Measuring the average volumetric heat transfer coefficient of a liquid–liquid–vapour direct contact heat exchanger

Abstract

The average volumetric heat transfer coefficient in a spray column liquid–liquid–vapour direct contact evaporator has been experimentally investigated. The experiments were carried out utilising a cylindrical Perspex tube of diameter 10cm and height and 150cm. Saturated liquid n-pentane and warm water at 45°C were used as the dispersed and continuous phases, respectively. Three different dispersed flow rates (10, 15 and 20L/h) and four different continuous phase flow rates (10, 20, 30 and 40L/h) were used in the study. The effect of different parameters, such as the initial drop size, continuous and dispersed phase flow rates and sparger configuration, on the average volumetric heat transfer coefficient in the evaporator was studied. The results showed that the average volumetric heat transfer coefficient was reduced as the initial drop size increased. Also, both the continuous phase and the dispersed phase flow rates have a significant positive impact on the average volumetric heat transfer coefficient.