JP4029957B2 - Heat pump water heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat pump water heater capable of supplying hot water by heating water in a hot water storage tank by a heat pump refrigeration cycle, and in particular, even if there is residual hot water in the hot water storage tank, the temperature of the entire hot water storage is set It is related with the heat pump water heater which can be almost equalized.
[0002]
[Prior art]
Conventionally, as an example of this type of heat pump water heater, for example, as shown in FIG. 5, a heat pump refrigeration cycle 1 that circulates a refrigerant, and a water circuit 10 that supplies water heated by the refrigeration cycle 1 to a hot water supply tank 12. There is a thing equipped with.
[0003]
The refrigeration cycle 1 is a closed loop in which a refrigerant is circulated by sequentially connecting a compressor 2, a primary heat exchange pipe 3a of a water heat exchanger 3, an expansion valve 5, and an outdoor air heat exchanger 6 in this order by a refrigerant pipe 7. Is configured. In addition, the code | symbol 8 in FIG. 5 is a defrost two-way valve opened by the controller 9 at the time of a defrost operation, and 17 is various temperature sensors.
[0004]
On the other hand, the water circuit 10 sequentially connects the primary heat exchange pipe 3a with the primary heat exchange pipe 3a of the water heat exchanger 3 to the secondary heat exchange pipe 3b, the auxiliary heater 11, the hot water supply tank 12, and the pump 13 in this order. To form a closed loop for circulating water (or hot water).
[0005]
The hot water storage tank 12 is provided with a hot water inlet / outlet 12a serving both as a hot water inlet and a hot water inlet through which hot water from the auxiliary heater 11 is supplied, and one end of a bifurcated branch pipe connected to the hot water inlet / outlet 12a is connected to the auxiliary heater 11 side. One end of the other branch pipe is connected to the hot water supply line 15. On the other hand, a water inlet 12b and a water outlet 12c for receiving water are provided at the bottom of the hot water supply tank 12, and a water supply line 16 is connected to the water inlet 12b.
[0006]
During the hot water storage operation, the refrigerant circulates in the direction indicated by the arrow in FIG. 5 and the water heat exchanger 3 acts as a condenser, while the air heat exchanger 6 acts as an evaporator. For this purpose, when the water pumped out from the water outlet 12c at the bottom of the hot water storage tank 12 by the pump 13 passes through the secondary heat exchange pipe 3b of the water heat exchanger 3, the primary heat exchange pipe 4b passes through the secondary heat exchange pipe 4b. The hot water is heated by the condensation heat of the high-temperature and high-pressure gaseous refrigerant that passes therethrough, and becomes hot water. The hot water is fed into the hot water storage tank 12 through the water pipe 14 from the hot water inlet / outlet 12 a by the water pipe 14.
[0007]
In the hot water storage tank 12, the upper hot water storage layer and the lower water storage layer in which water having a lower temperature than the hot water storage is distributed with little mixing, and the hot water heated by the water heat exchanger 3 is distributed. The hot water tank 12 is supplied from the upper hot water inlet / outlet 12a, so that the hot water is stored in the upper hot water reservoir and gradually descends to the lower hot water reservoir, and finally rises. Since the hot water flows into the water heat exchanger 3, when the inlet water temperature of the water heat exchanger 3 reaches a set temperature (for example, about 30 ° C.), the hot water storage temperature in the hot water storage tank 12 is a predetermined value (for example, The controller 9 determines that the temperature has reached 85 ° C.), ends the hot water storage operation, and waits for the hot water supply operation.
[0008]
That is, the hot water storage temperature of the hot water storage layer in the hot water storage tank 12 is determined by the inlet water temperature of the water heat exchanger 3, and the rotational speed of the compressor 2 is controlled so as to reach this set temperature during the hot water storage operation. Further, the discharge flow rate of the pump 13 is set to a flow rate at which all of the water in the hot water storage tank 12 makes a round in the late-night power time period (generally 8 hours) when the power rate is reduced. After this hot water storage operation, the hot water supply operation is performed, and the hot water in the hot water storage tank 12 is supplied from the hot water inlet / outlet 12a to the hot water supply portion (not shown) via the hot water supply line 15 and is approximately the same amount as the hot water supply amount. Is supplied to the hot water storage tank 12 through the water supply line 16.
