Air-side performance of brazed aluminum heat exchangers under dehumidifying conditions

For smaller louver angles (Lα < 27°), the sensible heat transfer coefficient for all fin pitches is smaller than that of a dry surface.

“for smaller louver angles ( L α &lt; 27 ∘ ), the sensible heat transfer coefficient for all fin pitches is smaller than that of a dry surface.”

As louver angle decreased, the amount of condensed water increased and fin and louver bridging became more obvious.

“This proved that as the louver angle decreased, the amount of condensed water increased and the fin and louver bridging became more obvious.”

For heat exchangers with small fin pitch (Fp < 1.4 mm) and large louver angles (Lα = 27°), the sensible heat transfer coefficient and friction are greater than those for dry surfaces for all operating conditions.

“The heat exchangers have small fin pitch ( Fp &lt; 1 . 4 mm ) and large louver angles ( L α = 27 ∘ ), and the sensible heat transfer coefficient and friction are greater than those for dry surfaces for all operating conditions.”

Correlations for the j factor and f factor were proposed by Kim and Bullard through the testing of 30 samples under wet conditions.

“Based on Chang and Wang ' s equation [108], the correlations for the j factor and f factor were proposed by Kim and Bullard [83] through the testing of 30 samples under wet conditions.”

At constant flow depth 20 mm, for fin pitches 1.0, 1.2, 1.4 mm, air-side heat transfer coefficient for dry conditions and sensible heat transfer coefficient for wet conditions increase as Reynolds number varies from 80 to 300.

“at a constant flow depth of 20 mm, for fin pitches of 1.0, 1.2 and 1.4 mm, the air-side heat transfer coefficient for dry conditions and sensible heat transfer coefficient for wet conditions increased as Reynolds number varied from 80 to 300.”

Enhanced thermal performance at high Reynolds number is due to increased mixing generated by streamwise vorticity of condensation water.

“the enhanced thermal performance at high Reynolds number was due to the increased mixing generated by the stream wise vorticity of condensation water.”

At low Reynolds numbers, heat transfer decreases due to increased thermal resistance.

“at low Reynolds numbers, heat transfer decreased due to increased thermal resistance”