JP5230352B2 - Water heater - Google Patents

Description

  The present invention relates to a water heater, and more particularly to a water heater that improves the heat exchange efficiency of a heat exchanger.

  2. Description of the Related Art A hot water storage system that stores heated water heated by a water heater in a hot water storage tank of a hot water storage tank unit is conventionally known. As a hot water storage tank unit used in such a conventional hot water storage system, for example, “the hot water storage tank unit 1 includes a hot water storage tank 7 for storing hot water, a hot water pipe 8 connected to the upper part of the hot water storage tank 7, and a hot water storage tank. A water supply pipe 9 connected to the lower part of the water supply pipe, a mixing valve 11 for mixing hot water from the hot water supply pipe 8 and low temperature water from the bypass pipe 10 branched from the water supply pipe 9, and hot water supply connected downstream of the mixing valve 11 A hot water temperature sensor 13 provided in the pipe 12, a hot water sensor 14 provided in the hot water pipe 12, a hot water temperature sensor 15 provided in the water supply pipe 9, and hot water branched from the hot water pipe 12 and connected to the bathtub 5. A branch pipe 16, a hot water valve 17 that opens and closes the hot water pipe 16, a hot water flow rate sensor 18 that integrates the flow rate flowing through the hot water pipe 16, and a hot water pipe 8 are branched. An overpressure relief valve 19 for releasing the continued overpressure of the hot water storage tank 7, a pressure reducing valve 20 for reducing the water supply pressure provided in the water supply pipe 9, and a plurality of hot water storage temperature sensors provided in the vertical direction of the side surface of the hot water storage tank 7. 21, a hot water supply control unit 22 mainly constituted by a microcomputer for controlling the hot water storage tank unit 1, the hot water storage tank 7 and the heating unit 2 are connected by an outgoing pipe 23 and a return pipe 24 to circulate hot water. The heating circulation circuit 25 is formed "(for example, see Patent Document 1).

  By the way, the amount of air that can be dissolved in water decreases as the temperature of water increases. For this reason, by heating water with the heat exchanger of a water heater, the air dissolved in the water becomes bubbles and is released into the heat exchanger (pipes thereof). In a conventional hot water storage system (see, for example, Patent Document 1), this air released from water flows through a heat exchanger and is stored in a hot water storage tank together with heated water. And the air stored in the hot water storage tank was discharged from the overpressure relief valve (overpressure relief valve 19) provided in the hot water storage tank.

JP 2006-226560 A (paragraph 0011, FIG. 1)

  In the conventional water heater, the air released from the water in the process of raising the temperature of the heat in the heat exchanger flows into the heat exchanger together with water as bubbles. For this reason, the flow rate decreases due to a decrease in the heat transfer rate to water in the heat exchanger and an increase in the flow resistance in the heat exchanger, and the heat exchange efficiency of the heat exchanger decreases. was there.

  In addition, if the pump that circulates water in the heat exchanger (hereinafter referred to as the feed water pump) is changed to one with a large maximum output value, and the reduction in heat exchange efficiency of the heat exchanger is compensated, the following problems will occur. there were.

  FIG. 8 is a characteristic diagram showing characteristics of the feed water pump. For example, it is assumed that the water supply pump A having the maximum output A1 and the minimum output A2 is used. In a state in which moderate air (bubbles) is released from the water flowing through the heat exchanger (normal (in the bubbles) pressure loss curve shown in the figure), the feed water pump A is 11 [L / min]. If it is going to distribute | circulate the water of a flow volume to a heat exchanger, the output of the feed water pump A will be A3 (X point in a figure). At this time, when a large amount of air (bubbles) is released from the water flowing through the heat exchanger (normal (bubble large) pressure loss curve shown in the figure), the flow rate of 11 [L / min] by the feed water pump A In order to distribute the water in the heat exchanger, it is necessary to maximize the output of the feed water pump A (point Y in the figure). However, if the increase in the output of the feed water pump A is slow, the head of the feed water pump becomes smaller than the flow path resistance in the heat exchanger, and water is cut off (a state in which heated water does not flow out of the water heater).

