JP3840573B2 - Heat pump type water heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat pump hot water supply apparatus.
[0002]
[Prior art]
As shown in FIG. 8, the heat pump hot water supply apparatus generally includes a tank unit 71 having a hot water storage tank 70 and a heat source unit 73 having a refrigerant circuit 72. The refrigerant circuit 72 is configured by connecting a compressor 74, a water heat exchanger 75, an expansion valve 77, and an evaporator 78 in this order. The tank unit 71 includes the hot water storage tank 70 and a circulation path 79, and a water circulation pump 80 and a heat exchange path 81 are interposed in the circulation path 79. In this case, the heat exchange path 81 is configured by a water heat exchanger 75.
[0003]
In the above apparatus, when the compressor 74 is driven and the pump 80 is driven (actuated), the stored water (hot water) flows out from the water intake provided at the bottom of the hot water storage tank 70 to the circulation path 79, which exchanges heat. Circulates the channel 81. At this time, the hot water is heated (boiling) by the water heat exchanger 75 and returned to the upper part of the hot water storage tank 70 from the hot water inlet. As a result, hot hot water is stored in the hot water storage tank 70. And since the current electricity rate system is set cheaper than the daytime electricity rate unit price in the middle of the day, in recent years, this operation is a low-cost time zone (for example, the time zone from 23:00 to 7:00) ) To reduce running costs. In this case, if the required amount of hot water is low per day, the required amount of hot water can be boiled only by operation at midnight, but if the required amount of hot water is large, in addition to the operation at midnight, Had a reckless driving. That is, there are a full-boiling operation in which the entire hot water storage tank 70 is boiled and a reheating operation in which the shortage is replenished.
[0004]
Conventionally, refrigerants such as dichlorodifluoromethane (R-12) and chlorodifluoromethane (R-22) have been used as refrigerants in the refrigerant circuit. However, ozone layer destruction, environmental pollution, etc. Due to problems, alternative refrigerants such as 1,1,1,2-tetrafluoroethane (R-134a) have been used. However, since this R-134a still has problems such as high global warming ability, in recent years, it has been recommended to use a natural refrigerant free from such problems. It is known that a supercritical refrigerant such as carbon dioxide is useful as this natural refrigerant.
[0005]
[Problems to be solved by the invention]
By the way, in the heat pump type hot water supply apparatus as described above, an attempt is made to reduce the volume of the hot water storage tank 70 as much as possible while ensuring the hot water storage tank capacity based on the use performance standard [JRA4050 (Japan Refrigeration and Air Conditioning Industry Association)] (the hot water storage tank 70). Therefore, it is necessary to fill the hot water storage tank 70 with a hot water temperature equal to or higher than a predetermined temperature. For this reason, during the total boiling operation, the operation is performed until the temperature of water entering the heat exchange path 81 becomes relatively high (for example, 60 ° C.). In fact, such boiling operation control is performed not only in the above-described total amount boiling operation but also in the reheating operation. In addition, in the above-mentioned usage performance standard, in a state where the hot water storage tank 70 is filled with hot water, the operation of pouring hot water by 1/13 from the top of the tank is repeated 12 times every hour, and the 12th hot water temperature (hot water temperature) ) Is equal to or higher than a predetermined temperature (for example, 60 ° C. or higher when the tank capacity is 370 liters), the volume of the hot water storage tank 70 can be displayed as the hot water storage capacity.
[0006]
When a supercritical refrigerant is used as described above, generally, the refrigerant cycle of this type of heat pump unit is shown by a solid line in FIG. However, if the incoming water temperature to the heat exchange path 81 rises, the entropy difference in the condensation process becomes narrower and the hot water supply capacity and COP decrease, as shown by the phantom line (two-dot chain line) in FIG. . That is, in the prior art, as shown in FIG. 5, the operation was performed until the incoming water temperature reached, for example, 60 ° C., so the capacity and COP in this operation suddenly decreased when approaching 60 ° C. as shown in FIG. To do. Therefore, if the chasing operation is continued until the incoming water temperature reaches 60 ° C., the running cost is greatly increased.
