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Over the course of the past decade, the automotive industry has made efforts to reduce the depth of the brazed aluminum, louver fin evaporators typically used in the air conditioning system for automobiles by increasing their compactness. Increasing fin and louver densities have led to the possibility of condensate affecting the air side performance of automotive evaporators. Condensate can “bridge” the space between two adjacent fins or louvers. Condensate bridging of the fins or louvers can alter the flow of air through the evaporator, causing a change in the heat transfer and friction characteristics. This study attempts to quantify these changes and determine which parameters will have an impact on them. Wind tunnel tests measuring the air side sensible heat transfer coefficient and pressure drop were conducted to examine how the air side heat transfer and friction characteristics of automotive evaporators are changed by the presence of condensate.

Condensate that forms on the air side surface of an evaporator can have a significant impact on the air side performance of brazed aluminum, louver fin automotive evaporators. Condensate can “bridge” the space between two adjacent fins or louvers and alter the flow of air through the evaporator, causing a change in the heat transfer and friction characteristics. This study attempts to determine how condensate drains from an evaporator in the hopes of improving the air side fin geometry and obtain an evaporator that retains a minimum amount of condensate. Using a table-top wind tunnel apparatus, qualitative observations of condensate draining from a single column of louver fins brazed to a refrigerant tube were made. The amount of condensate retained in an evaporator core was determined using the experimentally-verified dip test method.