A Critical Review on Mechanical Heat Switches for Engineering and Space Applications

Abstract

Thermal switches are typically used to regulate the heat flow between two surfaces. They are broadly categorized as mechanical, gas-gap, superconducting, and magneto-resistive heat switches. Among these, the mechanical heat switches can be used in a wide temperature range of 5–400 K. Based on different actuation methods, the mechanical heat switches can be further subclassified in piezoelectric actuated, paraffin wax, differential thermal expansion, and shape memory alloy type of heat switches. This work presents a broad overview of different kinds of mechanical heat switches and compares their performances as well as physical parameters. The review suggests that differential thermal expansion types can enforce approximately 30 times extra contact force, whereas the shape memory heat switches have the highest switching ratio among the other types of mechanical heat switches. Moreover, the paraffin wax types of heat switches have minimum response time, while the piezo-electric types are relatively poor in performance due to the lesser contact area.