[0009]
[Problems to be solved by the invention]
However, in such a conventional heat pump water heater, after the hot water supply operation, as shown in FIG. 6, when the remaining hot water amount of the hot water storage layer A accumulated in the upper portion of the hot water storage tank 12 is large, By repeating the operation and the hot water supply operation, there is a problem in that the temperature of the remaining hot water layer A is not always used and the temperature is lowered due to heat loss, and the total heat storage amount is reduced, that is, the predetermined heat storage amount cannot be stored.
[0010]
That is, as shown in FIG. 6, before the hot water storage operation is started, for example, in the midnight time zone when the power rate is low, the remaining hot water layer A whose temperature is lowered due to heat loss is stored in the hot water storage tank 12 at a lower temperature. Since it is distributed above the layer B, the hot water in these layers A and B is distributed in a state of being hardly mixed. As shown in FIG. 7, at the end of the hot water storage operation in the midnight power hours, the remaining hot water The remaining hot water in the layer A is gradually lowered in the hot water storage tank 12 while being further reduced due to heat loss (for example, 70 ° C.), and the remaining hot water is heated on the remaining hot water layer A by the water heat exchanger 3. The hot water storage layer C that has reached the target temperature (for example, 85 ° C.) is distributed, and the hot water of these layers A and C is higher in the hot water in the upper layer than in the lower layer. It remains separated and hardly mixed.
[0011]
For this reason, as the hot water supplied from the water outlet 12c of the hot water storage tank 12 to the hydrothermal exchanger 3, even if the temperature is lowered due to heat loss, a relatively hot remaining hot water is supplied. Before the remaining hot water of A reaches the target temperature, the inlet water temperature of the water heat exchanger 3 reaches a set temperature (for example, 30 ° C.), and the hot water storage operation ends. For this reason, in the hot water storage tank 12, the hot water layer C that has reached a predetermined target temperature (for example, 85 ° C.) and the remaining hot water layer A having a temperature lower than this are distributed vertically. Since the hot water storages of both layers A and C are not mixed and are almost separated, the hot water storage temperature in the entire hot water storage tank 12 is not uniform.
[0012]
Therefore, as shown in FIG. 8, when the hot water storage operation is completed (before midnight electric power hot water storage), the remaining hot water layer in which the temperature is further lowered (for example, lowered from 70 ° C. to 65 ° C.) due to the heat loss of the hot water in the hot water storage tank 12. A remains in the upper part of the hot water storage tank 12. In other words, the daily hot water layer A is reduced in temperature day by day by heat loss, and the hot water of the residual hot water layer A is supplied hot water, so that the hot water supply temperature cannot be raised to the target temperature. It becomes a challenge.
[0013]
By the way, although there is a remaining hot water in the hot water storage tank 12 in this way, it is possible to think that the amount of heat storage may be small, but there is a case where a large amount of hot water supply at the target temperature is suddenly required. Need to be secured every day. That is, it is necessary to store hot water (heat storage) almost uniformly at the target temperature over almost the entire amount of hot water stored in the hot water storage tank 12.
[0014]
The present invention has been made in consideration of such circumstances, and its purpose is to store hot water in the hot water storage tank almost uniformly at a target temperature (heat storage) at any time even when there is remaining hot water in the hot water storage tank. It is in providing the heat pump water heater which can do.
