Begell House Inc.
Heat Transfer Research
HTR
1064-2285
47
3
2016
PREFACE: INTERNATIONAL WORKSHOP ON HEAT TRANSFER ADVANCES FOR ENERGY CONSERVATION AND POLLUTION CONTROL (IWHT-2013) PART 2
ii
Bengt
Sunden
Division of Heat Transfer, Department of Energy Sciences, Lund University, P.O. Box 118,
SE-22100, Lund, Sweden
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
ESTIMATION OF THE LOSS COEFFICIENT FOR CONDUIT BENDS WITH CIRCULAR CROSS SECTION BY THE SECOND LAW APPROACH
203-217
Haochun
Zhang
School of Energy Science and Engineering, Harbin institute of Technology, Harbin, 150001, China
Y.-Y.
Guo
School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, China
Hai-Yan
Yu
School of Energy Science and Engineering, Harbin Institute of Technology
L.-M.
Yan
School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, China
Y.
Ji
School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, China
Y.
Li
Institute of Composite Material, Harbin Institute of Technology, Harbin, China
Energy loss in a flow field occurs due to the dissipation of mechanical energy, and an accurate estimation of the loss coefficient is important for both energy conservation and engineering design. In the current study, the concept of the head loss coefficient K of a local structure for turbulent flows was extended to a laminar flow. The thermodynamic definition of K is proposed, and the value of K can be simulated by integrating the entropy production of the flow field. The Re dependence of K for a 90° bend with a circular cross section and 90° bend combinations was investigated using the second law approach. In addition, the correlation between K and the bending curvature was also derived.
A NUMERICAL STRATEGY OF IDENTIFYING THE SHAPE OF A TWO-DIMENSIONAL THERMAL BOUNDARY WITH KNOWN TEMPERATURE
219-229
Xunliang
Liu
School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory for Energy Saving and Emission Reduction of Metallurgical Industry, Beijing 100083, China
Lijun
Gu
School of Mechanical Engineering, University of Science and Technology Beijing, Beijing,
P.R. China
Zhi
Wen
School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory for Energy Saving and Emission Reduction of Metallurgical Industry, Beijing 100083, China
A numerical strategy of combining a conjugate gradient method with a finite volume method is developed to identify the shape of a two-dimensional thermal boundary with known temperature. The finite volume method is utilized to discretize the governing equations and the domain extension method is used to deal with an irregular computational domain. The numerical algorithm is verified with different inverse problems. The results show that the inverse solution is validated for constant thermal conductivity condition. The effects of the magnitude of thermal conductivity, the initial guess shape, and the number of measuring points are investigated to reveal the accuracy of the inversion values. Further, validity of the strategy is discussed for the case with nonconstant thermal conductivities.
EXPERIMENTAL STUDY OF CATALYTIC REMOVAL OF OZONE IN AN AIRCRAFT CABIN
231-242
Yuanwei
Lu
Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conservation, Beijing Municipality, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China
Xiaohua
Zhao
Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conservation, Beijing Municipality, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China
Zhilong
Yang
Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conservation, Beijing Municipality, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China
Yuting
Wu
MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation，Beijing University of
Technology, Beijing 100124，China; Beijing Key Laboratory of Heat Transfer and Energy Conversion，Beijing University of Technology,
Beijing 100124，China
Xingjuan
Zhang
School of Aeronautic Science and Engineering, Beihang University, Beijin 100191, China
Chunxin
Yang
School of Aeronautic Science and Engineering, Beihang University, Beijin 100191, China
In order to remove ozone from the bleed air in aircraft cabins by catalysis method, two different catalysts (nanometer TiO2 and MnO2−CuO) were chosen to analyze the ozone removal efficiency. A plasma ozone generator was used to control the ozone concentration in a reactor. The effects of flow velocity, initial concentration, and humidity on the ozone removal were analyzed. The results show that the MnO2−CuO catalyst was more effective in ozone degradation. The results in this paper can be a foundation for further research on catalytic removal of ozone for bleed air purification in an aircraft cabin in the future.
