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

•Measurements of Uv in a 3-phase spray column DCHE.•Effect of Qc, Qd, Do, Hv and sparger configuration was examined.•Uv decreases with Do and Hv.•Uv increases with increasing continuous and dispersed phase flow rates.•Very slight effect of sparger configuration on Uv. 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.