Summary

The proper functioning and reliability of electronic componentsdepend upon adequate thermal management since high temperature is the principal vector of failure in these devices. The growing complexityof current electronic component design associated with the everincreasing power consumption and the continuous scale reduction place thermal management of electronics as one of the most strategic challenges for technological innovation in heat transfer. Therefore, new concepts for high heat flux removal are required, such as mechanical vapor compression refrigeration, which is among the most promising active cooling technologies. This thesis presents a novel heat sink for thermal management of electronic devices. The cooler was designed to operate integrated with a compact vapor compression refrigeration system and combines the expansion device and the evaporator in a single cooling unit, thus producing a highly effective two-phase jet impingement cooling of the heated surface. An experimental apparatus was designed and built which operates with a small-scale oil-free linear compressor using R-134a as the working fluid. A purpose-built calorimeter was developed to measure the heat dissipation rate through the compressor shell, thus providing closure for the overall system energy balance. The thermal performance of both the jet impingement cooling module and the vapor compression refrigeration system were evaluated for a variety of operating conditions. In addition, a comprehensive thermodynamic analysis was performed using different performance metrics. Experiments have been carried out with single and multiple orifice configurations of the jet heat sink. The influence of the following parameters was quantified: (i) applied thermal load, (ii) orifice diameter, (iii) orificeto-heater distance, (iv) hot reservoir temperature and (v) compressor piston displacement. At operating conditions for which the system pressure ratio ranged from 1.4 to 2.2, the two-phase jet heat sink was capable of dissipating cooling capacities of up to 160 W and 200 W from a 6.4-cm2 surface for single and multiple orifice configurations,respectively, maintaining the temperature of the impingement surface lower than 40ºC with heat transfer coefficients ranging from around 14,000 to 16,000 W/(m2K).been carried out with single and multiple orifice configurations of the jet heat sink. The influence of the following parameters was quantified: (i) cooling capacity, (ii) orifice diameter, (iii) orifice-to-heater distance and (iv) compressor stroke. At operating conditions for which the system pressure ratio ranged from 1.4 to 2.2, the two-phase jet heat sink was capable of dissipating cooling capacities of up to 160 W and 200W from a 6.4-cm2 respectively, maintaining the temperature of the impingement surface lower than 40ºC with heat transfer coefficients ranging from around14,000 to 16,000 W/(m²K).

Material for download