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# International Journal of Heat and Mass Transfer (v.53, #9-10)

Turbulent collision rates of arbitrary-density particles by Leonid I. Zaichik; Olivier Simonin; Vladimir M. Alipchenkov (

*pp. 1613-1620*).

**Keywords:** Collision rate; Turbulence; Particles; Bubbles

Unstably stratified Darcy flow with impressed horizontal temperature gradient, viscous dissipation and asymmetric thermal boundary conditions by A. Barletta; M. Celli; D.A. Nield (

*pp. 1621-1627*).

**Keywords:** Linear stability; Horizontal temperature gradient; Viscous dissipation; Porous layer; Darcy’s law; Rayleigh number

Solidification and melting behaviors and characteristics of molten salt in cold filling pipe by Lu Jianfeng; Ding Jing; Yang Jianping (

*pp. 1628-1635*).

**Keywords:** Molten salt; Filling process; Solidification; Melting; Volume of fluid model

Thermal models of railroad wheels and bearings by K.D. Cole; C.M. Tarawneh; A.A. Fuentes; B.M. Wilson; L. Navarro (

*pp. 1636-1645*).

**Keywords:** Annular fin; Heat transfer coefficient; Parameter estimation; Contact conductance

Fluid–structure interaction analysis of flow and heat transfer characteristics around a flexible microcantilever in a fluidic cell by Khalil Khanafer; Abdalla Alamiri; Ioan Pop (

*pp. 1646-1653*).

**Keywords:** Fluid-structure interaction; Fluidic cell; Heat transfer; Microcantilever

Local and average heat transfer in the thermally developing region of an asymmetrically heated channel by Ramjee Repaka; V.V. Satyamurty (

*pp. 1654-1665*).

**Keywords:** Forced convection; Asymmetric heating; Modified Nusselt number; Heat transfer continuity; Wall heat transfer

Free convective visco-elastic flow with heat and mass transfer through a porous medium with periodic permeability by Rita Choudhury; Debasish Dey (

*pp. 1666-1672*).

**Keywords:** 1991 AMS Mathematics subject classification; 76A05; 76A10Visco-elastic; Heat transfer; Mass transfer; Prandtl number; Sherwood number; Nusselt number; Schmidt number

Preparation and pool boiling characteristics of copper nanofluids over a flat plate heater by R. Kathiravan; Ravi Kumar; Akhilesh Gupta; Ramesh Chandra (

*pp. 1673-1681*).

**Keywords:** Nanofluids; Copper nanoparticles; Critical heat flux; Sputtering; Boiling

Heat and fluid flow characteristics of liquid sodium flowing past a nuclear fuel element with non-uniform energy generation by M.K. Ramis; G. Jilani (

*pp. 1682-1690*).

*Pr*=0.005 for liquid sodium as constant, numerical results are presented and discussed for a wide range of aspect ratio

*A*

_{r}, conduction–convection parameter

*N*

_{cc}, total energy generation parameter

*Q*

_{t}and Reynolds number Re

_{H}. It is concluded that the rate of heat dissipation from the fuel element to the coolant is independent of

*A*

_{r},

*N*

_{cc}and

*Q*

_{t}, whereas it increases in proportion to the increase in Re

_{H}. It is also found that for a given material of the fuel element, there is an upper limiting value of

*N*

_{cc}and Re

_{H}beyond which decrease in coolant temperature is negligibly small.

**Keywords:** Nuclear fuel element; Conjugate heat transfer; Finite difference schemes; Conduction–convection parameter; Non-uniform energy generation

Visualization of heat flow using Bejan’s heatline due to natural convection of water near 4°C in thick walled porous cavity by Yasin Varol; Hakan F. Oztop; Moghtada Mobedi; Ioan Pop (

*pp. 1691-1698*).

**Keywords:** Heatline; Maximum density; Conjugate; Natural convection

Theoretical study of conjugate heat transfer effects on temperature profiles in parallel flow with embedded heat sources by Ananthanarayanan Veeraragavan; Christopher Cadou (

*pp. 1699-1711*).

*x*) and the transverse (

*y*) directions. Thermal coupling between the structure and gas is achieved by requiring that the temperatures and heat fluxes match at the interface. The outer structure boundary can be either adiabatic or have a convective heat loss based on Newton’s law of cooling. The resulting solution is a Fourier series (for both structure and gas temperature fields) which depends on the flow Pe and the outer structure boundary condition. This simple model and the resulting analytical solution provide an extremely computationally efficient tool for exploring the effects of varying channel height and gas velocity on the temperature distribution associated with reacting (combusting) flow in a channel. Understanding these tradeoffs is important for developing miniaturized, combustion-based power sources.

**Keywords:** Micro/mesoscale combustion; Parallel plate; Conjugate heat transfer; Heat recirculation

Development of a new simulation model of spin coating process and its application to optimize the 450mm wafer coating process by Jung-Yeul Jung; Yong Tae Kang; Junemo Koo (

*pp. 1712-1717*).