  Therefore, in order to avoid this water break, it is assumed that the feed water pump B (the maximum output B1 and the minimum output B2) having a larger maximum output value than the feed water pump A is used. However, the feed water pump B having a larger maximum output value than the feed water pump A also has a minimum output greater than that of the feed water pump A. For this reason, there existed a problem that the flow control range will become small. For example, in a state where a large amount of air (bubbles) is released from the water flowing through the heat exchanger (normal (bubble large) pressure loss curve shown in the figure), the flow rate control range of the feed water pump A is 6 [L / min] (range 1), whereas the flow rate control range of the feed water pump B is 5 [L / min] (range 2). Further, there is a problem that the minimum control flow rate becomes large, and low-temperature water that is not sufficiently heated by the heat exchanger flows into the hot water storage tank. For example, in a state where not much air (bubbles) is released from the water flowing through the heat exchanger (normal (small bubble) pressure loss curve shown in the figure), the minimum flow rate of the feed water pump A is 8 [L / min]. (V point in the figure), the minimum flow rate of the feed water pump B is 12 [L / min] (W point in the figure).

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a water heater that suppresses the amount of bubbles flowing through the heat exchanger and improves the heat exchange efficiency of the heat exchanger. To do.

  The water heater according to the present invention includes a plurality of heat exchangers for heating water, and at least one of pipes connecting the heat exchanger on the upstream side of the water flow and the heat exchanger on the downstream side of the water flow. The two pipes, in order from the upstream side of the water flow, are provided with a pressure reducing means for reducing the pressure of water flowing through the pipe, and an air venting means for discharging air released from the water by being reduced in pressure from the pipe. It is what.

  In the present invention, the water flowing in the pipe connecting the heat exchanger is decompressed by the decompression means. Thereby, the air dissolved in the water flowing through the pipe is released into the pipe as bubbles. And this air (bubble) is discharged | emitted out of piping by an air venting means. Accordingly, it is possible to suppress a decrease in the heat transfer rate to water in the heat exchanger and an increase in flow path resistance in the heat exchanger, and the heat exchange efficiency of the heat exchanger is improved.

Embodiment.
In the present embodiment, a case will be described in which the present invention is implemented in a water heater using a refrigeration cycle apparatus as a heat source.

  FIG. 1 is a piping circuit diagram showing a hot water storage system according to an embodiment of the present invention. In FIG. 1, the direction of water flow is also indicated by arrows. The hot water storage tank 1 is a tank that stores high-temperature hot water (heated water) heated by a hot water supply device, the lower part is connected to the hot water supply 30 via a water inflow pipe 31, and the upper part is connected to a water outflow pipe 32. It is connected to the water heater 30. Thereby, the low temperature water stored in the lower part of the hot water storage tank 1 flows into the water heater 30 through the water inflow pipe 31. The high temperature water (heated water) heated by the hot water heater 30 is stored in the hot water storage tank 1 through the water outflow pipe 32. The details of the water heater 30 will be described later.

  A lower part of the hot water storage tank 1 is connected to a water receiving tank 2 through a water supply pipe 3. The water supply pipe 3 is provided with a water supply valve 4 for controlling the amount of water supplied from the water receiving tank 2 to the hot water storage tank 1. A hot water supply pipe 5 is connected to the upper part of the hot water storage tank 1. The other end of the hot water supply pipe 5 is connected to a water-water heat exchanger 21 for heating the hot water in the bathtub 23. The hot water supply pipe 5 is provided with a hot water supply pump 6 for sending high temperature water stored in the hot water storage tank 1 to the water-water heat exchanger 21. The water-water heat exchanger 21 is also connected to an intermediate portion of the hot water storage tank 1 through the return pipe 7. In addition, an air vent valve 9 for discharging the air stored in the hot water storage tank to the atmosphere is connected to the upper part of the hot water storage tank 1. The hot water supply pump 6 may be provided in the return pipe 7.

