Heat transfer and pressure drop correlations for the multi-louvered fin compact heat exchangers

Experimental studies on the air side heat transfer and pressure drop characteristics for 20 types of multi-louvered fin and flat tube heat exchangers were performed. A series of tests were conducted for air Reynolds numbers of 200–2500 based on the louver pitch with different fin pitch, fin height, fin thickness, fin louver angle and flow length at a constant tube side flow rate of 2.8 m3/h.The air side thermal performance data were analyzed using the effectiveness-NTU method. Characteristics of the heat transfer and pressure drop for the different geometry parameters were reported in terms of Colburn j-factor and Fanning friction f  -factor as a function of ReLpReLp. The general correlations for the j and f factors were derived by regression analysis and F test of significance. The correlations of the j and f factors predict the test data within a rms error of ±10% and ±12%, and the mean deviations are 4.1% and 5.6%, respectively. In addition, two comparison methods were adopted to evaluate the air side thermal hydraulic performance of the multi-louvered fins.