Begell House Inc.
Heat Transfer Research
HTR
1064-2285
49
11
2018
PREFACE: HEAT TRANSFER ADVANCES FOR ENERGY CONSERVATION AND POLLUTION CONTROL
v-vi
Tzu-Chen
Hung
Department of Mechanical Mechatronic Engineering,
National Taipei University of Technology,
Taiwan
Qiu-Wang
Wang
Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
Yitung
Chen
Nevada Center for Advanced Computational Methods, University of Nevada Las Vegas, University of Reno, Las Vegas, NV, U.S.A.
Zhixiong
Guo
Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
EFFECT OF THE HEIGHT OF THE HORIZONTAL LAYER OF LIQUID ON THE DEVELOPMENT OF CRITICAL PHENOMENA IN EVAPORATION AT REDUCED PRESSURES
979-990
Vladimir
Zhukov
Department of Chemical Engineering, Novosibirsk State Technical University, 20 K. Marx Ave., Novosibirsk, 630073, Russia
Aleksandr N.
Pavlenko
Kutateladze Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences,
Novosibirsk, Russia
This experimental study is devoted to heat transfer under conditions of evaporation of a horizontal thin layer of VM-1S vacuum oil at a reduced pressure. The experimental data have been evaluated in accordance with the heat-flux density dependence on the temperature difference and by estimating the critical heat flux within a wide range of liquid heights. The values of the heat flux prove to increase by an order of magnitude within a narrow range of liquid heights. The critical heat-flux density has been estimated in the layers of thickness less than a capillary constant presented by the Kutateladze formula. The increase in the layer thickness influences the growth of the critical heat flux. The obtained output constant data are found to be in satisfactory agreement with Yagov's and Landau's evaluating dependences.
POOL BOILING EXPERIMENT ON A MODIFIED MICROPIN-FINNED SURFACE WITH MECHANICAL OSCILLATION
991-1001
Jinjia
Wei
School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, P.R. China; Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong Uniersity, Xi'an, 710049,
P.R.China
Xin
Kong
State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an,
Shaanxi, 710049, P.R. China
Jie
Ding
State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an,
Shaanxi, 710049, P.R. China
Yonghai
Zhang
State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an,
Shaanxi, 710049, P.R. China; School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an 710049, China
To further enhance pool boiling heat transfer, a new oscillation device was proposed. An oscillating plate was located over the heater surface with a vertical oscillation amplitude of 20 mm and frequency of 6 Hz. Three N-type phosphorus-doped silicon chips were used as heater surfaces. One was a smooth surface, and the other two were micropin-finned chips with a fin side length of 30 μ;m and fin height of 60 μ;m (chip PF30-60), and the pin fins were arrayed with aligned and staggered arrangements, respectively. Absolute ethyl alcohol was used as a working fluid. The results showed that mechanical oscillation can enhance boiling heat transfer in both convective region and high heat flux region. The wall superheat showed a considerable decrease of 20-30°C in the convective region by thinning the thermal boundary layer on the heater surface, and the critical heat flux could also be increased by 20%. In addition, the micropin-finned chips showed better performance due to much more fresh liquid supply from the interconnected tunnels formed by micropin fins, which is driven by capillary force.
EVALUATION OF THE PERFORMANCE OF CAVITIES IN NUCLEATE BOILING AT MICROSCALE LEVEL
1003-1022
Yu-Tong
Mu
School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049,
China
Li
Chen
Key Laboratory of Thermo-Fluid Science and Engineering of MOE, School of Energy and Power
Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China; Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico,
87545, USA
Qin-Jun
Kang
Computational Earth Science Group (EES-16), Los Alamos National Laboratory, Los Alamos,
NM, USA
Wen-Quan
Tao
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science & Engineering, Tongji University, Shanghai 200092, China; Key Laboratory of Thermo-Fluid Science and Engineering of MOE, School of Energy and Power
Engineering, Xian Jiaotong University, Xian 710049, China
Nucleate boiling heat transfer (NBHT) from enhanced structures is an effective way to dissipate a high heat flux. In the present study, the behavior of cavities with nucleation on roughened surfaces is studied numerically during the entire ebullition cycle based on the phase-change lattice Boltzmann method. The adopted model is firstly validated by the Laplace law and the two-phase coexistence curve and then is applied to investigate the effects of the cavity structure on NBHT. The bubble departure diameter, departure frequency, and the total boiling heat flux of the ebullition cycle are also studied. It is shown that the cavity widths and the cavity grooves exhibit a significant influence on the NBHT features. A cavity with a circular groove in the present research shows the best performance for NBHT in terms of the averaged heat flux and bubble release frequency. When a specific cavity is combined with other different cavities on roughened surfaces, its nucleation process on different roughened surfaces may differ greatly.
