R407c إنتقال الحرارة وهبوط الضغط خلال عملية التكثيف في أنبوب عمودي للمائع

Abstract

This work included a theoretical analysis for heat transfer, pressure drop, and flow characteristics of refrigerant R407c during the condensation process for the annular flow pattern in the vertical tube. The (Gauss-Seidel) method was used to solve the conservation equations of mass, momentum, and energy governing in the flow process, and develop a computer program in EES
(Engineering Equation Solver). The study was conducted for three tube diameters which are (8,10 and 12mm), three mass flow velocities, namely, (75,100 and 125kg/m2 .s), and three values of the temperature difference between the saturated vapor flowing in tube and tube wall, namely, (2,4 and 6K). The results showed that the change in temperature difference has a significant effect on a heat transfer coefficient, and on most two-phase flow characteristics followed by the effect of changing the mass flow velocity of vapor, and the less the effect is the change of tube diameter. The ratio of the increase rate in heat transfer coefficient reached 3.738% when tube diameter reduced from (12mm) to (8mm) and the ratio of the rate was 20.516%when the mass flow velocity of vapor increased from (75kg/m2.s) to (125kg/m2 .s), while the ratio of the decreasing rate when increasing the temperature difference from(2K) to (6K) 27.574%.