JPH0650196B2 - Solar water heater - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hot water supply device utilizing solar heat.

2. Description of the Related Art A conventional solar water heating system will be described with reference to FIG.

The compressor 1, the heat exchanger 2, the heat collector 3, and the four-way valve 4 are connected by piping to form a heat collecting circuit, and the hot water storage tank 5, the circulation pump 6, and the heat exchanger 2 are connected by piping to form a hot water supply circuit. Has been done. A supply port 7 for supplying water to the circulation pump 6 is provided at the bottom of the hot water storage tank 5, and a return port 8 of the heated hot water is provided at the top. The water inlet 9 to the hot water storage tank 5 is at the bottom,
A hot water supply port 10 is provided above.

A hot water temperature sensor 11 for detecting the hot water temperature is provided at the outlet of the heat exchanger 2, and a water temperature sensor 12 for detecting the hot water temperature is provided at the inlet.
The pump controller 13 controls the circulation pump 6 based on the detection results of the hot water temperature sensor 11 and the water temperature sensor 12.

Next, the driving operation will be described.

During normal heat collection operation, low-temperature water is sent from the feed port 7 of the hot water storage tank 5 to the heat exchanger 2 by the circulation pump 6. In the heat exchanger 2, water is heated by the solar heat collected by the heat collector 3 and sent as hot water to the return port 8 of the hot water storage tank 5 for circulation. Here, in order to maintain the hot water temperature at the outlet of the heat exchanger 2 at the set temperature, the pump controller 13 receives a signal from the hot water temperature sensor 11.
Then, an appropriate flow rate is calculated, the number of revolutions of the circulation pump 6 is changed so as to reach this flow rate, and hot water of an appropriate temperature is stored from the upper part of the hot water storage tank 5.

Problems to be Solved by the Invention Hereinafter, problems due to the above configuration will be described.

(1) When the heat collection operation is stopped once, and after a while, it is restarted, the cold water in the heat exchanger 2 and the circulation pump 6 is sent from the return port 8 into the hot water storage tank 5, and the hot water is stored at the set temperature. It mixed with the hot water that had been used and lowered the temperature of the hot water, making it unusable.

(2) In winter, when the four-way valve 4 is turned on and the reverse cycle operation is performed during the defrosting operation of the heat collector 3, very low-temperature water is sent to the hot water storage tank 5 to transfer heat from the heat exchanger 2, The temperature drops significantly.

(3) The water temperature sensor 12 is provided in order to prevent water in the heat exchanger 2 and the circulation pump 6 from freezing when the heat collection operation is stopped in winter.
When the temperature falls below the set temperature, the circulation pump 6 is started to prevent freezing, but similarly the hot water temperature in the hot water storage tank 5 drops.

As described above, the hot water temperature is lowered due to various driving operations, and the usability of hot water supply becomes extremely poor, which is not practical.

The present invention has been made in view of the above problems, and an object thereof is to provide a solar water hot water supply apparatus which is easy to use and which does not decrease in hot water temperature.

Means for Explaining the Problems In order to solve the above problems, the present invention is provided with return ports to the hot water storage tank at the upper part and the lower part, respectively, and selects and circulates by a switching valve according to the operation. There is.

Operation With the above configuration, the control unit switches the switching valve when the heat collecting operation other than the normal heat collecting operation is started, during the defrosting operation, and during the antifreezing operation, and the heat is not sufficiently exchanged. Therefore, the first return port provided in is selected.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted.

Explaining the configuration of the hot water supply circuit, the hot water storage tank 14 has a feed port 7 to the heat exchanger 2 and a water feed port 9 from the water supply in the lower part, and a little above the first return from the heat exchanger 2. A mouth 15 is provided. The heat exchanger 2 is on the top.
A second return port 16 and a hot water supply port 10 are provided.
And the outlet of the heat exchanger 2 and the first and second return ports 15,
An electric three-way switching valve 17 is provided as a switching valve between 16 and is linked to a controller 18.

Next, the operation will be described.
At the time of rising for about 20 minutes, since each part is cold and the hot water temperature sensor 11 naturally detects the set temperature such as 45 ° C. or less, the controller 18 sets the electric three-way switching valve 17 to the first return port 15 side. Open, hot water storage tank 1 by circulation pump 6
Only the bottom of 4 will be cycled.

When the temperature of each part stabilizes and reaches a predetermined heat collecting capability, the hot water temperature at the outlet of the heat exchanger 2 also rises, so that the temperature exceeds the set temperature. When the hot water temperature sensor 11 detects this, the controller 18
Means to open the second return port 16 side of the electric three-way switching valve 17 and store hot water from the upper part of the hot water storage tank 14. Therefore, the temperature of the hot water in the upper part is not disturbed at all and a constant hot water temperature can be maintained.

