Effect of attack angles on air side thennal and pressure drop of the cross flow heat exchangers with staggered tube arrangement

摘要

The experimental investigation of the air side heat transfer and pressure drop characteristics at steady state for the cross flow heat exchangers having flat tube configuration with staggered arrangement are presented. The effect of attack angles on the air side is major to study. In addition, the effect of tubes aspect ratios was also studied. Nineteen heat exchangers with four aspect ratios (0.18, 0.39, 0.66 and 1) and six attack angles (0°, 30°, 60°, 90°, 120° and 150°) are investigated. The water temperature of 75 °C and the air at ambient condition flowed through the heat exchangers with velocity range from 2 to 6 m/s. The results show that the thermal and the pressure drop characteristics had governed by the attack angles and the tube aspect ratios. For all values of the air velocity of each tube aspect ratios, to increasing the attack angles (0°-90°) the heat transfer rate and the pressure drop were increased, while the thermal hydraulic performance was decreased. When considered effect of tubes aspect ratios on thermal and pressure drop characteristics, the results indicated that to change of the attack angles of lower tube aspect ratios had effected on thermal and pressure drop more than attack angle changed of higher tube aspect ratios.