Optimization of thermal parameters in a double pipe heat exchanger with a twisted tape using response surface methodology

In the present work, design of experiments has been used to study the effect of thermal parameters on heat transfer enhancement in a double pipe heat exchanger using a passive technique. A twisted tape is considered as the heat augmentation device with tape width, tape pitch and mass flow rate as the input parameters and Nusselt number (Nu) and pressure drop (ΔP) as the output variables. Response Surface methodology (RSM) is used to develop a mathematical prediction model. The effect of the above input parameters on Nu and ΔP was investigated by ANOVA analysis. It showed that both linear and interaction terms are influencing the responses. Results reveal that mass flow rate and pitch of the tape are significant for Nu, whereas mass flow rate and tape width are significant for pressure drop. In the tested range, optimum conditions for higher Nu and lower ΔP were determined using RSM optimizer. Optimum values of Nu and ΔP were obtained corresponding to a tape pitch of 20 mm, width of 3.8 mm and a mass flow rate of 0.5 kg/s with optimum values for Nu and ΔP being 48 and 895 Pa.