**Keywords:** Spin coating; Photoresist; Photoresist consumption minimization; Wafer enlargement

A fully coupled, transient double-diffusive convective model for salt-gradient solar ponds by Francisco Suárez; Scott W. Tyler; Amy E. Childress (

*pp. 1718-1730*).

**Keywords:** Solar pond; Convection; Double-diffusive convection; Stability; Radiation absorption; Transient model

System instability of evaporative micro-channels by Hee Joon Lee; Shi-chune Yao (

*pp. 1731-1739*).

*S*, and a non-dimensional surface heat flux. This model has been validated experimentally.

**Keywords:** System; Instability; Evaporation; Parallel micro-channels; Incipient boiling

Flow instability of evaporative micro-channels by Hee Joon Lee; Dong Yao Liu; Shi-chune Yao (

*pp. 1740-1749*).

**Keywords:** Instability; Evaporation; Micro-channel; Inlet orifice; Expanding channel; Cross-cutting

Modeling fluid spread in thin fibrous sheets: Effects of fiber orientation by A. Ashari; T.M. Bucher; H. Vahedi Tafreshi; M.A. Tahir; M.S.A. Rahman (

*pp. 1750-1758*).

**Keywords:** Fibrous porous media; Two-phase flows; Anisotropic permeability; Fiber orientation; Absorbency; CFD simulation

Laminar natural convection in an air-filled square cavity with partitions on the top wall by W. Wu; C.Y. Ching (

*pp. 1759-1772*).

*Gr*

_{H}of approximately 1.3×10

^{8}) and non-dimensional top wall temperatures

*θ*

_{T}of 0.56 (insulated) to 2.3. Experiments were performed with an aluminum partition with non-dimensional height

*H*

_{P}/

*H*of 0.0625 and 0.125 attached to the top wall at

*x*/

*H*=0.1, 0.2, 0.4 and 0.6. The blockage effect and/or the thermal effect of the partition resulted in changes to the temperature and flow fields, but were mainly limited to the vicinity of the partition. The partition on the heated top wall resulted in a recirculating flow between the partition and the heated vertical wall. For a given partition height, the structure of this recirculating flow was dependent on the partition location and

*θ*

_{T}. A thermal boundary layer developed along the rear surface of the partition due to the thermal effect of the partition. The ambient temperature outside the boundary layer and

*Nu*near the corner region was affected by the partition height due to the change in the recirculating flow and due to the thermal effect on the rear surface of the partition.

**Keywords:** Laminar natural convection; Square cavity; Partition height and location

Nucleate boiling heat transfer enhancement for water and FC-72 on titanium oxide and silicon oxide surfaces by W. Wu; H. Bostanci; L.C. Chow; Y. Hong; M. Su; J.P. Kizito (

*pp. 1773-1777*).

_{2}) nanoparticle modified surface. A 1cm

^{2}copper heater with 1μm thick TiO

_{2}coating was utilized in saturated pool boiling tests with water and highly-wetting FC-72, and its performance was compared to that of a smooth surface. Results showed that TiO

_{2}coated surface increased CHF by 50.4% and 38.2% for water and FC-72, respectively, and therefore indicated that boiling performance enhancement depends on the level of wettability improvement. A silicon oxide (SiO

_{2}) coated surface, exhibiting similar surface topology, was tested to isolate the roughness related enhancement from the overall enhancement. Data confirmed that hydrophilicity of TiO

_{2}coated surface provides an additional mechanism for boiling enhancement.

**Keywords:** Boiling enhancement; Titanium oxide; Silicon oxide; Hydrophilic

A general correlation for evaporative heat transfer in micro/mini-channels by Wei Li; Zan Wu (

*pp. 1778-1787*).

**Keywords:** Micro-channel; Saturated-flow boiling; Heat transfer; Bond number; Reynolds number

Heat transfer in a second grade fluid through a porous medium from a permeable stretching sheet with non-uniform heat source/sink by M. Subhas Abel; Mahantesh M. Nandeppanavar; Sharanagouda B. Malipatil (

*pp. 1788-1795*).

**Keywords:** Stretching sheet; Second grade fluid; Porous medium; Non-uniform heat source/sink; Suction/injection

Heat flow choking in carbon nanotubes by Hai-Dong Wang; Bing-Yang Cao; Zeng-Yuan Guo (

*pp. 1796-1800*).

**Keywords:** Thermal wave; Choking; Thermal inertia; Carbon nanotube

A study of the influence of initial liquid volume on the capillary flow in an interior corner under microgravity by Cai-Xia Wang; Sheng-Hua Xu; Zhi-Wei Sun; Wen-Rui Hu (

*pp. 1801-1807*).

**Keywords:** Capillary flow; Concus–Finn condition; Critical contact angle

Use of infrared thermography for the study of evaporation in a square capillary tube by F. Chauvet; S. Cazin; P. Duru; M. Prat (

*pp. 1808-1818*).

