Boiling heat transfer has a wide range of applications such as electronics cooling, thermal power generation, nuclear reactor vessel cooling, desalination, etc. High heat transfer coefficients can be achieved through boiling because of its ability to capitalize on latent heat transport. There is a significant need to enhance the boiling heat transfer coefficient and critical heat flux to meet future needs in thermal management. Researchers have studied various techniques such as surface structuring, surface wettability modification, and working fluid modification with additives to enhance the boiling heat transfer [1]. Surface structuring with microchannels or minichannels looks promising as it can enhance both critical heat flux and heat transfer coefficients compared to a flat surface. Liquid subcooling increases the critical heat flux by condensing the rising vapor bubbles in the pool and delays the vapor blanket formation and film boiling. However, with the increase in liquid subcooling, the heat transfer coefficient decreases due to the dominance of single-phase heat transfer. Minichannel surfaces can enhance the pool boiling heat transfer by improving the bubble nucleation and liquid resupply. Also, minichannels are relatively easier to fabricate and less expensive than microchannels. Therefore, there is a significant need to investigate the combined effects of liquid subcooling and minichannel surfaces on pool boiling heat transfer. The majority of the pool boiling studies with water are reported on microchannel surfaces at atmospheric pressure and saturated conditions [2,3]. A very few studies are reported on saturated pool boiling with water over minichannel surfaces [4].&nbsp; However, no studies reported on the combined effects of subcooling and minichannel surfaces, and the present work bridges that gap. In the present work, the pool boiling experiments are conducted on minichannel surfaces at atmospheric pressure with water as working fluid. The pool boiling experiments are being conducted for liquid subcooling of 0K (saturated), 5K, 10K, and 20K at atmospheric pressure. The pool boiling experiments are performed on minichannel surfaces with two different configurations. The minichannels having a square cross-section with a side length of 1mm and 2mm are milled on the copper surface. High-speed imaging is used to study the bubble dynamics on minichannel surfaces for different liquid subcoolings. The flat copper surface has a boiling area of 1 sq.cm, and the boiling area of minichannel surfaces is normalized with respect to the wetted area to ensure no area enhancement from the minichannels and neglect the fin efficiency effects. The thermal performance of the boiling surface is characterized by the critical heat flux and heat transfer coefficient. The critical heat flux and heat transfer coefficient of the copper minichannel surfaces are compared to the flat copper surface at different liquid subcoolings, and the detailed results will be reported.References:[1]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Liang, G., and Mudawar, I., 2019, “Review of Pool Boiling Enhancement by Surface Modification International Journal of Heat and Mass Transfer Review of Pool Boiling Enhancement by Surface Modification,” Int. J. Heat Mass Transf., 128(January), pp. 892–933.[2]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Jaikumar, A., and Kandlikar, S. G., 2015, “Enhanced Pool Boiling Heat Transfer Mechanisms for Selectively Sintered Open Microchannels,” Int. J. Heat Mass Transf., 88, pp. 652–661.[3]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Walunj, A., and Sathyabhama, A., 2018, “Comparative Study of Pool Boiling Heat Transfer from Various Microchannel Geometries,” Appl. Therm. Eng., 128, pp. 672–683.[4]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Gheitaghy, A. M., Samimi, A., and Saffari, H., 2017, “Surface Structuring with Inclined Minichannels for Pool Boiling Improvement,” Appl. Therm. Eng., 126, pp. 892–902.&nbsp;

Effect of Subcooling on Pool Boiling Heat Transfer Over Minichannel Surfaces of Subcooling on Pool Boiling Heat Transfer Over Minichannel Surfaces.

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.