Abstract: Panels for supporting heat transfer tubing are provided with a tubing-receiving track having a multi-faceted inner surface that enhances reception of the tubing, installation of the panels and ultimately heat transfer effectiveness.

Abstract: In a Stirling engine comprising: a cylinder having an expansion space; a housing accommodating a heat accumulating unit; and a heating unit through which said expansion space is communicated with the heat accumulating unit, the heating unit is formed by using a flattened pipe, and preferably heat transferring fins, and reinforcing members for preventing the increase in volume of the flow path in the heating unit are provided in the latter, so that in connecting the heating unit to the cylinder and the housing, the number of assembling steps is decreased, and the heating unit is sufficiently large in dead volume ("flow path sectional area" x "flow path length") and in heat transfer area.