Next, the defrosting operation of the heat collector 3 will be described. When the heat collector 3 is frosted, the evaporation temperature decreases, and the evaporation temperature sensor 19
Detected, the four-way valve 4 is reversed, and reverse cycle operation is performed for about 10 minutes.
It is carried out for a minute, but at this time, the heat of the heat exchanger 2 is absorbed and released to the heat collector 3, so that the outlet hot water temperature of the heat exchanger 2 becomes extremely low. When the hot water temperature sensor 11 detects this, the controller 18 controls the second return port 1 of the electric three-way switching valve 17.
Since the 6th side is switched to the 1st return port 15 side, the water at the lowermost portion of the hot water storage tank 14 is slightly lowered, and the hot water temperature at the upper portion is not lowered. Then, when the defrosting operation is completed for the lowermost water and the heat collecting operation is started again, the water is heated by the heat exchanger 2 and stored in the hot water from the upper part.

Finally, the freeze prevention operation will be described. During winter, when the heat collection operation is stopped, the inlet water temperature of the heat exchanger 2 drops significantly, and if left alone, freeze damage occurs. In order to prevent this, when the water temperature sensor 12 detects about 2 ° C. or less, the controller 18 switches the electric three-way switching valve 17 to the first return port 15 side, and the circulation pump 18
To drive. Then, the heat at the bottom of the hot water storage tank 14 is released to prevent freezing. Naturally, when water of 2 ° C. or higher is sent to the water temperature sensor 12, the circulation pump 18 is stopped and the freeze prevention operation is completed.

In the present embodiment, an example in which the electric three-way switching valve is used is shown, but the same effect can be obtained even with a temperature expansion three-way switching valve such as a liquid expansion type or a wax thermo type.

EFFECTS OF THE INVENTION As is clear from the above, the following effects can be obtained with the solar water heating system of the present invention.

(1) The constant-temperature hot-water storage type hot-water supply circuit allows heat collection operation without lowering the hot water temperature of the hot-water storage tank.

(2) During defrosting, heat is temporarily taken out from the bottom of the hot water storage tank and does not affect the temperature of the hot water in the upper part, which is more practical in winter.

(3) Even in a severe cold season, there is no damage due to freezing, and there is no disturbance in the upper hot water temperature, which makes it possible to realize a very stable hot water supply life.

(4) The structure is simple, the reliability is high, and the cost is low.

[Brief description of drawings]

FIG. 1 is a block diagram of a hot water supply system using solar heat which is an embodiment of the present invention, and FIG. 2 is a conventional block diagram. 1 ... Compressor, 2 ... Heat exchanger, 3 ... Heat collector, 4 ...
Four-way valve, 6 ... Circulation pump, 7 ... Feed port, 14 ... Hot water storage tank, 15 ... First return port, 16 ... Second return port,
17 ... Switching valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshitsugu Fujimoto 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Kazuhiko Miyamoto 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 56) References JP-A-61-46847 (JP, A)

Claims (4)

[Claims] 1. A heat collecting circuit comprising a heat collector and a compressor, a hot water supply circuit comprising a hot water storage tank and a circulation pump, a heat exchanger for exchanging heat between the heat collecting circuit and the hot water supply circuit, Defrosting means provided in the heat collecting circuit, a feed port for feeding water to the heat exchanger provided at the bottom of the hot water storage tank, and a first return port from the heat exchanger provided in the vicinity of the feed port And a second return port from the heat exchanger provided at the top of the hot water storage tank, and a switching valve that selects the first return port and the second return port, and a normal heat collection operation A solar heat utilization hot water supply device provided with a control unit that sometimes selects the second return port and switches the switching valve so as to select the first return port during the start-up of the heat collection operation, the defrosting operation, and the freeze prevention operation. 2. A hot water supply system using solar heat according to claim 1, wherein the controller selects the first return port side of the switching valve when the hot water temperature sensor provided at the outlet of the heat exchanger detects a temperature below the set temperature. . 3. The method according to claim 1, wherein when the water temperature sensor provided at the inlet of the heat exchanger detects a temperature equal to or lower than the set temperature, the circulation pump is driven and the control section selects the first return port of the switching valve. Solar water heater. 4. The controller selects the first return port of the switching valve when the evaporation temperature sensor detects a temperature equal to or lower than the set temperature at the heat collector inlet and causes the heat collecting circuit to perform the reverse cycle operation. The hot water supply device using solar heat according to item 1.