JPS5843358A - Heat collecting plate of solar heat collector - Google Patents

Abstract

PURPOSE:To make all of the flow rates in heat collecting tubes nearly constant by a structure wherein the efflux passage side cross-sectional area of an influx branch passage is made smaller than the influx passage side cross-sectional area of the influx branch passage at the heat collecting plate, in which an influx passage and an efflux passage are respectively communicated to the influx branch passage and an efflux branch passage and said both branch passages are communicated to each other by means of a plurality of the heat collecting tubes. CONSTITUTION:The heat collecting plate 1 consists in the manner that in communicating the influx passage 6 and the efflux passage 9, both of which communicate to a hot water storage tank respectively, to the influx branch passage 3 and to the efflux branch passage 2 respectively and in communicating both the branch passages 3 and 2 to each other by means of a plurality of the heat collecting tubes. In this case, the cross-sectional area S1 of the influx branch passage 3 in the portion ranging 1/10-1/2 of its total length L of the passage 3 starting from the efflux passage 8 side is made 1/4-4/5 times smaller than the cross-sectional area S of the influx branch passage 3 at the influx passage 6 side in order to form a throttling part 10. Owing to the structure as described above, because the flow speed is suppressed at the throttling part 10 in the circulation of working fluid in the plate 1, the flow speed of the fluid passing through the influx passage 6 side heat collecting tubes 4 can be nearly equalized with that of the fluid passing through the efflux passage 8 side heat collecting tubes 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat collecting plate for a solar heat collector, and in particular, the cross-sectional area of at least a part of an inflow branch passage or a heat collecting pipe is reduced to reduce the flow rate when the cooling circuit is completely shut down. By keeping the value approximately constant, the heat collection efficiency is greatly improved.

2. Description of the Related Art Conventional heat collecting plates for solar heat collectors include those constructed as shown in FIGS. 1 and 2, for example. This heat collecting plate 1 is used for a natural circulation type solar cooler, and has an outflow passage 8 and an inflow passage 6 arranged vertically on the left and right at the upper and lower ends thereof. Each of them is connected by an outflow branch passage 2, an inflow branch passage 3, and these branch passages 2 and 3 are connected by a large number of heat collecting pipes 4 having a smaller cross-sectional area than the branch passage 2.3. This is how the heat collecting circuit 5 is constructed.

In the figure, 7 is a connecting pipe that connects the upper end of the inflow passage 6 to a hot water storage tank (not shown), and 9 is a connecting pipe that also connects the upper end of the outflow passage 8 to the hot water storage tank.

In this way, the low-temperature liquid stored in the hot water storage tank flows into the inflow passage 6 of the heat collection plate 1 through the connection pipe 7, and furthermore, the liquid that flows from the inflow passage 6 into the inflow branch passage 6 flows into the heat collection pipe 4. Here, it is heated by solar heat and rises through the heat collecting tube 4 by natural convection based on the difference in specific gravity.

When the hot water is collected in the outflow branch passage 2 at the top of the heat collecting pipe 4 and returned to the hot water storage tank via the connecting pipe 9, the liquid temperature in the hot water storage tank is gradually increased. There is.

However, the heat collecting plate 1 having the heat collecting circuit 5 as shown in FIG.
So, there is a certain limit to the increase in liquid temperature of 6°"c**m.
"ii=""i<・2、By appropriately improving the material of the film such as black paint or selective absorbing material attached to aYfuo#It or the surface of the heat collecting plate 10, the heat collecting efficiency can be increased. However, even with methods like Jin, a significant improvement in heat collection efficiency could not be achieved.