**Keywords:** Evaporation; Capillary tube; Liquid film; Corner flow; Infrared thermography

Analysis of mixed convection in a lid-driven porous square cavity with linearly heated side wall(s) by Tanmay Basak; S. Roy; Sandeep Kumar Singh; I. Pop (

*pp. 1819-1840*).

*Pr*=0.015–10) and Reynolds number (

*Re*=1–10

^{2}). The isotherms are generally symmetric at smaller

*Pr*irrespective of

*Da*and

*Re*at

*Gr*=10

^{5}for linearly heated side walls. The isotherms are also almost symmetric at small

*Re*with higher

*Gr*(Gr=105) and

*Da*(Da=10-3) and natural convection is found to be dominant whereas the isotherms are compressed near the left and bottom walls at higher

*Re*for linearly heated side walls. Compression of isotherms and dominance of forced convection is also observed at

*Re*=10

^{2}for linearly heated left wall and cooled right wall. The local Nusselt number of the bottom wall(Nub) for low

*Da*is almost constant whereas

*Nu*

_{b}for higher

*Da*and

*Pr*shows non-monotonic variation at

*Re*=10 and an overall decreasing trend is observed at

*Re*=10

^{2}for linearly heated side walls. The local Nusselt numbers of left and right walls(NulandNur) increase for

*Da*=10

^{−3}and

*Pr*=0.7 whereas oscillatory trend is observed at

*Re*=10–10

^{2}and

*Pr*=10. For linearly heated left wall and cooled right wall,

*Nu*

_{b}increases from the left edge towards the right edge of the bottom wall for both cases

*Re*=10 and 10

^{2}irrespective to

*Pr*and

*Da*. It is also observed that

*Nu*

_{r}for higher

*Pr*and

*Da*is found to increase monotonically at bothRe=10and102andNul show non-monotonic trend for higher

*Pr*and

*Da*at

*Re*=10 whereas forRe=102,

*Nu*

_{l}increases monotonically. Average Nusselt numbersNub¯,Nul¯,Nur¯ are found almost invariant with

*Gr*for low

*Pr*with all

*Da*for linearly heated side walls or cooled right wall. On the other hand,Nub¯ is found to vary exponentially at higher

*Pr*and

*Da*and oscillations inNul¯andNur¯ are observed for

*Re*=10 whereas increasing trend is observed forNul¯andNur¯ for

*Re*=10

^{2}for both linearly heated side walls or cooled right wall.

**Keywords:** Mixed convection; Square cavity; Porous medium; Uniform and non-uniform heating; Penalty finite element method

CuS/Cu

_{2}S nanofluids: Synthesis and thermal conductivity by Xiaohao Wei; Tiantian Kong; Haitao Zhu; Liqiu Wang (

*pp. 1841-1843*).

_{2}S nanofluids and experimentally measure their thermal conductivity. The measured thermal conductivity shows that the presence of nanoparticles can either upgrade or downgrade fluid conductivity, a phenomenon predicted by the recent thermal-wave theory of nanofluids.

**Keywords:** Thermal-waves; Nanofluids; CuS/Cu; _{2}; S nanoparticles; Chemical solution method; Thermal conductivity; Conductivity enhancement

Blood flow velocity and ultra-filtration velocity measured by CT imaging system inside a densely bundled hollow fiber dialyzer by Junfeng Lu; Wen-Qiang Lu (

*pp. 1844-1850*).

**Keywords:** Blood flow velocity measurement; Ultra-filtration velocity measurement; Densely bundled hollow fiber dialyzer; CT imaging technology; Dialyzer design

Influence of initial heat generation on dynamic characteristics of transient boiling crisis of water by V.I. Deev; K.V. Kutsenko; A.A. Lavrukhin; V.S. Kharitonov (

*pp. 1851-1855*).

**Keywords:** Power transients; Water pool boiling; Critical heat flux; Physical models

Convective diffusion from strip-like micro-probes into colloidal suspensions by Ondřej Wein (

*pp. 1856-1867*).

*p*=1) to ideal slip (

*p*=0). The range of generalized Peclet number

*H*from

*H*=0.01 (almost pure spatial diffusion) to

*H*=100 (diffusion layer with negligible longitudinal diffusion) covers all cases of possible experimental relevance. The main result is expressed as a relative deviation of actual total diffusion flux

*N*from its diffusion-layer approximation

*N*

_{DLA},

*Ψ*=

*N*/

*N*

_{DLA}−1.

**Keywords:** Electrodiffusion friction probes; Microdisperse fluid flow; Longitudinal diffusion

Convective diffusion from convex microprobes into colloidal suspensions: The edge effects by Ondřej Wein (

*pp. 1868-1873*).

*p*=1) to ideal slip motion (

*p*=0). Correction on the edge effects due to spatial diffusion at medium Peclet numbers is given, using the recent numerical data about the strip-like probes by Wein Simple correction formulas are presented for the disk-like probes.

