Method and apparatus for the utilization of solar energy, by means of a double-conical heat accumulator surrounded by a helical space collector
The invention relates to a method and an apparatus for the utilization of solar energy, by means of a double-conical heat accumlator, which can be used for heating and pumping a large quantity of liquid by means of solar energy, it can be used furthermore for maintaining heating and cooling circulations.
There are known solar heat accumulators with body of revolution, that are suitable for heating air and water. Such solar heat accumulators for heating air are described in the US-PS 4.084.573 and US-PS 4.094.195, for heating water described in the US-PS 4.056.093 and US-PS 4.086.911.
The solar heat accumulator according to the US-PS 4.056.093 comprises a spherical tank painted black on the outer surface and provided with a transparent protective covering, which can be used for heating water.
In the US-PS 4.086.195 a solar heat accumulator is
described, which comprises an isolated tank of truncated cone shape, provided with a black absorber pipe wound around the superficies and on the cover plate provided furthermore with a preheating unit, a heater tank with input and output pipe stubs inside the collector and thermal governor valves, whereby the whole assembly is covered with a transparent, solid isolating material with an appropriate air gap therebetween, and in the absorber pipe water of network pressure flows.
The drawback of the above mentioned solar heat accumulators, especially those for heating water is that a big part of their absorber surfaces - resulting from the pathway of the sun above the skyline - are shaded, furthermore, that, as a consequence of the relatively small surface energy density of the solar radiation, the utilisable energy on the outer absorber surface of the collector raises the temperature of the water contained in the encircled heater tank in a small degree, or only a smaller part of the heater tank is used.
As a consequence of the abovementioned unfavourable features, for the utilization of solar energy plane collectors are preferred. These ulteriors need, however, separate heater tank and pumps, because of their settlement and position, big base areas, the effective radiation received by them is limitted, and finally, they utilize the scattered radiation relative to their space surfaces less efficiently.
The aim of the present invention has been to eliminate the abovementioned drawbacks. The method according to the present invention is based
on that an isolated heater means is placed between the cold liquid input and the heated liquid output, said heater means is surrounded with a double-conical means standing preferably on a horizontal plane, the half bevel-angle of said double-conical means is equal to the difference of 90° and the degree of latitude, this difference is in case of use mainly in the summer periode appropriately increased, in case of use mainly in the winter periode appropriately decreased, in case of use on 45 degree of latitude, the tangent of the half bevel-angle determining the base surface of the heater means by the outer conical surface is settled preferably to be greater than 1/3, which relation up to the limit of the space surrounded by the outer conical means is increased towards the equator, and decreased towards the poles, and the heater means is connected on the top and on the bottom with a continuous helical absorber pipe.
The apparatus according to the present invention comprises a double-conical, isolated heater means fed by cold liquid, a preferably black and preferably multiple-start screw absorber absorber pipe, where said absorber pipe is connected with the heater means on the top and on the bottom and wound on the outer conical superficies, said heater means is provided on the top with a pipe stub of spill-way system, and said heater means is covered with a conical means of transparent, shatter-proof, double-walled, corrugated material, with an air gap therebetween.
The method and apparatus according to the present invention is described hereinafter more detailed by way of an example with reference to the accompanied drawing, where
Figure 1 shows the space collector partly in cross- section;
Figure 2 shows the space collector in top-view, without the isolaing conical means.
Referring now to Figure 1, there are shown a helical absorber pipes 1, preferably made of black, corrugated polypropylene double-thread screw tube, a transparent isolating conical means 2, preferably made of a double-walled, corrugated polycarbonat sheet, an isolator layer 3 separating the heater tank from the absorber pipes in the time of heat absorption. The heater tank 4 of double-conical form is provided with input and output pipe stubs.