TEMPERATURE FLUCTUATION CHARACTERISTICS OF POOL BOILING WITHIN SPACE-CONFINED STRUCTURES
243-258
Xuehu
Ma
Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
Wei
Xu
Institute of Chemical Engineering, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Dalian University of Technology, Dalian, China
Chunjian
Yu
Institute of Chemical Engineering, Dalian University of Technology, Dalian 116012, China
Zhong
Lan
Institute of Chemical Engineering, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Dalian University of Technology, Dalian, China
Zhaolong
Hao
Institute of Chemical Engineering, Dalian University of Technology, Dalian 116012, China
In this paper, the surface temperature fluctuation magnitude and frequency at the nucleation sites in the process of boiling a specially designed space-confined structure is investigated using infrared thermography. Water and ethanol are used as working fluids. The results show that the magnitude of temperature fluctuations is less than 1 K in experiments, while the theoretical prediction of this value is equal to at least 5 K if bubbles are in direct contact with the heating surface. The average temperature fluctuation frequencies and the average bubble departure frequencies on plain and E0.15 surfaces are close in value to each other. A remarkable discrepancy can be found between the surface temperature fluctuation frequency and the bubble departure frequency. The experimental results illustrate that bubbles are not in direct contact with the heating surface, instead, a microlayer of liquid exists between bubbles and heating surface all the time. The bubbles predominately affect the boiling heat transfer characteristics through the temperature fluctuation of the liquid layer.
COMPREHENSIVE EVALUATION OF POWER SUPPLY SYSTEMS FOR COMMERCIAL BUILDINGS BASED ON GRAY RELATIONAL ANALYSIS AND ANALYTIC HIERARCHY PROCESS
259-275
Qingqing
Yong
Department of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China; Department of Electric Engineering, Shanghai Dianji Univeristy, Shanghai, 200120, China
mo
yang
university of shanghai for science and technology
W.
Lu
Department of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
J.
Chen
Department of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
This study establishes a scientific, reasonable, and feasible comprehensive evaluation system for green building's power supply system design and implementation to achieve optimization of their thermal, environmental, and economic performance. Unlike traditional evaluation methods that use single index such as economic performance or exergy efficiency for the criterion, the proposed evaluation method takes annual revenue, exergy efficiency, CO2 emission, and system reliability as indices. This advanced comprehensive evaluation method is based on a combination of the method of the gray relational analysis (GRA) and the analytic hierarchy process (AHP) to assess the multiobjective performance of building's power supply systems. The method is applied to compare four kinds of the power supply system of a hospital to determine the optimal system. The result shows that the system which combines cooling, heating, and power supply systems (CCHP) adding solar photovoltaic (PV) panels has the best comprehensive performance when the capacitance of solar PV panels is large enough.
LINEAR STABILITY ANALYSIS OF POISEUILLE−RAYLEIGH−BENARD FLOW AFFECTED BY A VERTICAL MAGNETIC FIELD AND A TEMPERATURE FIELD
277-293
Chan
Liu
Laboratory of Liquid Metal Modeling for Multiphysical Fluid Mechanics (LLiMM-MFM), School of Physics, University of Chinese Academy of Sciences, Beijing 101408, China
Ming-Jiu
Ni
Laboratory of Liquid Metal Modeling for Multiphysical Fluid Mechanics (LLiMM-MFM), School of Physics, University of Chinese Academy of Sciences, Beijing 101408, China
Nian-Mei
Zhang
Laboratory of Liquid Metal Modeling for Multiphysical Fluid Mechanics (LLiMM-MFM), School of Physics, University of Chinese Academy of Sciences, Beijing 101408, China
The temporal instability of the Poiseuille−Rayleigh−Benard flow subjected to a vertical magnetic field has been investigated by a Chebyshev collocation method. The magnetic field and the temperature gradient are two main factors that affect the stabilities. The magnetic field strongly stabilizes the two- and three-dimensional perturbations in basic flow. When heated from below, the buoyancy driven by a temperature gradient destabilizes the flow. For three-dimensional perturbations, the effects of spanwise disturbance on the instability are investigated. With a small temperature gradient, the increase of the oblique angle γ leads to larger critical Reynolds numbers; but with a great temperature gradient, the increase of γ results in smaller critical Rayleigh numbers. When affected by a weak magnetic field, two-dimensional disturbances are more unstable. Meanwhile, for a moderate or strong magnetic field, three-dimensional disturbances can cause the instability at a smaller Reynolds number than two-dimensional ones.