**Keywords:** Electrodiffusion diagnostics of flow; Microdisperse liquids; Spatial diffusion; Edge effects

Autocalibration of electrodiffusion friction probes in microdispersion liquids by Ondřej Wein (

*pp. 1874-1881*).

**Keywords:** Electrodiffusion friction probes; Voltage-step transient; Edge effects; Microdispersion liquids; Non-linear velocity profiles

Explicit full field analytic solutions for two-dimensional heat conduction problems with finite dimensions by Ru-Li Lin (

*pp. 1882-1892*).

**Keywords:** Green’s function; Conformal mapping; Image method; Heat conduction

The effect of cycle boundary conditions and adsorbent grain size on the water sorption dynamics in adsorption chillers by I.S. Glaznev; Yu.I. Aristov (

*pp. 1893-1898*).

*T*

_{e}=5 and 10°C,

*T*

_{c}=30 and 35°C and

*T*

_{HS}=80°C. The size of the Fuji silica grains was varied from 0.2 to 1.8mm to investigate its effect on water sorption dynamics. For each boundary set and grain size the experimental kinetic curve could be described by an exponential function up to 80–90% of the equilibrium conversion. Desorption runs are found to be faster than appropriate adsorption runs by a factor of 2.2–3.5, hence, for optimal durations of the isobaric ad- and desorption phases of the chilling cycle should be selected accordingly. The size

*R*of the adsorbent grains was found to be a powerful tool to manage the dynamics of isobaric water ad-/desorption. For large grains the characteristic time was strongly dependent on the grain size and proportional to

*R*

^{2}. Much less important appeared to be an impact of the boundary conditions which variation just weakly affected the dimensionless kinetic curves for the four tested cycles. The maximal specific cooling/heating power was proportional to the maximal temperature difference Δ

*T*and the contact area

*S*between the layer and the metal plate, and can exceed 10kW/kg. The heat transfer coefficient

*α*estimated from this power was as large as 100–250W/(m

^{2}K) that much exceeds the value commonly used to describe the cycle dynamics.

**Keywords:** Heat and mass transfer; Adsorption kinetics; Adsorbent; Transport processes; Adsorption chillers; Large temperature jump method

Heat transfer characteristics of premixed flame impinging upwards to plane surfaces inclined with the flame jet axis by G.K. Agrawal; Suman Chakraborty; S.K. Som (

*pp. 1899-1907*).

*k*–

*ε*model has been used to compute the turbulence, and the Discrete Ordinates model has been used for radiative transfer in the flame. It has been observed that the heat flux distribution for an inclined plate is asymmetric about the transverse axis of tilt that divides the plate into uphill and downhill part. The heat flux in the uphill part is higher as compared to that at corresponding locations in downhill part. The local heat flux in the downhill part of the plate increases with a decrease in the plate inclination angle, while in the uphill part, the local heat flux at locations away from the plate centre is almost independent of the plate inclination angle. The local heat flux decreases with an increase in heating height. A fuel rich mixture increases the plate heat flux. The average Nusselt number,Nu¯, increases with an increase in jet Reynolds number, Re, and a decrease in the plate inclination angle. The increase inNu¯ is profound at higher values of Re and for a decrease in plate inclination angle from 10° to 0°.

**Keywords:** Flame impingement; Heat transfer; Premixed flame

Pore-scale simulations on relative permeabilities of porous media by lattice Boltzmann method by Liang Hao; Ping Cheng (

*pp. 1908-1913*).

**Keywords:** Pore-scale; Relative permeability; Porous media; Lattice Boltzmann method

Influence of carbon nanotube suspension on the thermal performance of a miniature thermosyphon by Zhen-hua Liu; Xue-fei Yang; Guo-san Wang; Guang-liang Guo (

*pp. 1914-1920*).

**Keywords:** Nanoparticle; Carbon nanotube; Nanofluid; Heat pipe; Boiling heat transfer

The theoretical simulation of the effect of solid–liquid contact angle on the critical heat flux of saturated water jet boiling on stagnation zone by Yu-hao Qiu; Zhen-hua Liu (

*pp. 1921-1926*).

**Keywords:** Jet; Boiling; Critical heat flux; Solid–liquid contact angle; Simulation

Convective heat transfer over a heated square porous cylinder in a channel by Horng-Wen Wu; Ren-Hung Wang (

*pp. 1927-1937*).

**Keywords:** Unsteady flow; Square porous cylinder; Convection heat transfer

An edge-based smoothed point interpolation method (ES-PIM) for heat transfer analysis of rapid manufacturing system by S.C. Wu; G.R. Liu; X.Y. Cui; T.T. Nguyen; G.Y. Zhang (

*pp. 1938-1950*).

