Begell House Inc.
Heat Transfer Research
HTR
1064-2285
48
13
2017
PORE PRESSURE IN CONCRETE STRUCTURE SUBJECTED TO FIRE LOADING DESCRIBED IN TERMS OF STOCHASTIC FINITE DIFFERENCES
1139-1150
Malgorzata
Kowalik
Department of Civil Engineering, Technical University of Czestochowa, 3 Akademicka Str.,
Czestochowa, 42-201 Poland
The stochastic finite differences technique is used for the analysis of pore pressure in a concrete structure with random material properties subjected to fire loading. The problem is described theoretically with assumption of random liquid contents. A system of partial differential equations is solved for the first two probabilistic moments of the random pressure field. An example of stochastic analysis in concrete structure with random liquid content is given.
EXPERIMENTAL INVESTIGATION OF THE THERMAL PERFORMANCE OF A HEAT PIPE UNDER VARIOUS MODES OF CONDENSER COOLING
1151-1164
A.
Arulselvan
Department of Mechanical Engineering, Periyar Maniammai University, Vallam,
Thanjavur — 613403, India
V.
Pandiyarajan
Department of Mechanical Engineering, A.C.Tech, Anna University, Chennai – 600 025, India
Ramalingam
Velraj
Institute of Energy Studies, Anna University, Chennai 600024, Tamil Nadu,
India
In the present work, three heat pipes of the same length of 1 m and outer diameter 0.031 m were constructed with some
modifications in the condenser section in order to provide three different modes of cooling, viz., air cooling, water cooling, and cooling with extended surfaces in the condenser section. Experiments are conducted to determine the surface and vapor temperature distributions under steady and transient conditions for all the above-mentioned three modes of cooling in the condenser section. The results obtained are compared and presented in this paper. Moreover, the effective thermal conductivity of the heat pipe is also determined and reported.
MIXED CONVECTION HEAT TRANSFER OF VISCOELASTIC FLUID ALONG AN INCLINED PLATE OBEYING THE FRACTIONAL CONSTITUTIVE LAWS
1165-1178
Jinhu
Zhao
School of Mathematics and Statistics, Fuyang Normal College, Fuyang 236037, Anhui, China
Liancun
Zheng
School of Mathematics and Physics, University of Science and Technology Beĳing, Beĳing 100083,
China
Xinxin
Zhang
School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Energy Saving and Emission Reduction for Metallurgical Industry, University of Science and Technology Beijing, Beijing 100083, China
Fawang
Liu
School of Mathematical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane,
Qld. 4001, Australia
The fractional constitutive laws are introduced into the study of mixed convection heat transfer of viscoelastic fluid along an inclined plate. Nonlinear fractional boundary layer governing equations are formulated and solved by a finite difference algorithm combined with the shifted Grünwald–Letnikov formula. The results show that the inclination angle, Prandtl number, and the temperature fractional derivative parameter have remarkable impacts on both temperature and velocity fields, while the effect of the velocity fractional derivative parameter on temperature is ignorable. With decrease of the inclination angle and Prandtl number, the temperature profile rises and the thermal boundary layer becomes thicker significantly. The average Nusselt number increases remarkably with the augmentation of the temperature fractional derivative
parameter. For larger velocity fractional derivative parameter, the intersections of velocity profiles demonstrate the strengthened viscoelasticity of the fluid. The average skin friction coefficient increases slowly first and then declines dramatically with the rise of the velocity fractional derivative parameter.
SINGLE-PHASE CONVECTIVE HEAT TRANSFER IN A CIRCULAR MINICHANNEL WITH UNSTEADY THERMAL LOADS
1179-1193
Makoto
Shibahara
Graduate School of Maritime Sciences, Kobe University, 5-1-1 Fukaeminami, Higashinadaku, Kobe, 658-0022, Japan
K.
Fukuda
Graduate School of Maritime Sciences, Kobe University, 5-1-1 Fukaeminami, Higashinadaku, Kobe,
658-0022, Japan
Qiusheng
Liu
Graduate School of Maritime Sciences, Kobe University, 5-1-1 Fukaeminami, Higashinadaku, Kobe, 658-0022, Japan
K.
