Abstract: A heat exchanger includes a thermally-conductive fluid barrier having first and second surfaces, at least one first type of foam element placed in thermally-conductive contact with the first surface of the thermally-conductive fluid barrier and having a first coefficient of thermal expansion and at least one second type of foam element placed in thermally-conductive contact with the second surface of the thermally-conductive fluid barrier and having a second coefficient of thermal expansion. The first coefficient of thermal expansion of the first type of foam element and the second coefficient of thermal expansion of the second type of foam element are substantially different.

Abstract: An aerospace platform includes a structure having a cavity and a light-transmissive portion that exposes the cavity to sunlight. The aerospace platform further includes a fluid heating system. The fluid heating system includes a fluid-carrying, thermally absorptive structure within the cavity, and a solar collector for collecting light transmitted through the light-transmissive portion and focusing the collected light onto the absorptive structure. The thermally absorptive structure has a high surface absorptivity that retains thermal energy when exposed to solar irradiance and heats fluid contained therein.