On the other hand, the inventors conducted an experiment to investigate the heat collection efficiency by circulating liquid in the heat collection circuit 5. It has been discovered that the flow velocity is not uniform in each section, and that the flow velocity gradually increases as the number of branches increases and the flow approaches the outflow passage 8. Therefore, when we examined the influence of the difference in flow velocity on the quality of heat collection efficiency, we found that the temperature of the liquid passing through the outflow passage 8 where the flow velocity is high becomes lower.
Obstructed by the flow force of the low-temperature fluid, the flow of the high-temperature fluid heated when passing through the heat collecting pipe 4 is blocked at the part of the outflow branch passage 2 that merges with the outflow connection part 8, and the outflow branch passage 2 portion It was found that a high-temperature liquid region was generated. For this reason, part of the thermal energy of the high temperature liquid 4. ．． ．． The problem is that only the residual thermal energy released from the high-temperature liquid region to the outside of the heat collection plate 1 contributes to heating the liquid in the hot water storage tank, and therefore no significant improvement in heat collection efficiency can be expected. there were.

This invention was made in order to solve the above-mentioned problems, and an object of the invention is to make the flow rate of each part of the heat collecting circuit of the heat collecting plate substantially constant, thereby improving the efficiency of the solar heat collector. To provide a heat collection plate for a solar heat collector that can be manufactured at the same cost as conventional ones without changing the heat collection area and can provide high heat collection efficiency.

That is, the present invention can be used for both natural circulation type solar heat collectors and forced circulation type solar heat collectors, as shown in the embodiments shown in Figures 4-11.
The heat collecting plate IK, an inflow passage 6 communicating with the hot water storage tank, and an outflow passage 8 also communicating with the hot water storage tank are communicated by an inflow branch passage 3 and an outflow branch passage 2, and an inflow branch passage 3 and an outflow branch passage 2 are connected. In a solar heat collector in which a heat collecting circuit 5 is formed by communicating 2 with a plurality of heat collecting pipes 4, the inflow branch passage 3 or the outflow passage 8 side of at least one of the heat collecting pipes 4 The present invention relates to a heat collecting plate for a solar heat collector characterized in that the cross-sectional area is smaller than the cross-sectional area of the inflow branch passage 3' or the inflow passage 6 side of the heat collecting pipe 4.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows an embodiment of Jin's invention, and is a plan view showing the internal structure of a heat collecting plate of a natural circulation type solar heat collector. The heat collecting plate 1 is illustrated by the connecting pipes 7 and 9.
connected to a hot water storage tank. 6 connects the connecting pipe 7 from the hot water tank to i
8 is an inflow passage for causing low temperature fluid to flow into the heat collection circuit 5;
This is an outflow passage that allows outflow through the connecting pipe 9.

Heat collection circuit 5, outflow passages 8 arranged vertically on the left and right sides of the heat collection plate 1
and the inflow passage 6 are connected to each other by an outflow branch passage 2 and an inflow branch passage 3 at their upper and lower ends, respectively, and furthermore, one of these branch passages 2 and 3 is connected to the branch passage 2.3) having a small area. A large number of heat collecting tubes 4 communicate with each other, forming a heat collecting circuit 5.

In the figure, 7 is a connecting pipe that connects the upper end of the inflow passage to a hot water storage tank (not shown), and 9 is a connecting pipe that also connects the upper end of the outflow passage 8 to the hot water storage tank.

Further, the cross-sectional area S1 of the inflow branch passage 3 from the outflow passage 8 side to the total length of the inflow branch passage 6 from 4 to 40 is defined as the cross-sectional area S of the inflow passage 6 side, and 5. 10 is formed.

When the i-thermal circuit 5 is configured as described above, the low-temperature liquid that has flowed into the inflow passage 6 via the connection pipe 7 with the hot water storage tank is transferred to the heat collecting plate 1.
It flows into the inflow branch passage 3 at the lower end, is branched into the heat collection pipe 4, ascends the core heat collection pipe 4 while being heated by solar heat, is collected in the outflow branch passage 2, and then flows from the outflow passage 8 through the connection pipe 9. Return to the hot water tank. In this case, the inflow branch passage 3
Since there is a constriction part 10, the flow velocity at the constriction part 10 is suppressed due to the viscosity of the liquid, and the heat collecting pipe 4 on the inflow passage 6 side is
The flow rate of the liquid passing through the heat collecting tube 4 on the outflow passage 8 side is approximately equal to the speed of the liquid M passing through the heat collecting tube 4 on the side of the outflow passage 8. Therefore, the flow rate of the entire heat collecting circuit 5 becomes approximately equal.

