Characteristics of a gas-liquid separator with a partial condenser in the absorption refrigeration cycle for automotive air conditioning

Experimental absorption refrigeration equipment with a generator driven by waste heat was manufactured and tested, with 2,2,2-trifluoroethane/1-methylpyrrolidine as the working fluid pair. A plate generator was used to reduce the heat transfer distance and to decrease the start-up time. However, the flow paths of the plate generator were not large enough to separate the refrigerant vapor from the two-phase flow. Therefore, a gas-liquid separator was introduced, and a cooling coil was embedded as a partial condenser in the separator to cool the refrigerant vapor and to condense the absorbent contained within it, thus increasing the concentration of the refrigerant vapor. The separator successfully separated the refrigerant from the solution in all tested conditions. The cooling rate of the partial condenser was varied from 143 to 222 W by changing the flow rate of cooling water. Then, a calculation model for the partial condenser was constructed to analyze its characteristics. In the calculation model, the helical coil partial condenser was modeled by being divided into 10 horizontal columns. It was assumed that only the solution phase had the concentration distribution from the bulk flow to the liquidvapor interface. We show that a heat and mass transfer area of 0.04 m(2) is needed to achieve an outlet vapor concentration of 0.95.