Experimental study of single and two-phase adiabatic flow distribution in compact heat exchangers.

Small-channel heat exchangers are widely used for car air-conditioning. However information about their behaviour remains scarce. An experimental device was built to characterize the distribution of single and two-phase adiabatic flows in a small channel heat exchanger, and to measure its singular and regular pressure losses. A transparent polycarbonate test section comprised a 16 mm diameter header connected to 8 flat tubes with 7 small channels (D h = 0.889 mm). Both were studied with horizontal flow and vertical down-flow through the manifold. 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. �