  The water-water heat exchanger 21 is connected to the bathtub 23 via a bathtub feed pipe 24 and a bathtub return pipe 25. The bathtub feed pipe 24 is provided with a circulation pump 26 for sending water stored in the bathtub 23 to the water-water heat exchanger 21.

  The hot water supply pipe 5 branches into a hot water supply hot water supply pipe 10 at a branching portion 8. The other end of the hot-water tap hot water supply pipe 10 is connected to the return pipe 7. A hot-water tap 11 is connected to the hot-water tap hot water supply pipe 10. This hot water tap 11 is installed in a kitchen, a bathroom, a washroom, etc., for example.

(Water heater)
Next, details of the water heater 30 will be described.
FIG. 2 is a piping circuit diagram showing the water heater according to the embodiment of the present invention. In FIG. 2, the direction of water flow is indicated by solid arrows, and the direction of refrigerant flow is indicated by broken arrows. The water heater 30 according to the present embodiment uses a refrigeration cycle apparatus 40 as a heat source. The refrigeration cycle apparatus 40 uses a CO ₂ refrigerant. The high-pressure CO ₂ refrigerant has a characteristic of being in a supercritical state. That is, the CO ₂ refrigerant in the supercritical state does not condense when heat is given to another fluid (here, water) by heat exchange, and remains in the supercritical state. For this reason, there is little loss by a state transition and it is suitable for heating water to high temperature.

The refrigeration cycle apparatus 40 includes two refrigerant-water heat exchangers (first refrigerant-water heat exchanger 42 and second refrigerant-water heat exchanger 43) as radiators. And the refrigeration cycle apparatus 40 is comprised by connecting the compressor 41, the 1st refrigerant | coolant-water heat exchanger 42, the 2nd refrigerant | coolant-water heat exchanger 43, the expansion valve 44, and the evaporator 45 in order by piping. doing. Incidentally, the refrigerant is not limited to CO ₂ refrigerant, various refrigerant can be used. In this case, the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43 function as a condenser.

  The first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43 are also connected to a water pipe through which water stored in the hot water storage tank 1 flows. More specifically, one water pipe connection port of the first refrigerant-water heat exchanger 42 is connected to the water inflow pipe 31. The other water pipe connection port of the first refrigerant-water heat exchanger 42 and one water pipe connection port of the second refrigerant-water heat exchanger 43 are connected by a water circulation pipe 33. The other water pipe connection port of the second refrigerant-water heat exchanger 43 is connected to the water outflow pipe 32. In addition, the water distribution pipe 33 is provided with a pressure reducing means 34 such as an expansion valve, an air venting means 35 such as an air vent valve, and a pressure boosting means 36 such as a compressor in order from the upstream side in the water flow direction. It has been. The water inflow pipe 31 is provided with a water supply pump 38 for sending the water in the hot water storage tank 1 to the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43.

(Operation)
Then, operation | movement of the hot water storage system 100 which concerns on this Embodiment is demonstrated. Of the water stored in the hot water storage tank 1, low-temperature water is present in the lower part of the hot water storage tank 1. This low-temperature water is sent to the first refrigerant-water heat exchanger 42 by the feed water pump 38. The low-temperature water that has flowed into the first refrigerant-water heat exchanger 42 is heated by the CO ₂ refrigerant flowing through the first refrigerant-water heat exchanger 42 to become medium-temperature water, and the first refrigerant-water heat exchange is performed. Out of the vessel 42. The medium-temperature water that has flowed out of the first refrigerant-water heat exchanger 42 flows into the second refrigerant-water heat exchanger 43 through the water circulation pipe 33. The intermediate temperature water that has flowed into the second refrigerant-water heat exchanger 43 is heated by the CO ₂ refrigerant flowing through the _second refrigerant-water heat exchanger 43 to become high-temperature water, and the second refrigerant-water heat exchange is performed. Out of the vessel 43. The high temperature water flowing out from the second refrigerant-water heat exchanger 43 flows into the upper part of the hot water storage tank 1 through the water outflow pipe 32 and is stored in the hot water storage tank 1. The details of the water heating process in the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43 and the details of the functions of the decompression means 34, the air vent means 35, and the pressure boost means 36 are as follows. It will be described later.

