Effect of Oil on R-134a Condensation in Parallel Flow Condensers

This paper reports tests to determine the effect of R- l34a-oil mixtures on condensation in a 1.32 mm hydraulic diameter extruded aluminum tube used in automotive refrigerant condensers. The tests were performed at 8 kW/mz heat flux for 600, 1000, and 1800 kg/m2s mass velocity with 3.25,6, and 10% oil concentration (by mass). At low vapor qualities, oil increases the condensation coefficient (h), and at vapor qualities above 50%, oil reduces the h-value. The h-reduction is more severe at increased oil content. Oil increases the pressure gradient, and the pressure-gradient increase is more severe at higher oil concentration.