JPS5896947A - Solar heat collector - Google Patents

Abstract

PURPOSE:To improve the heat collecting efficiency by filling the space around a heat transfer medium pipe with only the vapor of working liquid by a method wherein a mixed gas reservoir is provided in a connecting pipe connecting the radiating section and heat dissipating section of a heat pipe in the solar heat collector employing a heat pipe consisting in mixing non-condensable gas into the working liquid. CONSTITUTION:The solar heat collector consists in housing a variable conductance type heat pipe (HP)1, which comprises a heat collecting section 2, the radiating section 3 and the heat dissipating section 4 and within which working liquid 5 mixed with non-condensable gas is sealed, within a light-transmitting vacuum tube 7. Furthermore, a heat exchanger consists in inserting the heat transfer medium pipe 9 between the heat collecting section 2 and the radiating section 3 in such a manner that the heat dissipating section 4 side is rendered to be higher than the heat collecting section 2 side. In this case, a mixed gas reservoir 13, the volume of which is suitable that the vapor of the working liquid 5 nearly fills the space of the radiating section 3 at the time of heat collecting operation, is formed in the connecting pipe 11 connecting the radiating section 3 and the heat dissipating section 4. Owing to the structure as mentioned above, the shift of the non-condensable gas to the radiating section 3 due to the lowering of the vapor pressure of the working liquid 5 is checked, resulting in accmplishing the desired object.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a solar heat collector using a variable conductance heat pipe.

Variable conductance heat pipes (hereinafter referred to as VCHP), which are made by mixing a small amount of non-condensable gas into a normal pure working liquid heat pipe, are widely used as having the function of a self-regulating temperature control element. It is used.

FIG. 1 and FIG. 2 are main part sectional views illustrating a conventional structure in which this VCHP is used as a solar heat collection/heat a collection part. In the figure, l is a VCHP having a heat collecting section 2, a heat dissipating section 3, and a heat dissipating section 4, and a working fluid 5 of Cape Fupun and a non-condensable gas 6 such as nitrogen are mixed therein. The heat collecting part 2 is made of a transparent material such as a glass tube through which light energy can pass, and is housed in a vacuum tube 7 with a sealing fitting 8. A heat medium pipe 9 through which a heat medium flows is inserted to form a heat exchange St-, and around it is a new heat material 1.
External and heat I from 0 k! l It is green. Furthermore, heat dissipation fins 4 are provided on the outer periphery of the heat dissipation section 4 which is connected to the heat dissipation section 3 through the connecting pipe U.
The heat dissipation part 3 is better than the heat collection part 2, and the heat dissipation part 4 is more like the heat dissipation part 3.
It is necessary to maintain a positional relationship in which the height increases sequentially.

In such a configuration, VCHPl is supplied through the vacuum tube 7.
When heat input from sunlight is applied to the heat collecting part 2 of the heat collecting part 2, the working fluid 5 sealed in this part evaporates, and the pressure of the vapor of this working fluid 5 compresses the non-condensable gas 6, and the vapor-gas interface move toward the end of the heat dissipation part. For this reason, the release III&s
3 is filled with vapor of the working fluid 5 to heat the heat medium flowing through the heat medium pipe 9. At this time, since the connecting pipe 11 and the heat dissipation section 4 are filled with the non-condensable gas 6, almost no heat is dissipated to the outside. The vapor of the working fluid 5 that has completed heat exchange within the heat dissipation section 3 is liquefied and returned to the heat collection section 2 by gravity, where it is again subjected to heat input from sunlight.

By repeating such an evaporation-condensation cycle of the working fluid, the heat medium is heated to constitute a heat medium circulation system.

The above is the operation during normal operation, but the heat medium does not flow into the heat medium tube 9 during installation or when it is not used for a long period of time, and heat input from sunlight is applied to the VCHPI inside the vacuum tube γ. In the so-called 9-firing state, the working fluid in the heat collecting section 2 continues to evaporate -1, and there is almost no heat exchange in the heat dissipating section 3, so the temperature inside the VCHPI tends to rise. However, in this case, the hydraulic fluid 5f)
Since the pressure of the W gas compresses the non-condensable gas 6 and moves the steam/gas interface to the heat dissipation section, the heat dissipation effect in this section works and the rise in steam temperature is suppressed. In other words, in this type of solar heat collector, the change in steam temperature due to an increase or decrease in heat input and the change in steam temperature due to an increase or decrease in heat conductivity of the heat radiation part cancel each other out, and have the effect of keeping the inside of the VCHP within a certain temperature range. are doing.

