Air Flow Distribution Through an A-Shaped Evaporator Under Dry and Wet Coil Conditions

This paper presents a study of the air flow distribution through a residential air-conditioning heat exchanger. The test subject was a finned-tube, A-shaped coil outfitted with a condensation collection pan required for horizontal installation. We examined the air flow distribution approaching and exiting the coil at the rated and a reduced air flow rate, and at two humidity levels. Our measurements showed that the presence of the condensation collection hardware greatly impedes air flow through the lower slab of the coil. Our measurements also uncovered portions of the coil where the airflow is blocked by the mounting hardware. The wet coil tests showed that the presence of water on the coil causes a large increase in air flow resistance which has an effect on the flow distribution. The distribution of water concentration was non-uniform and time dependent. We also developed a computational model of the flow through the test coil, based on a momentum resistance modeling approach.