Abstract: Process and apparatus for transiently measuring surface temperatures and heat flux at the interface of two media, one of which is solid. In a solid wall through which a thermal stream flows, a cut is made which opens into the interface between the wall and the other medium. The cut is parallel to the stream at a point of contact corresponding to the interface. A microthermocouple is arranged in a plane of the cut in the immediate vicinity of the interface. The cut is closely covered by the material of the solid wall or a material with thermal characteristics similar to those of the peripheral material.

Abstract: The measuring device comprises two flat-wall heat exchangers (3a, 3b), one to each side of a flat plate (1), two samples (2a, 2b) of similar thickness (E) of the material being tested, placed between the outer surface of the heat exchanger (3a, 3b) and one surface of the central plate (1), a device for positioning and holding the heat exchangers (3a, 3b) and at least two temperature sensors, one of which (T2) consisting of a thermocouple is incorporated in the central plate (1), the other (T1) also consisting of a thermocouple, being incorporated in the outer wall of the plate of one of the heat exchangers (3a). Application in the injection of plastics.