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Odelu Ojjela^*, N. Naresh Kumar
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-12, 2014, DOI:10.5098/hmt.5.22
Abstract This article deals the Hall and ion slip currents on free convection flow, heat and mass transfer of an electrically conducting couple stress fluid through porous channels with chemical reaction, Soret and Dufour effects. Assume that there is symmetric suction or injection along the expanding or contracting walls, which are maintained at different constant temperatures and concentrations. The governing partial differential equations are reduced to nonlinear dimensionless ordinary differential equations using the similarity transformations and solved numerically by the method of quasilinearization. The effects of various parameters on non-dimensional velocity components, temperature distribution and concentration More >

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Suripeddi Srinivas^a , Akshay Gupta^b,*, Ashish Kumar Kandoi^b
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-12, 2014, DOI:10.5098/hmt.5.21
Abstract The present work deals with the flow and thermal analysis of nanofluid in the wavy channels. The governing flow equations are solved numerically using CFD package assuming single phase approach. To study the effect of the concentration and size variation of the nanoparticle, the concentration and size are varied from 0% - 5% and 25 nm - 100 nm respectively over the Reynolds number range of 250-1500 for Au-water nanofluid. The effect on heat transfer enhancement because of corrugation of wavy channel is analyzed on four different shapes (sinusoidal, triangular, trapezoidal and square) channels. The More >

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Edoardo Gino Macchi^* , Giovanni Braschi, Mario Gallati
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-8, 2014, DOI:10.5098/hmt.5.20
Abstract Radiofrequency thermal ablation (RFTA) is a medical procedure currently widely adopted for liver tumors treatment. Its outcome is strongly influenced by temperature distribution near the RF applicator therefore continuous measurements are required both to validate RFTA numerical models and to better control the outcome of the procedure. The space-time evolution of the thermal field during RFTA on ex vivo porcine liver tissue has been measured by infrared thermal imaging in different experimental setups. A three-dimensional simulation of the whole experiment reproduces all the features of the thermal field measurements and validates the proposed measurement methodology. More >

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Amnart Boonloi^a, Withada Jedasadaratanachai^b,*
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-15, 2014, DOI:10.5098/hmt.5.19
Abstract 3D numerical investigations for heat transfer characteristics and flow configurations in a fin–and-oval-tube heat exchanger with V-tip pointing downstream delta winglet pairs (DDWP) are examined. The DDWPs are placed on the fin surface with pointing downstream and the oval tube row number is set at three in a staggered arrangement. The flow attack angles (θ = 15°, 30°, 45° and 60°) and the distance from V-tip to the oval tube center in transverse axis (a = 3.77, 4.77 and 5.77 mm) are investigated for Reynolds number based on hydraulic diameter, Re = 500 – 2500. The numerical results… More >

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Zan Wu^a, Zhaozan Feng^b, Bengt Sundén^a,*, Lars Wadsö^c
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-10, 2014, DOI:10.5098/hmt.5.18
Abstract Thermal conductivity and rheology behavior of two aqueous nanofluids, i.e., alumina and multi-walled carbon nanotube (MWCNT) nanofluids, were experimentally investigated and compared with previous analytical models. Information about the possible agglomeration size and interfacial thermal resistance in the nanofluids were obtained and partially validated. By incorporating the effects of interfacial thermal resistance, a revised model was found to accurately reproduce the experimental data based on the agglomeration size extracted from the rheology analysis. In addition, the thermal conductivity change of the alumina/water nanofluid with elapsed time was investigated. Thermal conductivity measurements were also conducted for More >

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Tomoki Hirokawa^a,*, Masahiko Murozono^a, Oleg Kabov^b,c, Haruhiko Ohta^a
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-8, 2014, DOI:10.5098/hmt.5.17
Abstract Experiments are performed to study the liquid film behavior and corresponding local heat transfer to shear-driven liquid film flow of water in the cocurrent nitrogen gas flow. The heated channel has a cross section of 30mm in width and 5mm in height, where the bottom is operated as a heating surface of 30mm in width and 100mm in length. The heated section is divided into segments to evaluate the local heat transfer coefficients. Under most gas Reynolds numbers, the local heat transfer coefficients are increased with increasing heat flux, where three mechanisms are important; (i) More >

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Junjie Chen^*, Longfei Yan, Wenya Song
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-6, 2014, DOI:10.5098/hmt.5.16
Abstract To understand the effect of different thermal conductivities on catalytic combustion characteristics, effect of thermal conductivity on micro-combustion characteristics of hydrogen-air mixtures in Pt/γ-Al₂O₃ catalytic micro-combustors were investigated numerically with detailed chemical kinetics mechanisms. Three kinds of wall materials (100, 7.5, and 0.5 W/m·K) were selected to investigate the effect of heat conduction on the catalytic combustion. The simulation results indicate that the catalytic reaction restrains the gas phase reaction in Pt/γ-Al₂O₃ catalytic micro-combustors. The gas phase reaction restrained by Pt/γ-Al₂O₃ catalysts is sensitive to thermal boundary condition at the wall. For most conditions, the gas phase More >