  The hot water stored in the hot water storage tank 1 is sent to the hot water tap 11 and the water-water heat exchanger 21 by the hot water supply pump 6. The high-temperature water sent to the hot-water tap 11 is discharged from the hot-water tap 11 when the user opens the hot-water tap 11, for example. The water that has not been released from the hot water tap 11 flows into the return pipe 7 through the hot water supply hot water supply pipe 10.

  The high-temperature water that has flowed into the water-water heat exchanger 21 radiates heat to the water stored in the bathtub 23 and flows into the return pipe 7. The water flowing into the return pipe 7 flows into the hot water storage tank 1 from the intermediate portion of the hot water storage tank 1. On the other hand, the water stored in the bathtub 23 circulates through the bathtub 23, the bathtub return pipe 25, the water-water heat exchanger 21, and the bathtub feed pipe 24 by the circulation pump 26. In this circulation process, the water flowing into the water-water heat exchanger 21 is heated.

  When the amount of water stored in the hot water storage tank 1 is reduced due to discharge from the hot water tap 11 or the like, the water supply valve 4 is opened and water is supplied from the water receiving tank 2 to the hot water storage tank 1.

(Water heating step and functions of the pressure reducing means 34, the air venting means 35, and the pressure increasing means 36)
Here, details of the water heating process in the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43 and details of the functions of the decompression means 34, the air venting means 35, and the pressure boosting means 36 are explained. explain. First, before describing these details, the characteristics of the dissolved air amount in water will be described.

FIG. 3 is a characteristic diagram showing characteristics of the amount of dissolved air in water. In FIG. 3, the horizontal axis indicates the water temperature [° C.], and the vertical axis indicates the amount of air [g] dissolved in the water 1000 [g]. Also, the thick curve in FIG. 3 indicates the amount of air [g] dissolved in water 1000 [g] when the water pressure is 100 [kPa], and the thin curve indicates when the water pressure is 300 [kPa]. The amount of air [g] dissolved in 1000 [g] of water is shown.
FIG. 3 shows that the lower the water temperature, the greater the amount of dissolved air in the water. And when water temperature becomes about 40 [degreeC] or more, it turns out that there is not much amount of dissolved air in water. It can also be seen that the higher the water pressure, the greater the amount of dissolved air in the water. And it turns out that the temperature dependence of the amount of dissolved air in water is so high that a water pressure is high.

  Based on the characteristics of the amount of dissolved air in the water, details of the water heating process in the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43, the decompression means 34, and the air vent means 35 Details of the function of the booster 36 will be described below.

  FIG. 4 is a characteristic diagram showing the relationship between the amount of discharged air and the temperature of water in the refrigerant-water heat exchanger according to the embodiment of the present invention. In FIG. 4, the solid line indicates the amount of air released in the refrigerant-water heat exchanger (the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43) according to the present embodiment. The broken line indicates the amount of air released in the conventional refrigerant-water heat exchanger. FIG. 5 is a characteristic diagram showing the relationship between water pressure and temperature in the refrigerant-water heat exchanger. In FIG. 5, the solid line indicates the pressure of water in the refrigerant-water heat exchanger (the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43) according to the present embodiment. A change is shown and the broken line has shown the pressure change of the water in the conventional refrigerant | coolant-water heat exchanger.

