JPH1151499A - Solar heat utilizing hot water supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an increase in the temperature of hot water in a hot water storage tank without stopping a circulation pump even when hot water in a hot water storage tank is increased in temperature, and to use a heating medium without deterioration in a short time. SOLUTION: A first temperature sensor 28 to detect a hot water temperature is mounted on the upper part of a hot water storage tank 14, a second temperature sensor 29 to detect the temperature of a heating medium is mounted in the vicinity of the outlet of a solar heat collector 10, and a temperature sensor 30 to detect a hot water temperature is mounted on the lower part of the hot water storage tank 14. The temperature sensors 28, 29, and 30 are all a thermistor and movement of a circulation pump 15 and a three-way valve 27 is controlled by a differential temperature controller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar hot water supply system for supplying hot water using solar heat.

[0002]

2. Description of the Related Art Conventionally, the following is known as a solar hot water supply system.

(1) A solar heat collector also serves as a hot water storage tank, a water-supply type system in which water is directly supplied to the solar heat collector and heated to store hot water. (2) A hot water storage tank above the solar heat collector The natural circulation system where hot water heated by the solar heat collector is replaced by water in the hot water storage tank by natural convection (3) A hot water storage tank is placed away from the solar heat collector, Direct heating type forced circulation system in which the water in the hot water tank is supplied to the solar heat collector by a direct circulation pump to heat it. (4) The hot water tank is placed away from the solar heat collector and heat is applied to the hot water tank. An indirect heating type that has a built-in heat exchanger, supplies a dedicated heat medium (for example, antifreeze) to the solar heat collector with a circulation pump and heats it, flows the heat medium through the heat exchanger, and heats the water in the hot water storage tank. Forced circulation system

[0004] Among these systems, the indirect heating type forced circulation system of (4) is known as the most excellent system for preventing freezing of piping in winter.

This indirect heating type forced circulation system is shown in FIG.
As shown in the figure, the inlet of the solar heat collector 10 and the heat exchanger 11
The solar heat collector 10 and the hot water storage tank 14 are connected by an outgoing pipe 12 connecting the outlet of the solar heat collector 10 and a return pipe 13 connecting the outlet of the solar heat collector 10 and the inlet of the heat exchanger 11.

[0006] A circulation pump 15 and a reserve tank 16 for storing a heat medium are attached to the outgoing pipe 12, and the heat medium flowing out of the heat exchanger 11 enters the reserve tank 16 through the outgoing pipe 12 and is further reserved. Tank 16
After passing through the circulation pump 15, it flows from the outgoing pipe 12 to the solar heat collector 10 and is heated by the solar heat collector 10. The heat medium heated by the solar heat collector 10 flows from the return pipe 13 to the heat exchanger 11, indirectly heats the water in the hot water storage tank 14, and exits from the heat exchanger 11.

Generally, near the outlet of the solar heat collector 10,
A high temperature side temperature sensor 17 for detecting the heating temperature of the heat medium is attached, and a low temperature side temperature sensor 18 for detecting the water temperature at the lower part of the hot water tank is attached to the hot water tank 14. When the difference between the temperature detected by the low-temperature side temperature sensor 18 becomes equal to or higher than a certain temperature, the circulation pump 15 is started to circulate the heat medium, and when the temperature difference between the two becomes equal to or lower than the certain temperature, the circulation pump 15 is stopped. I do.

Therefore, when the sun comes out on the morning of a sunny day, the heat medium in the solar heat collector 10 is heated and the temperature rises, and the difference between the heat medium temperature and the water temperature in the hot water storage tank 14 is equal to or higher than a certain temperature. Then, the circulation pump 15 is started to start the heat collecting operation. During the daytime, after continuing to collect heat, when the difference between the temperature of the heat medium in the solar heat collector 10 and the temperature of the hot water in the hot water storage tank 14 becomes lower than a certain temperature, the circulation pump 15 is stopped to prevent the heat radiation operation. Collects solar heat efficiently.

A hot water supply pipe 19 is provided above the hot water storage tank 14.
A water supply pipe 20 is provided at the bottom of the hot water storage tank 14.
When a certain amount of hot water is taken out from the hot water supply pipe 19, the same amount of water is supplied into the hot water storage tank 14 via the water supply pipe 20. In the figure, 21 is an air vent valve, 22 is a safety valve, and 23 is a pressure reducing check valve.

[0010]

In the above-described system of the indirect heating type forced circulation system, if the amount of hot water in the hot water storage tank 14 is small or the sunny day continues when the hot water is not used at all, the hot water in the hot water storage tank 14 is not used. Since the temperature of the hot water is high and it is dangerous, the circulation pump 15 is normally stopped when the hot water temperature in the hot water storage tank 14 reaches 80 to 90 ° C., and the heat collecting operation is stopped to prevent the temperature from rising any more. I am trying to do it.

