ASSESSING THE CONDENSATE-DRAINAGE BEHAVIOR OF DEHUMIDIFYING HEAT EXCHANGERS

Contemporary compact heat exchangers often employ very high fin densities. In many air-conditioning applications such as automotive cooling, the heat exchanger operates to dehumidify the conditioned air. It has been observed that the amount of condensate retained on the air-side surface significantly increases with increased fin density. Retained condensate not only affects the thermal-hydraulic performance, but it also has adverse implications on the quality of conditioned air. Conventional wind tunnel experiments to assess performance are expensive. A method for characterizing water drainage from heat exchanger surfaces, the so-called dynamic dip test, is described. The dynamic dip test is explored as a fast and efficient method for comparative and screening studies for applications where off-cycle drainage is important. Results from more than 30 automotive-style heat exchangers are presented, and condensate drainage characteristics are explored to assess surface tension effects in inter-fin and louver gaps of highfin-density, compact heat exchangers.