JP2008241116A - Hot water supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive hot water supply system having improved waste heat utilizing efficiency at a gas combustion part. <P>SOLUTION: The hot water supply system comprises a heat pump unit having a compressor, an expansion valve, an air heat-exchanger and a water heat-exchanger, a gas combustion unit for heating water heated by the heat pump unit, a hot water storage tank connected to water supply and drain passages for storing water heated by the gas combustion unit, and a water circulating means for supplying the water in the hot water storage tank to a water flow pipe of the water heat-exchanger. Herein, an exhaust gas utilizing means is provided for guiding exhaust gas which is used for heating the water from the water heat-exchanger with the gas combustion unit, around the hot water storage tank, and heating the hot water storage tank. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement of a hybrid gas heat pump hot water supply system that uses a heat pump and a gas combustion unit as a heat source, and more particularly to a hot water supply system that improves the economic efficiency by effectively using exhaust gas from the gas combustion unit. is there.

Conventionally, a heat pump hot water supply means and a hot water storage tank for heating and supplying hot water by exchanging heat and heat from the condenser of the heat pump circuit are provided, and hot water heated by the heat pump hot water supply means is stored in the hot water storage tank. A hot water supply system configured to be able to supply hot water from the hot water storage tank to a hot water supply load, wherein the hot water supply path from the hot water storage tank to the hot water supply load can supply hot water directly or via an auxiliary hot water storage tank, or There is known a hot water supply system (Patent Document 1) including auxiliary hot water supply means by oiling.
In such a hot water supply system that combines a heat pump and gas heating means, the heat pump can be fully operated during low-cost hours such as midnight, and cheap hot water can be stored in a hot water storage tank. It is economical and can take advantage of the characteristics of gas that can be heated in a free temperature range, so it can enjoy the excellent merit that hot water can be used economically in a wide range from high temperature to low temperature. is there.
JP 2006-349202 A

And, for the hot water supply system that combines the heat pump and gas heating means as described above, waste heat accompanied with exhaust gas is generated because it uses the gas heating method, and this waste heat is used to circulate to the hot water storage tank. Attempts have been made to increase the thermal efficiency of the system by heating water.
FIG. 6 is a block diagram showing the concept of the hot water supply system using waste heat as described above, and FIG. 7 is a view showing a part of the hot water storage tank shown in FIG.
In this case, the hot water supply system S0 includes a heat pump unit 1 including a compressor, an expansion valve, and a water heat exchanger, a hot water supply unit 5 including a hot water storage tank 3, a water heat exchanger 7 of the heat pump unit 1, and the hot water storage tank. And a gas combustion unit 9 that heats the water in the pipe in the middle of the pipe that connects to the pipe 3.
Water discharged from the water heat exchanger 7 flows from the secondary heat exchanger 9b of the gas combustion unit 9 to the upper part of the hot water storage tank 3 through the primary heat exchanger 9a and is accumulated.
The water in the hot water storage tank 3 is circulated by water circulation means such as a pump provided in the water flow pipe of the water heat exchanger 7.
The primary heat exchanger 9 a is directly heated by the gas combustion unit 11. Since the high-temperature primary combustion waste heat obtained by heating water with the primary heat exchanger 9a still retains a sufficient amount of heat, it is further discharged after being heated with the secondary heat exchanger 9b. The
An example of the temperature distribution in the vicinity of the upper portion of the hot water storage tank 3 in this case is shown in FIG. For example, when the outside air temperature is −10 ° C. and the hot water temperature at the top of the hot water storage tank 3 is 90 ° C., the temperature of the heat insulating material layer 3a covering the outer periphery of the hot water storage tank 3 is about 35 ° C. The temperature of the air layer 3b surrounding the outer periphery is about -5 ° C. The temperature described in the following description is an example (reference value) and does not limit the temperature of this system. In addition, about the structure of the said heat pump unit 1 and the structure of the hot water supply part 5, since it described in FIG. 6, please refer.
Thus, since the primary waste heat which was not able to be utilized with the primary heat exchanger 9a is utilized with the secondary heat exchanger 9b, the utilization degree of the heating air in the gas combustion part 11 increases, and it is efficient. A hot water system is achieved.
However, in the system using the waste heat of the gas combustion section 11 as described above, the water circulating in the hot water storage tank 3 is only heated by the waste heat, so depending on the heat exchange efficiency of the heat exchanger used there, it is sufficient. There is a possibility that the waste heat will not be used.
In addition, such a heat exchanger is expensive and may increase the price of the entire hot water storage system.
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hot water storage system capable of increasing the utilization efficiency of waste heat in a gas combustion section.

