Optimization of Electrospray Cooling Performance Using Isopropyl Alcohol-Water Binary Mixtures: A Full Factorial Design Approach

This study tested the performance of Electrospray (ES) cooling using binary mixtures of water and isopropyl alcohol (IPA). The main aim was to identify how combinations of fluid property, flow rate, and electrical potential interact under conditions of constant heat flux (3850 W/m²). A full 33 factorial experiment was performed for each of three values of mixture composition (10, 30, and 50% IPA) using three different flow rates (15, 30, and 45 ml/h) and three different levels of voltage (9, 10, and 11 kV). The analysis showed that flow rate has the greatest influence on cooling performance (57.02% impact). Fluid properties were found to produce the best cooling results with the 30% IPA/70% water mixture because of their ability to provide a balance of thermal capacity and low surface tension. Using the optimum condition of a high voltage (11 kV) allowed for a stable cone-jet mode that provided effective atomization and surface wetting. Lower levels of IPA were shown to hinder the formation of stable jets because of the increase in surface tension, while higher concentrations of IPA were limited by lack of thermal capacity. From the analysis of data, the optimum operating conditions were found to be flow rates of 45 ml/h, voltages of 11 kV, and 30% IPA, resulting in a minimum temperature difference of 14.12 K. These results were confirmed by the statistical regression analysis (R2=0.974) model.