1 Effects of Non-Uniform Refrigerant and Air Flow Distributions on Finned- Tube Evaporator Performance

An experimental investigation was implemented to determine the capacity degradation due to non-uniform refrigerant and air flow distributions, and to assess the potential to recover the lost capacity via controlling refrigerant distribution between individual refrigerant circuits. The tests were performed on a three-circuit, three-depth-row, finned-tube evaporator. Refrigerant inlet quality, exit saturation temperature, and exit superheats for the individual circuits were controlled. The study showed that capacity degradation due to refrigerant maldistribution can be as much as 30 %, even when the overall evaporator superheat is kept at the target 5.6 ºC. Experimental data indicate that part of this capacity degradation was caused by the internal heat transfer within the evaporator assembly. For the coil and air maldistributions studied, the maximum capacity degradation was found to be 8.7 %. A 4.0 % capacity recovery was obtained by controlling refrigerant distribution to obtain the target 5.6 ºC at each circuit exit