GB2301178A

GB2301178A - Solar collector panel

Info

Publication number: GB2301178A
Application number: GB9510709A
Authority: GB
Inventors: Zygmunt Dabrowski
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-05-26
Filing date: 1995-05-26
Publication date: 1996-11-27
Also published as: GB9510709D0

Abstract

A solar collector comprises a tubular heat exchanger 22, together with a radiant absorptivity screen 29 sealed inside a housing formed or transparent panels 23 separated from each other by a spacer 38 at their periphery. Both inlet and outlet 31, 32 of the heat exchanger are brought out through sealed openings in the spacer. The outer face 24 of the front panel 23 is treated to maintain its transparency and the inner faces of both panels have low emissivity coating 25. The solar collector panel may also function as a window or window shutters.

Description

SOLAR COMBINATION CELL This invention relates to a solar combination cell and, in particular, to the system of heat collection and its versatility of application.

A large variety of solar heat panels are now available. They can, in general, be divided into two groups. The first group embraces designs incorporating focal reflectors and sophisticated heat transfer devices, for example, heat pipes. The second group covers designs based on various forms of heat exchanges and methods of insulation. The first group of solar panels tends to be expensive, the second group is generally not to be very efficient and both groups are intended to perform a single function.

Accordingly, the present invention provides a solar combination cell consisting of a heat exchanger which, in its simplest form, can be a length of tubing wound on a former of a chosen pattern in a single plane with both ends of the tubing on the outer periphery of the pattern. The wound tubing pattern is , in turn, secured within the sealed space of a unit, constructed of two transparent panels secured to either side of a spacer on their periphery and having specific property which facilitates retention of rnost energy received directly from the Sun, within the sealed space.

Such cells may be mounted, singly or in batteries, on any structure, such as a wall or a roof, which provides maximum exposure to the Sun. They can also take the form of conventional windows, window shutters or can be built into double-glazed structures so as to provide more than one function together with the additional benefit of decorative features of the tubing pattern.

However, it is equally possible to use other forms of heat exchangers in place of shaped tubing, for example, heat exchanger produced from pressed metal panels, cast or moulded in plastic.

High thermal efficiency of the said cell is due to the fact that the short wavelength radiation from the Sun, when absorbed by a body, is reradiated by it in the long wavelength form, known as infrared radiation. By incorporating into both transparent panels of the cell filters which transmit short wave radiation and reflect the long wave form, it is possible to trap the latter between the said panels and thus increase temperature of the heat exchanger and therefore its heat output. Thus the created conditions within the cell ensure that most of the energy entering it is absorbed by the heat exchanger for extraction by a circulating fluid.

A low emissivity material with the corresponding properties to the above described filter, is readily available.

Performance of the cell is dependent on the ratio of the projected area of the heat exchanger in this case, tubing pattem, to the effective size of the cell. Therefore, where the cell is solely intended for energy collection, the above ratio is required to be high, whereas in a combined application of a solar cell and a window, will have a lower ratio in order to facilitate adequate light transmission.

Heat transfer of the cell can be optimised by making the heat exchanger in a material which has both high heat conductivity and energy absorptivity, whereas heat loss, through conduction, can be minimised by filling the sealed space with dry rarefied air or, even, with a suitably selected noble gas, for example Argon.

To ensure that the transparency of the front panel is not impaired by rain or air contaminants, its outer face may be modified with a propriety protective surface treatment.

In the case where the heat exchanger is shaped tubing, collection of the solar energy by the cell can be enhanced by enclosing a high absorptivity screen within the sealed space.

A specific embodiment of the invention will now be described by way of an example with reference to the accompanying drawings in which: Figure 1 shows part section across the runs of the tubing pattern of the solar combination cell.

Figure 2 shows example of a solar combination cell as a roof window.

Figure 3 shows example of a solar combination cells as window shutters.

Figure 4 shows a battery formed of a number of solar cells.

Figure 5 shows, diagrammatically, how the solar energy is accumulated within the sealed space of the solar cell.

