Abstract: A thermodynamic energy conversion device (14) based on the effect of differential evaporation generated by a convex liquid surface and by a temperature gradient is constructed for the use either as a heat or hydraulic pump. In one arrangement the device (14) comprises two heat conductive containers (1) and (2); a working liquid (5) disposed in said containers with open surfaces (6) and (6?); a vapor (7) of the working liquid; a porous device (8) for creating at least one convex meniscus (9) on the open surface (6), of the working liquid (5) in one of the containers said convex meniscus having higher mean curvature than that of the open surface (6?); means (10) for connecting containers (1) and (2) to an external hydraulic circuit (11). An efficient external combustion engine using such a device (14) is disclosed.

Abstract: A thermodynamic energy conversion device (14) based on the effect of differential evaporation generated by a convex liquid surface and by a temperature gradient is constructed for the use either as a heat or hydraulic pump. In one arrangement the device (14) comprises two heat conductive containers (1) and (2); a working liquid (5) disposed in said containers with open surfaces (6) and (6?); a vapour (7) of the working liquid; a porous device (8) for creating at least one convex meniscus (9) on the open surface (6), of the working liquid (5) in one of the containers said convex meniscus having higher mean curvature than that of the open surface (6?); means (10) for connecting containers (1) and (2) to an external hydraulic circuit (11). An efficient external combustion engine using such a device (14) is disclosed.