Introduction and basic technical description of Stirling EnginesThe New Stirling engine technology is a substantial advancement of the Stirling engines referred to here as "classic". First, the thermodynamics on which all Stirling engines are based and the functioning of the classic engines are described here.
A Stirling engine is a periodically operating heat engine that converts thermal energy into mechanical energy ("Heat-To-Power"). In the Stirling engine, an enclosed volume of gas is heated in a space (cylinder) that is kept continuously hot, causing it to expand.
The expansion of the gas drives the machine. In another room (cylinder) the gas is cooled and compressed. It oscillates back and forth between these two spaces. Stirling engines are mostly designed as piston engines, but there are also other designs.
The machine can deliver work because the work required for compression at cold temperature is less than that released for expansion at hot temperature.
The heat is supplied from the outside to the enclosed gas mass, so the machine can be operated with any external heat source. Since the gas is not exchanged, a particularly suitable gas such as helium or hydrogen can be used.
Conventional Stirling engines ("classic machine") store the heat contained in the working gas in a reservoir (regenerator) on the way from the hot to the cold room in order to improve efficiency. The regenerator releases the heat when the gas flows back from the cold to the hot room.
"Yet the general knowledge and understanding of Stirling engines is still at such low level that, even among experts a wide divergence of opinion can be found, not only as to their basic applications or desirable constructional features, but even as to the analytical approach appropriate for their design and optimisation."
T. Finkelstein (Foreword for Allan J.Organ: Thermodynamics and Gas Dynamics of the Stirling cycle Machine)