높은 환산압력 조건에서 R1234ze(E)의 관내측 응축 현상 연구

Abstract

The condensation heat transfer coefficients of R-1234ze(E) were experimentally measured. The test facility comprised a test part, a preheating part, and a condensing part. The test section of copper tube with a diameter of 1/2 inch and a length of 2 m was installed, inside a PVC pipe, which was cooled by brine. A thermocouple was attached to the surface of the copper tube by soldering, and the surface temperature of the copper tube was measured for each section. Tests were performed under the conditions of a mass flow rate of 300-500 kg/㎡s and a reduced condensation pressure of 0.5-0.7. The condensation heat transfer coefficient of the R-1234ze(E) refrigerant decreased by 19%, as the reduced condensation pressure increased from 0.5 to 0.6 or 0.6 to 0.7, and the pressure drop also decreased as the reduced pressure increased. The predictions by the Cavallini correlation and the Traviss correlation showed the mean deviation for the condensation heat transfer coefficients by 91.8% and 61.6% of the experimental results, respectively. Thus, the existing correlations for the condensation heat transfer coefficients can be used, by considering the decreasing rate of 19% with increase of reduced pressure under the high reduced pressure conditions.