Open Access

ARTICLE

B. V. K. Reddy, Matthew Barry, John Li, Minking K. Chyu^*
Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-7, 2013, DOI:10.5098/hmt.v4.2.3001
Abstract In this study, the thermoelectric performance of an integrated thermoelectric device (iTED) with rectangular, round end slots, and circular flow channel designs applied to waste heat recovery for several hot stream flow rates has been investigated using numerical methods. An iTED is constructed with p- and n-type semiconductor materials bonded to the surfaces of an interconnector with flow channels drilled through it. This interconnector acts as an internal heat exchanger directing waste heat from the hot stream to thermoelectric elements. The quantity of heat extracted from the waste heat source and the subsequent amount of… More >

View

384

Download

257

Open Access

ARTICLE

Shigenao Maruyama^a, Masud Behnia^b, Masasazumi Chisaki^c, Takuma Kogawa^c,*, Junnosuke Okajima^a, Atsuki Komiya^a
Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-6, 2013, DOI:10.5098/hmt.v4.2.3002
Abstract The diffusion process of deep seawater drawn up by a vertical pipe deployed in the ocean is investigated. This vertical pipe is based on the principal of perpetual salt fountain. Numerical simulations of seawater upwelling from the pipe are performed based on experiments conducted in the Mariana trench region. Two turbulence modeling approaches were examined: k-ε model and Large Eddy Simulations (LES). The results in both models show that diffusion of the deep seawater diffusion after ejection from the pipe. The LES results show a 50% lower vertical penetration compared to the k-ε model as well More >

View

431

Download

381

Open Access

ARTICLE

Krishnendu Bhattacharyya^*
Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-9, 2013, DOI:10.5098/hmt.v4.2.3003
Abstract The steady boundary layer stagnation-point flow of Casson fluid and heat transfer towards a shrinking/stretching sheet is studied. Appropriate similarity transformations are employed to transform the governing partial differential equations into the self-similar ordinary differential equations and those are then solved numerically using very efficient shooting method. The numerical computations are carried out for several values of parameters involved (especially, velocity ratio parameter and Casson parameter) to know the possibility of similarity solution for the boundary layer stagnation-point flow. It is found that the range of velocity ratio parameter for which similarity solution exists is More >

View

459

Download

267

Open Access

ARTICLE

Heather Dillon^a , Ashley Emery^b,† , Ann Mescher^b
Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-9, 2013, DOI:10.5098/hmt.v4.2.3004
Abstract A computational model is presented that extends prior work on unsteady natural convection in a tall rectangular cavity with aspect ratio 10 and applies Proper Orthogonal Decomposition to the results. The solution to the weakly compressible Navier-Stokes equation is computed for a range of Rayleigh numbers between 2 × 10⁷ and 2.2 × 10⁸ with Prandtl number 0.71. A detailed spectral analysis shows dynamic system behavior beyond the Hopf bifurcation that was not previously observed. The wider Rayleigh range reveals new dynamic system behavior for the rectangular geometry, specifically a return to a stable oscillatory behavior More >

View

365

Download

356

Open Access

ARTICLE

Shihong Zhang^*，Zhihua Wang
Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-6, 2013, DOI:10.5098/hmt.v4.2.3005
Abstract This article discussed exhaust gas temperature and pollutant emissions characteristics of the combustion of rich natural gas-air mixtures in Pd metal based honeycomb monoliths burner during the period of start-up process. The burner needs to be ignited by gas phase combustion with the excessive air coefficient (a) at 1.3. The chemistry at work in the monoliths was then investigated using the stagnation point flow reactor or SPFR. The experimental results in catalytic monolith can be explained from SPFR. The exhaust gas temperature and pollutant emissions were measured by thermocouple K of diameter 0.5 and the More >

View

346

Download

300

Open Access

ARTICLE

Bradley Doleman^a , Messiha Saad^a,*
Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-8, 2013, DOI:10.5098/hmt.v4.2.3006
Abstract Thermal diffusivity, specific heat, and thermal conductivity are important thermophysical properties of composite materials. These properties play a significant role in the engineering design process of space systems, aerospace vehicles, transportation, energy storage devices, and power generation including fuel cells. This paper examines these thermophysical properties of the AS4/3501-6 composite using the xenon flash method to measure the thermal diffusivity in accordance with ASTM E1461 and differential scanning calorimetry to measure the specific heat in accordance with ASTM E1269. The thermal conductivity was then calculated using a proportional relationship between the density, specific heat, and More >

View

592

Download

356

Open Access

ARTICLE

Vijayakumar Thulasi^*, Thundil Karuppa Raj Rajagopal
Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-5, 2013, DOI:10.5098/hmt.v4.2.3007
Abstract Researchers across the world are exploring the potential of using diethyl ether as an alternate fuel to meet the stringent emission norms due to the high oxygen content in the fuel. The spray characteristics of any injected fuel are highly influenced by its physical properties. Due to high injection pressure in CI engines the fuel tends to cavitate inside the nozzle greatly. The change in fuel properties will affect the cavitating behavior of the fuel. In this paper computational technique is used to study and compare the internal flow characteristics of a fuel injector for More >

View

326

Download

372

Open Access

ARTICLE

Etim S. Udoetok^*
Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-5, 2013, DOI:10.5098/hmt.v4.2.3008
Abstract A model for the coefficient of thermal conductivity of binary mixtures of gases has been derived. The theory presented is based on the assumption of random fluctuations between two possible extreme arrangements of a binary gas mixture. The results obtained from the new model compared favorably with published experimental results. The proposed new model provides a simple approach without sacrificing much accuracy compared to previous models. It is applicable to any binary mixture of gases which includes monoatomic gas mixture, polyatomic gas mixtures and mixtures involving rare gases. The new model can be very useful More >

View

433

Download

281