Li, J. and Hrnjak, P., "Phase Separation in Second Header of MAC Condenser," SAE Technical Paper 2015-01-1694, 2015, doi:10.4271/2015-01-1694.
This paper presents results of the visualization of the separation in the vertical header of the automotive condenser. A prototype of a heat exchanger was made that has inlet in the middle of the header, with 21 microchannel tubes as the first pass. In the second header liquid separates and leaves through 4 microchannel tubes beneath while mostly vapor leaves through 11 microchannel tubes on the top as another exit. That way the 2nd pass has liquid below first pass and vapor above it. R134a was used in the tests. Mass flow at the inlet to the header was in the range 8.4 - 30 g/s (mass flux of 54 kg/m2·s-193 kg/m2·s) and quality at the inlet to second header was varied over a range of 0.05 to 0.25, to see their impact on the separation of two-phase flow inside the transparent header. Visualization was performed to better understand and define the physical parameters that dominate the separation phenomena. Efficiencies of separation are defined to quantify the separation effect of the special design of headers, which could affect the amount of heat exchanged in the condenser.