Begell House Inc.
Heat Transfer Research
HTR
1064-2285
48
9
2017
NATURAL CONVECTION IN NANOFLUID-FILLED SQUARE CHAMBERS SUBJECTED TO LINEAR HEATING ON BOTH SIDES: A NUMERICAL STUDY
771-785
Mostafa
Mahmoodi
Department of Mechanical Engineering, Amirkabir University of Technology, Tehran 15875-4413,
Iran; Department of Mechanical Engineering, University of Kashan, Kashan 87317-53153, Iran
Ali Akbar Abbasian
Arani
Department of Mechanical Engineering, University of Kashan, Kashan 87317-53153, Iran
S. Mazrouei
Sebdani
Department of Mechanical Engineering, University of Kashan, Kashan 87317-53153, Iran
P.
Tajik
Department of Mechanical Engineering, Amirkabir University of Technology, Tehran 15875-4413,
Iran
Buoyancy-driven heat transfer in two-dimensional nanofluid-filled square enclosures with linear temperature profile on the side walls and adiabatic horizontal walls is studied numerically. Numerical simulations are performed for Rayleigh numbers ranging from 103 to 106, the volume fraction of the nanoparticles ranging from 0 to 0.06, and for three different combinations of the temperature distribution on the side walls. The results are presented in terms of streamlines and isotherms inside the cavities, local Nusselt number along the left wall, and average Nusselt number of the hot portions of the side walls. The results show that the flow and temperature fields inside the cavity vary significantly when the temperature profile on the side walls of the cavities is changed. At Ra = 103 the flow intensity is shown to decrease with increasing volume fraction of the nanoparticles, while at Ra = 106 it is not the case. The values of the maximum and minimum local Nusselt number at the ends of the left wall are shown to increase with increasing Rayleigh number and volume fraction of the nanoparticles. Moreover, along the both heating and cooling portions of the left wall, the increase in the volume fraction of the nanoparticles enhances the rate of heat transfer.
KINETICS OF FENUGREEK DRYING IN AN INDIRECT SOLAR DRYER
787-797
vipin
shrivastava
Lakshmi Narain College of Technology, RGPV
Anil
Kumar
Energy Technology Research Center, Department of Mechanical Engineering, Faculty
of Engineering, Prince of Songkla University Hat Yai, Songkhla, 90110, Thailand
Prashant
Baredar
Department of Energy, Maulana Azad National Institute of Technology (MANIT), Bhopal,
462003, India
In this paper, kinetics of fenugreek drying on different trays of an indirect solar dryer was examined so as to increase its shelf life. For this purpose, a thin layer of 2 kg of fenugreek was placed on three different trays of dimensions 0.7 m × 0.7 m, to be further dried until there is no variation in its mass. The drying rate is fitted in different models available in the literature and the best model is obtained by comparing the values of the diffusion coefficient, root means square error, and the sum of square due to error. The diffusion coefficient of fenugreek on different trays was also investigated and found in the range of 2.422 × 10-8 m2/s to 3.872 × 10-8 m2/s. An average efficiency of the dryer in peak hours on the first and second days of drying was 38.63% and 7.56%, respectively.
STAGNATION-POINT FLOW AND HEAT TRANSFER OVER A HYPERBOLIC STRETCHING SHEET
799-810
Tariq
Javed
Department of Mathematics and Statistics, International Islamic University, Islamabad 44000, Pakistan
Irfan
Mustafa
Department of Mathematics and Statistics, FBAS, International Islamic University, Islamabad
44000, Pakistan
In this study, steady two-dimensional boundary-layer stagnation-point flow of viscous incompressible fluid over a hyperbolic stretching sheet and heat transfer in it have been investigated. The governing equations of the flow problem are transformed into dimensionless partial differential equations using nondimensional variables. A numerical solution of the obtained partial differential equations is done by using an implicit finite difference scheme known as the Keller-Box method.
