A regenerative cycle reciprocating internal combustion engine

A regenerative constant-volume internal combustion engine cycle is presented and analyzed. It is shown how a reciprocating piston-in-cylinder version can be achieved in practice by using separate compression (cold) and expansion (hot) cylinders interconnected by a transfer port packed with a regenerative matrix. By injecting a volatile liquid, such as water, during compression it is possible to achieve a measure of isothermality which, together with regenerative operation and high instantaneous maximum combustion temperatures, can yield theoretically energy conversion efficiencies intermediate between those of Carnot and conventional internal combustion engine cycles. The potential advantages of this type of machine are described