Analysis of refrigerant mal-distribution: in fin-and-tube evaporators

Refrigerant mal-distribution in fin-and-tube evaporators for residential air-conditioning is investigated numerically in this paper. Essentially the influence of refrigerant mal-distribution on capacity of an evaporator is reported. In order to investigate, a model of a fin-and-tube evaporator is developed in the object-oriented modeling language Modelica.

The evaporator model is a dynamic distributed one-dimensional homogeneous model, but will be used here to present results in steady state. Fin-and-tube evaporators usually have a complex circuitry, however the evaporator will be simplified to be two straight tubes. The refrigerant maldistribution is then induced to the evaporator by varying the vapor quality at the inlet to each tube and the air-flow across each tube.

Finally it is shown that mal-distribution can be compensated by an intelligent distributor, that ensures equal superheat temperature in both tubes. The refrigerant is R410a.