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We have previously reported on the development of a novel active heat sink (AHS) for high-power electronic components offering unparalleled capacity in high-heat flux handling and temperature control. AHS employs convective heat transfer in a working fluid circulating in a miniature closed and sealed flow loop. High flow velocity, good flow attachment, and relatively high thermal conductivity of working fluid lead to ultra-low thermal resistance around 0.1 deg C/W. AHS appears very suitable for directly interfacing a hybrid electric vehicle (HEV) inverter to engine coolant loop. Alternatively, AHS may be used to interface inverter electronics to an air-cooled heat exchanger. As a result, the traditional dedicated liquid coolant loop for thermal management of the inverter can be eliminated, the inverter subsystem can be greatly simplified, and the power train electronics made much more compact. Our previous work focused on AHS with working fluids based on liquid metals.

We report on the development of a novel active heat sink (AHS) for cooling of high-power electronic chips in inverters for hybrid electric vehicles (HEV) and plug-in HEV (PHEV). AHS employs convective heat transfer in liquid metal circulating in a miniature closed and sealed flow loop. The liquid metal removes high-flux waste heat from the chips and transfers it at a much reduced flux to engine coolant. Alternatively, AHS may be used to interface inverter electronics to an air-cooled heat exchanger (HEX). As a result, the presently used dedicated liquid coolant loop for thermal management of the inverter can be eliminated and the inverter sub-system can be greatly simplified. High flow velocity, good flow attachment, and relatively high thermal conductivity of liquid metal offer ultra-high heat transfer rates. Liquid metal flow can be maintained electromagnetically without any moving parts. Depending on the configuration, AHS thermal resistance can be around 0.1°C/W.

This paper reports an active heat sink (AHS) that allows high-density electronic components to operate at a stable temperature over a broad range of ambient conditions. AHS receives heat at high flux and transfers it at reduced flux to environment, coolant fluid (e.g., air or engine coolant), or structures. Temperature of the heat load can be controlled electronically. Target applications for AHS include thermal management of the new class of high-power electronics being developed for electric hybrid vehicles. AHS also enables precise control over junction temperature (and, thus, light color) of high-power light-emitting diodes (LED) used for solid-state headlights and allows for compact air-cooled heat sinks. Depending on the configuration, AHS thermal resistance can be as low as 0.1 degC/W. AHS physics, engineering design, and performance simulations are presented.

There is a need for an automotive engine cooling system capable of handling increased heat load while, at the same time, having reduced size and weight. This paper evaluates a concept for an engine cooling system with a passive heat accumulator that averages out peak heat loads. Heat load averaging permits relaxation of the cooling system requirements and allows substantial reduction of system size and weight. This also translates to a smaller coolant inventory allowing for faster engine warm-up and reduced emissions of harmful pollutants during a cold engine start.

The current trend to downsize automotive engines calls for engine performance recovery via torque enhancement techniques, such as hybrid drive or supercharging. Traditional supercharging techniques using mechanical chargers or turbochargers are costly and have a limited time response [1]. This study investigates a fluid-dynamic supercharger (FDS) operated by compressed air which provides momentary supercharging during increased torque demand. FDS offers precise, computer-controlled boost of up to 11 psi (75 kPa) with instant response to demand. Compressed air for FDS operation can be generated using recovery of kinetic energy during vehicle deceleration. FDS is compact, simple, economical, and it does not require an intercooler. Simulations show that even with a down-sized engine, an FDS-equipped automotive vehicle would be “fun-to-drive.”