However, the circulation pump 15
When the solar radiation is large when the solar heat collector is stopped,
The heat medium remaining inside may be heated to 100 ° C. or higher in some cases, and the heat medium exceeds the heat-resistant temperature of the heat medium.

Usually, an antifreeze such as polypropylene glycol is used as a heat medium. If the antifreeze is continued to be used while being deteriorated, the evaporation residue is clogged in the circulation path of the solar heat collector or the circulation pump. Driving becomes impossible.

Therefore, when the heat medium deteriorates, it is necessary to immediately remove all the heat medium from the reserve tank and supply a new heat medium. However, an increase in the number of these operations increases costs and workability. Not desirable.

The present invention has been made in view of the above point, and can prevent a rise in the temperature of hot water in a hot water tank without stopping a circulation pump even when the temperature of hot water in the hot water tank becomes high. It is an object of the present invention to provide a solar hot water supply system that can be used without deteriorating a heat medium in a short period of time.

[0015]

A solar hot water supply system according to the present invention includes a solar heat collector, a hot water storage tank for storing hot water,
A first heat exchanger mounted near the bottom of the hot water tank;
A second heat exchanger mounted on the top of the hot water storage tank;
Pipe connecting the outlet of the second heat exchanger to the outlet of the second heat exchanger, a three-way valve attached to a branch of the bypass pipe from the inlet of the second heat exchanger, and a solar heat collector A return pipe connecting the outlet of the solar heat collector and the inlet of the first heat exchanger, and a return pipe connecting the outlet of the solar heat collector and the inlet of the first heat exchanger. ,
A circulation pump for circulating a heat medium between the solar heat collector and the first and second heat exchangers, and a reserve attached to an outgoing pipe between an outlet of the second heat exchanger and the circulation pump A tank, a control circuit for starting and stopping the circulation pump, a water supply pipe attached to the bottom of the hot water tank, a hot water supply pipe attached to the top of the hot water tank, and a first heat exchanger in the hot water tank. A temperature and pressure control valve or a temperature control valve for detecting hot water temperature is provided near the hot water tank, a first temperature sensor for detecting hot water temperature is mounted on an upper portion of the hot water storage tank, and a heat medium is provided near an outlet of the solar heat collector. A second temperature sensor for detecting the temperature is attached, a third temperature sensor is attached to the lower part of the hot water tank, and when the detected temperature of the first temperature sensor is equal to or lower than the set temperature, the heat medium is returned to the return pipe, First heat exchanger, bypass pipe, reserve When the detected temperature of the first temperature sensor exceeds the set temperature and is higher than the detected temperature of the second temperature sensor, the heat medium flows in the order of ink, circulation pump, outgoing pipe, and solar heat collector. , A return pipe, a first heat exchanger, a bypass pipe, a second heat exchanger, a reserve tank, a circulation pump, an outgoing pipe, and a solar heat collector.

[0016] The solar hot water supply system of the present invention further comprises:
The set temperature is characterized by being lower than the set temperature of the temperature control valve or the temperature control valve, and further, the set temperature of the temperature control valve or the temperature control valve is
The temperature is 60 to 99 ° C.

[0017]

In the solar hot water supply system of the present invention, when the normal heat collecting operation is performed, that is, when the temperature detected by the first temperature sensor is lower than the set temperature (for example, 60 ° C.), the heat medium is supplied to the second heat exchange system. It does not flow into the vessel, but flows only into the first heat exchanger to warm the water in the hot water storage tank. That is, the heat medium flows in the order of the return pipe, the first heat exchanger, the bypass pipe, the reserve tank, the circulation pump, the outgoing pipe, and the solar heat collector.

However, when the amount of hot water in the hot water tank is small or unused, the sunny day continues, the temperature of the hot water in the hot water tank rises and exceeds the set temperature, the amount of solar radiation is small, and When the temperature of the heat medium near the outlet is lower than the hot water temperature in the hot water storage tank, that is, when the detected temperature of the first temperature sensor exceeds the set temperature and is higher than the detected temperature of the second temperature sensor, The heat medium also flows into the second heat exchanger to perform a heat radiation operation, and keeps the temperature of the hot water in the hot water tank at or below the set temperature. That is, the heat medium is supplied to the return pipe, the first heat exchanger, the bypass pipe, and the second pipe.
Heat exchanger, reserve tank, circulation pump, going pipe,
It flows in the order of the solar collector.