To achieve the above object, the present invention provides a heat pump unit including a compressor, an expansion valve, an air heat exchanger, and a water heat exchanger, a gas combustion unit that heats water heated by the heat pump unit, A hot water supply tank connected to the path and the drainage path, the hot water storage tank storing water heated by the gas combustion unit, and water circulation means for supplying the water in the hot water storage tank to the water flow pipe of the water heat exchanger In the system,
The exhaust gas used for heating the water from the water heat exchanger in the gas combustion unit is guided to the periphery of the hot water storage tank, and is provided with exhaust gas utilization means for raising the ambient temperature of the hot water storage tank. It is configured as a hot water system.
As a result, it is possible to provide a hot water storage system that can increase the utilization efficiency of waste heat.

In this case, the gas combustion unit includes a plurality of stages of gas water heat exchangers, and the exhaust gas utilization means uses combustion exhaust gas discharged from the final stage in the plurality of stages of gas water heat exchangers. It is desirable to have a configuration. More specifically, it is desirable that the hot water storage tank is disposed on the gas combustion unit, and the rising exhaust gas discharged from the gas combustion unit is guided around the hot water storage tank.
In this way, a hot water supply system with good electric heating efficiency can be achieved.
Further, in order to reduce loss due to heat dissipation, an external casing for accommodating the hot water storage tank is provided, and an air passage is formed between the hot water storage tank and the external casing for circulating the exhaust gas discharged from the gas combustion unit. Such a configuration is desirable. The outer casing is preferably configured to further accommodate the gas combustion unit.
In this case, a preferable configuration is one in which heat storage means is formed in an air passage through which the exhaust gas discharged from the gas combustion unit flows between the hot water storage tank and the outer casing.

According to the present invention, a heat pump unit including a compressor, an expansion valve, an air heat exchanger, and a water heat exchanger, a gas combustion unit that heats water heated by the heat pump unit, a water supply path, and a drain path are provided. In the hot water supply system comprising: a hot water storage tank for storing water heated by the gas combustion unit; and a water circulation means for supplying water in the hot water storage tank to a water flow pipe of the water heat exchanger. A hot water supply comprising exhaust gas utilization means for guiding the exhaust gas used for heating water from the water heat exchanger in the combustion unit to the surroundings of the hot water storage tank and increasing the ambient temperature of the hot water storage tank Configured as a system.
As a result, it is possible to provide a hot water storage system that can increase the utilization efficiency of waste heat.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a schematic sectional view showing the concept of a hot water storage tank unit including a gas combustion unit used in the hot water supply system according to the first embodiment of the present invention. FIG. 2 is a hot water storage in the hot water supply system shown in FIG. FIG. 3 is a diagram showing the temperature distribution in the upper part of the tank, FIG. 3 is a schematic sectional view of the upper part of the hot water storage tank used in the hot water supply system according to the second embodiment, and FIG. 4 is the hot water supply according to the second embodiment shown in FIG. FIG. 5 is a schematic sectional view showing the structure of the heat storage material used in the system, and FIG. 5 is a view showing the temperature distribution in the upper part of the hot water storage tank in the hot water supply system according to the second embodiment.

