Research

We design the thermal system having compactness and light-weight features working in widely varying environmental conditions. The thermal system is optimized through advanced thermodynamic analysis for its best performance and efficiency: minimizing energy consumption or maximizing power generation. Applications include thermal control system for future space craft, solar organic Rankine cycle(ORC), and waste heat recovery power cycle.

We investigate into the transport phenomena of flow boiling in micro-channel heat sinks in two-phase cooling and refrigeration loops. The relation between two-phase flow and its heat transfer mechanisms in micro-channel heat sinks has not been fully understood by its complex characteristics those appear as several phenomena are coupled together such as instability induced periodic flows, flow oscillations and following dry out, and heat transfer dependence on transient flow patterns. Flow visualization techniques; high-speed imaging, IR-thermography, and stereo PIV, and accurate measurement techniques have been employed for experimental verification in conjunction with theoretical and computational endeavors. Results can be applied to cooling of electric vehicle(EV), battery and electronics, and avionics.

We have been delving into the fundamentals of flow instabilities in two-phase thermal systems and their impacts on the thermal systems as they influence to the system safety, reliability and lifespan. Flow instabilities are largely categorized into static and dynamic instabilities, and they include Ledinegg, parallel channel instability, density wave instability, and pressure drop oscillation, respectively. Identifying various types of instabilities in the thermal systems and unveiling its nature and impact on heat transfer mechanisms are our primary research interests. Instabilities are commonly observed in micro-channel heat sinks, nuclear reactor cooling loop, and natural circulation loop, and prediction and suppression of instability are considered as important design factors.