[0007]
The present invention has been made to solve the above-mentioned conventional drawbacks, and its object is to maintain a high capacity and COP during reheating operation, and to reduce the running cost. To provide an apparatus.
[0008]
[Means for Solving the Problems]
Accordingly, the heat pump hot water supply apparatus of claim 1 includes a hot water storage tank 3, a circulation path 12 connecting the upper side and the lower side of the hot water storage tank 3, and a heat exchange path 14 interposed in the circulation path 12. The heat exchange path 14 can be heated with a heat pump heating source to heat up the hot water flowing out from the lower side of the hot water storage tank 3 into the circulation path 12 and return it to the upper side of the hot water storage tank 3. In addition, a heat pump hot water supply device that performs a full-boiling operation for boiling the entire amount in the hot water storage tank 3 and a reheating operation for boiling the shortage, and the heat exchange path when the reheating operation is finished It is characterized by having comprised so that the incoming water temperature to 14 may become lower than the incoming water temperature when the whole amount boiling-up operation is complete | finished.
[0009]
In the heat pump hot water supply apparatus according to claim 1, since the incoming water temperature to the heat exchange path 14 when the reheating operation is finished is set to be lower than the incoming water temperature when the full-boiling operation is finished. It is possible to avoid a decrease in the capacity and COP during the chasing operation.
[0010]
The heat pump type hot water supply apparatus according to claim 2 is characterized in that the reheating operation is terminated at a water inlet temperature that is higher by a predetermined value than the top water temperature at the start of the reheating operation.
[0011]
In the heat pump type hot water supply apparatus according to the second aspect, the reheating operation is terminated at a water inlet temperature that is higher by a predetermined value than the upper entry water temperature at the start of the reheating operation. If the incoming water temperature at the start of the chasing operation is about 10 ° C., the chasing operation is completed at the incoming water temperature of about 15 ° C. For this reason, it is possible to stop the operation before the incoming water temperature rises greatly, and it is possible to reliably avoid a decrease in the capacity and COP during the reheating operation.
[0012]
The heat pump type hot water supply apparatus according to claim 3 is characterized in that the reheating operation is terminated when the hot water temperature at a predetermined position of the hot water storage tank 3 reaches a predetermined temperature.
[0013]
In the heat pump type hot water supply apparatus according to the third aspect, since the hot water in the hot water storage tank 3 is circulated through the circulation path 12, the hot water temperature at a predetermined position of the hot water storage tank 3 is monitored to grasp the incoming water temperature. can do. For this reason, when the hot water temperature at a predetermined position of the hot water storage tank reaches a predetermined temperature, the chasing operation is terminated, thereby preventing an increase in the incoming water temperature and preventing a decrease in capacity and COP. Can do.
[0014]
The heat pump type hot water supply apparatus according to claim 4 is characterized in that the chasing operation is performed for at least a predetermined set time.
[0015]
In the heat pump type hot water supply apparatus according to the fourth aspect, it is possible to avoid “hot water out” where the hot water in the hot water storage tank is reduced and no hot water is consumed by performing the chasing operation for at least a predetermined set time. Moreover, ON / OFF of the driving | operation within a short time can be avoided.
[0016]
The heat pump type hot water supply apparatus according to claim 5 is characterized in that the above-described total boiling operation is performed in the midnight time zone, and the reheating operation is performed in the daytime outside this midnight time zone to secure a necessary amount of hot water for one day. It is said.
[0017]
In the heat pump type hot water supply apparatus according to claim 5, since the current electricity rate system is set at a lower price than the daytime electricity rate unit price, the total amount boiling operation is performed at a low price in the midnight time zone (for example, , From 23:00 to 7 o'clock), and the amount that is lacking in boiling the whole amount is performed in the daytime, and the necessary amount of hot water per day can be secured at a low charge. In addition, in daytime chasing operation where the unit price is high, driving is performed while maintaining high capacity and COP, so that an increase in electricity bill can be prevented.
