Thermal characterization of microscale heat convection in rare-gas environment by a steady-state “hot wire” method

In this work, a steady-state "hot wire" method is developed to study thermal transport around a microwire in a rare-gas environment. The convection heat transfer coefficient (h) around a 25 µm platinum wire is determined to be from 14 W m−2 K−1 at 7 Pa to 629 W m−2 K−1 at atmospheric pressure. In the free-molecule regime, the Nusselt number is found to be inversely proportional to the Knudsen number, the slope of which is used to determine the slip length as 7.03 × 10−4 m. In the transition regime, the slip length is found to be 20 times the wire diameter. Under a certain pressure, h decreases with increasing wire temperature, and this trend is more sensitive at high pressures.