Referring to Figure 1, the solar combination cell has a front transparent panel 23 and a back transparent panel 21, both bonded to spacer 38 with sealing compound 27. Within the sealed space 26, filled with the low thermal conductivity gas, is located by means of formers 39, and protrusions 37, in this case tubing pattern 30 and its individual tubing runs 22. The inner faces of both panels 21 and 23 have low emissivity coating 25 and the outer face of the front panel 23 has maintained transparency coating 24.

Tubing pattern 30 is wound with gaps 28 between respective tube runs 22 and its inlet 31 and outlet 32, located on the outside periphery.The inlet 31 and outlet 32 are brought outside through respective sealed openings 41 in the spacer 38.

An example, in this case of a window 10 in a roof 35 which combines functions of a window and a solar cell, is shown in Figure 2, together with one form of tubing pattern 30. To facilitate window opening, where desired, the heat exchanger, inlet 31 and outlet 32, are both brought out on or close to window hinge axis for connection to flexible or rotary couplings, not shown. Another application of a unit which combines functions of window shutters 20 and solar cells, is shown in Figure 3. Here, the tubing pattern 30 is shaped to give a degree of visual appeal to window 36.

Yet another example, Figure 4, represents a battery, formed of a number of solar cells 40, interconnected and positioned on a roof or any suitable place facing the Sun.

The improvement in performance, claimed for the solar combination cell, is explained here by reference to the diagram, Figure 5. Solar energy, short waves 33, pass through the transparent panel 23 and are absorbed as heat, in this case, by the tubing pattern 30 and the screen 29. Some of this heat is reradiated in the form of long waves 34 which are, in turn, reflected back by the low emissivity coatings 25 on panels 21 and 23 thus causing build up of heat within the sealed space 26 and therefore rise in temperature of the tubing pattern 30 and the screen 29.

To minimise heat loss through conduction the sealed space 26 may be filled with dry air at a reduced pressure or, alternatively, it may be filled with one or more of the noble gases, for example Argon.

The transparency treatment, applied to the outer surface of panel 23, will ensure its good performance even under adverse conditions brought about by contaminated air and rain.

As explained above, it can be seen that the solar combination cell, according to the present invention, has important advantages over previously known solar heat collectors. These advantages include high heat output due to Greenhouse Effect, ease with which solar cells can be produced using inexpensive materials and established processes and, the fact, that they can be used as solar cells by themselves or combined with windows, window shutters real or simulated or any glazed structures in order to serve combined functions. Furthermore, heat exchangers and tubing patterns, in particular, can be designed to add visual appeal to any of the above said units.

Claims

1. A solar combination cell comprising a heat exchanger, in this case a length of tubing wound on a former into a pattern, a screen and a housing of two transparent panels having low emissivity coating on their inside faces together with transparency treatment on the outside of the front panel and joined to opposite sides of a spacer on their periphery, thus enclosing, within the so formed sealed space, the heat exchanger and the screen, except for the inlet and the outlet of the heat exchanger, which protrude outside through the spacer.

2. A solar combination cell as claimed in Claim 1 wherein is provided a low emissivity coating on inner faces of both transparent panels.

3. A solar combination cell as claimed in Claims 1 and 2 wherein the heat exchanger and the screen have external surfaces of high radiation absorptivity.

4. A solar combination cell as claimed in Claim 1 wherein its function can be combined with a function of a window, window shutters and the like.

5. A solar combination cell as claimed in Claim 1 and 3 wherein the exchanger in the form of tubing pattern provides visual appeal.

6. A solar combination cell as claimed in Claim 2 wherein transparency retention treatment is applied to the outside face of the front panel.

7. A solar combination cell as claimed in Claim 3 wherein the heat exchanger is combined with a screen.

8. A solar combination cell as claimed in Claim 1 wherein the heat exchanger is hermetically sealed within the housing.

9. A solar combination cell as claimed in Claim 7 wherein the sealed spaces is filled with low thermal conductivity gas.

10. A solar combination cell as described herein with reference to Figures 1-5 of the accompanying drawings.