JPS6321443A - Film covered heat storage pond - Google Patents

Abstract

PURPOSE:To improve the efficiency in the process of sun-light heat storage by filling a natural or an artificial pond with a heat storage fluid such as water or other suitable matters and covering the surface of the filling material with a film. CONSTITUTION:Because a film 3 has a high sun-light transmissivity tau it does not give hindrance to the absorption of sun-light S by a heat storage fluid 2, and, therefore, it secures the function of a heat storage pond 1 to absorb solar energy. When a heat insulation layers 4 are provided, those layers are formed with materials with a high sun-light transmissivity tau such as air, nitrogen gas, etc. of relatively thin layers, and the heat absorption action of the heat storage fluid 2 is not substantially hindered. The heat loss prevention action is provided by the coverage with a film 3 of the surface of the heat storage fluid 2, and even if the heat storage pond 1 is exposed to a high wind, the surface of the heat storage fluid 2 develops no wave or water splash so that the surface heat loss especially the surface heat loss amount during a high wind can be suppressed remarkably.

Description

[Detailed Description of the Invention] Industry - Utilization of H)! The present invention relates to a heat storage pond that absorbs and stores solar energy, and particularly to a film-coated heat storage pond that reduces heat loss from the surface by coating with a film.

A heat storage pond such as a solar pond is an artificial or natural pond filled with water, salt water, or other heat storage fluid in a certain manner, and the heat storage fluid absorbs and stores solar energy, and is used day and night. It has the advantage of being able to be safely driven continuously in winter and even in northern countries. The applicant has filed a patent application for
In No. 9120, we disclosed a technology to increase the overall usage efficiency by adding a pool to a solar pond, and we also applied for a patent application in 1973.
No. 8-149121 discloses a solar heat-utilizing heat pump device in which the fluid in the non-paired wave layer, which is the heat storage fluid of a solar pond, is circulated to a heat pump unit.

In conventional heat storage ponds, there is considerable conduction, convection, and radiation of heat from the surface of the heat storage fluid to the atmosphere.

The resulting heat loss from the surface (hereinafter referred to as surface loss).

) was large, so the efficiency of the heat storage process was low. The surface area is particularly large when the heat storage fluid surface is exposed to strong winds and waves and splashes occur.In the case of solar ponds, the surface area is 5 when the energy of sunlight incident on the heat storage fluid is 100 tons.
There are also reports that it is over 0%. In order to reduce this surface area, methods such as floating a polyethylene net on the surface of the solar pond and arranging PVC pipes at appropriate intervals have been proposed, but a satisfactory solution has not yet been obtained.

− is trying to go to U Therefore, the problem to be solved by the present invention is as follows.

This consists in reducing the surface area of the heat storage pond.

. One embodiment of the heat storage pond 1 according to the present invention shown in FIGS. film 3 on the surface of
It is constructed by covering the Preferably, a plurality of membranes 3 are provided and held by support members 5 at appropriate intervals. membrane 3
has a large transmittance τ for sunlight S (wavelength 0.3-2.5 μm), a small heat absorption rate and thermal conductivity ε, and a heat ray L with a long wavelength (wavelength 2.5 μm or more) (Figure 4). Examples of V3 materials include films of polyester, polycarbonate, acrylic resin, glass, etc., or films on which a heat ray reflective film is formed by vapor deposition or the like.

In the embodiments shown in FIGS. 2 and 4, four films 3 are used, and the solar reflectance of each of the six films 3 is (2)ε2. ε3, ε
4, and the heat ray reflectance is expressed as /・ε2′・(
3' and ε4'.

Preferably, a heat insulating layer 4 is formed between adjacent films 3, which is made of a material 1, such as vacuum, air, or nitrogen gas, which allows sunlight to pass through well and has a small solar absorption rate a and a small heat ray absorption rate a'. In the examples shown in FIGS. 2 and 4, three layers of heat insulation layers 4 are provided between four rF23 sheets, and the solar absorption rate of each heat insulation layer 4 is set to al,
a2. Indicated by a3.

The heat ray absorption coefficients are shown as aI', a2', and a3'.

Referring to FIG. 1, since the membrane 3 has a large solar transmittance, it does not interfere with the absorption of sunlight S by the heat storage fluid 2.
Therefore, the function of the heat storage pond 1 to absorb solar energy is ensured. Even when the heat insulating layer 4 is provided, the layer is formed in a relatively thin layer using a substance with high solar transmittance, such as air or nitrogen gas, so that the heat absorption effect of the heat storage fluid 2 is substantially reduced. will not be hindered.

To explain the heat loss prevention effect, since the surface of the heat storage fluid 2 is covered with the film 3, even if the heat storage pond l is exposed to strong winds, no waves or splashes will occur on the surface of the heat storage fluid 2, and the heat storage fluid 2 will not be affected by the wind. The surface area, especially during strong winds, is significantly reduced.

In order to reduce the surface area due to heat conduction, it is possible to form a heat insulating layer 4 by sealing a material 1 with low thermal conductivity, such as dried air or nitrogen, between adjacent films 3, or to create a vacuum between adjacent films 3. or take measures such as increasing the distance between adjacent films 3, for example, It, Q2)fI3 in FIG.