[0015]
[Means for Solving the Problems]
The invention of claim 1 includes a refrigeration cycle in which a refrigerant is circulated by sequentially connecting a compressor, a first heat exchange pipe of a water heat exchanger, an expansion valve, and an air heat exchanger, and the first of the water heat exchanger. A heat exchange pipe and a second heat exchange pipe capable of exchanging heat, a hot water inlet and a hot water inlet for receiving hot water from the second heat exchange pipe are provided in the upper portion, and a water supply inlet and a water outlet for receiving water are provided. A hot water storage tank provided in the lower part, a main circuit for sequentially circulating water by connecting a pump, a bypass path connecting the water discharge side of the pump and the hot water inlet side of the hot water storage tank, and an intermediate part of the bypass path Before the hot water storage operation for circulating the water in the hot water storage tank with the on-off valve and the water in the hot water storage tank to the water circuit and raising the temperature of the water to the set value of the inlet water temperature of the water heat exchanger, When the remaining hot water in the tank is detected, the above water heat exchange is performed according to the remaining hot water amount. After the end of the hot water storage operation by the hot water storage temperature control means, the hot water storage temperature control means for correcting the inlet water temperature setting value to a preset value higher than the inlet water temperature set value of And a hot water storage temperature equalizing means for operating the pump while opening and closing the on-off valve for a predetermined time.
[0016]
According to this invention, after the hot water supply operation and before the start of the hot water storage operation, when the remaining hot water in the hot water storage tank is detected, the set value of the inlet water temperature of the second heat exchange pipe of the water heat exchanger (the set value of the hot water temperature) Is corrected to a temperature higher than the set value by the hot water storage temperature control means in accordance with the amount of remaining hot water, and the hot water storage operation is performed. For this purpose, hot water storage hot water heated by a water heat exchanger is supplied at a predetermined flow rate on a low temperature remaining hot water layer whose temperature has been reduced due to heat loss in the hot water storage tank. When the inlet water temperature reaches the correction set value, the hot water storage operation ends.
[0017]
After completion of this hot water storage operation, the hot water storage temperature equalizing means opens the bypass passage opening and closing valve and operates the pump for a predetermined time. For this purpose, the low-temperature remaining hot water at the bottom of the hot water tank is boosted by the pump, bypasses the water heat exchanger, passes through the open / close valve and bypass passage, and enters the hot water tank. It is supplied directly from the upper hot water inlet.
[0018]
For this reason, in the hot water storage tank, hot water such as residual hot water or water having a lower temperature is supplied onto the hot water storage layer, so that it is mixed by natural convection and the temperature of the hot water in the hot water storage tank as a whole. Distribution is made uniform at high temperatures. Therefore, even if there is remaining hot water in the hot water storage tank, hot water can be stored at a predetermined temperature. In addition, at this time, since the remaining hot water in the hot water storage tank is directly returned to the upper part of the hot water storage tank by bypassing the hydrothermal exchanger having a large flow path resistance, the amount of the recirculation can be increased. For this reason, since mixing of hot water having different temperatures in the hot water storage tank can be promoted, the temperature equalizing operation time can be shortened.
[0019]
According to the invention of claim 2, the hot water storage temperature equalizing means sets in advance the operation time of the pump operated by opening the on-off valve in accordance with the amount of remaining hot water, or the inlet of the water heat exchanger 2. The heat pump water heater according to claim 1, wherein the pump is stopped when the water temperature reaches a set value corresponding to a predetermined hot water storage temperature.
[0020]
According to the present invention, since the pump operation time after opening the on-off valve of the bypass passage is set according to the amount of remaining hot water in the hot water storage tank, the hot water storage temperature in the hot water storage tank is determined regardless of the amount of remaining hot water. It can always be kept almost constant. Also, when the water temperature at the inlet of the water heat exchanger reaches the inlet temperature of the water heat exchanger corresponding to the temperature of the hot water stored in the hot water storage tank, the operation of the pump is stopped by the hot water temperature equalizing means. Regardless of the amount of remaining hot water, the hot water storage temperature can always be kept substantially constant.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. In these drawings, the same or corresponding parts are denoted by the same reference numerals.
[0022]
FIG. 1 is a block diagram showing an overall configuration of a heat pump water heater 21 according to an embodiment of the present invention. The heat pump water heater 21 includes a water circuit 31 that circulates water in the arrow direction in the figure, and a heat pump refrigeration cycle 41 that circulates a refrigerant as a heating medium for heating the water in the water circuit 31 in the arrow direction in the figure. ing.
