CONDENSATION AND EVAPORATION IN MICRO-FIN TUBES AT EQUAL SATURATION TEMPERATURES

Data were taken for condensation and evaporation in a micro-fin tube a t the same saturation temperature to examine similarities and differen ces of condensation and evaporation in micro-fin tubes. The condensati on and evaporation data were taken in the same tube at 24.4 degrees C saturation temperature, for a range of mass velocities (150-327 kg/m(2 )-s), and vapor qualities (0.1-0.9). If the heat transfer mechanism is ''convection dominated'', one would expect that the condensation and evaporation coefficients should be nearly equal. The present data show that this behavior was verified, except for a possible nucleate boili ng contribution at low vapor quality. Both vaporization and condensati on show a small effect of heat flux in the high vapor quality regions. These data provide insight of the heat transfer mechanisms, and sugge st a basis for developing heat transfer correlations that may apply to both condensation and evaporation.