**Keywords:** Numerical methods; Meshfree method; Transient heat transfer; Gradient smoothing; Point interpolation method; Rapid plasma deposition dieless manufacturing

Water transport characteristics in a passive liquid-feed DMFC by Chao Xu; Amir Faghri (

*pp. 1951-1966*).

**Keywords:** Passive DMFC; Water transport; Two phase model; Air filter layer

A general criterion for evaporative heat transfer in micro/mini-channels by Wei Li; Zan Wu (

*pp. 1967-1976*).

**Keywords:** Micro-channel; Saturated-flow boiling; Heat transfer; Bond number; Reynolds number

An analytical model for a liquid plug moving in curved microchannels by Zhizhao Che; Teck Neng Wong; Nam-Trung Nguyen (

*pp. 1977-1985*).

**Keywords:** Curved microchannel; Plug flow; Analytical model; Vortex; Flow resistance

A comprehensive numerical model for melting with natural convection by Shimin Wang; Amir Faghri; Theodore L. Bergman (

*pp. 1986-2000*).

^{8}and a Stefan number of 0.1, are essentially identical; such a similarity can be used as a foundation for conducting room temperature experiments to investigate the melting/solidification characteristics of high temperature phase change materials (PCMs). A benchmark solution for the entire melting process of sodium nitrate is provided as well.

**Keywords:** Solid–liquid phase change; Melting; Solidification; Natural convection; Numerical model

A three-dimensional theoretical model for predicting transient thermal behavior of thermoelectric coolers by Chin-Hsiang Cheng; Shu-Yu Huang; Tsung-Chieh Cheng (

*pp. 2001-2011*).

**Keywords:** Thermoelectric cooler; Theoretical model; Transient behavior; Experiment

Finite element modeling of coating formation and transient heat transfer in the electric arc spray process by Yongxiong Chen; Xiubing Liang; Yan Liu; Jinyuan Bai; Binshi Xu (

*pp. 2012-2021*).

**Keywords:** Thermal spraying; Finite element analysis; Arc sprayed coating; Transient heat transfer

Convective heat transfer enhancement in low Reynolds number flows with wavy walls by Fernando V. Castellões; João N.N. Quaresma; Renato M. Cotta (

*pp. 2022-2034*).

**Keywords:** Low Reynolds number flows; Micro-channels; Wavy walls; Heat transfer enhancement; Forced convection; Integral transforms

Investigation of steel emissivity behaviors: Examination of Multispectral Radiation Thermometry (MRT) emissivity models by Chang-Da Wen (

*pp. 2035-2043*).

**Keywords:** Steel; Emissivity; Temperature measurement; Multispectral Radiation Thermometry

Thermocapillarity and magnetic field effects in a thin liquid film on an unsteady stretching surface by N.F.M. Noor; I. Hashim (

*pp. 2044-2051*).

**Keywords:** Thermocapillarity; Thin film; Unsteady stretching; Magnetic field; Homotopy analysis method

Comparison of frictional pressure drop models during annular flow condensation of R600a in a horizontal tube at low mass flux and of R134a in a vertical tube at high mass flux by A.S. Dalkilic; O. Agra; I. Teke; S. Wongwises (

*pp. 2052-2064*).

^{−2}s

^{−1}for R600a and 300–400 for R134akgm

^{−2}s

^{−1}) and different condensing temperatures (30–43°C for R600a and 40–50°C for R134a) were tested under annular flow conditions. The quality of the refrigerant in the test section was calculated considering the temperature and pressure obtained from the experiment. The pressure drop across the test section was directly measured with a differential pressure transducer. The most agreeable correlations of various available options were then identified according to the results of analysis during annular flow regime.

**Keywords:** Condensation; Pressure drop; Horizontal flow; Downward flow; R600a; R134a

Line fountain behavior at low-Reynolds number by N. Srinarayana; N. Williamson; S.W. Armfield; Wenxian Lin (

*pp. 2065-2073*).

*Re*and is well described by theFr∼1.0 line. Over the range10

**Keywords:** Line fountain; Flapping; Buoyancy; Laminar; Transition; Unsteadiness

Effect of turbulence and devolatilization models on coal gasification simulation in an entrained-flow gasifier by Armin Silaen; Ting Wang (

*pp. 2074-2091*).

_{2}mass fractions, but lower H

_{2}and heating value, and hence, achieves lower gasification efficiency. Combustion of volatiles is modeled with two-stage global reactions with an intermediate stage via benzene.Turbulence models significantly affect the simulated results. Among five turbulence models employed, the standard

*k*–

*ε*and the RSM models give consistent results. The time scale for employing stochastic time tracking of particles also affects simulated result. Caution has to be exerted to select the appropriate time constant value. Smaller particles have a higher surface/volume ratio and react faster than larger particles. However, large particles possessing higher inertia could impinge on the opposing jet and change the thermal-flow filed and the reaction rates.

