Estimation and Analysis of Surface Heat Flux During Quenching in CNT Nanofluids

In this article, water based carbon nanotube (CNT) nanofluids have been used as quenchants to study their effects on the heat transfer rate during immersion quenching. For this purpose, water based CNT nanofluids were prepared by dispersing CNTs with and without the use of surfactant. Quench probes with a diameter of 20 mm and a length of 50 mm were prepared from 304L stainless steel. Thermocouples were fixed at the selected location inside the quench probes and the probes were quenched in distilled water and CNT nanofluids. During quenching, time-temperature data were recorded using a data acquisition system. The heat flux and temperature at the quenched surface were estimated through the inverse heat conduction method. The computation results showed that the peak heat flux was higher by 37.5% during quenching in CNT nanofluid prepared without surfactant than that in water. However, surfactant assisted CNT nanofluid promoted a prolonged vapor phase during quenching and hindered the heat transfer rates significantly. The peak heat flux was dropped by 24.9% during quenching in CNT nanofluid prepared with surfactant as compared with its base fluid of water.