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DESIGN AND DEVELOPMENT OF DIFFERENTIAL CTE BASED THERMAL SWITCH FOR SPACECRAFT APPLICATION

M. C. Gajjar
Mechanical Engineering Department, Institute of Technology, Nirma University, Ahmedabad, Gujarat, India

V. K. Malpani
Thermal Engineering Division, Space Application Centre ISRO, Ahmedabad, Gujarat, India

A. Verma
Optical Payload Mechanical Group, Space Application Centre ISRO, Ahmedabad, Gujarat, India

V. J. Lakhera
Mechanical Engineering Department, Institute of Technology, Nirma University, Ahmedabad, Gujarat, India

DOI: 10.1615/IHMTC-2017.2770
pages 1975-1979

Abstract

A thermal switch is used for the passive thermal management of a low earth orbit satellite where the operation time for spacecraft is less. It is used to control the temperature of electrical components within the working range temperature. It is inserted between the electrical component and an outer radiator. Presently a heat pipe is used for the same purpose but an additional heater is to be provided to prevent the temperature of the component from falling below the lower limit of working temperature range as the heat pipe does not have a switching facility so it will continue to transfer heat during the OFF condition of the component. Instead, if a thermal switch is used in place of a heat pipe, the requirement of an additional heater can be removed as it has very low OFF state conductance.
In this research paper, authors have designed and developed a new mechanically actuated thermal switch using the CTE (coefficient of thermal expansion) of the material as actuation mechanism. A prototype was built to demonstrate the principle of the operation. The performance test was conducted in the vacuum condition. The thermal performance of the prototype was observed to be 15.62 W/K as ON conductance and the ratio of ON conductance to OFF conductance was found to be 126.

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