Considering heat radiation with reference to FIG. 4, heat storage fluid 2
Since the heat ray reflectance ε' of the film 3 with respect to the heat MAL radiated from the heat rays to the atmosphere is large, a large portion of the heat rays is reflected to the heat storage fluid 2, and the surface area due to radiation is greatly suppressed. By providing a plurality of membranes 3 and heat insulating layers 4, the radiation surface area can be further suppressed.

Referring to FIG. 5, in which the thickness of the membrane is greatly exaggerated, the surface of the membrane 3 in direct contact with the heat storage fluid 2 has a heat absorption rate ao'
If the selective reflective Fi film 6 is formed by vapor deposition or the like using a material that has a small value and a particularly high heat reflectance @o', such as titanium oxide, tin oxide, indium oxide, or a film in which silver is sandwiched between dielectric materials, the surface area due to radiation can be reduced. It can be further reduced.

Regarding convection, heat loss due to convection from the heat storage fluid 2 to the atmosphere can be suppressed by using a plurality of membranes and sealing a material 1 with low thermal convection, such as dry air or nitrogen, between the membranes. Therefore, compared to conventional heat storage ponds in which the heat storage fluid is in direct contact with the atmosphere, the surface area due to convection is significantly reduced in the present invention. As shown in FIG. 6, when a plurality of heat insulating layers 4 are provided, the convection α1, α2) and α3 in each heat insulating layer 4 are kept very small, so that convection from the heat storage fluid 2 to the atmosphere is reduced. surface area is significantly reduced.

In this way, the objective of the present invention, the reduction of heat storage pond surface loss, is achieved.

Moxibustion j The present inventor manufactured the membrane 3 with a thickness of about 1 mm in a factory, stacked several membranes to form a multilayer structure, folded it and transported it to the installation site, and installed the membrane 3 at the construction site between the layers, that is, between adjacent membranes. The membrane was filled with dry air or nitrogen so that the distance between adjacent membranes was about 20 cm, and then floated on the heat storage fluid 2 of an artificial heat storage pond 1 and supported by the support member 5 shown in FIG.

In reality, the membrane 3 having the multilayer structure described above can be fixedly installed by floating on a natural lake or ocean and moored to an anchor (not shown) or the like.

The effect of reducing the surface area of the solar heat storage pond by the above film 3 was investigated. Referring to Figure 7, solar radiation energy is 3.0
00 Kcal/m”e day, and the heat storage fluid temperature is 80°C.
The atmospheric temperature is 30°C, and the distance between adjacent films 3 is 20°C.
cm, the sealing material of the heat insulating layer 4 is dry air, and the sunlight transmittance τ of one sheet of 11513 is 80 dollars.

If the low-temperature emissivity τ' (Fig. 4) of one film 3 is 1 oz, then without the film 3, the amount of heat loss exceeds the amount of heat collected, which is 3.0
00 Kcal/m2s day or more, the amount of heat loss is almost equal to the amount of heat collected with one membrane 3, and the amount of heat storage is approximately 1350 Kcal/m with two membranes 3 and one layer of heat insulation layer 4.
The amount of heat stored by the three membranes 3 and the two layers of heat insulating layer 4 is approximately 720 Kcal/m2・day, and the amount of heat stored by the four membranes 3 and three layers of heat insulating layer 4 is approximately 820 Kcal/m2・day. Kca
l/m′! It was found that this is the day e.

The results of this study are shown in the graph of FIG. 8. A study result of 0 or more indicates that the heat storage pond 1 according to the present invention is effective in improving the efficiency of the solar heat storage process.

As explained above, the heat storage pond 1 according to the present invention significantly reduces surface species, and therefore has the remarkable effect of significantly improving the efficiency of the solar heat storage process.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the heat storage pond according to the present invention, Fig. 2 is an explanatory diagram of the solar heat absorption process, Figs. 3 to 6 are explanatory diagrams of the surface species reduction effect, and Figs. 7 and 8 are explanatory diagrams of the solar heat absorption process. It is an explanatory diagram of an example. l... Heat storage pond, 2... Heat storage fluid, 3...
Membrane, 4... Heat insulation layer, 5... Support member, 6...
Thin film. Patent applicant Kajima Corporation Patent application agent Patent attorney Tsugube Ichizuka Figure 1 Figure 2

Claims (3)

[Claims] (1) In a heat storage pond that stores a heat storage fluid that absorbs solar heat, the heat storage fluid comes into contact with the atmosphere through a film that has high solar transmittance, low thermal conductivity and heat absorption, and high reflectance for heat rays with long wavelengths. A membrane-covered heat storage pond with a surface covered. (2) In the membrane-coated heat storage pond according to claim 1, the air contact surface of the heat storage fluid is coated with a plurality of the above films, and between the adjacent films there is a large solar transmittance and a small amount of heat. A membrane-coated heat storage pond formed by forming a heat insulating layer having conductivity. (3) A film-coated heat storage pond according to claim 1, wherein a thin film having a high reflectance to long-wavelength heat rays is formed on the surface of the film that comes into contact with the heat storage fluid. .