The history of the Stirling Motor
The first Stirling motor was patented by the Scottish intellectual, Robert Stirling. The first machine worked as a water pump for draining a flooded quarry in Scotland. At that time in history, boiler explosions in steam engines were relatively common-place. Stirling wanted to make work in the quarries and coal mines safer. The influx of warmth could be controlled well, and the relative low pressure in the machine could not lead to serious accidents. Other than the bettered safety conditions, the motor was found to have lower fuel consumption, compared to the steam engine, which played a roll in the development of this new technology.
At the beginning of the 20th century, about 250,000 Stirling motors were in use world-wide as table-top fans, water pumps and engines for small apparati like sewing machines. Thus, the private house hold and small manual labor operations were supplied with mechanical energy. When Otto, diesel, and electric motors became more and more popular, Stirling motors were forced off the market.
An unending domain of Stirling motors is the production of very low temperatures. With minimal temperature Stirling cryomachines, temperatures down to 80 K (ca. -193°C) (Explanation Kelvin) can be reached. Air or methane condensation and cooling of infrared sensors are typical examples for low temperature utilization. The military has been producing these machines in large numbers for years, since it needs many cooling units for automatic weapons and infrared visors.
Dish/Stirling systems are made of a parabolic concentrator, a receiver, and a Stirling motor with a coupled generator. In comparison to large units like solar towers and parabolic rim fields (50 to 200 MWe), dish/Stirling systems are designated for decentralized uses of quite a few kW up to a few MW of electrical performance. The modular size is between 5 kWe and 25 kWe in present systems. Through very high concentration factors and temperatures, dish/Stirling units reached a 29 % of the highest conversion level of the best solar thermal unit.
Block-type thermal power stations have become increasingly interested in Stirling models, because they represent alternatives to heating and energy supply down to the private household.