CAREER: Vapor-Liquid Separation for Sustainable Condensation Heat Transfer

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Improving the performance of condensation heat transfer reduces size, weight, and cost in refrigeration, air conditioning, heat exchangers, and thermal management systems. To achieve a large heat transfer coefficient, condensates on a surface must be rapidly removed to provide liquid-free areas for vapor-liquid phase change to occur. The ideal surface is one that provides a large heat transfer area and rapidly removes condensates for sustainable condensation. Present challenges include the removal of ultralow surface tension refrigerants and the lack of long-term durability of engineered surfaces. The goal of this CAREER project is to address those challenges by developing a vapor-liquid separation process to advance condensation heat transfer of ultralow surface tension fluids, and integrate the new knowledge into education to train the next generation of heat transfer leaders.The objective of this project is to achieve: (1) dropwise condensation of ultralow surface tension fluids (e.g., R134a), and (2) sustainable vapor-liquid separation that provides large liquid-free areas for rapid condensation. The proposed approach will use the newly developed durable quasi-liquid surface to achieve dropwise condensation and rapid removal of ultralow surface tension condensates. The super slippery quasi-liquid surface will prevent the dropwise to filmwise transition. To achieve a high heat transfer performance, the vapor and liquid will be separated on a slippery rough surface with quasi-liquid lubrication which will provide a large surface area for condensation. X-ray nano-imaging will be used to investigate the nucleation and liquid removal inside microstructures of the slippery rough surfaces. The surface durability and sustainable condensation performance of quasi-liquid lubricated microstructures will be studied under various subcooling and shear stress conditions. The preliminary results in heat transfer and materials fabrication provide a solid foundation to execute those activities. The proposed project is in line with the PI’s long-term career goal to address heat transfer challenges by incorporating learning from multidisciplinary areas.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.