Numerical Simulation Of Air Flow Over Louvered Fin In Domestic Air-conditioning Heat Exchangers

The popularization of high efficiency air-conditioning in China promotes technological upgrading of air-conditioning industry. Performance improvement of heat exchangers is significant for improving efficiency of air-conditioning. Aluminum louvered fin heat exchangers with features such as compact, high efficiency etc become one of the alternatives for domestic air-conditioning. Therefore, study on louvered fin heat exchangers is of great significance.This paper studies the effect of frontal velocity and fin pitch on air flow over louvered fin in domestic air-conditioning heat exchangers. Calculation methods of pressure drop for louvered fin with correlations by Chang and Wang and Davenport were presented.A FLUENT computational model was developed to predict the fluid flow and flow efficiency characteristics of louvered fin geometry and different computational schemes were compared with correlations by Chang and Wang. Comparisons show that the computational scheme, which block-hexahedral meshes and single period model are applied to, has the best agreement and gives a mean deviation of 3.34%. Based on the optimal computational scheme, 3-D numerical simulations of louvered fin with fin pitch of 1.0~1.3mm were conducted, which spanned frontal velocity of 1~5m/s.Results show that flow efficiency increases with frontal velocity, while decreasing with fin pitch, and it's directly proportional to louver pitch to fin pitch ratio. The increase in frontal velocity from 1m/s to 2m/s causes an increase of 6.97% in flow efficiency and the increase in frontal velocity from 4m/s to 5m/s causes an increase of 0.92% in flow efficiency for Fp = 1.3mm. Flow efficiency has an reduction of 50% while increasing fin pitch from 1.0mm to 1.3mm for V = 2.5m/s. Flow efficiency is strongly depended on fin pitch, especially at low frontal velocity. Compared to frontal velocity, fin pitch has a stronger effect on flow efficiency. Pressure drop increases with frontal velocity,while decreasing with fin pitch.The transverse distance of fluid flow decreases with fin pitch and the boundary layer thickness on fin surface increases with frontal velocity. Air flow in louvered fins has symmetry in the direction of fin hight.Frontal velocity has a strong effect on boundary layer and fin pitch has a strong effect on flow efficiency, which influence the heat transfer capacity in louvered fins.This research provides reference for understanding of flow and heat transfer mechanism in louvered fin and optimizing the structure of louvered fin to improve its performance.