However, the temperature at which the solar heat collector collects heat is approximately 3
The temperature range is wide from 0°C to Zoo00C, and the heat input to the heat collecting part 2 is relatively small at the normal heat collection temperature. For this reason, the aforementioned VCHP
Due to the characteristics of , self-control works to suppress the release of heat due to heat exchange in the heat radiating section 3, and the steam/gas interface moves inside the connecting pipe 11 to the heat radiating s3.In this case, conventionally, the connecting pipe 11
Since the structure had a small volume in order to reduce heat loss, this caused the fluctuation of the steam/gas interface to become larger, and in reality, the steam/gas field Due to the axial heat conduction of the tube wall, it cannot be in a clear state, so the vapor of the working fluid 5 and the non-condensable gas 6 are mixed in the same section of the heat medium tube 9 in the heat radiation section 3. The effective condensing area of the pipe becomes smaller, and the apparent heat transfer coefficient of working steam in the condensing section (heat transfer coefficient due to the mixed gas of working steam and non-condensable gas) decreases, and the temperature difference between the heat collecting section and the condensing section decreases. It has the disadvantage of being thick (it has the disadvantage of being thicker).The heat collection efficiency is also lower than that of K.

The present invention has been designed with these points in mind, so that only the vapor of the working fluid always exists around the heat transfer pipe.
The object of the present invention is to provide a solar heat collector with good heat collection efficiency in which the thermal resistance of the condensation part in the heat dissipation part of a VCHP is reduced.Hereinafter, the embodiments of the present invention will be described with reference to the main part sectional views in Fig. 3 and Fig. #E4. explain. In the figure, B is a mixed gas reservoir that is a feature of the present invention, and other parts are the same as in Figures 1 and 2, so the same parts are given the same reference numerals and their explanation will be omitted. ing.

That is, the connecting pipe U that connects the heat dissipation section for exchanging heat with the liquid to be heated and the heat dissipation section for preventing overheating has a volume sufficient to almost fill the inside of the heat dissipation section with the vapor of the working fluid during heat collection. The present invention has a structure in which a mixed gas reservoir is provided and thermally insulated from the outside by a heat insulating means that is wrapped together with the heat dissipating section 3 by a heat insulating material. Even in the case of heat, the movement of non-condensable gas due to the pressure drop of the working fluid vapor is reduced, and the heat dissipation section is always filled with the working fluid vapor. Further, since the mixed gas reservoir is surrounded by a heat insulating material together with the heat radiating portion having a high temperature, unnecessary heat radiation does not occur during normal operation. Therefore, the thermal resistance in the condensing section is always small, and the heat collection efficiency targeted by the present invention is achieved.

[Brief explanation of the drawing]

Figure wi1 and Figure 2 explain the conventional structure! ! 3 and 4 are sectional views of essential parts for explaining the present invention in detail. 1...Variable inductance heat pipe (VCHP)
), 2... Heat collection section, 3... Heat dissipation section, 4... Heat dissipation section, 5... Working fluid, 6... Non-condensable gas, S-- Heat medium pipe, 10...・Insulation material, 11... Connecting pipe, 13...
Mixed gas reservoir: Figure 1 Figure 2U2U Figure f'4 Figure

Claims (1)

[Claims] (Violet) The truth of translucency! Working fluid and non-condensable gas are mixed into a heat pipe, which is constructed by connecting a heat collecting section housed in the pipe, a heat dissipating section through which a heat medium pipe is inserted, and a heat dissipating section having heat dissipating fins on the outer periphery so that they become higher. In the solar heat collection system 1s, a mixed gas reservoir having a volume of approximately 100 ml is provided in the connecting pipe connecting the heat radiating part and the heat radiating part to fill the inside of the heat radiating part with vapor of a working fluid during heat collection. A solar heat collector characterized in that the mixed gas reservoir has a heat insulating means.