[0023]
The refrigeration cycle 41 includes a compressor 42 whose rotation speed per unit time (rotational speed) can be controlled by controlling an operation frequency by an inverter (not shown), and a first (primary side) heat exchange pipe of the water heat exchanger 43. 43a, a flow rate adjustable expansion valve 44 including an electric valve, etc., and an air heat exchanger 45 installed outside the room are sequentially connected by a refrigerant pipe 46 in this order to constitute a closed loop for circulating the refrigerant. The discharge side of the compressor 42 and the refrigerant inlet side of the air heat exchanger 45 are communicated with each other by a defrost bypass passage 47, and a defrost bypass valve made up of an electromagnetic two-way valve or the like is provided in the middle of the defrost bypass passage 47. 48 is interposed.
[0024]
The water heat exchanger 43 and the air heat exchanger 45 are each provided with a fan (not shown) for promoting heat exchange between water and air or the refrigerant, while the water heat exchanger 43 detects the refrigerant condensation temperature. A condensing temperature sensor 49 is provided, an evaporating temperature sensor 50 for detecting the evaporating temperature of the refrigerant is provided on the downstream side of the expansion valve 44, and the compressor 42 further includes a suction side temperature sensor 51 for detecting the suction side temperature. A discharge side temperature sensor 52 for detecting the discharge side temperature is provided.
[0025]
The suction side and discharge side temperature sensors 51 and 52, the evaporation temperature sensor 50, the condensation temperature sensor 49, the expansion valve 44, the defrost bypass valve 48, and a heat exchange fan (not shown) are connected to the controller 53 by a signal line (not shown). Electrically connected.
[0026]
On the other hand, the water circuit 31 includes a primary side heat exchange pipe 43a through which the refrigerant of the water heat exchanger 43 passes, a secondary side heat exchange pipe 43b through which heat exchangeable water passes, an auxiliary heater 32, a hot water supply tank 33 which is a hot water storage tank, The main circuit of the closed loop which circulates water in the direction of the arrow in the figure by sequentially connecting the pump 34 with variable flow rate in this order by the water pipe 35 is configured. During the hot water storage operation, the pump 34 only needs to have the capability of making a round of hot water (water) in the hot water storage tank 33 in about 8 hours in the midnight hours when the electricity rate is cheap, and the water heat exchanger 43 also has a low temperature amount. It only has to have the ability of.
[0027]
The hot water storage tank 33 is provided with a hot water inlet / outlet 33a that serves both as a water inlet for receiving hot water (hot water) from the auxiliary heater 32 and a hot water outlet for supplying hot water to a hot water supply unit (not shown). One branch end of the bifurcated branch pipe connected to is connected to the outlet water channel side of the auxiliary heater 11, while the other branch end is connected to the hot water supply pipe 38. On the other hand, at the lower part of the hot water storage tank 33, a water receiving port 33b connected to the water supply pipe 39 and a water outlet 33c for supplying water in the hot water storage tank 33 or supplying hot water are formed.
[0028]
Then, the heat exchange bypass passage 36 that connects the discharge side of the pump 34 and the water outlet side of the water heat exchanger 43 to bypass the water heat exchanger 43 and the heat exchange bypass passage 36 are interposed in the middle. Water temperature sensor 40a for detecting the temperature of the hot water from the heat exchanger bypass valve 37, the secondary heat exchange pipe 43b of the water heat exchanger 43, and the water temperature for detecting the temperature of the water from the water outlet 33c of the hot water storage tank 33 The sensor 40b and the 2nd water temperature sensor for detecting the water temperature in the hot water storage tank 33, and detecting remaining hot water are provided. The second water temperature sensor, the auxiliary heater 32, the pump 34, and the heat exchange bypass valve 37 are electrically connected to the controller 53 through a signal line (not shown).
[0029]
The controller 53 comprises, for example, a microprocessor or the like, and includes a remaining hot water amount detection means, a hot water storage temperature control means, a hot water storage temperature equalization means, a frost detection means, a defrost completion detection means, an expansion valve opening control means, and a variable flow rate pump 34. Are provided with pump control means and compressor control means for controlling the rotation speed (the number of revolutions per unit time).
[0030]
The remaining hot water amount detecting means is a means for detecting the remaining hot water amount in the hot water storage tank 33 based on a temperature detection value detected by a second water temperature sensor (not shown) in the hot water storage tank 33 after the hot water supply operation and before the hot water storage operation. .
