JPS58182054A - Solar heat collector - Google Patents

Abstract

PURPOSE:To prevent deterioration of the function of the titled solar heat collector and to lower the temperature of the heat collector at the time of idle burning by mounting a heat pipe using as an operating liquid a heat medium which does not almost operate at a low temperature of about 100 deg.C or less and starts operation at high temperatures, on a heat collecting member. CONSTITUTION:A condensing part 5 encircles a heat transfer pipe 6 and an idle burning preventive heat pipe 4 is connected to the outer periphery of the pipe of the condensing part 5. As the operating liquid of the heat pipe for heat collections, a heat medium capable of operating at a temperature in the range of 50-100 deg.C is used, and as the heat pipe for preventing idle burning, ''Therm'' S or mercury which does not almost transfer heat at low temperatures below 100 deg.C but transfers heat at high temperatures above 150 deg.C is used. At the time of operating an ordinary heat collectors, the temperature of the collector is 100 deg.C or below and hence the heat pipe for preventing idle burning does not operate. However, when the temperature becomes as high as about 150 deg.C or higher, the heat pipe for preventing idle burning starts its operation and deprives of the heat of the heat collecting heat pipe and emits the heat thus collected through radiation fins.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction suitable for use in solar heat collectors, particularly for completely preventing voids in solar heat collectors.

Solar heat collectors are normally used when the beam heat temperature is below 100C, but if the solar heat collector is not collecting heat even though it is exposed to sunlight (hereinafter referred to as the "empty-fired state"), the light receiving part of the heat collector (hereinafter referred to as (called a heat collector) becomes abnormally high temperature. %, the X-tube type heat collector reaches a high temperature of 250C or more, which causes problems such as a decline in the performance of the selective absorption surface and high pressure inside the heat collection tube.

For this reason, we usually circulate hot water through a heat collector to prevent dry heating. Countermeasures such as using fins to dissipate heat are currently being developed. However, these methods require hot water to be circulated even when the heat is not collected, which wastes energy. As other measures,
A method is being considered in which a heat pipe type heat collector is used, in which a non-condensable gas is sealed inside the heat pipe, and a radiation fin is attached above the condensing part of the heat pipe (hereinafter referred to as a gas heat pipe). % Application No. 55-1582071゜This method makes it possible to reduce the temperature during empty heating without reducing the performance of the collector itself.However, this method requires that the amount of non-condensable gas be accurately enclosed. Is it difficult?
Furthermore, there is a problem that performance deteriorates if other non-condensable gases are generated from inside the heat pipe during use.

An object of the present invention is to provide a solar heat collector that is easy to manufacture, highly reliable, and capable of preventing overheating.

The present invention focuses on the fact that there is a heat medium that hardly operates at a low temperature of about 100 C or higher, but starts operating at a high temperature, and the present invention develops a heat pipe that uses such a heat medium as a working fluid. By attaching it to the heat collector of a total solar heat collector, it is possible to reduce the temperature of the heat collector when it is not heated, which degrades the performance during normal operation.

An embodiment of the present invention will be described based on FIG.

The evacuated glass tube 1 is similar to a commonly used evacuated tube type heat collector, and the inside of the glass tube is sealed and bent with a vacuum, and a heat pipe is installed inside the glass tube in the axial direction. Several of these vacuum glass tubes are arranged side by side as a set, the heat pipe is taken out from the glass tube, and the condensing part 5 is connected to the pipe 4. The heat pipe for preventing dry heating and the condensing section of the heat collector heat pipe are joined by brazing each with heat transfer fins 7 shown in FIG. 2. - Also, the condensing part of the heat pipe for preventing air leakage is taken out to the outside, and heat radiation fins 3 are attached. Furthermore, the working fluid of the heat collector heat vibrator contains a heat medium such as freon, water, or alcohol that can operate at 50 to 100C, and the heat pipe for preventing dry heating contains a heat medium that hardly transports all heat at low temperatures below 100C. , 15
When the temperature reaches 0C or higher, heat-transporting material such as Zam-Ebe (also known as Dow Sam) or mercury is used.

Since this embodiment has the above structure, it operates as follows. During normal operation of the collector, the temperature of the condensing part of the collector heat pipe is below 100C, the drying prevention heat pipe does not operate, and the heat collected by the collector heat pipe is not radiated. On the other hand, when the temperature reaches a high temperature of about 150C or more, the heat pipe for preventing air leakage starts operating, absorbs heat from the heat collector heat pipe, and releases it from the radiation fins. Therefore, the temperature of the heat collector heat pipe reaches 250 U or more when all the heat pipes for preventing air leakage are not installed, but by installing the heat pipe, the temperature can be reduced to 200 C or less.

