Liquid Control for High Evaporator Efficiency

Abstract

This chapter provides details of the results of experiments conducted to study liquid control for high evaporator efficiency. It is pointed out that for extended surface coolers, the heat conductance resistance from the extended parts of the surface wall to the prime surface often plays an important part, and this resistance usually is accounted for by introduction of the fin efficiency factor into the calculations. The chapter also outlines that simple static evaluation of evaporators show, that improvements of heat transfer on the refrigerant side is very important for shell- and tube coolers, it is also important for extended surface air coolers, but it does not seem important for bare pipe air coolers. It is indicated that the amount of liquid recirculation must be chosen so that the liquid temperature rise does not occupy too much of the available temperature difference for the heat transfer. The results show that different refrigerants have different possibilities for improved performance with this system, and the possible improvement is best with high heat loads.