JPS608270Y2 - solar heat collector - Google Patents

Description

[Detailed description of the invention] This invention relates to a solar heat collector, and in particular, in a unit heat collecting plate in a natural circulation type solar heat collector, a plurality of fluid passages are connected between an upper branch passage and a lower branch passage. Equivalently horizontal heat collection circuits connected in parallel are arranged in multiple circuits above and below and in parallel with each other, thereby greatly improving heat collection efficiency.

This type of solar heat collector is constructed as shown in FIG.

In the figure, reference numeral 1 denotes a hot water storage tank, to which a water supply pipe 2, an upper hot water supply pipe 3, and a lower water supply pipe (water supply drain pipe) 4 are connected.

5 is a ball tap for adjusting the liquid level.

Reference numeral 6 denotes a heat collection box, in which a heat collection plate 8 is disposed on a heat insulating material 7 laid on the bottom surface, and a transparent plate 9 is attached to the top surface.

10 and 11 are connection pipes for circulating liquid between the hot water storage tank 1 and the heat collecting plate 8, and 12 is a wire rod for fixing to the rooftop.

The conventional structure of the solar heat collector plate of the above configuration is that a pair of branch pipes are arranged horizontally at the upper and lower edges, and between them a tubular fluid passage with a smaller cross-sectional area than the branch pipes is run up and down. There is one in which a large number of pipes are connected in parallel in the direction to form a heat collection circuit, and one end of a pair of branch pipes is connected to a hot water storage tank, respectively.
Alternatively, there is one in which a plurality of heat collectors each having such a heat collecting circuit are disposed vertically and in parallel.

(Japanese Unexamined Patent Publication No. 55-68557).

In addition to the heat collector with the above structure, for the purpose of increasing the strength of the heat collecting plate, adjacent fluid passages are connected to the intermediate position of a pair of branch pipes by using fluid passages with the same or smaller cross-sectional area. Structures connected horizontally are also used.

In conventional solar heat collectors, regardless of which type of heat collector plate is used, the low-temperature liquid contained in the hot water storage tank flows into the branch pipe at the lower end of the heat collector plate and is divided into the fluid passages. High-temperature liquid heated by solar heat rises through the fluid passage due to natural convection based on the difference in specific gravity, is collected in a branch pipe at the upper end, and is returned to the hot water storage tank.This circulation process is repeated, gradually increasing the liquid temperature in the hot water storage tank. It is designed to let you do so.

However, in such a heat collection circuit, there is a certain limit to the rise in liquid temperature, and the heat collection efficiency is low. The heat collection efficiency has been increased by appropriately improving the material of the coating, but with such means,
There was a problem in that unless the heat collection area was changed, a significant improvement in the amount of heat collection could not be expected.

Such a problem is thought to be due to the large flow path resistance in the heat collection circuit of the conventional solar heat collector.

It has been found that the reason for this high flow resistance is the vertical structure in which the number of fluid passages is small and their length is large.

This idea was made to solve the above problems, and its purpose is to significantly reduce the flow path resistance of the unit heat collection plate and improve heat collection efficiency. The purpose is to make it possible to obtain a sufficient heat collecting effect even with a relatively small area heat collecting plate, and further, the purpose is to provide a solar heat collector that can be provided at the same cost as conventional solar heat collectors.

That is, in this invention, as in the illustrated embodiment, the plurality of fluid passages 18a; 18b are connected to the upper branch passages 16a;
b and the lower branch passages 17a; 17b, a plurality of heat collecting circuits connected in parallel are disposed in the unit heat collecting plate 8 in a vertical direction and mutually connected in parallel. Related to solar heat collectors.

In this way, in this invention, a plurality of fluid passages are connected in parallel between an upper branch passage and a lower branch passage in a unit heat collection plate in a natural circulation type solar heat collector. By arranging multiple circuits vertically and in parallel with each other, we were able to significantly improve heat collection efficiency.

Here, we will explain the principle of this invention and clarify its effects.

That is, if the cross-sectional area of the heat collecting tubes constituting the heat collecting circuit is S, the number of heat collecting tubes is N, the length of the heat collecting tube is L, and the flow path resistance is R, then For a vertical heat collector A and a horizontal heat collector B with the same cross-sectional area S, the number of heat collection pipes in the former is Na (the number of heat collection pipes in the latter is Nb, and the length of the heat collection pipe in the former is La). )
Since the length of the latter heat collecting pipe is Lb, by applying the value of this inequality to the above equation 1, it becomes: the flow path resistance Ra of the former) and the flow path resistance Rb of the latter.

Therefore, it turns out that the horizontal heat collecting tube with low flow path resistance has higher heat collecting efficiency than the vertical heat collector.

Therefore, by connecting a plurality of such horizontal heat collection circuits in parallel in a unit heat collection plate, the unit heat collector becomes a horizontal heat collection system that can increase the heat collection amount with high heat collection efficiency. It can be configured as a container.

Examples of this invention will be described below with reference to the drawings.

FIG. 2 is a plan view showing the internal structure of the heat collecting plate of this invention, in which two heat collecting circuits are arranged vertically and in parallel.

This heat collecting plate 8 is connected to a hot water storage tank (not shown) by a connecting pipe 10.11.

Reference numeral 14 designates an inflow passage that allows low temperature liquid to flow into the heat collection circuit from the hot water storage tank via the connection pipe 10, and 15 represents an outflow passage that allows high temperature liquid to flow out from the heat collection circuit to the hot water storage tank via the connection pipe 11.