[0018]
The heat pump type hot water supply apparatus according to claim 6 is characterized in that a supercritical refrigerant used in a supercritical state is used as a refrigerant in a refrigerant circuit of a heat pump type heating source.
[0019]
In the heat pump hot water supply apparatus according to the sixth aspect, since the supercritical refrigerant used in the supercritical state is used as the refrigerant, it is possible to prevent the occurrence of problems such as ozone layer destruction, environmental pollution, and global warming.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Next, specific embodiments of the heat pump type hot water supply apparatus of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a simplified diagram of the heat pump type hot water supply apparatus. The heat pump type hot water supply apparatus includes a tank unit 1 and a heat pump unit (heat source unit) 2, and heats the water (hot water) in the tank unit 1 by the heat pump unit 2. To do. The tank unit 1 includes a hot water storage tank 3, and hot water stored in the hot water storage tank 3 is supplied to a bathtub or the like (not shown). That is, the hot water storage tank 3 is provided with a water supply port 5 on its bottom wall and a hot water outlet 6 on its upper wall. Then, city water is supplied from the water supply port 5 to the hot water storage tank 3, and hot hot water is discharged from the hot water outlet 6. The hot water storage tank 3 has a water intake 10 at the bottom wall and a hot water inlet 11 at the top of the side wall (peripheral wall). The water intake 10 and the hot water inlet 11 are connected by a circulation path 12. Has been. The circulation path 12 is provided with a water circulation pump 13 and a heat exchange path 14. A water supply channel 8 is connected to the water supply port 5.
[0021]
By the way, the hot water storage tank 3 is provided with five remaining hot water detectors 18a, 18b, 18c, 18d, and 18e at a predetermined pitch in the vertical direction. Each of the remaining hot water detectors 18a... Is composed of, for example, a thermistor. The circulation path 12 is provided with a water intake thermistor 20 on the inlet side of the heat exchange path 14 and a hot water thermistor 21 on the outlet side of the heat exchange path 14.
[0022]
Next, the heat pump unit (heat source unit) 2 includes a refrigerant circuit, which includes a compressor 25, a water heat exchanger 26 that constitutes the heat exchange path 14, an electric expansion valve (decompression mechanism) 27, The air heat exchanger 28 is connected in order. That is, the discharge pipe 29 of the compressor 25 is connected to the water heat exchanger 26, the water heat exchanger 26 and the electric expansion valve 27 are connected by the refrigerant passage 30, and the electric expansion valve 27 and the air heat exchanger 28 are connected. Are connected by a refrigerant passage 31, and the air heat exchanger 28 and the compressor 25 are connected by a refrigerant passage 33 in which an accumulator 32 is interposed. Thus, when the compressor 25 is driven, the water flowing through the heat exchange path 14 is heated in the water heat exchanger 26. For example, a supercritical refrigerant such as carbon dioxide can be used as the refrigerant in the refrigerant circuit. The air heat exchanger 28 is provided with a fan 34 that adjusts the capacity of the air heat exchanger 28.
[0023]
By the way, the control part of this heat pump type hot water supply apparatus includes a remaining hot water amount detecting means 37 and a control means 38 to which data (numerical value) from the detecting means 37 is input as shown in FIG. That is, as shown in FIG. 1, the remaining hot water amount detecting means 37 is provided with first, second, third, fourth and fifth remaining hot water detectors 18a, 18b, 18c, 18d and 18e attached to the hot water storage tank 3. Can be configured. As shown in FIG. 2, the temperature of the first remaining hot water amount detector 18a (first tank temperature T1), the temperature of the second remaining hot water amount detector 18b (second tank temperature T2), and the third remaining hot water amount detector 18c. (Third tank temperature T3), the temperature of the fourth remaining hot water detector 18d (fourth tank temperature T4), the temperature of the fifth remaining hot water detector 18e (fifth tank temperature T5), the temperature of the intake thermistor 20 ( The incoming water temperature T6) and the like are input to the control means (controller) 38, and based on these data, the water circulation pump 13 and the compressor 25 are driven to perform the operation described later. The control means 38 can be configured using a microcomputer, for example.
