Heat transfer in jet impingement on a hot steel surface using surfactant based Cu-Al layered double hydroxide nanofluid

The cooling rate of steel strips on a Run-out Table (ROT) in a hot strip mill affects both the metallurgical microstructure and mechanical properties. The current study focuses on the enhancement of heat transfer rate of an AISI 304 steel plate in both transition and nucleate boiling regimes by jet impingement methodology. The heat transfer studies during jet impingement have been carried out in the case of a steel plate (100 mm x 100 mm x 6 mm) from an initial temperature of around 900 degrees C at the surface. Nanofluid is used along with the base fluid in order to improve the thermal properties which affect the rate of heat transfer. The nanofluid employed here is Cu-Al layered double hydroxide (LDH) at 120 ppm along with different additives at their optimized concentrations, namely sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), polyoxyethylene (20) sorbitan monolaurate (Tween 20) and polyvinylpyrrolidone (PVP). The nanofluid based additives have been characterized based on the thermo physical properties. The maximum rate of cooling was attained in the case of Cu-Al LDH/Tween 20 nanofluid, as supported by the enhancement of thermal conductivity and reduction in surface tension. (C) 2016 Elsevier Ltd. All rights reserved.