NUMERICAL STUDY OF SLIP EFFECT AT THE POROUS MEDIUM/FLUID INTERFACE IN AN ENCLOSURE PARTIALLY FILLED WITH A POROUS MEDIUM
295-308
Baoming
Chen
School of Energy and Power Engineering, Shandong University, Jinan, China; School of Thermal Energy Engineering, Shandong Jianzhu University, Jinan, China
Fang
Liu
School of Thermal Energy Engineering, Shandong Jianzhu University, Jinan, China
Guoqing
Zhang
Key Laboratory of Renewable Energy Utilization Technologies in Building, Ministry of Education, Shandong Key Laboratory of Renewable Energy Application Technology, School of Thermal Engineering, Shandong Jianzhu University, Jinan, Shandong 250101, PR China
Zhi
Liu
Key Laboratory of Renewable Energy Utilization Technologies in Building, Ministry of Education, Shandong Key Laboratory of Renewable Energy Application Technology, School of Thermal Engineering, Shandong Jianzhu University, Jinan, Shandong 250101, PR China
Xiang
Ji
Key Laboratory of Renewable Energy Utilization Technologies in Building, Ministry of Education, Shandong Key Laboratory of Renewable Energy Application Technology, School of Thermal Engineering, Shandong Jianzhu University, Jinan, Shandong 250101, PR China
Fluid flow and heat transfer in a cavity partially filled with a porous medium are studied numerically and the finite element method is used to solve the mathematical model based on a one-domain approach. The sketch of a real porous structure obtained by using X-ray computed tomography is imported into the physical model. The flow properties in the transition region and stress jump coefficient at the porous medium/fluid interface are analyzed for different Rayleigh numbers. The numerical results show that the shear stress in the transition region increased quickly compared with those in homogeneous regions. The change rate of velocity is larger than the change rate of shear stress. The coefficient keeps nearly constant at Ra ≤ 104, and increases slowly with the Rayleigh number, then quickly increases when Ra ≥ 106.
EFFECT OF THE ASPECT RATIO ON NATURAL CONVECTION IN A POROUS CAVITY WITH A SINUSOIDAL ACTIVE THERMAL WALL
309-325
Feng
Wu
School of Chemical Engineering, Northwest University, Taibai North Road 229, Xi'an 710069, China
Wenjing
Zhou
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
Gang
Wang
Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, P. R. China; and School of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
Xiaoxun
Ma
School of Chemical Engineering, Northwest University, Taibai North Road 229, Xi'an 710069, China
This study reports a numerical investigation of a natural convective flow and heat transfer in a rectangular cavity filled with a heat-generating porous medium by adopting a local thermal nonequilibrium model. All of the walls of the enclosure are adiabatic except for the left wall, which is partially heated and cooled. The results reveal that, as the periodicity is decreased on increase in N, the streamlines vary in different patterns, including simultaneous clockwise and counterclockwise rotations when N > 1. The temperature fields near the left wall and local Nusselt number of the left wall vary periodically because of the sinusoidal boundary condition. The sinusoidal symmetrical velocity profiles V are observed, and the vertical velocity increases with an increasing aspect ratio. The sinusoidal local Nusselt number profiles are observed with increasing N, and the wave amplitude of the local Nusselt number decreases with an increasing aspect ratio. The aspect ratio has a significant influence on the average Nusselt number of the fluid phase. On the contrary, it has a weak effect on the Nusselt number of the solid phase. There exists an optimal aspect ratio value Ar = 5 that can significantly enhance the heat transfer of the porous cavity.