[0024]
According to the heat pump type hot water supply apparatus configured as described above, when the compressor 25 is driven and the water circulation pump 13 is driven (actuated), the stored water (from the water intake 10 provided at the bottom of the hot water storage tank 3) Hot water) flows out and flows through the heat exchange path 14 of the circulation path 12. At this time, the hot water is heated (boiling) by the water heat exchanger 14 and returned to the upper part of the hot water storage tank 3 from the hot water inlet 11. By continuously performing such an operation, hot hot water can be stored in the hot water storage tank 3.
[0025]
In this case, the vehicle is operated for a predetermined time from a certain time (for example, 24:00 after the start of the midnight time) at a midnight time (from 23:00 to 7:00 am on the next day), and the predetermined time (the midnight time end time, In other words, the entire boiling operation is performed to boil the hot water in the hot water storage tank 3 at 7 am. In addition, if the required amount of hot water per day exceeds the capacity of the hot water storage tank 3, after the operation at midnight hours, the chasing operation is further performed in the daytime outside the midnight hours. Secure. In this case, when a quantity of hot water that satisfies the capacity of the hot water storage tank 3 is boiled, if a predetermined amount (for example, 50 liters) of hot water is used and the amount of stored hot water decreases, the reduced predetermined amount The water is heated up and heated. In addition, since the electricity rate unit price for midnight is set to be lower than that for the daytime, the total electricity heating operation is low in the above-mentioned midnight time zone (for example, the time zone from 23:00 to 7:00) I'm trying to do it.
[0026]
By the way, the full-boiling operation is completed when the temperature of the water intake thermistor 20 (incoming water temperature) reaches a predetermined temperature (for example, 60 ° C.). In this case, if the incoming water temperature reaches 60 ° C., the capacity and COP are greatly reduced as shown in FIG. 6. However, as described above, it is necessary to carry out this total boiling operation according to the usage performance standard. is there.
[0027]
On the other hand, in the reheating operation, unlike the case of the full boiling operation, it is not necessary to operate until the incoming water temperature reaches 60 ° C. In this heat pump hot water supply apparatus, the reheating operation is completed. The temperature of the incoming water is configured to be lower than the incoming water temperature when the full boiling operation is completed.
[0028]
Next, the operation method of this heat pump type hot water supply apparatus will be described based on the flowchart of FIG. First, while driving the compressor 25, the boiling operation (all amount boiling operation) which drives (actuates) the water circulation pump 13 is started. Then, it is determined whether or not the temperature (T6) detected by the water intake thermistor 20 in step S1 is equal to or higher than a predetermined temperature (for example, 60 ° C.). If it is less than 60 ° C., this operation is continued, and if it is 60 ° C. or more, the operation proceeds to step S2 to stop the operation. That is, the total amount boiling operation is completed.
[0029]
Thereafter, a determination is made as to whether or not to perform a chasing operation. That is, in step S3, it is determined whether or not the temperature (T5) of the fifth remaining hot water detector 18e is lower than a predetermined temperature (for example, 45 ° C.). And if T5 is 45 degreeC or more, since the hot water of 45 degreeC or more will exist to the lower part of the hot water storage tank 3, it is not necessary to perform a chasing operation, and the state is maintained as it is. If T5 is less than 45 ° C., the amount of remaining hot water in the hot water storage tank 3 is reduced as a result of the use of hot water, and low temperature hot water is present in the lower part of the hot water storage tank 3, so Since it is necessary to carry out, it moves to step S4 and starts a chasing operation.
[0030]
Next, the process proceeds to step S5, where it is determined whether or not to end the chasing operation in step S5. That is, in step S5, it is determined whether T5 ≧ 60 ° C. and a predetermined time (for example, 30 minutes) has elapsed since the start of the chasing operation. And if T5 is 60 degreeC or more and 30 minutes have passed, this chasing operation will be complete | finished. Further, if T5 is less than 60 ° C. or 30 minutes have not passed, the chasing operation is continued. That is, if T5 is 60 ° C. or more, as shown in FIG. 5, the incoming water temperature T6 has reached about 15 ° C., and thus the reheating operation is finished assuming that the reheating end temperature has been reached. However, if the chasing operation is started and only a short time has passed, the chasing operation is performed for at least 30 minutes even if T5 is 60 ° C. or higher. If T5 is 60 ° C. or higher and the incoming water temperature T6 is 15 ° C. or higher, as shown in FIG. 6, the capacity and COP will decrease rapidly.・ If OFF is repeated, the ratio of the start-up operation loss at the time of ON becomes excessive, which causes a decrease in COP. Further, in the operation for about 30 minutes, it is considered that there is very little possibility that T5 will be 60 ° C. or higher, and it is preferable to continue this reheating operation until 30 minutes have passed since the renewal operation was started. Even in such a control, there are many cases where the water supply temperature is stopped (terminated) before the incoming water temperature rises greatly.
[0031]
Therefore, in the heat pump type hot water supply apparatus, a deficient reheating operation can be reliably performed. In this recurring operation, the water temperature can be stopped (terminated) before the water temperature rises greatly. Can be kept high, and running (electricity cost) can be reduced. In addition, it is possible to perform a full boiling operation in the midnight time zone, to perform a deficient chasing operation during the daytime, and to secure a necessary amount of hot water for one day at a low charge.
[0032]
By the way, in the flowchart shown in FIG. 4, the reheating operation is completed by monitoring the temperature (T5) of the fifth hot water detector 18e. However, as another embodiment, the renewal operation is started. The chasing operation may be terminated at an incoming water temperature that is higher by a predetermined value than the entry water temperature. That is, the water intake temperature T6 (for example, 10 ° C.) by the intake thermistor 20 at the start of the reheating operation is detected, and after the reheating operation is started, this T6 has increased by 5 ° C. (that is, has reached 15 ° C.). ) Sometimes, this chasing operation may be terminated. Even in this case, it can be stopped (terminated) before the incoming water temperature rises greatly, and the capacity and COP can be kept high.
[0033]
As another embodiment, a temperature thermistor (not shown) is provided at the bottom of the hot water storage tank 3 in addition to the remaining hot water detector 18a to the remaining hot water detector 18e, and the detected temperature of the temperature thermistor reaches a predetermined temperature. For example, the chasing operation may be stopped. That is, since the detected temperature of this temperature thermistor is substantially the same as the incoming water temperature, by monitoring the temperature of this temperature thermistor, it can be stopped (terminated) before the incoming water temperature rises greatly, and the capacity and COP are reduced. Can be kept high.
[0034]
Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention. For example, the incoming water temperature at the end of the reheating operation is not limited to 15 ° C., and can be changed within a range in which the operation is stopped before the capacity and COP are reduced. Further, in the flowchart shown in FIG. 4, the reheating operation is terminated based on the temperature of T5. In this case, 60 ° C. is used as a reference, but the temperature is not limited to 60 ° C. That is, since the temperature of T6 with respect to T5 differs depending on the height position of the detector 18e for obtaining T5, it is necessary to change the temperature to be determined according to the height position of the detector 18e. is there. Furthermore, in the case of performing the chasing operation, the operation is performed for a predetermined time (30 minutes) or more. However, the predetermined time can be changed in consideration of a decrease in capacity and COP. Even if the refrigerant in the refrigerant circuit is a refrigerant such as dichlorodifluoromethane (R-12) or chlorodifluoromethane (R-22), 1, 1, 1, An alternative refrigerant such as 1,2-tetrafluoroethane (R-134a) may be used.
[0035]
【The invention's effect】
According to the heat pump type hot water supply apparatus of claim 1, since the incoming water temperature at the end of the reheating operation is lowered, it is possible to avoid a decrease in the capacity and COP at the time of the reheating operation, and to reduce the running cost. Is possible.
[0036]
According to the heat pump type hot water supply apparatus of claim 2, the operation can be stopped before the incoming water temperature rises greatly, the decrease in the capacity and COP during the reheating operation can be surely avoided, and the stable follow-up can be performed. A whispering operation can be performed.