First, the gas combustion unit used in the hot water supply system S according to the first embodiment will be described with reference to FIG.
Parts having the same structure as those of the conventional hot water supply system shown in FIG.
In the hot water storage tank section T of the hot water supply system S, the hot water storage tank 3 and the gas combustion unit 19 are housed in a single sealed casing 21 (external casing) that encloses them. The gas combustion unit 19 is arranged at the lower part of the hot water storage tank 3, and the combustion gas generated by the gas combustion part 11 passes through the primary heat exchanger 19a to heat the water, and is arranged at the upper part as it is at high temperature. After the water from the heat pump unit 1 is heated by the secondary heat exchanger 19b, the casing 21 passes through the exhaust gas passage 23 formed around the heat insulating material layer 3a covering the periphery of the upper hot water storage tank 3. It is discharged to the outside through an exhaust port 25 provided at the top. In the present embodiment, the space between the inner wall surface of the casing 21 and the heat insulating material layer 3 a becomes the exhaust gas passage 23. The above configuration is an example of the exhaust gas utilization means in the present invention.
In order to improve the exhaust, the exhaust port 25 is provided with an exhaust fan 27 as necessary.
Since the exhaust passage 23 is formed around the heat insulating material layer 3a of the hot water storage tank 3 as shown in the figure, the ambient temperature of the hot water storage tank 3 is increased by the exhaust gas discharged from the secondary heat exchanger 19b. To rise. Therefore, the ambient temperature of the hot water storage tank 3, in other words, the temperature between the heat insulating material layer 3 a covering the periphery of the hot water storage tank 3 and the housing 21 is kept higher than when the exhaust gas is not guided into the housing 21. be able to. Therefore, the heat radiation from the heat insulating material layer 3a is reduced, and as a result, the heat retention efficiency of the hot water storage tank 3 is improved.
That is, the water flowing out from the pipe P3 provided in the lower part of the hot water storage tank 3 is heated by the water heat exchanger 7 of the heat pump unit 1 similar to that shown in FIG. 6, and is connected to the pipe P1 through the pipe P1. The secondary heat exchanger 19b passes through the secondary heat exchanger 19b where it is heated with the secondary waste heat. The water heated by the secondary waste heat is further heated by the gas combustion unit 11 through the primary heat exchanger 19a, and then supplied to the upper portion of the hot water storage tank 3 through the pipe P2. In this way, the water flowing out from the pipe P3 provided at the lower part of the hot water storage tank 3 passes through the water pipe, the pipe P1, the secondary heat exchanger 19b, the primary heat exchanger 19a, and the pipe P2 of the water heat exchanger 7. A water circulation path is formed so as to return to the upper part of the hot water storage tank 3. A pump (an example of water circulation means) is provided in the middle of this water circulation path, and the water in the hot water storage tank 3 can be circulated by operating this pump.
The secondary exhaust gas accompanied by the secondary waste heat discharged from the secondary heat exchanger 19b passes through the exhaust gas passage 23 formed around the heat insulating material layer 3a on the outer periphery of the hot water storage tank 3 to the outside from the exhaust port 25. When discharged, the ambient temperature of the hot water storage tank 3 and the heat insulating material (heat insulating material) layer 3a disposed around the hot water storage tank 3 is increased.
As a result, as described above, the amount of heat contained in the secondary exhaust gas increases the thermal insulation effect of the hot water in the hot water storage tank 3, and the utilization of the waste gas heat that has been conventionally discarded is remarkably promoted.
Therefore, similarly to the temperature distribution shown in FIG. 7, the temperature distribution under the condition that the external temperature is −10 ° C. and the hot water temperature at the upper part of the hot water storage tank 3 is 90 ° C. is as shown in FIG. It rises to 65 ° C., which is higher than the conventional temperature (FIG. 7), and reaches 30 ° C. inside the exhaust gas passage 23, and is maintained at a temperature much higher than the conventional temperature distribution shown in FIG. I understand.
In FIG. 1, P4 is a pipe for supplying water to the hot water storage tank 3 (water supply path), and P5 is a pipe for sending hot water accumulated in the hot water storage tank 3 to a hot water supply load such as a heating device or hot water supply means ( Drainage route).