[0031]
The hot water storage temperature control means sets a target value of the hot water temperature supplied into the hot water storage tank 33 by setting the inlet water temperature of the secondary side heat exchange pipe 43b of the water heat exchanger 43 to a predetermined value. When the remaining hot water is detected, the inlet water temperature set value of the water heat exchanger 43 is corrected so as to increase by a predetermined value according to the remaining hot water amount, and the hot water storage operation is performed. Electricity for hot water storage operation is performed using, for example, electric power in the midnight time zone where the electric power charge is low.
[0032]
In the hot water storage operation, for the refrigeration cycle 41, the defrosting bypass valve 48, which is a two-way valve for defrosting, is closed and the hot water storage operation is performed, the heat exchange bypass valve 37 of the water circuit 31 is closed, and the pump 34 is operated. The stored water or hot water in the hot water storage tank 33 is sent to the secondary heat exchange pipe 43b of the water heat exchanger 43, where it is heated by the condensation heat of the high-temperature and high-pressure gaseous refrigerant passing through the primary heat exchange pipe 43a. Until the hot water storage temperature reaches a set value (target value), that is, the water temperature sensor indicates that the inlet water temperature of the secondary heat exchange pipe 43a of the water heat exchanger 43 has reached a predetermined set temperature (for example, about 30 degrees). It is operated until it is detected by 40b. The hot water supply operation is an operation of supplying hot water in the hot water storage tank 33 to a hot water supply portion (not shown) through the water supply pipe 38 by opening a water supply valve (not shown) of the hot water supply pipe 38 and operating a water supply pump after the hot water storage operation.
[0033]
The hot water storage temperature equalizing means equalizes the overall temperature of the hot water stored in the hot water storage tank 33 even when hot water remains in the hot water storage tank 33 after the hot water supply and before the hot water storage operation. After the hot water storage operation performed by correcting the set value of the inlet water temperature of the water heat exchanger 43 by the hot water storage temperature control means, the heat exchange bypass valve 37 is opened and the pump 34 is operated for a predetermined time. The hot water stored in the tank 33 is mixed by natural convection so that the hot water temperature of the entire hot water is almost equalized. The opening time of the heat exchange bypass valve 37 and the operation time of the pump 34 are both hot water storage tanks. A set value set in advance corresponding to the amount of remaining hot water in 33 is used.
[0034]
The frost detection means detects frost generated in the air heat exchanger 45 acting as an evaporator (cooler) by the hot water storage operation of the refrigeration cycle 41, and is detected by the hot water storage operation time and the evaporation temperature sensor 50. The frost formation is detected based on the lowest inlet temperature of the air heat exchanger 45, and when the frost formation is detected, the defrost bypass valve 48 is opened and the high temperature and pressure discharged from the compressor 42 is detected. The gaseous refrigerant is bypassed by the water heat exchanger 43 and the expansion valve 44 and directly introduced into the air heat exchanger 45 through the defrost bypass passage 47, where the air heat exchanger 45 is caused by the condensation heat of the refrigerant to be condensed and liquefied. It heats and defrosts by heating and frosting the frost. This defrosting operation is continued until the completion of defrosting is detected by the defrosting completion detecting means.
[0035]
This defrosting completion detection means continues the detection temperature of the suction side temperature of the compressor 42 detected by the suction side temperature sensor 51 at, for example, 2.5 ° C. or more for 80 seconds, or the detection temperature becomes 5 ° C. or more. Or if the defrosting operation has continued for 10 minutes or more, it is determined that the defrosting operation has been completed, and after that determination, the defrosting bypass valve 48 is closed again as shown in FIG. It is configured to return from the frost operation to the hot water storage operation again.
[0036]
The compressor control means controls an inverter (not shown) to control the operating frequency of the compressor 42, thereby controlling the rotational speed, and controlling the circulation flow rate of the refrigerant circulating in the refrigeration cycle 41, thereby making the water heat exchanger The water outlet temperature of the water heat exchanger 43 is controlled by controlling the amount of heat of condensation (radiation) of the primary side heat exchange pipe 43a of 43 and controlling the amount of heat supplied to the water passing through the secondary side heat exchange pipe 43b. Is to control.