The effects of the velocity ratio parameter a/c and the Prandtl number Pr on the velocity profile, temperature profile, local skin friction coefficient, and the local Nusselt number have been studied and shown graphically. It is observed that the heat transfer rate increases rapidly in the presence of the velocity ratio parameter a/c as compared to the absence of the velocity ratio parameter.
MASS BALANCE IN LATTICE BOLTZMANN METHOD WITH DIRICHLET VELOCITY BOUNDARY CONDITION
811-826
Zheng
Li
College of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;
Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211, USA
mo
yang
university of shanghai for science and technology
Ya-Ling
He
Key Laboratory of Thermo-fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
Yuwen
Zhang
University of Missouri, Columbia, MO 65201, USA
Many different methods can be used to treat open boundary conditions in the lattice Boltzmann method. The Zou–He method, finite difference velocity gradient method, and regularized method are reviewed and compared for the Dirichlet velocity condition for Poiseuille flow with different Reynolds numbers. Using the same convergence criterion, all the numerical procedures are carried on until steady states are reached. The obtained velocities and pressures are checked and compared with analytical solutions and mass balances for different methods. The results indicate that all the numerical data agreed well with the analytical solutions and the Zou–He method results satisfy the mass balance better than the others.
NUMERICAL SIMULATION OF A BELLOWS-TYPE RECIPROCATING MECHANISM-DRIVEN HEAT LOOP (RMDHL)
827-848
Olubunmi T.
Popoola
Department of Mechanical and Materials Engineering, Florida International University, Miami, Florida 33174, USA
Soheil
Soleimani
Department of Mechanical and Materials Engineering, Florida International University, Miami,
Florida 33174, USA
Yiding
Cao
Department of Mechanical and Materials Engineering, Florida International University,
Miami, Florida 33174
A bellows-type Reciprocating Mechanism-Driven Heat Loop (RMDHL) could attain a high heat transfer rate through
reciprocating flow of the working fluid inside a heat transfer device while maintaining substantial temperature uniformity over its evaporator section. The objective of this paper is to numerically simulate a bellows-type RMDHL to predict its operational performance under different working conditions as well as a conventional dynamic pump-driven heat loop (DPDHL) as a benchmark for comparison. The numerical results are also compared with relevant experimental data with good agreement. The results indicate that the bellows-type RMDHL can meaningfully reduce the peak temperature of an electronic device and result in a significantly more uniform temperature across the electronic device. Considering the advantage of coolant leakage free for electronics-related applications, the single-phase bellows-type RMDHL could be an alternative to a conventional Liquid Cooling System (LCS) for electronic cooling applications.
MIXED CONVECTION HEAT TRANSFER OF NON-NEWTONIAN CARREAU–YASUDA FLUID DRIVEN BY POWER LAW TEMPERATURE GRADIENT
849-864
Jinhu
Zhao
School of Mathematics and Statistics, Fuyang Normal College, Fuyang 236037, Anhui, China
Liancun
Zheng
School of Mathematics and Physics, University of Science and Technology Beĳing, Beĳing 100083,
China
Xinxin
Zhang
School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Energy Saving and Emission Reduction for Metallurgical Industry, University of Science and Technology Beijing, Beijing 100083, China
Mixed convection heat transfer of non-Newtonian fluid in a square cavity is studied. The Carreau–Yasuda model is introduced to characterize the viscosity constitutive relation the modified Fourier's law is used in the energy equation. Numerical cases are performed using the finite volume method with the SIMPLE algorithm. The effects of Carreau–Yasuda parameters, namely, the power law indices n and a (the width of the transition region between zero shear rate viscosity and the power law region), and temperature power law index m on velocity and temperature fields are analyzed. The results obtained indicate that with augmentation of n, the pressure drop decreases almost linearly firstly and then rises, while the Nusselt number increases. Moreover, with augmentation of m, the pressure drop increases and the Nusselt number decreases.