**Keywords:** Gasification modeling; Entrained-flow gasifier; Clean coal technology; Syngas production; Multiphase flow

Flow dynamical behaviors and characteristics of aligned and staggered viscous pumps by Lu Jianfeng; Ding Jing (

*pp. 2092-2099*).

**Keywords:** Viscous pump; Staggered pump; Flow pattern; Driving power

Visualization of heat transport due to natural convection for hot materials confined within two entrapped porous triangular cavities via heatline concept by Tanmay Basak; S. Roy; D. Ramakrishna; I. Pop (

*pp. 2100-2112*).

*Pr*increases from 0.015 to 1000. In contrast, variation of Prandtl number gives negligible change in heating pattern within the upper triangle and intensity of streamlines and heatlines are less irrespective of Prandtl number. Heat transfer rates are estimated in terms of local(Nul,Nuh) and average Nusselt numbers(Nul¯,Nuh¯). Heat transfer rates are also explained based on heatlines. Local Nusselt numbers with spatial distribution exhibit monotonic trend irrespective of

*Da*and

*Pr*for the upper triangle whereas wavy distribution of local Nusselt number occur for the lower triangle. ForDa=10-3, average Nusselt numbers(Nuh¯andNul¯) increase exponentially with

*Ra*at higher Rayleigh numbers. But, overall lower heat transfer rates are observed for the upper triangle. Finally, it is concluded that lower triangle has always has higher heat recovery capacity compared to upper triangle. To achieve efficient heat transfer, fluids with high Prandtl numbers are recommended for the lower triangle whereas any fluid with any Prandtl number may be acceptable for the upper triangle.

**Keywords:** Penalty finite element method; Natural convection; Porous medium; Inverted triangular cavity; Streamlines; Isotherms; Heatlines; Heat recovery

Direct numerical simulation for a time-developing combined-convection boundary layer along a vertical flat plate by Mohammad Zoynal Abedin; Toshihiro Tsuji; Yasuo Hattori (

*pp. 2113-2122*).

**Keywords:** Combined convection; Turbulent boundary layer; Direct numerical simulation; Convective heat transfer; Transition

A fitting algorithm for solving inverse problems of heat conduction by Andrzej Fra¸ckowiak; Nikolai D. Botkin; Michał Ciałkowski; Karl-Heinz Hoffmann (

*pp. 2123-2127*).

**Keywords:** Inverse problems; Fitting functional; Adjoint equations; Finite Element Method

On the scale effect and scale-up in the column apparatuses. 3. Circulation zones by K. Panayotova; M. Doichinova; Chr. Boyadjiev (

*pp. 2128-2132*).

**Keywords:** Column apparatuses; Mass transfer; Velocity distribution; Circulation zones

An exact analytical solution for two-dimensional, unsteady, multilayer heat conduction in spherical coordinates by Prashant K. Jain; Suneet Singh; Rizwan-uddin (

*pp. 2133-2142*).

*multilayer heat conduction*in

*r*–

*θ*spherical coordinates. Spatially non-uniform, but time-independent, volumetric heat sources may exist in the concentric layers. Proposed solution is valid for any combination of homogenous boundary conditions of the

*first*or

*second*kind in the

*θ*-direction. However, inhomogeneous boundary conditions of the

*first*,

*second*or

*third*kind may be applied at the inner and outer radial boundaries of the concentric layers. It is noted that the proposed solution is “free” from imaginary eigenvalues. Real eigenvalues are obtained by virtue of precluded explicit dependence of radial eigenvalues on those in the

*θ*-direction. Solution is shown to be relatively simple for the most common spherical geometries−(multilayer) hemisphere and full sphere. An illustrative problem of heat conduction in a three-layer hemisphere is solved. Results along with the isotherms are shown graphically and discussed.

**Keywords:** Transient; Multilayer; Spherical; Analytical; Conduction; Hemisphere; Cones and wedges

Optimization of capillary structures for inverted meniscus evaporators of loop heat pipes and heat switches by Valery M. Kiseev; Valeri V. Vlassov; Issamu Muraoka (

*pp. 2143-2148*).

**Keywords:** Loop heat pipe; Inverted meniscus; Capillary structure; Heat switch

Experimental investigation of mixed convection heat transfer from longitudinal fins in a horizontal rectangular channel by M. Dogan; M. Sivrioglu (

*pp. 2149-2158*).

*w*

_{in}⩽0.16m/s) using a flow rate control valve so that Reynolds number was always about

*Re*=1500. Experiments were conducted for modified Rayleigh numbers 3×10

^{7}<

*Ra*

^{∗}<8×10

^{8}and Richardson number 0.4<

*Ri*<5. Dimensionless fin spacing was varied from

*S*/

*H*=0.04 to

*S*/

*H*=0.018 and fin height was varied from

*H*

_{f}/

*H*=0.25 to

*H*

_{f}/

*H*=0.80. For mixed convection heat transfer, the results obtained from experimental study show that the optimum fin spacing which yields the maximum heat transfer is

*S*=8–9mm and optimum fin spacing depends on the value of

*Ra*

^{∗}.

