Abstract
The results of an experimental study to evaluate the characteristics of R-407C thermofluid during condensation in a helically coiled copper tube heat exchanger are presented. The effects of saturation temperature (T-sat), and mass and heat fluxes of refrigerant R-407C on thermal performance and pressure drop were determined. The relationship between the refrigerant wall subcooling and heat transfer coefficients was also investigated. This paper reports the effect of the temperature of the water used as cooling medium on the heat transfer rate of condensing R-407C. The study was conducted with mass flux of R-407C in the range of 100-450 kg/m(2)s, mass flux of the coolant water in the range of 500-5000 kg/m(2)s and T(sat)of 31 degrees C, 35 degrees C, and 39 degrees C. Compared with a straight smooth tube, the use of the helical coiled (helicoidal) tube increased the condensation rate with a corresponding pressure drop that depended on the value of T(sat)of the refrigerant and temperature of the coolant.