In the chart shown in FIG. 7, the symbol 11g represents the flow velocity at each branch portion of the inflow branch passage 3 in the heat collector plate having the above configuration. As this chart shows, the flow velocity from the 2nd branch to the (n-1)th IF branch is approximately equal, but at the 1st branch and the 9th branch, The flow velocity at all branching sections is slightly slower. This is thought to be due to the viscosity coefficient of the liquid, and the heat collection efficiency in this part decreases due to the delay in flow velocity, and as a result, the heat collection efficiency of the collector as a whole also decreases slightly. There is.

Therefore, in order to eliminate the delay in flow velocity, the inventors conducted various experiments and found that the first branch from the inflow passage 6 side of the inflow branch passage 3 and the second branch from the same side. By providing an orifice 11 with a reduced cross-sectional area in the same way as the constriction part 10, the flow rate of the liquid can be adjusted to
As shown by the broken line, we were able to make major improvements.

Collection of the above configurations: - Plate 1 (1 shade, without orifice 11.

stomach. The results of a comparative experiment between a solar heat collector (applied with ) and a solar heat collector with a conventional heat collection plate are shown below, and are shown in the heat collection characteristics diagram in Figure 8.

The size of the constricted portion 10 is determined by setting five lengths, ``&'', 4, =, and twice the length of the inflow branch passage 3, where L is the total length of the inflow branch passage 3. "/4%""/2,"/ of the cross-sectional area S on the inflow passage 6 side
Each experiment was conducted for three types of cross-sectional areas: , .

The figure shows the same ratio when the heat collection efficiency is multiplied by that of a conventional heat collection plate. As is clear from the figure, the highest heat collection efficiency can be obtained by reducing the cross-sectional area S1 of the diaphragm part 10 to 4, which is the cross-sectional area S of the other parts, and the efficiency is even higher than that of the conventional one. We were able to improve heat collection efficiency.

The curve @f in the chart shown in FIG. 9 indicates the ratio of the heat collection efficiency with a conventional heat collection plate when the heat collection plate 1 having the above structure is used in a forced circulation type solar heat collector. As shown in the figure and below, in this case as well, the heat collection efficiency was improved by up to 8 inches compared to the conventional method.

In addition, even in the forced circulation method, the same results as shown in the diagram of FIG. 7 were obtained regarding the flow velocity of each branch part of the inflow branch passage 6.

Furthermore, as shown in FIGS. 10(f) and (b), the inflow branch passage 3 is deformed by changing the cross-sectional area of the heat collecting pipe 4, as explained in the first embodiment. You can get the same effect as in the case.

The diagram shown in FIG. 11 explains the above matter, and there are two aspects. That is, one of them is the solid lines gl, g2. As shown by g3 (corresponding to the case in FIG. 10 (a)), the cross-sectional area TI of the heat collecting pipe 4 between the length 51 of the inflow branch passage 3 and the outflow passage 8 of the entire length of the 4 is - Specifically, the cross-sectional area T on the inflow passage 6 side is /~
This is a case where it is multiplied by 4 times. The solid line g1 represents the cross-sectional area T1,
The cross-sectional area T is multiplied by I, and the actual #g2 is
Similarly, the solid line g3 is multiplied by 7, and solid line g3 is multiplied by n.

The second aspect is based on the broken lines hl, h2. h3
As shown in FIG.
In the case where the cross-sectional area TI between the length 51 is gradually decreased from 7 to 7 times the cross-sectional area T on the inflow passage 6 side, the rate of change is as shown in the figure. It may be compensated for proportionally, or it may be changed in a rectangular hyperbolic manner. child. , sea urchin, □4.4...;1
It is possible to obtain the same effect as in the above embodiment in which 1.Sen□Tll-111g is varied.

