The optimum conditions for calcium sulfate fouling rate under subcooled flow boiling using Taguchi statistical method

A comprehensive experimental investigation as well as a statistical design of experiment method (the Taguchi method with L16 orthogonal array robust design) was performed in order to measure the heat transfer reduction and fouling rate of CaSO4 aqueous solutions. Moreover, the effects of different variables (flow rate, CaSO4 concentration, heat flux and bulk temperature) were investigated for two heat transfer mechanisms including forced convection and subcooled flow boiling. Each parameter was studied at two levels so that 16 experiments were totally conducted aiming at introducing the best set of conditions in order to resulting the fewer fouling rate of CaSO4. Based on analysis of variance (ANOVA), the percentage contributions of each factor are ranked as follows: (1) concentration (34%), (2) heat flux (24%), (3) flow rate (23%), and (4) bulk temperature (13%). It also verifies that the interaction of heat flux and flow rate has the greater impact rather than other parameters interactions with a contribution of 2.9%. This experimental result optimum conditions with a fouling rate of 2.1 x 104 m2K/kW.min was very close to the predicted value (1.99 x 104 m2K/kW.min). This demonstrates a good consistency between the experimental and the predicted values, with only a 5% deviation, and approves the effectiveness of the experimental design to attain the optimal condition.(c) 2023 Elsevier Ltd. All rights reserved.