Faculty Publications
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Item Effect of surface vibration on boiling heat transfer froma copper flat circular disc(Begell House Inc. orders@begellhouse.com, 2016) Sathyabhama, A.; Pandiyan, P.S.This paper presents the experimental investigation of the effect of surface vibration on pool boiling heat transfer from a copper flat circular surface immersed in saturated water at atmospheric pressure. The forced vertical vibrations were induced on this copper test surface with the help of a mechanical vibrator. The frequency was varied in the range 0-25 Hz and the amplitude of vibration was varied in the range 0-5 mm. The results indicate that the heat transfer coefficient increases at low frequency and amplitudes; at higher amplitude and frequency, heat transfer deteriorates in the investigated range. Rohsenow-type correlation was developed, which predicts the present experimental data with an average absolute error of 30%. © 2018 by Begell House, Inc.Item Effect of boiling surface vibration on heat transfer(Springer Verlag service@springer.de, 2017) Sathyabhama, A.Experimental investigation of effect of forced vertical surface vibration on nucleate pool boiling heat transfer of saturated water at atmospheric pressure is presented in this paper. Vertical vibration was induced externally to the circular copper test surface on which boiling took place, using a vibration exciter. Frequency was varied in the range 0–25 Hz and amplitude of vibration was varied in the range 0–5 mm. Boiling takes place at much lower superheats for the same heat flux, slope of boiling curve decreases remarkably, when the surface is given external excitation. High frequency and high amplitude oscillations lead to more intensive heat transfer. There are some combinations of frequency and vibration amplitude, which cause up to two times increase in heat transfer coefficients. © 2016, Springer-Verlag Berlin Heidelberg.Item Enhancement of Boiling Heat Transfer Using Surface Vibration(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2017) Sathyabhama, A.; Pandiyan, S.P.An experimental investigation of the effect of mechanical vibrations of a copper flat circular surface on the pool boiling heat transfer coefficient of water at atmospheric pressure are presented in this paper. A vibration exciter was used to vibrate this copper test surface vertically. Effect of frequency and amplitude of vibration on the boiling heat transfer coefficient was studied. An increase in the heat transfer coefficient was observed at low frequency and amplitudes, at higher amplitude and frequency heat transfer deteriorates. Heat transfer coefficient increases up to 26% with vibration intensity, represented by vibrational Reynolds number. © 2015 Wiley Periodicals, Inc.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 Experimental and numerical investigation of pool boiling heat transfer from finned surfaces(Elsevier Ltd, 2023) Jaswal, R.; Sathyabhama, A.; Singh, K.; Yandapalli, A.V.V.R.P.An experimental study of the pool boiling process on three test surfaces, namely, Plain surface, Rectangular finned surface, and Trapezoidal finned surface, was carried out using distilled water as the working fluid at atmospheric pressure. A parametric study of finned surfaces was performed to understand the effect of fin spacing and fin height on the pool boiling performance. A high-speed camera was employed to capture the pool boiling process. A numerical investigation was also performed using the Eulerian multiphase model associated with the RPI wall boiling model. A 2-D rectangular boiling chamber filled with distilled water was considered for the numerical study. The numerical results with default models were validated with the experimental results. A correction was proposed for the Bubble Waiting Time coefficient (Cw) of the quenching heat flux to improve the numerical results. Experimental results showed that using rectangular and trapezoidal finned surfaces improved the heat flux values by 52.3% and 101.5%, respectively, compared to the plain surface. The heat transfer coefficient (HTC) depends upon the area availability and type of boiling surface used. Increasing the height of the fins was beneficial, whereas increasing the fin spacing adversely affected the fin performance. © 2023 Elsevier LtdItem 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.