Hata
Graduate School of Maritime Sciences, Kobe University, 5-1-1 Fukaeminami, Higashinadaku, Kobe,
658-0022, Japan
Transient forced-convection heat transfer coefficients were measured for water flowing in a circular minichannel with exponentially increasing heat input. A stainless steel tube (SUS 304) with an inner diameter of 1.0 mm and a length of 47.4 mm, mounted vertically in the experimental water loop, was used as the experimental tube. In the experiment, the upward flow velocity ranged from 10 to 16 m/s and the inlet temperature ranged from 301 to 319 K. The heat generation rate increased exponentially. The e-folding time ranged from 39 ms to 15 s. The experimental results indicated that the turbulent heat transfer coefficients of the minichannel increased with decreasing e-folding time and increasing flow velocity. When the e-folding time was shorter than approximately 0.1 s, the heat transfer coefficients were significantly higher. Correlations of the steady and transient heat transfer for water flowing in a stainless steel tube were obtained from experimental data.
ESTIMATION OF THE CRITICAL RAYLEIGH NUMBER AS A FUNCTION OF THE INITIAL TURBULENCE OF THE BOUNDARY LAYER AT A VERTICAL HEATED PLATE
1195-1202
Artur V.
Dmitrenko
Department of Thermal Physics, National Research Nuclear University "MEPhI", 31 Kashirskoe Shosse, Moscow, 115409, Russia; Department of Power Engineering, Moscow State University of Railway Engineering (MIIT),
9 Obraztsov St., Moscow, 127994, Russia
Based on stochastic equations and equivalence of measures,
formulas of critical Rayleigh numbers depending on the initial
turbulence of the boundary layer on a vertical heated plate are derived analytically. The results of calculations using new formulas show agreement with experimental data for the first and second Rayleigh numbers.
SORET/DUFOUR EFFECTS ON COUPLED HEAT AND MASS TRANSFER BY FREE CONVECTION OVER A VERTICAL PERMEABLE CONE IN POROUS MEDIA WITH INTERNAL HEAT GENERATION AND THERMAL RADIATION
1203-1216
Chuo-Jeng
Huang
Department of Aircraft Engineering, Air Force Institute of Technology, Taiwan (R.O.C.)
This study numerically analyzed the Soret/Dufour effects on coupled heat and mass transfer by free convection over a vertical permeable cone in a saturated porous medium with internal heat generation and thermal radiation. The surface of the vertical cone has a variable wall temperature and variable wall concentration (VWT/VWC). The surface blowing/suction velocity is also variable. The similarity solution is obtained by internal heat generation in exponential decaying form. The Rosseland diffusion approximation is employed to describe the radiative heat flux. Similar governing equations are solved
by the Keller box method. Comparisons showed excellent agreement with the numerical data given in previous works. Numerical data for the dimensionless temperature profile, dimensionless concentration profile, local Nusselt number, and the local Sherwood number are presented graphically for the exponent of VWT/VWC λ, buoyancy ratio N, Lewis number Le, internal heat generation coefficient A*, Soret parameter S, Dufour parameter D, lateral mass flux parameter fw, and the thermal radiation parameter Rd. The physical aspects of the problem are discussed in detail.
EXPERIMENTAL INVESTIGATION OF LOOP HEAT PIPE APPLIED IN A RAILING-TYPE COLLECTOR SOLAR WATER HEATER
1217-1236
Chien
Huang
Engineering & System Science Department, National Tsing-Hua
University 101, Sec. 2, Kuang Fu Rd., Hsinchu, Taiwan
Wei-Keng
Lin
Department of Engineering and System Science, National Tsing-Hua University, Hsinchu City,
Taiwan
Yu-Lin
Chuang
Department of Engineering and System Science, National Tsing Hua University, Hsinchu City,
Taiwan
This paper presents an experimental examination of a railing-type collector solar water heater (RTCSWH), employing a loop heat pipe (LHP) as a heat transfer device. The structure and characteristics of the RTCSWH are also outlined. The LHP is a high-efficiency heat transfer device capable of transporting thermal energy over long distances without the need for other mechanical forces, such as pumps. This makes LHPs particularly suitable for applications involving solar water heaters. We conducted various experiments to investigate the start-up behavior and thermal storage efficiency under various filling ratios with different heat loads and tilt angles. The experimental results revealed that 70% is the ideal filling
ratio for an RTCSWH and that the heat load presents critical limitations with regard to stable operations. The highest thermal storage efficiency obtained in this study was 77%. We also determined that when a railing-type collector has a nonzero tilt angle, loose limitations pertaining to heat load can be relaxed without sacrificing stable operations. We also investigated the characteristics of the start-up behavior, including oscillation, overshoot, dry out, and failure.