Plant for the recovery of thermal energy from solar radiation

(42) Date of commencement of the patent: 15.11.1998 (45) Date of issue: 26. 7.1999

<td>(56) Documents:</td><td>(73) Patent owner:</td>

<td>US 5228293A</td><td>KLAPPER ULRICH DIPL.ING. Ar-6800 FELDKIRCH, VORARLBERG (AT). (72) Inventor: KLAPPER ULRICH DIPL.ING. FELDKIRCH. VORARLBERG (AT).</td>

AT 405 320 (54) STORAGE FOR HEAT TREATMENT OF SOLAR RADIATION (57) The invention relates to a system for heat energy generation from solar radiation (2). A Stiriingmotor (4), which drives a pump (6), is used to the heated liquid from a solar collector (1) to a mostly lower heat energy storage (7) (eg a boiler) or heat energy consumers (eg another Stiriingmotor) to pump. The Stiriingmotor (4) draws its energy from the heated liquid in the collector. An energy supply, except for solar radiation, is therefore not necessary. If the Stiriingmotor (4) mounted above the solar collector (1) and the outlet of the solar collector with the warm side and the inlet of the collector connected to the cooling of the engine, so the Stiriingmotor automatically then heated liquid to the thermal energy storage (7) or heat energy consumer, when the temperature of the liquid from the collector is greater than that coming from the thermal energy storage or heat energy consumer. By suitable valves (8), a reflux at times when the collector is not irradiated, and overheating, eg a boiler, be prevented.

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DVR 0078018

AT 405 320 Β

The invention relates to a system for solar energy use according to the preamble of claim 1, wherein by means of a solar collector, a Stirling engine and a pump, warm liquid from the collector can be pumped without a different energy input than the sun, to a heat energy storage or heat energy consumer.

For solar panels, such as those used for domestic hot water heating, the following problem arises. The solar collector is at a very high point in the system - usually the house roof - appropriate, the boiler is often in the basement. The liquid in the circuit is heated on the roof, thereby reducing the specific weight. Therefore, the specific heavier cold liquid must be pumped onto the roof so that the heated one can get into the boiler. Conventional systems do this with an electric pump. The disadvantage is that one must supply such a system for (heat) energy production electrical energy.

Known systems with Stirling engine (eg US 5,228,293 A) use the Stirling engine to recover the energy collected in the solar collector. However, a pump is again required, which (i electrical) energy must be supplied. In the present invention, the pump is driven by the Stirling engine. It is envisaged, though not necessarily, that the Stirling engine be used only to power the pump. As a result, in contrast to all known systems, the pump can be driven directly by the heat energy collected by the solar collector.

The present invention makes it possible that by appropriate arrangement of a Stirling engine, the pump can be driven directly with the heat collected by the solar collector heat energy.

According to claim 1, the pump is driven by a Stirling engine. So you can also use the heat energy of the sun's light to pump down the warm liquid .

If the Stirling engine according to the invention (claim 2) mounted higher than the solar collector, so increases at standstill of the Stirling engine heated by the sun rays liquid in the circuit from the solar collector to the engine. As a result, the Stirling engine is heated on one side, starts to run and drives the pump. As a result, the heated liquid to the heat energy consumer, which can thus be lower, pumped. The warm liquid is always passed by the Stirling engine, which supplies it with sufficient energy for operation. If no more warm liquid comes out of the collector, the engine stops working, which makes sense, otherwise the heat energy consumer would be cooled rather than heated.

According to claim 3 of the Stirling engine can be cooled with the cooler from the consumer pumped liquid. Since the Stirling engine can only run as long as there is a temperature difference between cold and warm side, this arrangement results in a considerable advantage. Only when there is a sufficient temperature difference between the liquid flowing through the solar collector and that coming from the thermal energy store or the heat energy consumer, does the engine run. If below the liquid is not much cooler any more, than that heated by a solar collector, then the engine and the pump stop their work. Whether then, for example a boiler in the basement is already very warm, or the collector can no longer heat the liquid, has the same effect.

A plant as just described can pump warm liquid to a lower level for various applications. Whether in a cellar another Stirling engine operated to generate electricity, or a boiler is heated does not matter. In the latter variant, or even when using a stone storage or the like, but other additives are useful.

A valve (according to claim 4), which prevents a flow of the liquid against the regular flow direction, prevents the cooling of the thermal energy storage in times of lack of sunlight.

The system can be extended (according to claim 5) by a mechanical, temperature-controlled valve (eg bimetal principle), which is thermally coupled to the thermal energy storage, and interrupts the fluid circuit when a critical temperature is exceeded. For example, a boiler can be protected against overheating. An electronic control, which would again require electrical energy - even if minimal - can thus be completely eliminated.

Preferred embodiments of the invention will be explained in more detail with reference to the drawings.

Showing:

Fig. 1 is a schematic representation of the heat recovery system according to the invention

Fig. 2 is a schematic representation of the heat recovery system with alternative cooling of the Stirling engine

A plant, as shown in Figures 1 and 2, comprises a solar collector (1) in which a liquid is heated by solar radiation (2). The liquid is guided in a closed line system (3) and rises to an elevated Stirling engine (4). There she gives you one

AT 405 320 Β

Heat exchanger (5) a small part of their energy to the Stirling engine (4) from. Due to the heating of this drives a pump (6), which in the sequence conveys the heated liquid through a conduit system (3) to a heat energy consumer (7). There, the liquid releases the rest of its heat energy. By a valve (8) prevents the process could run in the reverse direction. This would be conceivable if, for example the heat energy consumer (7) is a memory and in turn could heat the, at another time cooler, liquid again.

In Figure 2, the heat energy consumer (7) is designed as a memory. It makes sense then by one

Temperature valve (9) to stop the liquid circuit from a certain temperature to prevent overheating of the memory (calcification of a boiler). As an alternative guidance of the lines (3), the cooling of the Stirling engine (4) in Figure 2 by a further heat exchanger (10). As a result, the temperature difference between the solar collector (1) and the heat energy consumer (7) is approximately always applied to the Stirling engine (4) during operation. This ensures that the pump (6) promotes liquid only when the temperature in the solar collector (1) is higher than that in the heat energy consumer (7).