Enhancement of nucleate boiling heat transfer by surface modification in a cold plate evaporator

R134a;surface modification;boiling;heat transfer;copper oxide;refrigerant;phase change;two-phase;structure;nanocoating;nanostructure;nano;roughness

Alexander, Gregory J. ; Hrnjak ; Pega

关键词: R134a;    surface modification;    boiling;    heat transfer;    copper oxide;    refrigerant;    phase change;    two-phase;    structure;    nanocoating;    nanostructure;    nano;    roughness;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/88096/ALEXANDER-THESIS-2015.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Electronics cooling applications have very high local heat fluxes, which allow for significant improvement of heat transfer by different methods. This thesis focuses on improving boiling heat transfer by surface modification with R134a in a microchannel cold plate evaporator. Internal copper and brass surfaces were modified with the deposition of copper oxide nanostructures with the intention of improving nucleate boiling heat transfer. The spike-like nanostructures increase the real internal surface area and thus allow for more efficient bubble nucleation. Heat transfer coefficients were calculated with both baseline and modified cold plates for varied heat and mass flux loadings to compare how effective the nanostructures are at improving heat transfer. Longevity of the coating in a working environment and any loss of effectiveness over time were explored. To better understand the differences caused by this surface modification, flow visualization was also considered.