Continued development of highly compact and powerful electronic componentshas led to the need for a simple and effective method for controlling the thermalcharacteristics of these devices. One proposed method for thermal control involvesthe use of a micro heat pipe system containing a working fluid with physical propertieshaving been speciffcally selected such that the heat pipes, as a whole, vary in effectivethermal conductance, thereby providing a level of temperature regulation. To furtherexplore this possibility, a design scenario with appropriate constraints was establishedand a model developed to solve for the effective thermal conductance of individualheat pipes as a function of evaporator-end temperature. From the results of thisanalysis, several working fluids were identified and selected from a list over thirteenhundred that were initially analyzed. Next, a thermal circuit model was developedthat translated the individual heat pipe operating characteristics into the system as awhole to determine the system level effects. It was found that none of the prospectivefluids could completely satisfy the established design requirements to regulate thedevice temperature over the entire range of operating conditions. This failure tofully satisfy design requirements was due, in large part, to the highly constrainednature of problem definition. Several fluids, however, did provide for an improvedlevel of thermal control when compared to the unmodified design. Suggestions for improvements that may lead to enhanced levels of thermal control are offered as wellas areas that are in need of further research.
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