A PREDICTION OF HEAT TRANSFER ENHANCEMENT OF CONDENSATION FOR NEW FLUIDS ON PIN-FIN TUBE

The attainment of the maximum heat transfer in condensation tubes is an important factor in their design process. Previous researchers have investigated the improvement imposed by adding pin-fin by measuring the enhancement ratio for different tubes and pin-fin geometries. A clear improvement was noticed upon the addition of the pin-fin system, which drove the current research to perform a multi-optimization study that targets the highest possible enhancement ratio. A wide range of geometrical parameters of tubes and pin-fins (pin height, longitudinal pin spacing at pin root, circumferential pin spacing, and pin thickness, and keeping tube diameter constant) are investigated to find the optimal ranges for each. Both the impact of gravity and the influence of surface tension are taken into consideration. The retention angles (i.e., the area of the tube that is covered by the condensate) is also calculated for different geometries based on previous analytical model. In addition, these parameters are used for predicting the condensation for new and safe refrigerants. As a result, a notable increase in the enhancement ratio is achieved by increasing the number of circumference pins, which can be obtained by decreasing the circumferential pin spacing and thickness. Moreover, the enhancement ratio roughly doubles when pin height is doubled.