Abstract: The invention presents a MONOBLOC fin and plate heat exchanger design preventing internal leakages and intermixing of high-temperature and low-temperature flows, e.g. oil and fuel. This is achieved through a particular configuration of the heat exchanger, whereby its core assembly is completely or partially produced from a one-piece monolithic metallic block. Owing to that, all brazed seams, which in conventional fin and plate heat exchangers contact with both hot medium and cold medium flows, are fully abolished thereby excluding a source for imperfections usually developing in brazed joints and base metal in the process of pressure-temperature cyclic loading. Employing custom-made individual fins allows about two-fold increase in the strength of brazed joints in comparison with ordinary corrugated fins (due to doubling of the brazed surface).

Abstract: An air cycle air conditioning system including a turbine for receiving air and providing expansion thereof, thus lowering the temperature and pressure of the air, an air--air heat exchanger defining a first air flow path for air to be cooled and a second air flow path for air from the turbine at sub-atmospheric pressure to pass therethrough and absorb heat from the air to be cooled, and a compressor, at least partially driven by the turbine, for drawing air at sub-atmospheric pressure through the second flow path for air, characterized by a pre-heater which heats a flow of air, preferably comprising a mixer of ambient air and recirculation air, and directs this mixed flow to the air--air heat exchanger, thereby increasing its temperature and, as a result, the outlet temperature of the secondary air flow, thereby increasing its water vapor absorption capacity.