The low-temperature water (point A) flowing into the first refrigerant-water heat exchanger 42 is heated by the CO ₂ refrigerant flowing through the first refrigerant-water heat exchanger 42 to become medium-temperature water, and the first refrigerant -Outflow from the water heat exchanger 42 (point B). At this time, as the water temperature increases, part of the air dissolved in the water is released as bubbles. The water pressure decreases due to pressure loss due to the generation of bubbles. The medium-temperature water and bubbles that have flowed out of the first refrigerant-water heat exchanger 42 flow into the decompression means 34 and are decompressed (point C). At this time, part of the air dissolved in the water is released as bubbles as the water pressure decreases. The medium-temperature water and air bubbles that have flowed out from the decompression means 34 pass through the air venting means 35 (or the pipe connection part 37 between the air venting means 35 and the water circulation pipe 33), and only the air bubbles are in the atmosphere by the air venting means 35. (D point). For this reason, the water that has passed through the air venting means 35 is water with a small amount of dissolved air.

The medium-temperature water from which bubbles are discharged into the atmosphere by the air venting unit 35 is pressurized by the boosting unit 36 (point E) and flows into the second refrigerant-water heat exchanger 43. And it is heated by the CO2 refrigerant | coolant which flows through the _2nd refrigerant | coolant-water heat exchanger 43, becomes high temperature water, and flows out out of the 2nd refrigerant | coolant-water heat exchanger 43 (F point). At this time, the medium temperature water flowing into the second refrigerant-water heat exchanger 43 has a small amount of dissolved air. Therefore, since air bubbles generated in the second refrigerant-water heat exchanger 43 can be suppressed, a decrease in heat exchange efficiency in the second refrigerant-water heat exchanger 43 can be suppressed. That is, the second refrigerant-water heat exchanger 43 according to the present embodiment has higher heat exchange efficiency than the conventional refrigerant-water heat exchanger.

  Although the booster 36 is provided in the present embodiment, the booster 36 is not necessarily provided. Even if the boosting means 36 is not provided, the amount of dissolved air in the medium-temperature water flowing into the second refrigerant-water heat exchanger 43 is small, so that the heat exchange efficiency of the second refrigerant-water heat exchanger 43 is improved. Reduction can be suppressed. However, by increasing the pressure by the pressure increasing means 36, the permissible dissolved amount of air increases in the medium temperature water flowing into the second refrigerant-water heat exchanger 43. For this reason, the bubble which generate | occur | produces in the 2nd refrigerant | coolant-water heat exchanger 43 can further be suppressed, and the fall of the heat exchange efficiency in the 2nd refrigerant | coolant-water heat exchanger 43 can further be suppressed.

Here, paying attention to FIG. 5, the pressure loss increases in the range where the water temperature is around 50 ° C. This is due to the characteristics of the CO ₂ refrigerant used in the present embodiment.
FIG. 6 is a characteristic diagram showing the relationship between the temperature and enthalpy of water and CO ₂ refrigerant flowing through the refrigerant-water heat exchanger according to the embodiment of the present invention. FIG. 6 shows changes in the temperatures of water and CO ₂ refrigerant flowing through the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43. In the present embodiment, the water flowing through the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43 and the CO ₂ refrigerant are in a counterflow. For this reason, the temperature change of the CO ₂ refrigerant from the time when it flows into the first refrigerant-water heat exchanger 42 to the time when it flows out of the second refrigerant-water heat exchanger 43 is the temperature from right to left in FIG. It becomes a change. Moreover, the temperature change of the water from flowing into the first refrigerant-water heat exchanger 42 to flowing out of the second refrigerant-water heat exchanger 43 is a temperature change from left to right in FIG. .

As can be seen from Figure 6, the temperature of CO ₂ refrigerant within an amount of around 50 [° C.], the temperature difference between the CO ₂ refrigerant and water is small. That is, in the vicinity of 50 [° C.], the heat exchange efficiency between the CO ₂ refrigerant and water is poor. For this reason, in the range where the temperature of the CO ₂ refrigerant is around 50 [° C.], it takes time to heat water. That is, the piping length necessary for heating water near 50 [° C.] becomes long. Therefore, as shown in FIG. 5, the pressure loss becomes large in the range where the water temperature is around 50 [° C.]. For this reason, it is preferable to decompress the water and discharge the bubbles into the atmosphere before the water temperature reaches around 50 [° C.]. In the state where the water temperature is in the vicinity of 50 [° C.], the pressure loss due to the bubbles can be reduced, so that the decrease in heat exchange efficiency in the second refrigerant-water heat exchanger 43 can be suppressed.