Further, the temperature of the hot water in the hot water storage tank rises and exceeds the set temperature, the amount of solar radiation is large, and the temperature of the heat medium in the solar heat collector becomes
When the temperature is higher than the temperature of the hot water in the hot water storage tank, that is, when the detected temperature of the first temperature sensor exceeds the set temperature and is lower than the detected temperature of the second temperature sensor, the heat medium is subjected to the first heat exchange. The heat collection operation is continued by flowing only through the heater, but if this set temperature is set lower than the set temperature of the hot pressure valve or temperature control valve in the hot water tank, the hot water temperature in the hot water tank will be When the set temperature of the valves is reached, only hot water around the first heat exchanger located near the bottom of the hot water tank is discharged from these valves to the outside, and the same amount of water as the discharged hot water is supplied to the water supply pipe. Is supplied to the bottom of the hot water storage tank, the temperature of the hot water around the first heat exchanger decreases, and when the temperature of the hot water near the hot pressure valve or the temperature control valve becomes equal to or lower than the set temperature of the hot pressure valve or the temperature control valve, Those valves close,
Water supply is stopped.

Even if the circulation pump continues to operate, the first
The cooled hot water around the heat exchanger will be heated, and when the temperature of the hot water around the first heat exchanger reaches the set temperature of the hot-pressure valve or the temperature control valve again, the hot-water pressure valve or the temperature control valve turns off. The operation of discharging only the hot water around the first heat exchanger is repeated.
Therefore, the hot water in the hot water storage tank is not heated above the set temperature of the hot-pressure valve or the temperature control valve, and the hot water temperature in the hot water storage tank is defined by the set temperature of the hot-pressure valve or the temperature control valve. .

Further, in the present invention, the hot water in the hot water tank above the first heat exchanger is hardly discharged from the hot-pressure valve or the temperature control valve, and the hot water around the first heat exchanger is discharged. At the same time, water is supplied from the bottom of the hot water storage tank, and the temperature of the hot water around the first heat exchanger is lowered at an early stage, and the temperature control valve and the temperature control valve are closed, so that the amount of discharged hot water is small. However, if the mounting position of the hot-pressure valve or the temperature control valve in the hot water tank is lower than that of the first heat exchanger, even if the amount of water supplied into the hot water tank is small, This is not preferable because the temperature of the hot water around the valve control drops and the valve closes, and the temperature of the hot water near the first heat exchanger hardly decreases.

Further, in the present invention, when the temperature difference between the detected temperature of the second temperature sensor and the detected temperature of the third temperature sensor becomes a certain temperature or more (for example, 4 to 10 ° C.),
When the circulation pump is started and the temperature difference between the two becomes lower than a certain temperature (for example, 1 to 3 ° C.), the circulation pump is stopped by controlling the circulation pump to stop. Since the temperature of the heat medium is close to the temperature of the hot water in the hot water storage tank, if the set temperature of the temperature control valve or the temperature control valve is lower than the heat-resistant temperature of the heat medium, specifically, 60 to 99 ° C., the solar heat collector It is possible to prevent the heat medium in the inside from deteriorating.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a solar hot water supply system of the present invention will be described in detail based on embodiments.

FIG. 1 is an explanatory view showing a solar hot water supply system according to the present invention.

In the figure, a solar heat collector 10 is placed in a vacuum glass tube (outer diameter φ126 mm × total length 2830 mm) in which the surface is selectively absorbing film-treated with a width of 116 mm and a length of 2620 m.
m, an iron heat collecting plate having a thickness of 0.4 mm, and an outer diameter φ15.88 mm caulked by a press on the central axis of the iron heat collecting plate.
Twelve tubes having a 0.6 mm thick copper heat transfer tube were used. The effective heat collection area was 3.
64 m ² . The hot water storage tank 14 is made of stainless steel (outside diameter φ530 mm × total length 1445 mm), and the amount of hot water stored is about 300 liters. The first heat exchanger 24 attached to the hot water storage tank 14 is made of stainless steel (outer diameter φ16 mm).
× total length 8 m), the heat transfer area is 0.4 m ² , the mounting position is in the range of 50 to 250 mm from the bottom of the hot water storage tank 14, and the second heat exchanger 25 is also made of stainless steel (outer diameter φ16
mm × 4 m in total length), the heat transfer area is 0.2 m ² , and the mounting position is in the range of 50 to 150 mm from the upper surface of the hot water storage tank 14.

The reserve tank 16 is a molded polyethylene product and has a capacity of about 20 liters. The output of the circulation pump 15 is 100 V · 115 W, the set pressure of the pressure reducing check valve 23 is 0.80 kg / cm ² , the set pressure of the safety valve 22 is 0.95 kg / cm ² ,
As a heat medium, an antifreeze solution of polypropylene glycol was used.

