Experimental study on thermal-hydraulic performance of moist air inside flat tube of two kinds of plate-fin heat exchangers

The plate-fin heat exchanger is the core component of the condensing clothes dryer, which has a significant effect on the performance of the dryer. Two types of plate-fin heat exchangers with different fin structures are proposed to improve the performance of condensing dryers, offset-fin heat exchanger and slit-fin heat exchanger. Experimental investigations are conducted to study the thermal-hydraulic performance of moist air inside flat tube. The heat transfer coefficient and pressure drop of the moist air inside flat tube, the heat transfer rate per unit area, latent heat and sensible heat are compared and analyzed under different experimental conditions. The comparison shows that the offset-fin heat exchanger compared with the slit-fin heat exchanger can increase heat transfer rate per unit area by approximately 15%. Moreover, the comprehensive performance improves by 5%, respectively. Finally, correlations for predicting the Nusselt number and Darcy friction factor inside flat tube are proposed. The values deviate within20% and 10%, respectively. The results provide a design guide for applying plate-fin heat exchangers to condensing dryers.