[0037]
Next, the operation of the heat pump water heater 21 configured as described above will be described.
[0038]
First, when the hot water storage operation is performed on the refrigeration cycle 41 side as shown in FIG. 1, the high-temperature and high-pressure gaseous refrigerant compressed by the compressor 42 passes through the primary heat exchange pipe 43 a of the water heat exchanger 43 to condense and liquefy. The water that passes through the secondary heat exchange pipe 44b of the water heat exchanger 44 is heated by this heat of condensation (heat radiation).
[0039]
On the other hand, the liquid refrigerant condensed and liquefied by the water heat exchanger 43 is decompressed when passing through the expansion valve 44 having a predetermined opening, and the refrigerant flow rate is appropriately controlled to flow into the air heat exchanger 45, Here, it evaporates and absorbs heat from the outside air, and in the form of a gaseous refrigerant, is again returned to the compressor 42 and returned from the suction side, compressed again by the compressor 42 and flows into the water heat exchanger 43 to condense and liquefy. Then, the water passing through the secondary heat exchange pipe 43b is heated by the condensation heat, and the water passing through the secondary heat exchange pipe 43b of the water heat exchanger 43 is gradually heated to high temperature water by repeating this operation.
[0040]
The hot water (hot water) heated by the water heat exchanger 43 comes out from the water outlet, is further heated by the auxiliary heater 32, and then is supplied to the hot water supply tank 33 from the upper water outlet 33a and stored.
[0041]
Further, the hot water in the hot water supply tank 33 is sucked into the variable flow rate pump 34 from the water outlet 33c at the bottom thereof, and after the pressure is increased here, the hot water is again passed through the secondary side heat exchange pipe 43b of the water heat exchanger 43. When the water is passed, it is heated again by the condensation heat of the high-temperature and high-pressure gaseous refrigerant passing through the primary side heat exchange pipe 43a to further increase the temperature of the hot water and further heated by the auxiliary heater 32 to supply hot water. It is supplied into the tank 33 from the hot water inlet / outlet 33a at the upper part thereof. Thereafter, the hot water storage operation is stopped when the hot water storage temperature in the hot water storage tank 33 is gradually raised to the target temperature by repeating this, and the hot water supply operation is prepared. During the hot water supply operation, hot water in the hot water supply tank 33 is supplied to the hot water supply portion via the hot water supply pipe 38.
[0042]
During the hot water storage operation, the air heat exchanger 45 is installed outside and acts as an evaporator (cooler), so that frost formation may occur in the air heat exchanger 45. This frost formation is detected by the frost detection means of the controller 53. When the frost detection means detects the frost formation of the air heat exchanger 45, the defrost bypass valve 48 is opened to switch from the hot water storage operation to the defrost operation.
[0043]
Then, the high-temperature and high-pressure gaseous refrigerant from the compressor 42 bypasses the water heat exchanger 43 and flows directly into the air heat exchanger 45 to be condensed and liquefied, and radiates heat. The frost can be defrosted by heating and thawing.
[0044]
Further, the refrigerant condensed in the air heat exchanger 45 is returned to the compressor 42 from the suction side, and the frost formation of the air heat exchanger 45 is defrosted by repeating this operation. When this defrosting is completed, the defrosting completion means of the controller 53 detects the completion of the defrosting based on the detected temperature from the suction side temperature sensor 51 and the like, and the defrosting bypass valve 48 is closed to complete the defrosting operation. The refrigeration cycle 41 is returned to the hot water storage operation.
[0045]
By returning to the hot water storage operation, the hot water storage operation is repeated again, and when the temperature of the hot water in the hot water storage tank 33 reaches a predetermined value, the water temperature sensor 40b that detects the inlet water temperature of the water heat exchanger 43 has a predetermined set temperature. (For example, 30 ° C.) is detected, so it is determined that the hot water in the hot water storage tank 33 has reached a predetermined set temperature (for example, 85 ° C.), and the compressor 42, pump 34, auxiliary heater 32, heat exchanger fan, etc. The hot water storage operation is terminated by stopping the operation, and waiting for the hot water supply operation.