THREE-DIMENSIONAL FINGERING STRUCTURE ASSOCIATED WITH GRAVITATIONALLY UNSTABLE MIXING OF MISCIBLE FLUIDS IN POROUS MEDIA
1023-1039
Shigeki
Sakai
Department of Energy Sciences, Tokyo Institute of Technology, 4259 G3-31, Nagatsuta, Midori-ku,
Yokohama 226-8502, Japan
Yuji
Nakanishi
Department of Mechano-Aerospace Engineering, Tokyo Institute of Technology, 4259 G3-31,
Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
Akimitsu
Hyodo
Department of Energy Sciences, Tokyo Institute of Technology, 4259 G3-31, Nagatsuta, Midori-ku,
Yokohama 226-8502, Japan
Lei
Wang
Department of Energy Sciences, Tokyo Institute of Technology, 4259 G3-31, Nagatsuta, Midori-ku,
Yokohama 226-8502, Japan
Tetsuya
Suekane
Department of Energy Sciences, Tokyo Institute of Technology, 4259 G3-31, Nagatsuta, Midori-ku,
Yokohama 226-8502, Japan
In the geological carbon dioxide (CO2) capture storage (CCS), the dissolution of CO2 into brine formation increases the storage security against potential leakage due to buoyancy. The density-driven natural convection between the brine and CO2 solution plays an important role in the process of dissolution in geological formations. We visualized convective mixing of miscible fluids due to the density difference in a packed bed of particles by means of an X-ray computer tomography scanning a system where the lower light layer is four times thicker than the upper dense layer. On the interface, the fingering structure associated with the Rayleigh-Taylor instability is formed. For a packed bed with particles of equal diameter, the structure of the formed fingers tends to be fine and the number density of the fingers increases with the Rayleigh number Ra. However, even for fine particles, although Ra is low, a fine fingering structure is formed. The fingers that merge with neighboring fingers to form a continuous structure extend with time and coalesce with the neighboring fingers, thereby increasing their diameter and reducing their number density. The mechanical dispersion has a strong impact on the broadening of the finger diameters and the merging process with neighboring fingers. The Sherwood number, a dimension-less measure of convective flux, is correlated with Ra with a power of 0.86. The Sherwood number for the three-dimensional Rayleigh-Taylor instability is a few times higher than those evaluated for the Rayleigh-Benard convection.
ANALYSIS OF THERMAL PERFORMANCE OF VOID CAVITY IN A PCM CANISTER UNDER MICROGRAVITY
1041-1057
gui
xiaohong
China University of Mining and Technology (Beijing)
Song
Xiange
Beĳing International Studies University, Beĳing, 100024, China
Qin
Zhiwen
Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beĳing, 100190, China
Nie
Baisheng
China University of Mining and Technology (Beĳing), Beĳing, 100083, China
A physical model and a mathematical model of phase change during the process of heat transfer in a PCM (Phase Change
Material) canister are suggested. Based on a theoretical analysis and calculation results of the PCM canister during the process of solidification, the model of improved void distribution in the PCM canister under microgravity is given. The phase change thermal storage process is numerically simulated with the use of the model of ignoring void cavity distribution, simple void cavity distribution, and improved void cavity distribution. The calculation results for three kinds of void
distribution are compared and analyzed. The results show that the form of the void cavity distribution has a great effect on calculation results. The melting ratio of PCM has a great difference in the form of different void cavity distributions. The form of void distribution has a great effect on the process of phase change. Under the combined effects of local thermal resistance of void cavity and of the side wall of the PCM canister, it is the most difficult for them to melt during the period of sunlight.