The upper heat collection circuit includes an upper branch passage 16a provided horizontally at the upper edge of the heat collection plate 8, a lower branch passage 17a provided horizontally at the center of the heat collection plate 8, and an upper branch passage 16a. It consists of a large number of fluid passages 18a arranged in parallel and connected in the vertical direction between the lower branch passage 17a, and the fluid passage 18a
The cross-sectional area of the upper branch passage 16a and the lower branch passage 17 is
It is smaller than a.

The length of the fluid passage 18a is shorter than that of the upper branch passage 16a and the lower branch passage 17a, so that one end of the upper branch passage 16a (the left end in the figure) is the upper end of the outflow passage 15. Partly, one end (the right end in the figure) of the lower branch passage 17a communicates with the central part of the inflow passage 14, respectively.

Like the upper heat collection circuit, the lower heat collection circuit also includes an upper branch circuit 16b, a lower branch circuit 17b, and a fluid passage 18b, and the upper branch passage 16b is located below the lower branch passage 17a of the upper heat collection circuit. The lower branch passage 17b is provided horizontally adjacent to the lower edge of the heat collecting plate 8, and one end (the left end in the figure) of the upper branch passage 16b communicates with the center of the outflow passage 15. Lower branch passage 17
Both ends of b communicate with the lower ends of the inflow passage 14 and the outflow passage 15, respectively.

In this way, the upper branch passage 16a of the upper and lower heat collecting circuits
16b and the lower branch passage 17a; 17b communicate with the outflow passage 15 and the inflow passage 14, respectively, and the two heat collection circuits are connected in parallel to each other in the unit heat collection plate 8, so that the functional consists of a horizontal heat collector.

The low-temperature liquid that has flowed into the inflow passage 14 through the connection pipe 10 with the hot water storage tank flows into the lower branch passage 17 of the upper heat collection circuit.
a and the lower branch passage 17b of the lower heat collecting circuit.

The low-temperature liquid that has entered the lower heat collection circuit ascends through the fluid passage 18b while being heated by solar heat and passes through the upper branch passage 1.
6b, and returns to the hot water storage tank via the inflow passage 15 and the connecting pipe 11.

On the other hand, the low-temperature liquid that has entered the upper heat collection circuit is also heated in the same way and ascends the fluid passage 18a to the upper branch passage 16.
a, and returns to the hot water storage tank via the outflow passage 15 and the connecting pipe 11.

If the flow of liquid that naturally circulates through the heat collection circuit is made into a parallel circuit in the unit heat collection plate as described above, the fluid resistance will be reduced compared to the conventional heat collection circuit, so the flow required to overcome the fluid resistance will be reduced. Solar energy is saved, which helps increase the liquid temperature.

When a metal plate is used as the heat collection plate, the lower branch passage 17a of the upper heat collection circuit and the upper branch passage 16b of the lower heat collection circuit.
The overlapping parts between the passages may be brought into close contact with each other by welding, etc. to separate the passages from each other, but the overlapping parts may not be brought into close contact and a narrow gap may be provided, and even if there is this gap, the liquid Since the flow of the liquid is obstructed and mixing of the low-temperature and high-temperature liquids is prevented, natural circulation of the liquid occurs smoothly.

The heat collection characteristics diagram in FIG. 3 shows the results of a comparative experiment between a solar heat collector to which the heat collection plate of the above configuration is applied and a solar heat collector with a conventional heat collection plate.

The temperature of the liquid (water) in the hot water tank was measured during the sunshine hours of the day using the same conditions such as the material of the heat collecting plate, the absorption coating, and the material of the transparent plate.

In the figure, curve A is a temperature curve obtained by the heat collecting plate of this invention, and curve B is a temperature curve obtained by a conventional heat collecting plate.

As is clear from the figure, according to this invention, the water temperature in the hot water tank reached a maximum of 4TC, whereas in the conventional system, the maximum temperature was 44°C.

When converting this temperature difference of 3°C into the amount of heat collected, it is 600Kca.
1/day, which means an increase of about 25% compared to the conventional heat collection amount.

In the above embodiment, the case where the heat collection circuit is arranged in two stages, upper and lower, was explained, but it may be increased as appropriate depending on the heat collection area of the heat collection plate, and by adding a heat collection circuit, the amount of heat collected can be increase than the case.

As mentioned above, this idea has multiple horizontal heat collection circuits arranged in parallel above and below on each heat collection plate, which greatly improves heat collection efficiency compared to conventional heat collection plates with the same heat collection area. Not only was this possible, but the manufacturing method and process for the heat collecting plates are also the same as conventional ones, so it has the excellent effect of producing a solar heat collector with high heat collection efficiency at the same cost. .

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a solar heat collector, FIG. 2 is a plan view showing an embodiment of the heat collector of this invention, and FIG. 3 is a chart showing heat collection characteristics. In the figure, 8 is a unit heat collecting plate, 10 and 11 are hot water storage tanks, and 16a
, 16b are upper branch passages, 17a and 17b are lower branch passages, and 18a and 18b are fluid passages.

Claims (1)

[Scope of utility model registration request] A plurality of heat collecting circuits in which a plurality of fluid passages are connected in parallel between an upper branch passage and a lower branch passage are arranged so as to be connected vertically and mutually in parallel in a unit heat collecting plate. A solar heat collector featuring: