Brazed aluminum heat exchangers are recently considered
as evaporators of automotive or residential air conditioners. In
this case, it is very important to distribute the two-phase
refrigerant (especially the liquid) evenly into each tube. In this
study, R-410A distribution in a two pass evaporator with upper
horizontal combining-dividing header was investigated. Tubes
were heated to yield a test section outlet superheat of 5oC with
inlet quality of 0.2. The number of tubes was 10 for the inlet
pass and 12 or 14 for the outlet pass. For each case, mass flux
was varied from 73 kg/m2s to 143 kg/m2s. In the
combining/dividing header, two-phase mixture out of the inlet
pass is first merged and then re-distributed to the outlet pass.
More liquid is forced downstream as mass flux or quality
increases yielding better flow distribution. Effect of insertion
device in the inlet header was also investigated. Efforts were
made to develop correlations to predict the liquid or gas
distribution in a header with limited success. Header pressure
drop data are also provided.
Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016.