Effect of Surfactants on Liquid–Solid Heat Transfer on High‐Temperature Wall

Abstract

During the quenching of high‐temperature steel plate, Leidenfrost phenomenon takes place, which prevents the coolant from extracting heat from high‐temperature wall. Adding surfactant to the basic fluid can reduce the surface tension, increase the solid–liquid contact area, and ultimately increase the cooling speed. Herein, aqueous solutions of 240 ppm cetyl trimethyl ammonium bromide (CTAB), 600 ppm sodium dodecyl sulfate (SDS), and 56 ppm polyoxyethy‐lene (20) sorbaitan monolaurate (Tween‐20) are used as coolants. Using a 50 mm thick high‐temperature AISI304 stainless steel plate, free surface jet experiments are designed and completed to study the influence of different coolants on the surface heat transfer and internal thermal conductivity. The experimental results show that surfactants can reduce the surface tension, which enhance the wettability of the fluid on the surface, whereas the time it takes for the fluid to completely wet the experimental region is shortened by up to 13.87%. The foaming can increase the width of wetting front and hinder the expansion speed of the wetted region. When aqueous Tween‐20 with low surface tension and low foaming is used as the coolant, the maximum heat flux increases by 12.11%, 7.03%, 9.33%, 7.70%, and 4.41% compared with that of pure water.