Faculty Publications
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Item Numerical Analyses of Single-Phase Pressure Drop and Forced Convective Heat Transfer Coefficient of Water–Ethanol Mixture: An Application in Cooling of HEV Battery Module(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2016) Suhas, B.G.; Sathyabhama, A.The present numerical analyses are related to the cooling of a hybrid electric vehicle (HEV) battery module by water–ethanol mixture. The fluid is passed through a cold plate consisting of two rectangular channels of 0.01 m depth, 0.015 m width, and 0.15 m length. The battery module is represented by a heater placed below the cold plate. The single-phase pressure drop and single-phase heat transfer coefficient for water, water–ethanol mixture of mass fraction of 25%, 50%, and 75%, and ethanol are determined numerically for different heat fluxes of 10, 15, 20, and 25 kW/m2 and different Reynolds numbers 500, 1000, 1500, 2000, and 2500. To solve the Navier–Stokes equation, the pressure correction method was used and to solve the energy equation, the Lax–Wendroff explicit method is used. Numerical results obtained for water are compared with the literature correlations. The friction factor for water deviated by an average of 8.02% from the Lewis and Robertson equation. The Nusselt number for water deviated by 7.35% from the Churchill and Ozoe equation at lower Reynolds number 500 and at higher Reynolds number 2500, Nusselt number deviated by 13.68% from the Stephan equation. The results showed that the heat transfer coefficient increased with an increase in Reynolds number and heat flux. The effect of the increase in Reynolds number is more significant than the increase in heat flux. At higher ethanol mass fraction and higher Reynolds number the heat transfer coefficient increased with heat flux when compared to water. There is no significant decrease in heat transfer coefficient with an increase in ethanol mass fraction. The pressure drop increased and the heat transfer coefficient decreased with an increase in ethanol mass fraction. © 2015 Wiley Periodicals, Inc.Item Experimental investigation of heat transfer coefficient and correlation development for subcooled flow boiling of water-ethanol mixture in conventional channel(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2017) Suhas, B.G.In this present work, bubble dynamics of subcooled ?ow boiling in water-ethanol mixture is investigated through visualization using a high-speed camera in horizontal rectangular channels. The heat transfer coef?cient of water-ethanol mixture during subcooled ?ow boiling is determined for various parameters like heat ?ux, mass ?ux, and channel inlet temperature. The effect of bubble departure diameter on heat transfer coef?cient is discussed. A correlation is developed for subcooled ?ow boiling Nusselt number of water-ethanol mixture. The parameters considered for correlation are grouped as dimensionless numbers by Buckingham p-theorem. The present correlation is compared with the experimental data. The mean absolute error (MAE) of Nusselt number of water-ethanol mixture calculated from the experimental data and those predicted from the present correlation is 10.39%. The present correlation is also compared with the available literature correlations developed for water. The MAE of Nusselt number of water predicted from the present correlation and those predicted with Papel, Badiuzzaman, Moles-Shaw, and Baburajan correlations is 41%, 19.61%, 29.9%, and 43.1%, respectively. © 2017 by ASM.Item Heat transfer and force balance approaches in bubble dynamic study during subcooled flow boiling of water–ethanol mixture(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2018) Suhas, B.G.; Sathyabhama, A.In this paper, the subcooled flow boiling heat transfer coefficient of pure water, water–ethanol mixture and pure ethanol is determined experimentally in horizontal rectangular channels for various parameters like heat flux, mass flux and channel inlet temperatures. Flow visualization is carried out using high speed camera. The bubble departure diameter, growth period and waiting period of bubbles are determined. Correlations are developed for subcooled flow boiling Nusselt number of water–ethanol mixture based on force balance approach and heat transfer approach. The parameters considered for correlation are grouped as dimensionless numbers by Buckingham ?-theorem. The significance of each dimensionless number on heat transfer coefficient is discussed. The correlations developed for subcooled flow boiling heat transfer coefficient are validated with the experimental data. They are found to be in good agreement with the experimental data. It is found that the correlation based on force balance approach predicts the subcooled flow boiling Nusselt number well when compared with that of heat transfer approach correlation. © 2017 Taylor & Francis.Item Experimental study on forced convective and subcooled flow boiling heat transfer coefficient of water-ethanol mixtures: an application in cooling of heat dissipative devices(Springer Verlag service@springer.de, 2018) Suhas, B.G.; Sathyabhama, A.The experimental study is carried out to determine forced convective and subcooled flow boiling heat transfer coefficient in conventional rectangular channels. The fluid is passed through rectangular channels of 0.01 m depth, 0.01 m width, and 0.15 m length. The parameters varied are heat flux, mass flux, inlet temperature and volume fraction of ethanol. Forced convective heat transfer coefficient increases with increase in heat flux and mass flux, but effect of mass flux is less significant. Subcooled flow boiling heat transfer increases with increase in heat flux and mass flux, but the effect of heat flux is dominant. During the subcooled flow boiling region, the effect of mass flux will not influence the heat transfer. The strong Marangoni effect will increase the heat transfer coeffient for mixture with 25% ethanol volume fraction. The results obtained for subcooled flow boiling heat transfer coefficient of water are compared with available literature correlations. It is found that Liu-Winterton equation predicts the experimental results better when compared with that of other literature correlations. An empirical correlation for subcooled flow boiling heat transfer coefficient as a function of mixture wall super heat, mass flux, volume fractions and inlet temperature is developed from the experimental results. © 2017, Springer-Verlag GmbH Germany.