  In the water heater 30 configured as described above, the pressure reducing means 34 and the air venting means 35 are connected to the water circulation pipe 33 that connects the first refrigerant-water heat exchanger 42 and the second refrigerant-water heat exchanger 43. Is provided. For this reason, since the amount of dissolved air is small in the medium temperature water flowing into the second refrigerant-water heat exchanger 43, a decrease in heat exchange efficiency in the second refrigerant-water heat exchanger 43 can be suppressed. That is, the second refrigerant-water heat exchanger 43 according to the present embodiment has higher heat exchange efficiency than the conventional refrigerant-water heat exchanger.

  Further, since the pressure increasing means 36 is provided between the air venting means 35 and the second refrigerant-water heat exchanger 43, the medium temperature water flowing into the second refrigerant-water heat exchanger 43 is air. The allowable dissolved amount of increases. For this reason, the bubble which generate | occur | produces in the 2nd refrigerant | coolant-water heat exchanger 43 can further be suppressed, and the fall of the heat exchange efficiency in the 2nd refrigerant | coolant-water heat exchanger 43 can further be suppressed.

  In addition, pressure loss due to bubbles when the water temperature is around 50 [° C.] can be reduced by reducing the pressure of the water and discharging the bubbles into the atmosphere before the water temperature becomes around 50 [° C.] A decrease in heat exchange efficiency in the second refrigerant-water heat exchanger 43 can be suppressed.

  In the present embodiment, the connection method of the air venting means 35 to the water circulation pipe 33 is not particularly mentioned. However, the pipe connection part 37 that is the connection part of the air venting means 35 and the water circulation pipe 33 is connected with water. You may provide the deceleration part which decelerates speed.

  FIG. 7 is a schematic cross-sectional view showing an example of the speed reducing portion according to the embodiment of the present invention. For example, as shown in FIG. 7A, the pipe cross-sectional area of the pipe connection part 37 may be increased to form the speed reduction part 50. The diameter S1 of the speed reduction part 50 is larger than the pipe diameter S2 before and after the speed reduction part 50. That is, the cross-sectional area of the speed reduction part 50 is larger than the cross-sectional area before and after the speed reduction part 50. As a result, the water flowing through the speed reducing unit 50 is decelerated, and the air bubbles easily flow into (up) the air venting means 35. Further, for example, as shown in FIG. 7B, a speed reduction plate 51 may be provided in the pipe connection portion 37 to form the speed reduction portion 50. The water that has collided with the speed reducing plate 51 decelerates, and bubbles easily flow into (up) the air venting means 35. Of course, the speed reducing plate 51 may be used in the speed reducing portion 50 having a large pipe diameter shown in FIG. The speed reduction part 50 shown in FIG. 7 is an exemplification, and various configurations are possible as long as the mechanism can reduce the speed of water.

  In this embodiment, water is heated using two refrigerant-water heat exchangers (first refrigerant-water heat exchanger 42 and second refrigerant-water heat exchanger 43). The number of heat exchangers is arbitrary as long as it is plural. At this time, the decompression means 34, the air vent means 35, and the pressure increase means 36 may be provided in all the water circulation pipes connecting the refrigerant-water heat exchangers, or the water circulation connecting the refrigerant-water heat exchangers. You may provide the pressure reduction means 34, the air venting means 35, and the pressure | voltage rise means 36 in a part of piping.

  In the present embodiment, the hot water storage system 100 is connected to the hot water storage tank 1, but the hot water supply system 30 may be connected to the hot water tap 11 or the like without using the hot water storage tank 1.

