Department of Mechanical engineering
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Item Experimental Investigation of Pool BHT Performance of R-141b on Micro/Nano-Porous Copper Coating Prepared by a Two-stage Electrodeposition Method(IEI Conferences, 2021) Belgamwar, Sachin U.Pool boiling heat transfer (BHT) of R-141b on po-rous Cu coated heating surface was experimentally studied. Porous Cu coating was fabricated on a plain Cu heating sur-face through a two-stage electrodeposition method. Surface characterization of Cu coating confirmed the successful syn-thesis of micro/nano-porous Cu coating. Experimental re-sults showed that the Cu coated heating surface introduced a significant enhancement in heat transfer coefficient (HTC) and a great reduction in wall superheat compared to the plain Cu surface. The maximum enhancement in HTC for the Cu coated heating surface was approximately 53% compared to the uncoated heating surface. This is believed to have re-sulted from the increase in active surface area, nucleation site density and cavitation activity owing to the microporous structure of Cu coating. Obtained results showed that the mi-croporous Cu coated heating surface could be employed in modern heat transfer applications.Item Fabrication of Cu@G composite coatings and their pool boiling performance with R-134a and R-1234yf(Taylor & Francis, 2022-01) Belgamwar, Sachin U.The present work explores the pool-boiling performance of refrigerants (R-134 and R-1234yf) on the plain Cu and graphene nanoplatelets (G) reinforced Cu matrix (Cu@G) composite coated heating surface. A two-step electrodeposition technique was employed to prepare microporous Cu@G composite coatings. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) studies confirmed the successful fabrication of microporous structure of Cu@G composite coatings. Surface profilometer investigation was done to know the surface roughness of prepared Cu@G composite coatings. Pool boiling experiments were carried out with increasing heat flux from 8.80 kW/m2 to 61.25 kW/m2 at a saturation temperature of 10°C. Test results of R-134 and R-1234yf were compared. The experimental results revealed that the heat transfer coefficients (HTCs) of R-134a were higher than R-1234yf for plain Cu and Cu@G composite coated heating surfaces.Item Experimental investigation of pool boiling heat transfer performance of refrigerant R-134a on differently roughened copper surfaces(Elsevier, 2021) Belgamwar, Sachin U.Pool boiling heat transfer of refrigerant R-134a at saturation temperature of 5 °C was investigated experimentally on copper. The effect of surface roughness was studied at various average roughness (Ra) values ranging from 0.130 to 0.274 µm. All experimental samples were vertically oriented, and experiments were carried out at varying heat flux ranges between 10 and 70 kW/m2. The investigations are carried out to calculate the boiling heat transfer coefficient (h), wall superheat (ΔT) and heat flux (q) for different roughness of heat transfer surfaces. The obtained results revealed that the Cu surface with Ra = 0.274 µm showed outstanding heat transfer performance compared to other Cu surfaces. The overall boiling performances enhanced with an increase in roughness value of the heat transfer surface owing to the increased number of cavities.