23 September 2011
Microchannel performance strongly depends on the heat, mass and momentum
transfer processes. In literature different models have been proposed for the prediction of
two-phase pressure drop and heat transfer coefficients during evaporation and condensation.
These models were mostly based on the experimental data obtained for pure refrigerants in
horizontal microchannels. In this work some recent models have been selected based on the
operating conditions and number of fluids tested and they have been applied to compute the
two-phase pressure drop and heat transfer coefficients for ammonia-water mixture (35%
ammonia and 65% water) during absorption and desorption in vertical microchannels. The
resulting performance has been evaluated for heat exchangers used in a compressionresorption heat pump system.