Faculty Publications
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Item Boiling of saturated water on grooved surface(Serbian Society of Heat Transfer Engineers, 2019) Sathyabhama, A.The flow patterns and pool boiling heat transfer performance of rectangular grooved surface immersed in saturated water were experimentally investigated. The effect of the aspect ratio (groove depth/fin thickness) on boiling performance was examined. The test surfaces were manufactured on a copper block with a base diameter of 19 mm with four fin thickness (0.5 mm, 1mm, 1.5 mm and 2 mm) and three groove depths (1.0 mm, 2.0 mm and 3.0 mm). All experiments were performed in the saturated state at atmospheric pressure. A plain surface was used as the reference standard and compared with the grooved surfaces. The photographic images showed different boiling flow patterns among the test surfaces at various heat fluxes. The test results indicated that closer and more number of grooves yielded a greater flow resistance against the bubble/vapor lift-off along the groove wall. At higher heat flux, numerous vapor mushrooms periodically appeared from the perimeter of the grooves. The developed correlation for Nusselt number predicts the experimental data with MAE of 7.42%. © 2018 Serbian Society of Heat Transfer Engineers.Item Effect of RIBS/FINS and Aspect Ratio on Flow Boiling Characteristics in Conventional Channels(American Society of Mechanical Engineers (ASME), 2024) Madan, K.; Sathyabhama, A.In this work, experiments are conducted with conventional rectangular channels of two different aspect ratios (AR =w/d) for the horizontal boiling flow conditions at atmospheric pressure. Distilled water was used as the working substance. The heat transfer coefficients (HTC) were measured for mass fluxes and heat fluxes ranging from 85.94 kg/m2-s to 343.77 kg/m2-s and 10 kW/m2 to 100 kW/m2, respectively, and at inlet subcooled temperatures of 303 K, 313 K, and 323 K. Visualization of the boiling phenomenon was done using a high-speed camera for the two channels under similar conditions. The results show that the AR has a dominant effect on the HTC. At low heat flux values, higher HTC was noticed for the channel of higher AR (AR=1.25) whereas, at high heat flux conditions, the HTC is higher for the channel of lower AR (AR =0.2). With an increase in inlet subcooled temperature, the HTC decreased for both channels due to increased thermal boundary layer thickness and reduced bubble formation. Further, the channel of AR=1.25 with ribs/fins performed better than the smooth channel due to the high bubble nucleation rate. © 2023 by ASME.