NATURAL CONVECTION HEAT TRANSFER IN A NANOFLUID-FILLED HORIZONTAL LAYER WITH SINUSOIDAL WALL TEMPERATURE AT THE BOTTOM BOUNDARY
1059-1076
G.
Wang
School of Civil Engineering, Lanzhou University of Technology, Lanzhou, Gansu, 730050,
P.R. China
Z. L.
Fan
School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou, Gansu, 730050,
P.R. China
Min
Zeng
Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
Qiu-Wang
Wang
Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
H.
Ozoe
Formerly at the Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga
Koen 6-1, Kasuga 816-8580, Japan
Transient natural convection heat transfer of a water-based nanofluid in an infinite horizontal layer submitted to the influence of a time-periodic boundary temperature is studied numerically using finite volume approach. The bottom wall
temperature of the horizontal layer is varied sinusoidally with time at a constant temperature, while the top wall is cooled at a relatively low temperature. CuO nanoparticles are taken into consideration. The computational region of height 1 and horizontal width 1 is adopted, and numerical computation is performed. By considering Brownian motion, the effects of the Rayleigh number and solid volume fraction on the flow and temperature patterns as well as the heat transfer rate within the horizontal layer are presented. It is found that the time-averaged heat transfer rate decreases with increasing solid volume fraction at low Rayleigh numbers. However, at high Rayleigh numbers, all of the time-averaged Nusselt numbers for the CuO–water nanofluid with different nanoparticle volume fractions are larger than that for pure water, and there is an optimum solid volume fraction which results in the maximum time-averaged heat transfer rate.
MAGNETOHYDRODYNAMIC CONVECTION FLOW ON AN UNSTEADY SURFACE STRETCHING WITH PRESSURE-DEPENDENT TRANSVERSE VELOCITY AND SURFACE TENSION LINEARLY VARYING WITH TEMPERATURE
1077-1101
Rehan Ali
Shah
Department of Basic Sciences and Islamiat, University of Engineering and Technology
Peshawar, Peshawar, KPK, Pakistan
Sajid
Rehman
Islamia College Peshawar
M.
Idrees
Department of Mathematics, Islamia College Peshawar, Khyber Pakhtoon Khwa, Pakistan
Tariq
Abbas
Department of Basic Sciences, Sarhad University Peshawar, Khyber Pakhtoon Khwa, Pakistan
We consider the fluid dynamics of unsteady MHD free surface flow over an unsteady stretching sheet. We study the Newtonian fluid mechanics by solving the boundary layer equations in Cartesian coordinates. Effects of natural
parameters such as the Hartmann number Ma, film thickness, unsteadiness parameter S, magnetic parameter, Grashof
number Gr, thermocapillary number M, and Prandtl number Pr are investigated. The results for the skin friction f''(0), Nusselt number (heat flux) θ'(0), and free surface temperature θ(1) are presented in tabular form.
ANALYSIS OF SQUEEZING FLOW OF A VISCOUS FLUID BETWEEN COROTATING DISCS WITH SORET AND DUFOUR EFFECTS
1103-1118
Rehan Ali
Shah
Department of Basic Sciences and Islamiat, University of Engineering and Technology
Peshawar, Peshawar, KPK, Pakistan
Aamir
Khan
Department of Basic Sciences and Islamiat, University of Engineering and Technology
Peshawar, Peshawar, KPK, Pakistan
Muhammad
Shuaib
Department of Basic Sciences and Islamiat, University of Engineering and Technology
Peshawar, Peshawar, KPK, Pakistan
A similarity solution is obtained for the modeled system of differential equations that accounts for the squeezing and
rotation effects. The governing equations are coupled with advection diffusion and energy equation which defines
heat/mass flux going from the lower to the upper disc. The similarity solution of modeled equations is obtained by
the Homotopy Analysis Method (HAM) via mathematica package BVPh 2.0 and is compared with the numerical
results obtained by BVP4c to assure the accuracy of HAM. The combined effects of the rotational motion of two discs,
upward/downward motion of the upper disc, thermal radiation effect, as well as the Soret and Dufour effects are studied
both graphically and numerically.