  In the present embodiment, the refrigeration cycle apparatus 40 is used as the heat source of the water heater 30, but the heat source of the water heater 30 is arbitrary. For example, a coil may be wound around the heat exchanger to pass a high-frequency current, and water flowing in the heat exchanger may be induction-heated by an eddy current generated in the heat exchanger. At this time, before the water temperature reaches around 40 [° C.], it is preferable to decompress the water and discharge the bubbles to the atmosphere. As shown in FIG. 3, the dissolved air amount of water is small at a temperature of about 40 ° C. or higher. Therefore, by reducing the pressure of water before this temperature and discharging the bubbles to the atmosphere, the bubbles generated in the second refrigerant-water heat exchanger 43 can be suppressed, and the second refrigerant-water heat exchanger 43 can be suppressed. Decrease in heat exchange efficiency can be suppressed.

It is a piping circuit diagram which shows the hot water storage system which concerns on embodiment. It is a piping circuit diagram which shows the water heater based on Embodiment. It is a characteristic view which shows the characteristic of the amount of dissolved air in water. It is a characteristic view which shows the relationship between the amount of discharge | released air and the temperature of water in the refrigerant | coolant-water heat exchanger which concerns on embodiment. It is a characteristic view which shows the relationship between the pressure and temperature of the water in the refrigerant | coolant-water heat exchanger which concerns on embodiment. Refrigerant according to the embodiment - is a characteristic diagram showing the relationship between the temperature and enthalpy of water and CO ₂ refrigerant flowing through the water heat exchanger. It is a cross-sectional schematic diagram which shows an example of the deceleration part which concerns on embodiment. It is a characteristic view which shows the characteristic of a circulation pump.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Hot water storage tank, 2 Receiving tank, 3 Water supply piping, 4 Water supply valve, 5 Hot water supply piping, 6 Hot water supply pump, 7 Return piping, 8 Branch part, 9 Air vent valve, 10 Hot water supply piping for hot water tap, 11 Hot water tap, 21 -Water heat exchanger, 23 bathtubs, 24 bathtub feed pipes, 25 bathtub return pipes, 26 circulation pumps, 30 water heaters, 31 water inflow pipes, 32 water outflow pipes, 33 water circulation pipes, 34 decompression means, 35 air Extraction means, 36 pressurizing means, 37 piping connection part, 38 feed water pump, 40 refrigeration cycle apparatus, 41 compressor, 42 first refrigerant-water heat exchanger, 43 second refrigerant-water heat exchanger, 44 expansion valve , 45 evaporator, 50 reduction part, 51 reduction plate, 100 hot water storage system.

Claims (7)

With multiple heat exchangers to heat water,
At least one pipe among the pipes connecting the heat exchanger on the upstream side of the water flow and the heat exchanger on the downstream side of the water flow,
From the upstream side of the water flow,
Decompression means for decompressing water flowing through the pipe;
Air venting means for discharging air released from water by being decompressed from the pipe;
A water heater characterized by that. In the pipe connecting the air venting means and the heat exchanger on the downstream side of the water flow from the air venting means,
2. The water heater according to claim 1, further comprising a booster. The heat exchanger is a refrigerant-water refrigerant heat exchanger that constitutes a part of the refrigeration cycle apparatus and heat exchange between the refrigerant circulating in the refrigeration cycle apparatus and water,
The refrigeration cycle apparatus uses a CO ₂ refrigerant,
The decompression means includes
The water heater according to claim 1 or 2, wherein water at 50 ° C or less is decompressed. In the pipe connection part of the air venting means,
The water heater according to any one of claims 1 to 3, further comprising a speed reduction unit that reduces the speed of water. The deceleration part is
The hot water heater according to claim 4, wherein a cross-sectional area of the pipe is a portion that is larger than a cross-sectional area of the pipe connected before and after the speed reduction portion. In the deceleration part,
The water heater according to claim 4 or 5, wherein a speed reducing plate for reducing the speed of water is provided.   The hot water supply device according to any one of claims 1 to 6, wherein the decompression means decompresses water of 40 ° C or less.

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