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Tapas Ray Mahapatra^a, Sumanta Sidui^b, Samir Kumar Nandy^c,*
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-15, 2014, DOI:10.5098/hmt.5.15
Abstract The effect of variable transverse magnetic field on steady two-dimensional indirect natural convection flow of an incompressible viscous fluid over a horizontal hot flat plate is theoretically studied. The governing partial differential equations are transformed into ordinary ones by similarity transformation and solved numerically using fourth order Runge-Kutta method with shooting technique. The results are obtained for the skin friction coefficient and the local Nusselt number as well as the dimensionless velocities, temperature for some values of the magnetic parameter (M) subject to either prescribed (constant or variable) surface temperature or prescribed (variable) heat flux. More >

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Anand Shukla^a, Alok Chaube^b, Shailesh Guptac^†, Arvind Sirsath^c
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-8, 2014, DOI:10.5098/hmt.5.14
Abstract One of the traditional methods used to improve the efficiency of a gas turbine is to increases the inlet temperature; thereby increasing the power output and in turn, the efficiency. The internal cooling passages of blades are roughened by artificial roughness to improve the cooling performance. The present study investigates the convective heat transfer and friction factor (pressure drop) characteristics of a rib-roughened square duct. The test section of the duct is roughened on its top and bottom wall with V and ᴧ- shaped square ribs. In the study, the Reynolds number (Re) varied from 10,000… More >

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Benjamin Lepers^a,*, Aditya Putranto^b,c, Martin Umminger^d, Guido Link^a, John Jelonnek^a
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-11, 2014, DOI:10.5098/hmt.5.13
Abstract The use of high power microwaves to perform explosive spalling of surface concrete is a promising technique with applications in the area of concrete facilities decommissioning. The mechanism that creates explosive spalling is an interactive process of the thermal stress from high temperature gradients and the pore pressure generated from the water vaporization. In order to better predict the total stress distribution, the temperature has to be calculated by including the effect of water vaporization and water transport through a porous medium. In this paper, a one dimensional model solving the heat and diffusion equation More >

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Manoj Kr. Triveni^* , Dipak Sen, RajSekhar Panua
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-8, 2014, DOI:10.5098/hmt.5.12
Abstract A numerical investigation has been performed for heat transfer analysis in a right-angled triangular enclosure filled with water. The side wall of the enclosure is maintained at high temperature compare to the base wall while hypotenuse is kept thermally insulated. Two - dimensional steady-state continuity, momentum and energy equations along with the boussinesq approximation are solved by finite volume method using commercial available software, FLUENT 6.3. The computational results are shown in terms of isotherms, streamlines and velocity contour for Rayleigh number (10⁵ ≤ Ra ≤ 10⁷ ). The heat transfer is presented in terms of More >

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K. Kaladhar^a , D. Srinivasacharya^b
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-6, 2014, DOI:10.5098/hmt.5.11
Abstract The effect of heat and mass stratification on mixed convection along a vertical plate embedded in a couple stress fluid has been presented. The nonlinear system of equations with appropriate boundary conditions is primarily reduced to non-dimensional form by pseudo-similarity transformations. Keller-box implicit finite difference scheme is employed to solve the resultant system of dimensionless equations. The validation of this scheme is shown through the comparison between the present and available literature under special case of the present problem. The couple stress parameter, mixed convection parameter and the double stratification parameter effects on the rates More >

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Biswajit De^*, Rajsekhar Panua
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-4, 2014, DOI:10.5098/hmt.5.10
Abstract As the world is facing crisis due to the dwindling resources of fossil fuels, rapid depletion of conventional energy is a matter of serious concern for the mankind. So there is a necessity to find alternate fuels. Vegetable oils, because of their agricultural origin, due to less carbon content compared to mineral diesel are producing less CO₂ emissions to the atmosphere is used as an alternate fuel in substitute to diesel fuel. In the present study optimum compression ratio for VCR diesel engine fuelled with Jatropha oil blends with diesel (30%) has been determined at 203 More >

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B. Barthelemy^1,2, J. Beam¹, W. Borger^1,3, M. Braydich^1,4, L. Chow^5,*, B. Donovan⁶, A. Faghri⁷, A. Garscadden¹, D. Jacobson⁸, E. Kennel^1,9, J. Leland^1,10,*, Q. Leland⁶, R. Ponnappan^1,11, M. Ramalingam¹², T. Reitz⁶, R. Rivir¹, B. Tsao¹⁰, V. Van Griethuysen⁶, K. Yerkes⁶
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-3, 2014, DOI:10.5098/hmt.5.9
Abstract This article has no abstract. More >

