JPS5857664B2 - solar water heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention connects a solar heat collector and a heat storage tank with piping, and a circulation pump is interposed in the piping, and the high temperature heated by the solar collector is provided by the operation of the pump. This invention relates to improvements in solar water heating equipment that stores water in a heat storage tank.

Generally, the circulation pump of such a hot water system is started and stopped by a high temperature sensor 2 that detects the hot water temperature at the outlet of the heat collector 1 and a low temperature sensor 4 that detects the hot water temperature in the heat storage tank 3, as shown in FIG. The circulation pump 6 is operated by detecting the temperature difference and operating the control circuit 5.

That is, under the conditions of "high temperature sensor 2 temperature>low temperature sensor 4 temperature", and when the temperature difference becomes about 10 degrees or more, the pump 6 is operated and stopped when the temperature difference is about 2 degrees.

The reason why the temperature difference between on and off times is changed is to suppress unnecessary starting and stopping of the pump, that is, bunching phenomenon.

However, in such a system, when the temperature difference is less than 10 degrees and there is only solar radiation, the pump 6 is not operated and heat cannot be collected.

Also, as the sun rises, the heat collector 1 gradually heats up, and the temperature difference between the high temperature sensor 2 and the low temperature sensor 4 becomes 10 degrees or more, and the pump 6 starts operating, but immediately cold water is introduced into the heat collector 1. The high temperature sensor 2 is cooled down and cannot detect a difference in temperature, so it is stopped.

For this reason, when solar radiation is weak, such as when heat collection begins in the early morning or when heat collection ends in the evening, the pump bunching phenomenon is repeated a considerable number of times, shortening the lifespan of equipment and systems.

Furthermore, such bunching phenomenon occurs not only at the start and end of heat collection, but also when the difference in temperature is 10 d due to the influence of clouds, etc., except on clear days.
When the pump is operated under conditions where the amount of solar radiation is only around eg, the bunching phenomenon inevitably occurs, and moreover, the number of occurrences is very large.

Furthermore, at night in summer, if the outside temperature does not drop and is high and the temperature inside the heat storage tank 3 is low, the pump will be operated even if there is no solar radiation at night when the temperature difference reaches a point where the pump can operate.

On the other hand, when the pump operation method is applied to a vacuum tube type heat collector, the bunching phenomenon occurs more frequently.

In other words, since the vacuum tube type heat collector has high heat collection efficiency, the temperature of the high temperature sensor 2 rises rapidly, the pump 6 starts operating, and then immediately cold water enters the heat collector and is cooled down, which causes the cycle to stop. It is done.

The present invention has been made in view of this point, and will be explained below with reference to FIG. 2. 7 is a solar collector constructed by combining a plurality of vacuum tube type heat collecting elements, 8 is a heat storage tank, and both are connected by piping 9. has been done.

Reference numeral 10 indicates a circulation pump installed in a pipe 9 between the outlet of the heat storage tank 8 and the inlet of the heat collector 7 to circulate hot water between the heat storage tank 8 and the heat collector 7 and store high-temperature water in the heat storage tank 8. It is something.

11 is a water supply pipe, 12 is a hot water outlet pipe, and 13 and 14 are a solar radiation detector and an outside temperature detector attached to the heat collector 7 or the vicinity of the heat collector, and both are integrated.

A solar cell is used as the solar radiation amount detector 13, and a copper-wound sensor whose resistance value changes depending on the temperature is used as the outside temperature detector 14.

A hot water temperature detector 15 detects the temperature of hot water in the lower part of the heat storage tank 8, and a copper-wound sensor similar to the outside air temperature detector 14 is used.

Reference numeral 16 denotes a control circuit that controls starting and stopping of the circulation pump 10, and is activated by the outputs from the solar radiation detector 13, the outside air temperature detector 14, and the hot water temperature detector 15, and outputs an on-off signal that starts and stops the pump 10. FIG. 3 shows a block diagram of the inside of this control circuit 16.

The present invention will be described in detail below based on this block diagram.

When the solar cell, which is the solar radiation detector 13, is irradiated with sunlight, an output approximately proportional to the intensity of the light is output, which is input to the output adjustment circuit 17 to linearize it and obtain the required output.

