Jiwon Yu^a , Seok-Won Kang^a, Saeil Jeon^b, Debjyoti Banerjee^a,*

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-9, 2012, DOI:10.5098/hmt.v3.1.3004

Abstract Experiments were performed to study the forced convective heat transfer of de-ionized water (DI water) and aqueous nanofluids in a microchannel and temperature measurements were obtained using an array of nanosensors (i.e., thin film thermocouples or “TFT”). Heat flux values were calculated from the experimental measurements for temperature recorded by the TFT array. The experiments were performed for the different test fluids where the flow rate, mass concentration (of silica nanoparticles ~10-30 nm diameter) in the colloidal suspension and the wall temperature profile (as well as applied heat flux values) were varied parametrically.
Anomalous enhancement of the convective heat… More >

Yaohua Zhang^a,*, Yoshio Utaka^b

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-12, 2012, DOI:10.5098/hmt.v3.1.3003

Abstract This paper reviews recent research on microlayer formed by confined vapor bubbles during boiling in mini/microchannels. Experimental measurements, simulations and theoretical studies are described and compared. As a reference to clarify the mechanism for the formation of a microlayer, Taylor flow (i.e. elongated bubble flow in mini/micro circular tubes under adiabatic conditions and at Re << 1) and elongated bubble flow at high velocity, with consideration of the influence of inertia, are also reviewed. Compared to the steady adiabatic conditions, one of the distinct points for the boiling condition is that the bubble grows exponentially due to rapid evaporation of… More >

Etienne Costa-Patry^a, Jonathan Olivier^b, John R. Thome^a,∗

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-14, 2012, DOI:10.5098/hmt.v3.1.3002

Abstract This article presents new experimental results for two-phase flow boiling of R-134a, R-1234ze(E) and R-245fa in a micro-evaporator. The test section was made of copper and composed of 52 microchannels 163μm wide and 1560μm high with the channels separated by 178μm wide fins. The channels were 13.2mm long. There were 35 local heaters and temperature measurements arranged in a 5×7 array as a pseudo-CPU. The total pressure drops of the test section were below 20kPa in all cases. The wall heat transfer coefficients were generally above 10’000W/m²K and a function of the heat flux, vapor quality and mass flux. A… More >

Tomio Okawa^*,†

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-8, 2012, DOI:10.5098/hmt.v3.1.3001

Abstract The present article summarizes the studies on the thermalhydraulic condition under which the onset of nucleate boiling (ONB) is triggered in subcooled flow boiling. Available correlations and experimental data show that the ONB is tended to be delayed in mini and microchannels. It is known that the ONB condition is significantly dependent on the surface condition even in conventional-sized channels. Accumulation of ONB data accompanied by the information on the surface condition is therefore considered of importance to elucidate the mechanisms of boiling incipience in microchannels. Discussion is also made for the bubble dynamics observed in mini and microchannels. It… More >

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-3, 2012, DOI:10.5098/hmt.v3.1.1001

Abstract This article has no abstract. More >

Majid Tahmasebi Kohyani^a, Behzad Ghasemi^a, Ahmad Pasandideh Fard^b,*

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-6, 2012, DOI:10.5098/hmt.v3.2.3008

Abstract Natural convection heat transfer in a square cavity with a porous medium subjected to a uniform energy generation per unit volume is studied numerically in this paper. Temperature of the vertical walls is not equal but it is constant . There are two effective parameters in this condition that appear in the nondimensionalized equations and they are functions of temperature difference between hot and cold walls and energy generation in the porous medium. Nondimensionalized governing equations are obtained based on the Darcy model. a control volume approach is used for solving these equations. The effects of the variation of two… More >

P. V. Ramana, Arunn Narasimhan^*, Dhiman Chatterjee

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-6, 2012, DOI:10.5098/hmt.v3.2.3007

Abstract The present experimental study investigates the effect of tube-to-tube porous interconnectors on the pressure drop and heat transfer (Nu) of tube banks. A copper wire mesh porous medium connects successive tubes of the in-line and staggered arrangement of six rows of tubes. The tubes are subjected to constant and uniform heat flux and cooled by forced convection using water as a cooling fluid in the laminar flow range (100 < ReDuct < 625). The inline configuration with the tube-to-tube porous medium inter-connectors provides marginal enhancement of heat transfer and 12% reduction in the pressure drop penalty respectively, compared to tube… More >

Jizhao Liu^1,2, Jiang Hui^1,2,*, Zhaofa Wang^1,2

Sound & Vibration, Vol.58, pp. 151-169, 2024, DOI:10.32604/sv.2024.045193

Abstract User authentication on smart devices is crucial to protecting user privacy and device security. Due to the development of emerging attacks, existing physiological feature-based authentication methods, such as fingerprint, iris, and face recognition are vulnerable to forgery and attacks. In this paper, GestureID, a system that utilizes acoustic sensing technology to distinguish hand features among users, is proposed. It involves using a speaker to send acoustic signals and a microphone to receive the echoes affected by the reflection of the hand movements of the users. To ensure system accuracy and effectively distinguish users’ gestures, a second-order differential-based phase extraction method… More >

Gintautas Miliauskas^*, Stasys Sinkunas, Kristina Norvaisiene, Kestutis Sinkunas

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-6, 2012, DOI:10.5098/hmt.v3.2.3006

Abstract Water droplet evaporation process is numerically modelled under various heat and mass transfer conditions. Regularities of heat transfer process interaction are examined. Modelling in this work was performed using the combined analytical – numerical method to investigate heat and mass transfer in the two-phase droplets-gas flow system. The influence of forced liquid circulation on the thermal state of droplets is taken into account by the effective coefficient of thermal conductivity. Calculating the rate of droplet evaporation and the intensity of convective heating, the influence of the Stefan’s hydrodynamic flow is taken into account. Balancing energy fluxes in the droplet to… More >

Arvind Pattamatta^a,*, Ghanshyam Singh^b

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-11, 2012, DOI:10.5098/hmt.v3.2.3005

Abstract The present study deals with the assessment of different turbulence models for heated wall jet flow. The velocity field and thermal characteristics for isothermal and uniform heat flux surfaces in the presence of wall jet flow have been predicted using different turbulence models and the results are compared against the experimental data of Wygnanski et al. (1992), Schneider and Goldstein (1994), and AbdulNour et al. (2000). Thirteen different turbulence models are considered for validation, which include the Standard k-ε (SKE), Realizable k-ε (RKE), shear stress transport (SST), Sarkar & So (SSA), v ² -f, Reynolds stress Model (RSM), and Spalart… More >