Experimental study of two phase adiabatic flow distribution in small channel heat exchanger

Small-channel heat exchangers are widely used for car air-conditioning. However information about their behaviour remains scarce. Thus an experimental device was built to characterize the distribution of a two-phase flow in a small-channel heat exchanger and to measure the singular and regular pressure losses. Both were studied with horizontal flow and vertical down-flow through the header. A transparent polycarbonate test section comprised a 16 mm diameter header connected to 8 multi-port flat tubes (Dh = 0.889 mm). The mass flux range was between 15 and 650 kg/(m².s) in the manifold and between 100 and 3 000 kg/(m².s) in the small channels. The range of vapour quality values at the test section inlet was between 0.1 and 0.9. The two-phase refrigerant was condensed at the outlet of each flat tube in order to measure each flow rate separately. The refrigerant distribution was studied in single and two-phase flows, the pressures losses were measured.