[0046]
As shown in FIG. 2, after the hot water supply operation and before the hot water storage operation, when the remaining hot water layer A in the hot water storage tank 33 is detected by the remaining hot water detection means of the controller 53, the hot water storage temperature control means performs the previous time. The set value of the inlet water temperature of the water heat exchanger 43 set during the hot water storage operation is corrected to a preset value higher than the previous set value of the inlet water temperature according to the amount of remaining hot water, and the stored hot water temperature detected by the hot water temperature sensor 40a. Is corrected to a correction set value (for example, 90 ° C.) that is higher by a predetermined value than the set value (for example, 85 ° C.) during the hot water storage operation.
[0047]
As a result, as shown in FIG. 3, in the hot water storage tank 33, a high temperature hot water layer C that reaches a temperature (for example, 90 ° C.) higher than a set temperature is distributed in the upper portion thereof, while The low temperature hot water layer of the remaining hot water, which has been cooled to about 70 ° C. due to heat loss or the like, is distributed, and these hot water layers C and A are hardly mixed because the high temperature hot water layer is distributed over the low temperature hot water layer. Separated.
[0048]
Therefore, as shown in FIG. 4, the hot water storage temperature equalizing means of the controller 53 opens the heat exchange bypass valve 37 for a predetermined time and operates the pump 34, and the water from the water outlet 33 c of the hot water storage tank 33 flows into the channel resistance. The large water heat exchanger 43 is bypassed by the bypass passage 37 and the water circuit 31 is circulated by the pump 34 at a large flow rate. The operation time of the pump 34 and the valve opening time of the heat exchange bypass valve 37 are set in advance by the hot water temperature equalizing means of the controller 53 according to the remaining hot water amount.
[0049]
As a result, the remaining hot water having a relatively low temperature in the hot water storage tank 33 is supplied at a large flow rate from above the high temperature hot water layer C in the hot water storage tank 33. The high temperature hot water layer C is mixed by natural convection, and the whole can be equalized to a predetermined set temperature of about 85 ° C., for example.
[0050]
Therefore, even if there is hot water in the hot water storage tank 33 after the hot water supply operation, the entire hot water storage in the hot water storage tank 33 can be substantially equalized at a predetermined set temperature by the next hot water storage operation, so the hot water temperature is substantially constant. Hot water can be supplied.
[0051]
In addition, during the hot water storage equalization operation, the water heat exchanger 43 is bypassed by the water circulating in the water circuit 31 by opening the heat exchange bypass valve 37, so that the hot water stored in the low temperature hot water A in the hot water storage tank 33 is stored. Can be supplied at a high flow rate onto the hot water storage of the high temperature hot water layer C, so that the mixing efficiency of the low temperature hot water layer A and the high temperature hot water layer C can be improved. For this reason, while shortening hot water equalization operation time can be aimed at, the enlargement of the pump 34 can be suppressed.
[0052]
【The invention's effect】
As described above, the present invention detects the remaining hot water in the hot water storage tank after the hot water supply operation and before the start of the hot water storage operation, and the set value of the inlet water temperature (the hot water temperature of the second heat exchange pipe of the water heat exchanger). The hot water storage operation is performed by correcting the set value) to a temperature higher than the set value by the hot water storage temperature control means in accordance with the remaining hot water amount. For this purpose, hot water storage hot water heated by a water heat exchanger is supplied at a predetermined flow rate on a low temperature remaining hot water layer whose temperature has been reduced due to heat loss in the hot water storage tank. When the inlet water temperature reaches the correction set value, the hot water storage operation ends.
[0053]
After completion of this hot water storage operation, the hot water storage temperature equalizing means opens the bypass passage opening and closing valve and operates the pump for a predetermined time. For this purpose, the low-temperature remaining hot water at the bottom of the hot water tank is boosted by the pump, bypasses the water heat exchanger, passes through the open / close valve and bypass passage, and enters the hot water tank. It is supplied directly from the upper hot water inlet.
