is possible to gradually increase the temperature of the hot water supply fluid that was initially low.

  Next, the hot water supply fluid temperature is detected based on the sensor signals of the temperature sensors 21 and 22 (S15), and it is determined whether or not the hot water supply fluid temperature exceeds a predetermined temperature A (S16). Then, the processes of S15 and S16 are repeated until the hot water supply fluid temperature exceeds the predetermined temperature A. When the hot water supply fluid temperature exceeds the predetermined temperature A (S16: YES), the operation of the compressor 15 is started. (S13).

  According to the configuration of the present embodiment described above, the hot water supply fluid pump 14 is started prior to the compressor 15 at the time of low temperature startup when the viscosity of the hot water supply fluid made of the antifreeze liquid is high. The viscosity of the hot water supply fluid can be lowered accordingly. When the hot water supply fluid temperature exceeds the predetermined temperature A, a sufficient flow rate of hot water supply fluid can be secured in the heat exchanger 16. For this reason, by starting the operation of the compressor 15 when the temperature of the hot water supply fluid exceeds the predetermined temperature A, the heat quantity of the high-temperature and high-pressure refrigerant can be reliably radiated to the hot water supply fluid by the heat exchanger 16. . For this reason, it is possible to prevent a problem that the flow rate of the hot water supply fluid is insufficient in the heat exchanger 16 and the temperature and pressure of the refrigerant rapidly increase. As a result, it is possible to use an antifreeze liquid whose viscosity changes with temperature as the hot water supply fluid without changing the fluid pump of the conventional heat pump type hot water heater using water as the hot water supply fluid.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different parts are described.

  As shown in FIG. 4, in the heat pump type water heater 10 of the second embodiment, a heater 23 is provided as an auxiliary heat source for heating the hot water supply fluid in the hot water supply fluid circulation circuit 12. The heater 23 is arranged on the upstream side of the hot water supply fluid pump 14 in the hot water supply fluid circulation circuit 12 and is included in the heat pump unit 300. In the present embodiment, an electric heater is used as the heater 23.

  Next, the operation of the heat pump type water heater 10 of the second embodiment will be described with reference to FIG.

  In the second embodiment, the hot water supply fluid temperature is determined not to exceed the predetermined temperature A in the determination process of S11, and the operation of the hot water supply fluid pump 14 is started at a high speed in the process of S14. It is determined whether a predetermined time has elapsed from the start of operation of the fluid pump 14 (S17).

  As a result, when it is determined that the predetermined time has not elapsed (S17: NO), the process proceeds to S15. On the other hand, when it is determined that the predetermined time has elapsed (S17: YES), the heater 23 is operated (S18), and the process proceeds to S15.

  Next, when it is determined in the determination process of S16 that the hot water supply fluid temperature is higher than the predetermined temperature A, it is determined whether or not the heater 23 is operating (S19). As a result, when it is determined that the heater 23 is not operating (S19: NO), the process proceeds to S13. On the other hand, when it is determined that the heater 23 is operating (S19: YES), the operation of the heater 23 is stopped (S20), and the process proceeds to S13.

  According to the configuration of the second embodiment described above, when the hot water supply fluid temperature does not rise to the predetermined temperature A even after a predetermined time has elapsed since the operation of the hot water supply fluid pump 14 is started at low temperature startup, the heater 23 The hot water supply fluid temperature can be forcibly raised to a predetermined temperature A or higher by heating the hot water supply fluid. As a result, even if the hot water supply fluid temperature in the hot water storage tank 11 is low and the hot water supply fluid in the hot water storage tank 11 circulates, the hot water supply fluid temperature does not increase. Therefore, a sufficient amount of hot water supply fluid can be secured in the heat exchanger 16.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows without departing from the spirit of the present invention.

  For example, in each of the above embodiments, the antifreeze liquid is used as the heating target fluid heated by the refrigerant in the heat exchanger 16, but the heating target fluid may be a fluid having a viscosity higher than water at a predetermined temperature A or lower, A different type of fluid from the antifreeze may be used.

  In the heat pump cycle 13 of each of the above embodiments, the supercritical refrigeration cycle is configured using carbon dioxide as a refrigerant. However, the present invention is not limited to this, and high pressure pressure is critical as in refrigerants such as chlorofluorocarbon and HC. You may comprise a subcritical refrigerating cycle using the refrigerant | coolant which does not exceed a pressure.

DESCRIPTION OF SYMBOLS 11 Hot water storage tank 12 Fluid circulation circuit for hot water supply 13 Heat pump cycle 14 Fluid pump (pressure feeding means)
15 Compressor 16 Heat exchanger 20 Control device (control means)
21 1st temperature sensor (temperature detection means)
22 Second temperature sensor (temperature detection means)
23 Heater (heating means)

Claims (3)

A heat pump cycle (13) having a heat exchanger (18) for exchanging heat between the high-temperature refrigerant discharged from the compressor (15) that compresses and discharges the refrigerant, and the hot water supply fluid;
A hot water storage tank (11) for storing hot water supply fluid heated by the heat exchanger (18), and a pressure feeding means for pumping the hot water supply fluid flowing out of the hot water storage tank (11) to the heat exchanger (18) (14) a hot water supply fluid circulation circuit (12),
Temperature detecting means (21, 22) for detecting the temperature of the hot water supply fluid;
Control means (20) for controlling the operation of the pressure feeding means (14) and the compressor (15) based on the temperature of the hot water supply fluid detected by the temperature detection means (21, 22),
The hot water supply fluid is a fluid whose viscosity at a predetermined temperature or lower is higher than that of water,
The control means (20) starts the operation of the pressure feeding means (14) prior to the compressor (15), and when the temperature of the hot water supply fluid exceeds the predetermined temperature, the compressor (15 ) Is started, a heat pump type water heater. The pumping means (14) is configured to change the flow rate of the hot water supply fluid pumped by changing the number of rotations,
When the temperature of the hot water supply fluid is higher than the predetermined temperature, the control means (20) operates the pressure feeding means (14) at a first rotational speed so that the temperature of the hot water supply fluid is the predetermined temperature. 2. The heat pump type hot water heater according to claim 1, wherein when the temperature is equal to or lower than the temperature, the pumping means is operated at a second rotation speed higher than the first rotation speed. Heating means (22) for heating the hot water supply fluid;
When the predetermined time has elapsed from the start of operation of the pressure feeding means (14), the control means (20) causes the heating means (22) to turn on the heating means (22) if the temperature of the hot water supply fluid does not reach the predetermined temperature. The heat pump type hot water heater according to claim 1 or 2, wherein the hot water supply fluid is heated.

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