**Keywords:** Mixed convection; Fins; Fin spacing; Fin height; Channel; Heat transfer

Experimental study on microchannel heat sinks considering mass flow distribution with non-uniform heat flux conditions by Eun Seok Cho; Jong Won Choi; Jae Sung Yoon; Min Soo Kim (

*pp. 2159-2168*).

**Keywords:** Microchannel heat sinks; Two-phase flow; Evaporation; Non-uniform heat flux; Header

Hybrid modeling of interfacial region thermophysics and intrinsic stability of thin free liquid films by Yu Gan; Van P. Carey (

*pp. 2169-2182*).

**Keywords:** Free liquid film; Bubble merging; Molecular capillarity theory; Liquid film stability; Nanoscale boiling

Effect of nanofluids on the thermal performance of a flat micro heat pipe with a rectangular grooved wick by Kyu Hyung Do; Seok Pil Jang (

*pp. 2183-2192*).

_{2}O

_{3}nanofluids as working fluid on the thermal performance of a flat micro-heat pipe with a rectangular grooved wick is investigated. For the purpose, the axial variations of the wall temperature, the evaporation and condensation rates are considered by solving the one-dimensional conduction equation for the wall and the augmented Young–Laplace equation for the phase change process. In particular, the thermophysical properties of nanofluids as well as the surface characteristics formed by nanoparticles such as a thin porous coating are considered. From the comparison of the thermal performance using both DI water and nanofluids, it is found that the thin porous coating layer formed by nanoparticles suspended in nanofluids is a key effect of the heat transfer enhancement for the heat pipe using nanofluids. Also, the effects of the volume fraction and the size of nanoparticles on the thermal performance are studied. The results shows the feasibility of enhancing the thermal performance up to 100% although water-based Al

_{2}O

_{3}nanofluids with the concentration less than 1.0% is used as working fluid. Finally, it is shown that the thermal resistance of the nanofluid heat pipe tends to decrease with increasing the nanoparticle size, which corresponds to the previous experimental results.

**Keywords:** Water-based Al; _{2}; O; _{3}; nanofluids; Heat transfer enhancement; Flat micro-heat pipe; Grooved wick structure; Thin porous coating layer

Multi-parameter model reduction in multi-scale convective systems by Emad Samadiani; Yogendra Joshi (

*pp. 2193-2205*).

**Keywords:** Multi-scale thermal-fluid systems; Reduced order modeling; Proper orthogonal decomposition; Galerkin projection; Data center

Macroscopic modeling of thermal dispersion for turbulent flows in channels by M. Drouin; O. Grégoire; O. Simonin; A. Chanoine (

*pp. 2206-2217*).

**Keywords:** Porous media; Turbulence; Thermal dispersion; Heat exchangers; Double averaging

Experimental study of R-134a evaporation heat transfer in a narrow annular duct by C.A. Chen; C.Y. Lee; T.F. Lin (

*pp. 2218-2228*).

*h*

_{r}are examined in detail. For the duct gap of 2.0mm, the refrigerant mass flux

*G*is varied from 300 to 500kg/m

^{2}s, imposed heat flux

*q*from 5 to 15kW/m

^{2}, vapor quality

*x*_{m}from 0.05 to 0.95, and refrigerant saturation temperature

*T*

_{sat}from 5 to 15°C. While for the gap of 1.0mm,

*G*is varied from 500 to 700kg/m

^{2}s with the other parameters varied in the same ranges as that for

*δ*=2.0mm. The experimental data clearly show that the evaporation heat transfer coefficient increases almost linearly with the vapor quality of the refrigerant and the increase is more significant at a higher

*G*. Besides, the evaporation heat transfer coefficient also rises substantially at increasing

*q*. Moreover, a significant increase in the evaporation heat transfer coefficient results for a rise in

*T*

_{sat}, but the effects are less pronounced in the narrower duct at a low imposed heat flux and a high refrigerant mass flux. Furthermore, the evaporation heat transfer coefficient increases substantially with the refrigerant mass flux except at low vapor quality. We also note that reducing the duct gap causes a significant increase in

*h*

_{r}. In addition to the heat transfer data, photos of R-134a evaporating flow taken from the duct side show the change of the dominant two-phase flow pattern in the duct with the experimental parameters. Finally, an empirical correlation for the present measured heat transfer coefficient for the R-134a evaporation in the narrow annular ducts is proposed.

**Keywords:** R-134a; Evaporation heat transfer; Mini-channel; Evaporating flow pattern

Study of heat transfer and kinetics parameters influencing the design of heat exchangers for hydrogen storage in high-pressure metal hydrides by Milan Visaria; Issam Mudawar; Timothée Pourpoint; Sudarshan Kumar (

*pp. 2229-2239*).

