Experimental Study on Heat Transfer and Resistance Performance of Elliptical Finned Tube Heat Exchanger with Different Air Entrance Angles

摘要

To save space, sometimes the heat exchanger is necessary to arranged obliquely. Inrnview of the fact that the air entrance flow direction is not orthogonal to the heatrnexchanger surface in many cases for the direct and in-direct air cooling system, thernpresent study describes the experimental system about the elliptical finned tube heatrnexchangers inclined towards the air oncoming flow. The inclined angles between thernminor axis of the oval tube and the oncoming air flow are 90° and 60° separately. Thernheat transfer and pressure drop characteristics are investigated. The results show that thernoverall heat transfer coefficient of 60° is about 9.96 % smaller than that of 90° when thernother conditions are the same, while the pressure drop has a significant change when thernair velocity is big to some extent. At last the correlations of the convection heat transferrncoefficient and resistant coefficient of the air side are acquired. And some conclusionsrnare drawn upon the effects of the air entrance angles on the heat transfer and resistancernperformance of the elliptical finned tube heat exchanger.