Outside the hot water storage tank 14, the first heat exchanger 2
A bypass pipe 26 is provided for connecting the outlet of the second heat exchanger 25 to the outlet of the second heat exchanger 25, and a three-way valve 27 is attached to a branch of the bypass pipe 26 from the inlet of the second heat exchanger 25. ing.

A first temperature sensor 28 for detecting the temperature of the hot water is mounted on the upper part of the hot water storage tank 14.
A second temperature sensor 29 for detecting the temperature of the heat medium is attached near the outlet of the hot water storage tank 14.
A third temperature sensor 30 for detecting the temperature of hot water is attached. Each of these temperature sensors 28, 29, 30 is a thermistor, and controls the operation of the circulation pump 15 and the three-way valve 27 by a differential temperature controller.

This control condition is such that the temperature detected by the first temperature sensor 28 is higher than 70 ° C.
When the temperature is higher than the temperature detected by the temperature sensor 29, the heat medium exiting the first heat exchanger 24 passes through the bypass pipe 26,
When the temperature detected by the first temperature sensor 28 is 70 ° C. or less, the first heat exchanger 24
Exits through the bypass pipe 26,
Set to flow.

The temperature control valve 31 mounted on the side wall near the heat exchanger 12 in the hot water storage tank 14 is of a wax thermo type, and its set temperature is 85 ° C. Temperature control valve 3
The length of the first thermo (thermosensitive part) varies depending on the size and shape of the first heat exchanger 24, but is made as long as possible so as not to contact the first heat exchanger 24, and the first heat The setting is made so that the temperature of the hot water around the exchanger 24 is detected. Temperature control valve 31
Is set at a position 230 mm from the bottom surface of the hot water storage tank 14.

[0031]

As described above, according to the solar hot water supply system of the present invention, when the amount of hot water in the hot water tank is small, or when the hot water in the hot water tank is not used at all, sunny days continue, and the hot water in the hot water tank becomes hot. However, since the temperature of the hot water in the hot water storage tank can be prevented from rising without stopping the circulation pump, it is possible to use the heat medium without deterioration in a short period of time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a solar hot water supply system of the present invention.

FIG. 2 is an explanatory view showing a conventional solar hot water supply system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Solar heat collector 11 Heat exchanger 12 Outgoing pipe 13 Return pipe 14 Hot water storage tank 15 Circulation pump 16 Reserve tank 19 Hot water supply pipe 20 Water supply pipe 24 1st heat exchanger 25 2nd heat exchanger 26 Bypass pipe 27 3 way Valve 28 First temperature sensor 29 Second temperature sensor 30 Third temperature sensor 31 Temperature control valve

Claims (3)

[Claims] 1. A solar heat collector, a hot water storage tank for storing hot water, a first heat exchanger mounted near a bottom of the hot water storage tank, and a second heat exchanger mounted on an upper part of the hot water storage tank. ,
The outlet of the first heat exchanger and the second
Pipe connecting the inlet and outlet of the heat exchanger, a three-way valve attached to the branch of the bypass pipe from the inlet of the second heat exchanger, the inlet of the solar heat collector and the second heat exchanger A return pipe connecting the outlet of the solar heat collector and the inlet of the first heat exchanger; and a return pipe attached in the middle of the forward pipe to connect the solar heat collector with the first and the second heat exchanger. A circulating pump for circulating a heat medium between the second heat exchanger, a reserve tank attached to an outgoing pipe between an outlet of the second heat exchanger and the circulating pump, A control circuit for stopping, a water supply pipe attached to the bottom of the hot water tank, a hot water supply pipe attached to the top of the hot water tank, and a hot water temperature attached near the first heat exchanger in the hot water tank. It has a temperature pressure valve or a temperature control valve to detect,
A first temperature sensor for detecting the temperature of hot water is attached to an upper portion of the hot water tank, a second temperature sensor for detecting a temperature of the heat medium is installed near an outlet of the solar heat collector, and a third temperature sensor is provided at a lower portion of the hot water tank. When the temperature sensor is attached and the detected temperature of the first temperature sensor is equal to or lower than the set temperature, the heat medium is
Return pipe, first heat exchanger, bypass pipe, reserve tank, circulation pump, outgoing pipe, solar collector
Also, the detection temperature of the first temperature sensor exceeds the set temperature,
And when it is higher than the detection temperature of the second temperature sensor,
A solar hot water supply system characterized in that a heat medium flows in the order of a return pipe, a first heat exchanger, a bypass pipe, a second heat exchanger, a reserve tank, a circulation pump, an outgoing pipe, and a solar heat collector. 2. The solar hot water supply system according to claim 1, wherein the set temperature is lower than a set temperature of the temperature control valve or the temperature control valve. 3. The temperature setting of a temperature control valve or a temperature control valve is 60 to
3. The solar hot water supply system according to claim 1, wherein the temperature is 99 ° C.