Abstract: An intermediate circuit is connected between the compression space acting as a first heat exchanger of the cylinder of a heat pump or a working machine and the water for industrial use or the burning space of an oil burner, the intermediate circulator comprising a second heat exchanger protruding within the water for industrial use.Through the utilization of an intermediate circulator with a gaseous or liquid auxiliary medium is possible to adapt the transfer of heat between the cylinder of the machine and the heat medium to the respective conditions which permits to increase the total efficiency.

Abstract: A hot-gas piston engine (4) has, as a compression chamber, a heat exchanger (6) which comprises a number of small pipes (7) or differently designed capillaries which protrude into the burner chamber (5) of a burner (1). In the compression phase, air in the small pipes (7), which serve as the compression chamber, is compressed and additionally heated by the burner flame, whereby the pressure increases, and the piston is driven to execute a downward movement. The scavenging then occurs in the bottom dead center region. The hot outgoing air from the engine enters burner supply line (10) and then the burner, whereby the efficiency of the plant is increased even further. The mechanical energy received at the driven shaft (11) may be used to produce electrical energy or to operate a heat pump. The upper ends of the small pipes protrude into the hot water whereby they are protected from overheating.