_{1.1}CrMn, must be kept below 10mm to achieve a fill time of 5min. A new parameter called non-dimensional conductance (NDC) is developed, which serves as a characteristic parameter to estimate the effects of various parameters on the reaction rate. Overall, it is shown that the hydrogen fill time is sensitive mostly to the effective thermal conductivity of the HPMH and the coolant’s temperature, followed by the contact resistance between the powder and cooling surface.

**Keywords:** Hydrogen storage; Heat exchanger; High-pressure metal hydride

The meshless analog equation method for solving heat transfer to molten polymer flow in tubes by S.P. Hu; C.M. Fan; D.L. Young (

*pp. 2240-2247*).

**Keywords:** Heat transfer; Viscous dissipation; Polymer flows; Power-law flow; Meshless method; Radial basis functions; Analog equation method

Constructal architecture for heating a stream by convection by Deok-Hong Kang; Sylvie Lorente; Adrian Bejan (

*pp. 2248-2255*).

*x*direction, which is oriented against the direction of the metal stream. The heat transfer is by convection. We show that minimal heat consumption is achieved when the heaters and the heat transfer contact area are distributed nonuniformly. The density of heaters per unit length must decrease as

*x*

^{−0.8}toward the entrance of the metal stream, and the heat transfer contact area must increase in proportion with

*x*. These features suggest that the metal must move not as a single stream but as a tree-shaped flow. The metal enters in several parallel streams, which serve as tributaries to larger streams, leading to a single stream that exits at the specified temperature.

**Keywords:** Constructal; Dendritic furnace; Distributed energy systems; Steel heating; Reheating furnace; Sustainable industries; Green energy

Numerical simulation of reactive flow in liquid composite molding using flux-corrected transport (FCT) based finite element/control volume (FE/CV) method by Hua Tan; Krishna M. Pillai (

*pp. 2256-2271*).

**Keywords:** Streamline-upwind Petrov–Galerkin (SUPG); Flux-Corrected Transport (FCT); Liquid Composite Molding; Mold Filling; PORE-FLOW

Three-dimensional adaptive phase field modeling of directional solidification of a binary alloy: 2D–3D transitions by Y.L. Tsai; C.C. Chen; C.W. Lan (

*pp. 2272-2283*).

**Keywords:** Three-dimensional; Adaptive; Phase field modeling; Directional solidification; Morphological instability

Momentum interaction in buoyancy-driven gas–liquid vertical channel flows by L.F. Echeverri; S. Acharya; P.W. Rein (

*pp. 2284-2293*).

**Keywords:** Drag coefficient correlations; Buoyancy-driven two-phase flows; Gas–liquid vertical channel flow; Circulation loop facility; Momentum interaction

Modeling of unsteady and steady fluid flow, heat transfer and dispersion in porous media using unit cell scale by A.A. Alshare; P.J. Strykowski; T.W. Simon (

*pp. 2294-2310*).

^{3}spanning the Darcian and the inertial flow regimes to construct a database of local flow and heat transfer resistances in terms of permeabilities, inertial coefficients, Nusselt numbers, and thermal dispersion coefficients. The resulting database is utilized in a system scale analysis of a serpentine heat exchanger, where these directional terms from the microscale analysis provide closure to the porous-continuum model.

**Keywords:** Porous media; Heat transfer; Unit cell; Heat exchanger; Steady and transient

Pool boiling of R-123/oil mixtures on enhanced tubes having different pore sizes by Nae-Hyun Kim; Do-Young Kim (

*pp. 2311-2317*).

*T*

_{sat}=4.4°C. The degradation increases 50–67% for

*T*

_{sat}=26.7°C. The heat transfer degradation is significant even with small amount of oil (20–38% degradation at 1% oil concentration for

*T*

_{sat}=4.4°C), probably due to the accumulation of oil in sub-tunnels. The pore size (or gap width) has a significant effect on the heat transfer degradation. The maximum degradation is observed for

*d*

_{p}=0.20mm tube at

*T*

_{sat}=4.4°C, and

*d*

_{p}=0.23mm tube at

*T*

_{sat}=26.7°C. The minimum degradation is observed for

*d*

_{p}=0.27mm tube for both saturation temperatures. It appears that the oil removal is facilitated for the larger pore diameter (along with larger gap) tube. The highest heat transfer coefficient with oil is obtained for

*d*

_{p}=0.23mm tube, which yielded the highest heat transfer coefficient for pure R-123. The optimum tube significantly (more than 3 times) outperforms the smooth tube even with oil. The heat transfer degradation increases as the heat flux decreases.

**Keywords:** R-123/oil mixture; Enhanced tube; Pore; Gap; Pool boiling

Analytical and experimental investigations on fluid flow and thermal characteristics of a plate-fin heat sink subject to a uniformly impinging jet by Kyu Hyung Do; Tae Hoon Kim; Sung Jin Kim (

*pp. 2318-2323*).

**Keywords:** Heat sink; Uniformly impinging jet; Volume averaging technique; Similarity transformation