Shihong Zhang^#, Ning Li, Zhihua Wang

Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-5, 2011, DOI:10.5098/hmt.v2.3.3004

Abstract This article discussed the thermal efficiency, stability and pollutant emissions characteristics of the combustion of lean natural gas-air mixtures in Pd metal based honeycomb monoliths by means of experiments on a practical burner V. The chemistry at work in the monoliths was then investigated by the stagnation point flow reactor( SPFR), a fundamental experimental reactor. It was found that catalytic combustion inhibited the extent of gas-phase oxidation and increased the surface temperature of homogeneous ignition. According to the applications of catalytic combustion in the condenser boiler, the data of catalytic combustion condenser boiler V were measured at atmospheric temperature and… More >

M. Yakut Ali^a,*, Fanghao Yang^a, Ruixian Fang^a, Chen Li^a, Jamil Khan^a,†

Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-11, 2011, DOI:10.5098/hmt.v2.3.3003

Abstract This study experimentally investigates single phase heat transfer and pressure drop characteristics of a shallow rectangular microchannel heat sink whose surface is enhanced with copper nanowires (CuNWs). The hydraulic diameter of the channel is 672 μm and the bottom wall is coated with Cu nanowires (CuNWs) of 200 nm in diameter and 50 μm in length. CuNWs are grown on the Cu heat sink by electrochemical synthesis technique which is inexpensive and readily scalable. The heat transfer and pressure drop results of CuNWs enhanced heat sink are compared with that of bare copper surface heat sink using deionized (DI) water… More >

D. S. Martínez^†, J. P. Solano, J. Pérez, A. Viedma

Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-10, 2011, DOI:10.5098/hmt.v2.3.3002

Abstract Non-Newtonian flow and heat transfer in tubes of heat exchangers with reciprocating insert devices have been numerically investigated. The heat exchanger is mechanically assisted by a reciprocating cylinder, which moves the scraping rods inserted in the tubes. An array of semi-circular elements is mounted on each rod, with a pitch p=5D. These elements fit the internal diameter of the tubes. During the reciprocating motion, they scrape the inner tube wall, avoiding fouling. Additionally, the movement of the inserted device generates macroscopic displacements of the flow, which continuously mix core regions with peripheral flow. A power law model with temperature dependent… More >

Georg F. Dietze^†, Reinhold Kneer

Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-14, 2011, DOI:10.5098/hmt.v2.3.3001

Abstract Despite the use of liquid films in a wide variety of technical applications involving heat and mass transfer (e.g. nuclear reactors, cooling towers and gas turbines), where they often play an important role, the underlying momentum and heat transport processes within these thin liquid layers remain to be fully elucidated. In particular, this applies to the influence that surface waves, developing due to the film’s natural instability, exert on the mentioned processes. In this context, it has been suggested by several experimental and numerical observations that momentum and heat transfer in the capillary wave region (which precedes large surface waves)… More >

Q.X. Wu^a, Y.L. He^b, T.S. Zhao^a,b,*

Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-14, 2011, DOI:10.5098/hmt.v2.3.2001

Abstract Running direct methanol fuel cells (DMFC) with concentrated fuel is desirable to maximize the specific energy of the fuel cell system and to improve the performance by mitigating the water flooding problem associated with diluted methanol operation. This article provides a comprehensive review of recent advances in understanding mass transport phenomena in DMFCs operating with concentrated fuel. The review starts with elaborating the key issues of mass transport of reactants and products associated with highly-concentrated methanol operation, followed by summarizing and discussing past experimental and numerical investigations into the effects of the membrane electrode assembly (MEA) design, flow field structure… More >

N. Gnanasekaran, C. Balaji^*

Frontiers in Heat and Mass Transfer, Vol.2, No.2, pp. 1-6, 2011, DOI:10.5098/hmt.v2.2.3008

Abstract This paper reports the results of an experimental investigation of transient, turbulent mixed convection in a vertical channel in which one of the walls is heated and the other is adiabatic. The goal is to simultaneously estimate the constants in a Nusselt number correlation whose form is assumed a priori by synergistically marrying the experimental results with repeated numerical calculations that assume guess values of the constants. The convective heat transfer coefficient “h”is replaced by the Nusselt number (Nu) and the constants in the Nusselt number are to be evaluated. From the experimentally obtained temperature time history and the simulated… More >

Sina Alavi, Mohammad Passandideh-Fard^*

Frontiers in Heat and Mass Transfer, Vol.2, No.2, pp. 1-9, 2011, DOI:10.5098/hmt.v2.2.3007

Abstract In this paper, a numerical study is performed to investigate the effects of thermal shrinkage on the deposition of molten particles on a substrate in a thermal spray process using the Volume-of-Fluid (VOF) method. Thermal shrinkage is a phenomenon caused by the variation of density during cooling and solidification of a molten metal. The Navier-Stokes equations along with the energy equation including phase change are solved using a 2D/axisymmetric mesh. The VOF method is used to track the free surface of molten particles, and an enthalpy-porosity formulation is used to model solidification. For the normal impact of tin particles in… More >

Nessa Johnson, John Abraham^*, Zach Helgeson, Michael Hennessey

Frontiers in Heat and Mass Transfer, Vol.2, No.2, pp. 1-7, 2011, DOI:10.5098/hmt.v2.2.3006

Abstract A numerical simulation has been performed on the hemodynamics associated with embolization procedures. The flow geometry includes a multibranch artery which is upstream of a targeted tumor. During the procedure, drug-eluting particles are released into the local arterial geometry and are carried downstream by the flowing blood. The intention is to cause embolization of a daughter artery which feeds the tumor. As particles are injected into the blood stream, and as the embolization progresses, it is possible for the particulates to substantially alter the blood flow in the main artery. This alteration may lead to a maldistribution of blood flow… More >

J.N. Chung^a,†, Tailian Chen^b, Shalabh C. Maroo^c

Frontiers in Heat and Mass Transfer, Vol.2, No.2, pp. 1-19, 2011, DOI:10.5098/hmt.v2.2.3004

Abstract Recent research progress in the area of nano/micro scale nucleate boiling is reviewed and an up-to-date summary is provided with a focus on the advances of fundamental boiling physics. This review examines nano/micro scale pool boiling experimental and theoretical/numerical work reported in the open literature. On the experimental side, the topics covered are moving contact line, critical heat flux, boiling curve, nucleation, single bubble boiling cycle, bubble coalescence boiling cycle, heater size effect, nanofluid, and nanoscale-structured heater surface. For the theoretical/numerical work, continuum mechanics modeling of the micro-region and molecular dynamics modeling of the nano-region are included. More >

Diego Angeli^a,*, Arturo Pagano^b, Mauro A. Corticelli^a, Alberto Fichera^b, Giovanni S. Barozzi^a

Frontiers in Heat and Mass Transfer, Vol.2, No.2, pp. 1-9, 2011, DOI:10.5098/hmt.v2.2.3003

Abstract A numerical analysis of transitional natural convection from a confined thermal source is presented. The system considered is an air-filled, square-sectioned 2D enclosure containing a horizontal heated cylinder. The resulting flow is investigated with respect to the variation of the Rayleigh number, for three values of the aspect ratio A. The first bifurcation of the low-Ra fixed-point solution is tracked for each A-value. Chaotic flow features are detailed for the case A = 2.5. The supercritical behaviour of the system is investigated using nonlinear analysis tools and phase-space representations, and the effect of the flow on heat transfer is discussed. More >