[0037]
According to the heat pump type hot water supply apparatus of the third aspect, it is possible to prevent an increase in the incoming water temperature and prevent a decrease in capacity and COP, and a stable reheating operation can be performed.
[0038]
According to the heat pump type hot water supply apparatus of the fourth aspect, it is possible to avoid “hot water shortage” in which the hot water in the hot water storage tank decreases and the hot water disappears. Moreover, ON / OFF of the driving | operation within a short time can be avoided, and it becomes possible to prevent the fall of COP. This is because if the ON / OFF operation is repeated within a short time, the ratio of the startup operation loss at the ON time becomes excessive, leading to a decrease in COP.
[0039]
According to the heat pump type hot water supply apparatus of claim 5, the total amount boiling operation is performed in a midnight time zone (for example, a time zone from 23:00 to 7:00) which is a low price, and this total amount boiling is insufficient. This is done in the daytime, and the required amount of hot water per day can be secured at a low charge. In addition, in daytime chasing driving where the unit price is high, driving is performed while maintaining high capacity and COP, and an increase in running cost can be prevented.
[0040]
According to the heat pump type hot water supply apparatus of the sixth aspect, it is possible to prevent the occurrence of problems such as destruction of the ozone layer, environmental pollution, and global warming, and the apparatus is excellent from the viewpoint of the global environment.
[Brief description of the drawings]
FIG. 1 is a simplified diagram showing an embodiment of a heat pump type hot water supply apparatus of the present invention.
FIG. 2 is a simplified block diagram showing data input to a control unit of the heat pump type hot water supply apparatus.
FIG. 3 is a simplified block diagram of a control unit of the heat pump hot water supply apparatus.
FIG. 4 is a flowchart showing the operation of the heat pump type hot water supply apparatus.
FIG. 5 is a graph showing the relationship between the incoming water temperature and the temperature at the lower part of the hot water storage tank.
FIG. 6 is a graph showing the relationship between incoming water temperature, capacity and COP.
FIG. 7 is a graph of a refrigeration cycle for explaining a drawback of a conventional heat pump hot water supply apparatus.
FIG. 8 is a simplified diagram of a conventional heat pump hot water supply apparatus.
[Explanation of symbols]
3 Hot water storage tank 12 Circulation path 14 Heat exchange path

Claims (6)

A hot water storage tank (3), a circulation path (12) connecting the upper side and the lower side of the hot water storage tank (3), and a heat exchange path (14) interposed in the circulation path (12), The heat exchange path (14) is heated by a heat pump heating source, and the hot water flowing out from the lower side of the hot water storage tank (3) to the circulation path (12) is boiled to the upper side of the hot water storage tank (3). A heat pump type hot water supply apparatus that enables a return operation and performs a full-boiling operation for boiling the entire amount in the hot water storage tank (3) and a reheating operation for boiling the shortage. A heat pump type hot water supply apparatus, characterized in that the incoming water temperature to the heat exchange path (14) when the heating is completed is lower than the incoming water temperature when the full-boiling operation is finished. 2. The heat pump hot water supply apparatus according to claim 1, wherein the reheating operation is terminated at an incoming water temperature that is higher by a predetermined value than a water temperature at the time when reheating operation is started. The heat pump hot water supply apparatus according to claim 1 or 2, wherein when the hot water temperature at a predetermined position of the hot water storage tank (3) reaches a predetermined temperature, the reheating operation is terminated. The heat pump type hot water supply apparatus according to any one of claims 1 to 3, wherein the reheating operation is performed at least for a predetermined set time. The full-boiling operation is performed in the midnight time zone, and the chasing operation is performed in the daytime outside the midnight time zone to secure a necessary amount of hot water for one day. One of the heat pump hot water supply devices. The heat pump type hot water supply apparatus according to any one of claims 1 to 5, wherein a supercritical refrigerant used in a supercritical state is used as a refrigerant in a refrigerant circuit of a heat pump type heating source.

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