It goes without saying that the length Ll of the constricted portion 10 may be within the range of 4 to A of the total length of the inflow branch passage 3.

As described above, the present invention makes the cross-sectional area of at least one of the inflow branch passage or the heat collection pipe on the outflow passage side smaller than the cross-sectional area of the inflow branch passage or the heat collection pipe on the inflow passage side. The flow rate of the liquid passing through each part of the heat collection circuit could be adjusted, and therefore the flow rate of each part of the heat collection circuit could be kept approximately constant. For this reason, it is possible to secure the flow of the high-temperature liquid heated when passing through the heat collection pipe, and it is possible to suppress the release of the collected thermal energy into the outside air, compared to the conventional method where the heat collection area is the same. Heat collection plates can also significantly improve heat collection efficiency. Moreover, although the manufacturing capacity, method, and process are different from those of conventional ones, it has the excellent advantage of being able to obtain a 4% Y solar collector heat collection plate with high heat collection efficiency at the same cost.

[Brief explanation of the drawing]

Figure 1 is a plan view of a conventional heat collecting plate, and Figure 2 is the H-
3 is a diagram showing the flow velocity characteristics of a conventional heat collecting circuit; FIG. 4 is a plan view showing an embodiment of the present invention;
Fig. 5 is a sectional view taken along the v-v line in Fig. 4, and Fig. 6 is a cross-sectional view taken along the line V-V in Fig. 4.
1-Vl line cross-sectional view, Figure 7 is a diagram showing the flow velocity characteristics of the heat collection circuit according to the present invention, Figure 8 is a diagram showing the heat collection characteristics, and Figure 9 is a diagram showing the flow velocity characteristics of the heat collection circuit according to the present invention. Figure 10 (a) is a sectional view showing another embodiment of the present invention, Figure 10 and (b) are sectional views showing another embodiment of the invention, and 11th The figure is a chart showing changes in the cross-sectional area of one heat collecting pipe. In the figure, 1 is a heat collection plate, 2 is an outflow branch passage, 6 is an inflow branch passage, 4 is a heat collection tube, 5 is a heat collection circuit, 6 inflow passages, 8 is an outflow passage, 10 is a constriction part, 11 is a It is an orifice. Patent applicant Nippon Yakin Kogyo Co., Ltd. Representative Patent attorney Satoshi Mori
Patent Attorneys Yoshi Naito and Akira Patent Attorneys Shimizu Sho 5 Deniri 9j Ilj Total length of the friend passage: L Figure 9 Total length of each ``Yoshi Input & Moxibustion Pass'': L Figure 10 (A) Go 5L, Iriwayama ( Total length of Tomomi: L Figure 10 (0) 5 Friends 9J! Tomomichi's total length: L

Claims (1)

[Scope of Claims] (1) An inflow passage communicating with the hot water storage tank and an outflow passage also communicating with the hot water storage tank are connected to the heat collecting plate through an inflow branch passage, an outflow branch passage, etc., and an inflow branch In a solar heat collector that includes a part of a heat collecting circuit in which a passage and an outflow branch passage are connected through a plurality of collecting pipes, the inflow branch passage! A heat collecting plate for a solar heat collector, characterized in that the cross-sectional area on the outflow passage side of at least one of the bamboo heat collecting pipes is smaller than the cross-sectional area on the outflow branch passage or the inflow passage side of the heat collecting pipe. . 2. A heat collecting plate for a solar heat collector according to claim 1, characterized in that: (3) From the outflow passage side of the entire length of the inflow branch passage of the heat collecting pipe -
The cross-sectional area between ~4 and ? The cross-sectional area on the inflow passage side is 14~
2. The heat collecting plate for a solar heat collector according to claim 1, wherein the heat collecting plate is made smaller in a linear manner or in a stepwise manner.