Heat exchanger, Flat Tube, Fin efficiency, Heat transfer, Pressure drop
Heat exchangers equipped with circular tubes are generally used in air conditioners. Recently, air conditioners using heat exchangers equipped with flat tubes for higher performance have been enlarging. It is also effective for increasing the efficiency of the air conditioner to improve the performance by optimal design of the heat exchanger. Therefore, it is important to improve the accuracy of the air side performance prediction method. In this study, we propose a new method to predict air side heat transfer characteristics and air side pressure drop characteristics of the flat tube heat exchanger using the numerical analysis. The calculation results, using a new fin efficiency equation with corrections in the row pitch direction and the column pitch direction, agree well with the numerical analysis results taking into account the air side local heat transfer coefficient. In addition, the calculation results, using non-dimensional equations for the air side heat transfer coefficient and the air side pressure drop under dry conditions in conventional form, and a new fin efficiency equation, agree well with the numerical analysis results and the measurement results. Furthermore, in wet conditions, it is suggested that the existence of the slit has a significant effect on the water film thickness around the pipe backcalculated from the measurement results and the non-dimensional equation.