The Study of an Integrated Sensor for Partial Nucleate Pool Boiling at Low Heat Flux

Abstract

To study local convention and heat transfer around an isolated growing vapor bubble during nucleate pool boiling on a well-characterized flat surface in microgravity, a microelectromechanical system (MEMS) sensor has been fabricated to pulse single bubble boiling. In this article, we present the design and fabrication process of an MEMS microchip, which can excite a bubble nucleus with accurate spatial and temporal positioning on the topside of the microchip, and meanwhile, the temperature on the heating surface around and underneath the growing bubble can be measured. The key points and difficulties of chip fabrication have been discussed, including the characteristics of the ultrathin Ti/Pt (10/35 nm) film, such as the effect of annealing on resistivity and its temperature coefficient of resistance (TCR). Then, the thermal cycling experiment has verified its stability. The results of the preliminary ground tests of the flight module SOBER-SJ10 show that the microchip works well as expected and laid a good foundation for meeting the requirements of future space experiments.