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Amnart Boonloi^*
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-12, 2014, DOI:10.5098/hmt.5.8
Abstract A mathematical analysis of the heat transfer enhancement, thermal performance and flow configurations in a heat exchanger square duct with diagonal inserted plate vortex generators is presented. The 30o V–shaped baffles are modified and placed on the double sides of the thin plate or frame (with no plate) which inserted diagonally in the square duct. The effects of blockage ratio (b/H, BR), the pitch ratio (p/H, PR), flow direction (V–Downstream and V–Upstream) and configuration of inserting plate are investigated for Reynolds number based on the hydraulic diameter of the square duct, D_h, Re = 100 –… More >

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Sally M. Smith^*, Brenton S. Taft^† , Jacob Moulton
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-9, 2014, DOI:10.5098/hmt.5.6
Abstract This study investigates the wettability of fluid-solid interactions of interest for oscillating heat pipe (OHP) applications. Measurements were taken using two techniques: the sessile drop method and capillary rise at a vertical plate. Tested surface materials include copper, aluminum, and Teflon PFA. The working fluids tested were water, acetone, R-134a, and HFO-1234yf. A novel low-pressure experimental setup was developed for refrigerant testing. Results show that the refrigerants have significantly lower hysteresis than the water and acetone-based systems, which is thought to lead to better heat transfer in OHP design. More >

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Zhen Tian^a,*, Wenbo Jin^a, Lei Wang^b, Zhi Jin^c
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-8, 2014, DOI:10.5098/hmt.5.5
Abstract Taking the axial heat conduction of wax deposition layer into account, a two-dimensional heat transfer model of calculating the temperature profile inside wax deposition layer was deduced and established based on the energy balance equation, the finite difference method was used to solve this model, and the influence of axial heat conduction on the distribution law of temperature profile inside the wax deposition layer under different boundary conditions and thickness were discussed. The results showed that: Temperature profile inside wax deposition layer in middle region of testing pipe section was mainly influenced by axial heat More >

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Machireddy Gnaneswara Reddy^*
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-9, 2014, DOI:10.5098/hmt.5.4
Abstract The numerical solution of transient natural convection MHD flow past a vertical cylinder embedded in a porous medium with surface temperature and concentration along with thermal radiation is presented. The temperature and concentration level at the cylinder surface are assumed to vary as power law type functions, with exponents m and n respectively in the stream wise co-ordinate. The governing boundary layer equations are converted into a non-dimensional form. A Crank-Nicolson type of implicit finite-difference method is used to solve the governing non-linear set of equations. Numerical results are obtained and presented with various thermal More >

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Ravishankar Sathyamurthy^a,*, P.K. Nagarajan^b, Hyacinth J. Kennady^a, T.S. Ravikumar^a, V. Paulson^c, Amimul Ahsan^d
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-5, 2014, DOI:10.5098/hmt.5.3
Abstract This paper presents the method of improvement of enhancing the performance of triangular pyramid solar still with and without latent heat energy storage. For comparing the productivity of solar still with and without LHTESS a solar still is designed, fabricated. Experiments are conducted in hot and humid climate of Chennai, India. Paraffin wax is used as LHTESS due to its feasible general and economic properties. The hourly productivity is slightly higher in case of solar still without LHTESS during sunny days. There is an increase of about 35% in production of fresh water with LHTESS More >

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Renganathan Manimaran^a, Rajagopal Thundil Karuppa Raj^b,*
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-9, 2014, DOI:10.5098/hmt.5.2
Abstract Diesel engine combustion modeling presents a challenging task with the formation and breakup of spray into droplets. In this work, 3D-CFD computations are performed to understand the behaviour of spray droplet diameter and temperature during the combustion by varying the swirl ratio and injection timing. After the validation and grid and time independency tests, it is found that increase in swirl ratio from 1.4 to 4.1 results in peak pressure rise of 8 bar and an advancement of injection timing from 6 deg bTDC to 20 deg bTDC results in increase of peak pressure by More >

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229

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Biswajit De^*, Rajsekhar Panua
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-6, 2014, DOI:10.5098/hmt.5.7
Abstract This paper presents a pre-mixed combustion model for diesel and Jatropha oil blends combustion studies. Jatropha oil blends are considered as a mixture of diesel and Jatropha oil. CFD package, FLUENT 6.3 is used for modeling the complex combustion phenomenon in compression ignition engine. The experiments are carried out on a single cylinder, four strokes, water cooled direct injection compression ignition engine at compression ratio of 17.5 at full load condition at constant speed of 1500 rpm fuelled with diesel and jatropha oil blends with diesel. The numerical model is solved by considering pressure based,… More >

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Jing Huang, Vitaly E. Gruzdev, Yuwen Zhang^*, J. K. Chen
Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-5, 2014, DOI:10.5098/hmt.5.1
Abstract Experimental study on laser sintering of nanosized titanium and nickel powders using a nanosecond laser is reported in this paper. Pulse laser with a wavelength of 532 nm and pulse width (FWHM) of 23 nanoseconds is used. The diameters of the metal nanoparticles are between 35 to 50 nanometers. Pulse repetition rates range between 100 and 10,000 Hz and the average power is from 1 to 20 W. The powder bed is placed on a moving stage to control the scanning velocity. Sintered metal strips with 20 mm length are formed by focusing the laser More >

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