What determines the performance of the heat pipe for preventing dry heating mentioned above is the area of the main heat dissipation area. The contact thermal resistance between the heat pipe for preventing dry heating and the condensing part of the heat collecting heat pipe can be reduced by brazing the two parts through heat transfer fins. When calculated considering the fins, the fin efficiency is about 95% or more, and there is no problem with heat transfer at the contact area.Figure 3 shows the relationship between the heat pipe temperature and the heat pipe for preventing drying. This figure shows the calculation results for the amount of heat dissipation. In this case, the temperature at which the amount of heat dissipated and the amount of heat transported in the heat collecting heat pipe match corresponds to the temperature of the heat collector when it is empty. From this result, it can be seen that in order to reduce the air-heating temperature to 200C or less, it is better to keep the ifI of the radiation fins at 0.3 or more.In Fig. 3, straight lines A, B, and C are Heat radiation i'i is shown when the radiation fin area is 0, 5 +) + 2.0.3 mt and 02 m2, respectively. The broken line is the heat transport amount of the MI heat pipe when the heat collection area is 1.15 rn''.

In the above embodiment, the radiation fins were attached to the heat collector in a skewered manner on the top of the horn cover, but it is possible to use a header cover instead of the radiation fins, or to attach them to the side of the glass tube. It goes without saying that all of these are within the scope of the above embodiments.

Although the above embodiments are all examples of a hollow tube type heat collector using a heat pipe, the present invention can be similarly applied to a flat plate type heat collector. In this case, as shown in Figure 4, a pipe is attached to the heat collecting plate 11 in the same manner as the heat collecting pipe to prevent drying, and the heat dissipating fins are attached to the parts taken out from the outer box 9. It is something.

If the efficiency required by the fin efficiency of the heat collecting plate is about 0.8, most of the heat can be absorbed. The width is 3 when calculating Hl based on the condition of 7.
It is good to install heat pipes to prevent heat pipes at a rate of about 1 per 0 cm.12 Since the width of a normal flat plate heat collector is about 1 m, it is good to install about 3 heat pipes. Although the heat dissipation fins were installed on the outside, it is also possible to use the outer box 9 instead of the heat dissipation fins.

According to the present invention, it is possible to reduce the temperature of the heat collector when the heat collector is air-heated by itself without using a special control device to control the air-heating temperature of the heat collector. The temperature during air-roasting can be reduced 71. For example, the internal pressure of the heat collector pipe can be reduced, and the thickness of the heat pipe can be reduced. Furthermore, compared to gas-filled heat pipes, the present invention does not require enclosing waste, and even if some non-condensable gas is generated inside the heat pipe during use, it does not have a big impact on performance, making it highly reliable. is high.

[Brief explanation of the drawing]

Fig. 1 is an external view showing the configuration of a heat pipe type vacuum tube type heat collector installed with the air gap prevention heat vibrator of the present invention, and Fig. 2 is a cross-sectional view taken along the line A-A' in Fig. 1. , 3rd
The figure shows the relationship between the amount of heat radiated from the radiating fins and the amount of heat transported in the collecting heat pipe with respect to the heat pipe temperature using the radiating fin area as a parameter. FIG. 7 is an external view of a modification example showing a configuration in which a heat pipe for preventing sagging is provided. 1...Vacuum glass tube, 2...Collector heat pipe,
3... Heat dissipation fin, 4... Heat pipe for preventing dry heating, End... Heat pipe condensing part for heat collection, 6... Heat transfer tube, 7... Heat transfer fin, 8... Header cover . Agent Ben Misakishi Akio Takahashi Pa"l':, 1shi) 1st closed 2nd figure (3rd figure heel l-7, ・If 逼/Tower 4th Kasumi

Claims (1)

[Scope of Claims] 1. In a solar heat collector composed of a heat collector that receives sunlight and a heat insulating part of the heat collector, heating of a heat pipe in which a heat medium is completely enclosed inside the heat collector the condensing part of the heat pipe is provided outside the heat insulating part, and the heat pipe mostly transports heat as a heat medium in the heat collection temperature range targeted by the solar collector. A solar heat collector characterized by using a heat medium that transports heat at a temperature higher than the above temperature range. 2. In the solar heat collector according to claim 1, in which a heat pipe is used as a means for transporting the heat received by the heat collector, the condensing part of the heat pipe is completely covered. A solar heat collector characterized by being equipped with a heating part of a heat pipe to prevent insignia from burning.