Multiple flow heat exchanger

Abstract

Air conditioning cycle with CO2 refrigerant is dominantly transcritical. External heat exchanger (gascooler) encounters strong refrigerant temperature change. If the gascooler has two or more refrigerant passes, the problem of heat losses between the passes may arise. If a corrugated fin is brazed between two refrigerant tubes of different temperatures, it may happen, under certain combination of boundary conditions, that respectable amount of heat flow passes conductively through the fin from the hotter to the colder side. This heat flow is considered a heat loss. Theoretical analysis and prototype testings were performed in order to evaluate this heat loss under various initial and boundary conditions of an automotive air conditioning system with CO2 refrigerant. The constructive solutions intended to prevent or substantially decrease this heat loss were proposed.