The apparatus according to the present invention operates, as follows:
The cold liquid, preferably water, enters the heater means 4 on its lower part, in vertical direction, as shown in the Figure with empty arrows, and via the input pipe stubs laying in tangential direction at the circumference of the outer superficies, on the bottom of the double-conical means. The liquid or water gets in the helical absorber pipes 1, where on the effect of the radiated heat energy of the sun, it will be gradually warmed up; due to the thermosiphon effect it streams upwards via the helical pathway of gradually decreasing radius of the absorber pipes 1, as shown in the Figure with a tangential black arrow, while in the course of the streaming increasing centrifugal forces are effective on the particles of the liquid resulting in an increasing stirring effect; finally, the heated liquid or water streams out to the place of utilization via the upper pipe stub of spill-way system, as shown in the Figure with a vertical black arrow,
whereby the output quantity of the heated liquid or water is proportional to the input cold liquid or water. In the case of an appropriate surface energy density, the circulation in the absorber pipes 1 is continuous, while the output of the liquid or water via the upper pipe stub is discontinuous, in general. The transparent isolating conical means 2 is made preferably of a double-walled structured or corrugated, polycarbonat sheet, said means 2 isolates the system from the cooling effect of the atmosphere, furthermore, the corrugations thereof shape arched surfaces resulting at the same time in a favourable incident radiation deviation. The isolator layer 3 of the double conical means serves for realizing a larger circula tion gradient and isolates the absorber pipes 1 from the heater tank 4, on the other hand said isolator layer 3 contributes to the better isolation of the heater tank 4 , that is further increased by the absorber pipe 3 containing the liquid or water to be heated, by the isolating conical means 2, and preferably by the appropriate air gap between the isolating conical means and the absorber pipe.
The method and apparatus according to the invention have the advantages, as follows:
- the possible effective radiation time periode of the surface is nearly the double, than that of knows space collectors or appropriately positioned plane collectors, supposed that the half bevel-angle of the helical absorber pipe is chosen in accordance with the geographical position of the settlement and the function of the space collector.
- the outer conical surface shaped according to the invention results relatively to its base area in a substantially larger active absorber surface, and a
double-conical heat accumulator of optimal volume can catch solar energy on the average 50 % more, than the known collectors of the same surfaces .
- the fact that the lower and the upper parts of the double-conical heat accumulator are connected with each other by means of helical absorber pipes, is very favourable in the point of view of hydrodinamics, because an appropriate motive force is available for the recirculation, and the necessary energy for this motive force is provided by the radiation energy of the sun. This embodiment prevents the collector from overheating, makes possible frost protection in the winter time and ensures in general a simple deaeration.
- the embodiment of the heat accumulator with a double conical means results in favourable static characteristics from constructional point of view.
- the heated medium, preferably water streams in the helical absorber pipes mounted on the outer conical surface via a pathway of decreasing radius, therefore the centrifugal force effective on the particles of the liquid is increasing, which in return results in a better stirring and heating, consequently a better heat transmission.
- the facts that the helical absorber pipe is made from a preferably black, corrugated polypropylene tube, results in a better heat transmission, and on the other hand that - as a consequence of the geometry of the conical means - the surfaces lean again each other and do not need additional fastening between the upper and the lower, i.e. the output and input pipe stubs, therefore the manufacturing is rather simple and cheap.
- the conical means made of transparent, preferably shatter-proof, double-walled, corrugated polycarbonat serves for isolation from the atmosphere, it is an effective isolator, and the corrugations thereof shape arched surfaces, which results at the same time in a favourable incident radiation deviation. The isolation of the heater tank inside the heat accumulator is further increased by the air gaps, by the absorber pipes filled with the warming liquid, and by the passive isolation of the heater tank itself.
- the structural members of the apparatus are suitable for constructing large building constructions, for ezample a roof, where the outer absorber surface of the space collector under the transparent, isolating, double-walled, corrugated polycarbonat plate contains a large double-conical, isolated heater tank in an enclosed coniructional unit. The space under the internal cone is suitable for the accomodation of sanitary installations or latent heat accumulators.