[0054]
For this reason, in the hot water storage tank, hot water such as residual hot water or water having a lower temperature is supplied onto the hot water storage layer, so that it is mixed by natural convection and the temperature of the hot water in the hot water storage tank as a whole. Distribution is made uniform at high temperatures. Therefore, even if there is remaining hot water in the hot water storage tank, hot water can be stored at a predetermined temperature. In addition, at this time, since the remaining hot water in the hot water storage tank is directly returned to the upper part of the hot water storage tank by bypassing the hydrothermal exchanger having a large flow path resistance, the amount of the recirculation can be increased. For this reason, since mixing of hot water having different temperatures in the hot water storage tank can be promoted, the temperature equalizing operation time can be shortened.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of a heat pump water heater according to an embodiment of the present invention.
FIG. 2 is a block diagram of the heat pump water heater shown in FIG. 1 when there is residual hot water in the hot water storage tank before the hot water storage operation.
FIG. 3 is a block diagram when a hot water storage temperature control operation is performed in the heat pump water heater shown in FIG.
4 is a block diagram when a hot water storage temperature equalizing operation is performed in the heat pump water heater shown in FIG. 1. FIG.
FIG. 5 is a block diagram showing an overall configuration of a conventional heat pump water heater.
6 is a block diagram in the case where residual hot water exists in the hot water storage tank before the hot water storage operation of the conventional heat pump water heater shown in FIG.
7 is a block diagram showing a state of the conventional heat pump water heater shown in FIG. 5 during a hot water storage operation.
8 is a block diagram showing a state after the hot water supply operation and before the hot water storage operation of the conventional heat pump water heater shown in FIG.
[Explanation of symbols]
21 Heat pump water heater
31 Water circuit
32 Auxiliary heater
33 Hot water tank
33a Hot spring entrance
33b Receiving port
33c Water outlet
34 Pump
35 Water piping
36 Heat Exchange Bypass
37 Heat Exchange Bypass Valve
38 Hot water pipe
39 Water supply pipe
40a Hot water temperature sensor
40b Water temperature sensor
41 Refrigeration cycle
42 Compressor
43 Water heat exchanger
44 Expansion valve
45 Air heat exchanger
46 Refrigerant piping
47 Defrost bypass path
48 Defrost bypass valve
49 Condensation temperature sensor
50 Evaporation temperature sensor
51 Suction side temperature sensor
52 Discharge temperature sensor
53 Controller

Claims (2)

A refrigeration cycle for circulating a refrigerant by sequentially connecting a compressor, a first heat exchange pipe of a water heat exchanger, an expansion valve, and an air heat exchanger;
A first heat exchange pipe of the water heat exchanger and a second heat exchange pipe capable of exchanging heat, a hot water inlet and a hot water inlet for receiving hot water from the second heat exchange pipe are provided on the upper side, while receiving water. A hot water storage tank provided with a water supply inlet and a water outlet at the lower part, a main circuit for circulating water by sequentially connecting a pump, a bypass passage for connecting the water discharge side of the pump and the hot water inlet side of the hot water storage tank, and this A water circuit having an on-off valve interposed in the middle of the bypass path;
When the remaining hot water in the hot water storage tank is detected before the hot water storage operation for circulating the water in the hot water storage tank to the water circuit and raising the temperature of the water to the set value of the inlet water temperature of the water heat exchanger. In addition, hot water storage temperature control means for correcting the inlet water temperature setting value to a preset value higher than the inlet water temperature setting value of the water heat exchanger by a predetermined value according to the amount of remaining hot water, and performing hot water storage operation,
After the hot water storage operation by the hot water temperature control means, the hot water storage temperature equalizing means for opening the on-off valve for a predetermined time and operating the pump;
The heat pump water heater characterized by comprising. The hot water storage temperature equalizing means sets the operation time of the pump that operates by opening the on-off valve in advance according to the amount of remaining hot water, or the water temperature at the inlet of the water heat exchanger becomes a predetermined hot water storage temperature. The heat pump water heater according to claim 1, wherein the pump is stopped when the corresponding set value is reached.

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