Experimental and numerical research on a C-type heat exchanger in duct air conditioner under non-uniform airflow

Abstract

The indoor unit of duct air conditioner typically employs an A-type heat exchanger (HX), but non-uniform airflow within the duct significantly degrades heat transfer performance. The current study proposes a C-type HX to accommodate the non-uniform airflow better. Experiments are conducted to compare the C-type and A-type HXs under varying conditions, including air volume flow rate, air velocity non-uniformity, inlet air temperature, and condensing temperature. Results indicate that as the non-uniformity of inlet air velocity increases, the heat transfer capacity of A-type HX decreases obviously. In contrast, the C-type is insensitive to the non-uniform air velocity distribution, which consistently outperforms the A-type in terms of heat transfer capacity throughout various operating conditions. Additionally, a numerical model is developed to compare the local parameters of the two HX types. The C-type demonstrates a more uniform outlet air temperature and exhibits a heat transfer capacity that is 19.1% higher than the A-type, while maintaining the identical heat transfer area and size parameters.