Begell House Inc.
Heat Transfer Research
HTR
1064-2285
46
6
2015
THREE-DIMENSIONAL BOUNDARY-LAYER FLOW OVER AN EXPONENTIALLY STRETCHING SURFACE WITH THERMAL RADIATION
503-514
Muhammad Y.
Malik
Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000, Pakistan
Sajjad
Rehman
Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000, Pakistan; Department of Computational Science and Engineering, Yonsei University, Seoul, South Korea
Sohail
Nadeem
Department of Mathematics, Quaid-i-Azam University 45320, Islamabad 44000, Pakistan
In the present work we have studied the effects of heat transfer for a three-dimensional flow of a viscous fluid over an exponentially stretching surface with thermal radiation. The boundary layer equations are converted into a set of nonlinear ordinary differential equations with the help of suitable similarity transformations. The reduced equations are finally solved analytically. The results of various parameters are discussed through graphs and tables.
ON MIXED CONVECTION FLOW OF JEFFREY FLUID OVER AN INCLINED STRETCHING SURFACE WITH THERMAL RADIATION
515-539
Tasawar
Hayat
Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000, Pakistan; Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science,
King Abdulaziz University, P.O. Box 80257, Jeddah 21589, Saudi Arabia
Muhammad Bilal
Ashraf
Quaid-i-Azam University Islamabad
Hamed H.
Alsulami
Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O.Box 80203, Jeddah 21589, Saudi Arabia
The thermal radiation and Deborah number effects in mixed convection flow of Jeffrey fluid are studied. Flow is induced by an inclined stretching surface. Computational analysis for flow and heat transfer is carried out by the homotopy analysis method (HAM). Convergence of developed series solutions is guaranteed. The values of skin friction coefficient and local Nusselt number are calculated numerically. Impact of various parameters involved in the flow and heat transfer is seen.
EFFECTS OF BLOCKAGE RATIO AND PRANDTL NUMBER ON STEADY FLOW AND HEAT TRANSFER AROUND AN INCLINED SQUARE CYLINDER
541-562
Jaber
Aboueian-Jahromi
Department of Mechanical Engineering, University of Sistan and Baluchestan, Zahedan, Iran
Alireza
Hossein Nezhad
Department of Mechanical Engineering, University of Sistan and Baluchestan, Zahedan, Iran
Amin
Behzadmehr
Numerical investigation of flow and heat transfer around a long heated inclined square cylinder placed in a horizontal plane channel in a steady laminar regime is carried out for the conditions: 1 ≤ Re ≤ 40, 0.7 ≤ Pr ≤ 100, inclination angle equal to 45° and blockage ratio to β = 1/8, 1/6, and 1/4. The streamlines and isotherms are presented to elucidate the effects of the channel confinement, Prandtl number, and two thermal boundary conditions (constant wall temperature, CWT, and uniform heat flux, UHF) on the physics of the problem. Generally, an increase in a blockage ratio increases the drag coefficient and decreases the wake length. The average Nusselt number also increases with Prandtl and/or Reynolds number. Furthermore, decreasing the blockage ratio decreases the dimensionless local pressure drop and increases the average Nusselt number for low Re and Pr numbers. This can be an economical result for improving the thermal efficiency of the problem. However, for larger Reynolds and Prandtl numbers the average Nusselt number and local pressure drop increase with the blockage ratio. Finally, some simple correlations are introduced for recirculation length, drag coefficient, dimensionless local pressure drop, and average Nusselt number at different blockage ratios.
HEAT TRANSFER PERFORMANCE OF A SEMI-CIRCULAR TUBE BANK
563-575
Emad Zedan
Ibrahiem
Mechanical Power Engineering Department, Faculty of Engineering, Zagazig University, Egypt
Amr Owes
Elsayed
Mechanical Power Engineering Department, Faculty of Engineering, Zagazig University, Egypt
An experimental investigation has been performed to clarify the characteristics of heat transfer from staggered semi-circular tube bank in cross flow. The flow field development inside the tube bank has been illustrated by the smoke flow visualization technique. The influence of the tube angle of attack and bank layout on heat transfer characteristics has been presented and discussed. Empirical correlation has been deduced to describe the thermal performance of the semi-circular bank. The correlation shows the variation of Nusselt number as a function of Reynolds number, angle of attack, and transverse to longitudinal pitch ratio. The tested Reynolds number is ranged from 4.2·103 to 5.4·104. The thermal performance of the semi-circular tube bank has been compared with circular and elliptical tube banks. Experimental results showed that the thermal performance of the semi-circular tube bank approaches the performance of a circular bank as the Reynolds number increases.
A THEORETICAL MODEL FOR PREDICTING TOTAL HEAT TRANSFER ON COMPRESSION OF A REAL GAS: ENERGY SAVING GUIDE
577-590
Ahmed
Sowayan
Al Imam Mohammad Ibn Saud Islamic University
In this study, a theoretical model is presented to compute the total heat transfer which is strongly related to energy consumption in compression devices. Two main sources of irreversibility have been considered, namely: (i) heat transfer due to the finite temperature difference between the system boundary and its surroundings and (ii) heat generated due to the friction within the system. The total amount of heat transferred during real gas compression is predicted for different values of compression ratios. This study will help understand the importance of heat transfer analysis in a compression process and its impact on the compressor performance during operation in terms of energy savings. The findings of this paper will provide some practical guidance to compressor designers in terms of savings in power consumption.
PREPARATION AND THERMAL PERFORMANCES OF NANO-ALUMINA/ PARAFFIN COMPOSITES AS A PHASE-CHANGE MATERIAL
591-597
Xuelai
Zhang
Institute of Energy Storage Technology, Shanghai Maritime University, No. 1550, Harbour Ave., 201306, Shanghai, China
Zhong
Han
Institute of Energy Storage Technology, Shanghai Maritime University, No. 1550, Harbour Ave., 201306, Shanghai, China
Nano-alumina/paraffin composites as a phase-change material were prepared. Paraffin was used as a PCM (phase-change material) and nano-alumina was added to improve the thermal conductivity. An infrared heat camera was used to observe the temperature distribution in samples. The thermal performances of the composites were investigated by the differential scanning calorimetry. After 50 cycles, the melting and solidifying latent heats of the composites were 168 Jg−1 and 176 Jg−1. The thermal conductivity of the paraffin with 0.5 wt.% nano-alumina (0.361 W · m−1 · K−1) increased by about 72% compared to pure paraffin (0.21 W · m−1 · K−1). Chemical degradation of the nano-alumina/paraffin composites did not occur.