• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2097-2101
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• 2007

This paper presents an optimal design of a micro evaporator which maximizes the heat transfer coefficient. Number of gaps, spanwise distance and streamwise distance are selected as the geometric design parameters. Mass flow rate of the refrigerant is selected as the non-geometric design parameter. Temperature at the surface of the heater is measured to valuate the heat transfer coefficient. Nine experiments are conducted using $L_9(3^4)$ orthogonal array. Maximum heat transfer coefficient is 640 W/$m^2K$ at the parameters of 2 gaps, 0.2 mm spanwise distance, 1.0 mm streamwise distance and 0.72 g/s mass flow rate. Among the 3 geometric parameters, the spanwise distance is the most sensitive parameter influencing the heat transfer coefficient. We conduct a second stage of experiment to increase the heat transfer coefficient by reselecting the mass flow rate. We concluded that 0.87 g/s is the optimized flow rate for an active micro cooler resulting in a heat transfer coefficient of 651 W/$m^2K$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.390-394
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• 2013

Observation satellites carrying high precision optical payload require extremely stringent pointing stability that may be violated in the presence of the disturbances corning from reaction wheels, cryocoolers or other actuating components onboard the satellite. The most common method to protect the sensitive payloads from external disturbances is implementation of vibration isolator. In this paper development of a single axis active vibration isolator using electromagnet and its performance in isolating micro-vibration is presented. The main components of the developed isolator are membrane structure providing the isolator with the required stiffness and an electromagnet for active control. The performance test results show that additional damping can be achieved by active control without degrading isolation performance in high frequency region and that the developed isolator can effectively isolate micro-vibration.