In a second embodiment to be described next, a heat storage material 29 is arranged in the exhaust gas passage 23 as shown in FIGS. In the present embodiment of FIG. 5, an exhaust gas passage 23 is provided between the inner wall surface of the casing 21 and the heat insulating material layer 3a. A space also exists between the exhaust gas passage 23 and the inner wall surface of the housing 21. Note that the exhaust gas passes through the exhaust gas passage 23 and does not pass through the space between the exhaust gas passage 23 and the inner wall surface of the housing 21. By doing so, the space between the exhaust gas passage 23 and the inner wall surface of the casing 21 becomes an air heat insulating layer between the outside of the casing 21 and the exhaust gas passage 23. Therefore, compared with the case where the exhaust gas passage 23 is configured as a space between the inner wall surface of the casing 21 and the heat insulating material layer 3a, the heat retention efficiency is improved. The exhaust gas passage 23 is connected to the exhaust port 25.
As shown in FIG. 4, the heat storage material 29 is arranged in the form of discontinuous scattered dots with the space 31 interposed therebetween as shown in FIG. 4, and the exhaust gas is guided through the space 31 upward in the exhaust gas passage 23. Finally, it is discharged from the exhaust port 25 to the outside.
There are various methods for arranging the heat storage material, such as vertical stripes in addition to discontinuous scattered dots, and a method in which the heat storage material is wound around the heat insulating material layer 3a and the waste heat gas is passed outside. It is done.
Various materials can be considered for the heat storage material 29, for example, polyethylene glycol, and a material such as paraffin is also suitable.
By providing the heat storage material 29 as described above, the escape of heat from the hot water storage tank 3 is further suppressed. Therefore, by providing the heat storage material 29, the temperature distribution under the same conditions as in FIG. 2 is as shown in FIG. 5, and in the heat insulating material layer 3 a at 80 ° C. and in the exhaust gas passage 23 provided with the heat storage material 27. It was possible to keep the temperature at about 50 ° C.
The heat storage material 29 may be provided by being wound around the heat insulating material layer 3a as shown in FIG. In this case, in the exhaust gas passage 23, the space between the inner wall surface of the casing 21 and the heat insulating material layer 3a becomes the exhaust gas passage 23.
In the above embodiment, the gas combustion unit 19 is provided almost directly below the hot water storage tank 3, but may be located at a shifted position as long as it is below the hot water storage tank 3. Alternatively, the gas combustion unit 19 may be installed beside the hot water storage tank 3 or at a location away from the hot water storage tank 3, and the exhaust gas may be guided to the periphery of the hot water storage tank 3 by a blower such as an exhaust fan 27.

The schematic sectional drawing which shows the concept of the hot water storage tank part containing the gas combustion unit used for the hot water supply system which concerns on the 1st Embodiment of this invention. The figure which shows the temperature distribution of the hot water storage tank upper part in the hot water supply system which concerns on the 1st Embodiment of this invention. The schematic sectional drawing of the hot water storage tank upper part used for the hot-water supply system concerning the 2nd Embodiment of this invention. The schematic sectional drawing which shows the structure of the thermal storage material used for the hot water supply system concerning the 2nd Embodiment of this invention. The figure which shows the temperature distribution of the hot water storage tank upper part in the hot water supply system concerning the 2nd Embodiment of this invention. The block diagram which shows the concept of the hot water supply system of the conventional waste heat utilization. The figure which shows a part of hot water storage tank shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Heat pump unit 3 ... Hot water storage tank 3a ... Heat insulation material layer 5 ... Hot water supply part 7 ... Water heat exchanger 9 ... Gas combustion unit 9a ... Primary heat exchanger 9b ... Secondary heat exchanger 11 ... Gas combustion part 19 ... Gas Combustion unit 19a ... primary heat exchanger 19b ... secondary heat exchanger 21 ... casing 23 ... exhaust gas passage 25 ... exhaust port 27 ... exhaust fan 29 ... heat storage material 31 ... space P ... piping S ... hot water supply system T ... hot water storage tank Part

Claims (6)

A heat pump unit including a compressor, an expansion valve, an air heat exchanger and a water heat exchanger; a gas combustion unit for heating water heated by the heat pump unit; In a hot water supply system comprising a hot water storage tank for accumulating water heated by a unit, and water circulation means for supplying water in the hot water storage tank to a water flow pipe of the water heat exchanger,
The exhaust gas used for heating the water from the water heat exchanger in the gas combustion unit is guided to the periphery of the hot water storage tank, and is provided with exhaust gas utilization means for raising the ambient temperature of the hot water storage tank. Hot water supply system.   2. The gas combustion unit includes a plurality of stages of gas water heat exchangers, and the exhaust gas utilization means uses combustion exhaust gas discharged from a final stage in the plurality of stages of gas water heat exchangers. Hot water supply system as described in.   3. The hot water supply system according to claim 1, wherein the hot water storage tank is disposed on the gas combustion unit, and the rising exhaust gas discharged from the gas combustion unit is led around the hot water storage tank.   An outer casing that houses the hot water storage tank therein is provided, and an air passage is formed between the hot water storage tank and the outer casing for flowing the exhaust gas discharged from the gas combustion unit. A hot water supply system according to any one of the above.   The hot water supply system according to claim 4, wherein the outer casing further stores the gas combustion unit.   The hot water supply system according to claim 4 or 5, wherein heat storage means is provided in the air passage.

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