An output adjusted by an input adjustment circuit 18 using this output and a resistance change according to the outside temperature by the outside temperature detector 14 is input to an amplifier 19 .

The output of the amplifier 19 and the signal of the hot water temperature detector 15 are compared in the comparator 20, and the comparison output ``H'' or L'' is applied to the next AN.
It is input to the D circuit 21.

On the other hand, the output signal from the output adjustment circuit 17 passes through the solar radiation limiting circuit 22 and the comparator 23, and outputs tt from the comparator 23 according to a predetermined lower limit setting value (line A in FIG. 4).
Hn, at I, pp are input to the AND circuit 21.

The outputs from both comparators 20 and 23 are: If the output from the solar radiation detector side > the output from the hot water temperature sensor > the output from the solar radiation detector side > the lower limit setting value, the output from the AND circuit 21 becomes the at Hpp signal. '', the timer circuit 24 is activated, and after the set time, the pump drive circuit 25 is activated to operate the pump 10.

The timer circuit 24 is provided to prevent the pump 10 from immediately stopping when the amount of solar radiation temporarily decreases due to clouds, etc. It has a set time of about 3 minutes, and the timer circuit 24 is designed to prevent the pump 10 from immediately stopping when the amount of solar radiation decreases temporarily due to clouds. If the situation recovers, the pump will not be stopped and will continue to operate.

That is, this is to prevent bunching of the pump.

FIG. 4 is an outside air temperature characteristic diagram showing an example of actual starting and stopping of the pump according to the present invention, in which the horizontal axis represents the hot water temperature in the heat storage tank 8, the vertical axis represents the amount of solar radiation, and the characteristic straight line Il2 represents the outside air temperature. The solid line represents the temperature, and the solid line indicates the starting point of the circulation pump 10 (hereinafter referred to as o).
n point) The dotted line also indicates the stopping point (hereinafter referred to as the OFF point).

Also, the A line is the solar radiation lower limit ON point, and the B line is the lower limit OFF point.
Show points.

That is, in FIG. 4, for example, if the temperature of the hot water in the heat storage tank 8 is 45
℃ and the outside temperature is 0℃, the amount of solar radiation is 200Kcal/rr, as is clear from the characteristic line of the mouth? This indicates that the circulation pump 10 becomes operable when the pressure exceeds hr.

Similarly, when the outside air temperature is 120°C, as is clear from the characteristic line A, even if the temperature inside the heat storage tank 8 is the same 45°C, the amount of solar radiation is 300 Kcal/rr? This indicates that the circulation pump 10 will not be operated if the amount of solar radiation is less than hr.

Furthermore, if the temperature inside the heat storage tank is 30℃ and the outside temperature is 20℃, the ON point of the circulation pump should be about 25W/m2hr of solar radiation, but this solar radiation is at the lower limit as shown by line A. Since it is below the on point, the pump is not operated.

As described above, the pump can operate stably as long as the heat collector is receiving more solar radiation than can collect heat based on the temperature inside the heat storage tank and the outside temperature, eliminating unnecessary startups and stops and extending the life of the system. This makes it possible to increase the length and collect heat with high efficiency.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a system diagram of a solar water heating device explaining the conventional structure, Fig. 2 is a system diagram of the solar water heating device of the present invention, and Fig. 3 is a system diagram of a solar water heating device of the present invention.
The figure is a block diagram of the control circuit of the present invention, and FIG. 4 is an outside air temperature characteristic diagram showing an example of starting and stopping the pump of the present invention. 7... Heat collector, 8... Heat storage tank, 10... Circulation pump, 14... Outside air temperature detector, 13... Past radiation amount detector, 15... Hot water temperature detector, 16 ...Control circuit.

Claims (1)

[Claims] 1. In a device in which a heat collector and a heat storage tank are connected through piping and a circulation pump is interposed in the piping, a solar radiation detector, an outside air temperature detector, and a hot water temperature in the heat storage tank are provided. A solar water heating system, which has a hot water temperature detector that detects hot water temperature, and a control circuit that operates a circulation pump at an amount of solar radiation equal to or higher than the temperature of the hot water in the heat storage tank and the temperature of the outside air. 2. Claim 1 in which the control circuit defines a lower limit set value for the amount of solar radiation necessary to operate the circulation pump.
The solar water heating device described in Section 1.