Begell House Inc.
Heat Transfer Research
HTR
1064-2285
48
4
2017
DOUBLE-DIFFUSIVE NATURAL CONVECTIVE PERISTALTIC PRANDTL FLOW IN A POROUS CHANNEL SATURATED WITH A NANOFLUID
283-290
Noreen Sher
Akbar
DBS&H, CEME, National University of Sciences and Technology, Islamabad, Pakistan
Sohail
Nadeem
Department of Mathematics, Quaid-i-Azam University 45320, Islamabad 44000, Pakistan
In the present article we discuss double-diffusive natural convective peristaltic flow of Prandtl nanofluid in a two-
dimensional porous asymmetric channel. The governing equations for Prandtl nanofluid with double diffusive natural
convection are modeled for the first time in the literature. To simplify the problem, an assumption of long wavelength
and low Reynolds number is used. A simplified form of problem has been solved numerically using vibrant boundary
conditions. Numerical solutions are presented graphically with physical interpretation of stream function, pressure
rise, velocity profile, temperature, solutal concentration, and nanoparticle fraction. Numerical solutions also present
the physical behavior of the involved fluid parameter.
APPLICATION OF A NOVEL LATTICE BOLTZMANN METHOD FOR NUMERICAL SIMULATION OF THREE-DIMENSIONAL TURBULENT NATURAL CONVECTION FLOWS
291-307
Ahmad Reza
Rahmati
Department of Mechanical Engineering, University of Kashan, Kashan, Iran
Mahmud
Ashrafizaadeh
Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
Ebrahim
Shirani
Foolad Institute of Technology, Fooladshahr, Isfahan, 8491663763, Iran
In the present study, for the first time, LES of the D3Q19 Fractional Volumetric Multi-Relaxation-Time Lattice Boltzmann
(FV-MRT-LB) model in conjunction with both Smagorinsky and mixed scale viscosity subgrid closure models is applied to
a three-dimensional turbulent natural convection flow in a side-heated cubic cavity at different Rayleigh numbers up to 1012 for a Prantdl number of 0.71. The results show that the (Hybrid Thermal) HT-FV-MRT-LB LES method produce reasonably accurate results at low Rayleigh numbers and stable results at high Rayleigh numbers.
EXPERIMENTAL INVESTIGATION OF RADIATING PIN FIN WITH CYLINDRICAL AND CONICAL CAVITIES
309-318
J. Ganesh
Murali
Department of Automobile Engineering, Karpagam College of Engineering, Coimbatore - 641032, India
Subrahmanya S.
Katte
Department of Mechanical Engineering, PES Institute of Technology, Bangalore - 560100, India
The overall thermal control of a satellite is achieved by balancing the energy emitted by the spacecraft as radiation against the energy dissipated by its internal components plus the energy absorbed from the environment. Since mass is at a premium on a spacecraft, the space radiator used in its temperature control system needs to be optimized with respect to mass. An experimental study was conducted to provide information about the heat radiated to the space from a pin fin with cylindrical and conical cavities. The pin fin with cylindrical cavity dissipates 1.3 times more heat and 3.2 times more heat loss per unit mass than a solid pin fin in vacuum. Further the pin fin with conical cavity losses 1.7 times more heat and 2.3 times more heat loss per unit mass compared to a solid pin fin in vacuum. It is a significant achievement in the enhancement of the heat transfer characteristics of the radiating fin.
NUMERICAL INVESTIGATION OF FLUID FLOW AND HEAT TRANSFER IN A C-SHAPED GEOMETRY OF RECTANGULAR CROSS SECTION
319-345
Yahia
Lasbet
LDMM, Ziane Achour University, Djelfa, Algeria
Ahcène
Loubar
Nuclear Research Center of Birine, Djelfa, Algeria
Khaled
Loubar
Ecole des Mines de Nantes, 44307 Nantes Cedex 3, France
Three-dimensional simulations are carried out to investigate heat transfer and fluid flow characteristics of a chaotic geometry using a computational fluid dynamics (CFD) soft ware. Heat transfer and pressure drop are investigated for Reynolds
numbers ranging from 50 to 1500. The model geometry is created and meshed using the Gambit soft ware. Preliminary
simulations using a laminar flow model are carried out to identify the transition Reynolds number. Fluid flow and heat
transfer are simulated and the results were compared using both laminar and turbulent flow models (standard k–ε model). Steady-state solvers are adopted to calculate pressure drop, flow and temperature fields. Model validation is carried out by comparing the simulation results for Nusselt and Poiseuille numbers against data from the literature. The simulations clearly highlighted the contribution of secondary flows (vortices) to the enhancement of heat transfer compared to a straight pipe, as well as the earlier occurrence of a transitional flow regime. The increase in the pressure drop remains the main drawback of the chaotic geometries. This disadvantage is avoidable through an optimization of the geometrical arrangement and an adequate choice of the operating conditions.
STUDY ON HEAT TRANSFER PERFORMANCES OF CIRCUMFERENTIAL OVERLAP TRISECTION HELICAL BAFFLE HEAT EXCHANGERS
347-359
Wei-Han
Wang
College of Urban Construction and Safety Engineering, Shanghai Institute of Technology,
Shanghai 201418, China
Dao-Lai
Cheng
College of Urban Construction and Safety Engineering, Shanghai Institute of Technology,
Shanghai 201418, China
Tao
Liu
Baoshan Iron & Steel CO., LTD, Shanghai 201900, China
Ya-Ping
Chen
School of Energy and Environment, Southeast University, Nanjing 210096, China
The circumferential overlap trisection helical baffle shell-and-tube heat exchangers are suitable for equilateral triangular lay-out of tubes and can dampen shortcut leakage in triangular zones of adjacent baffles. The performance tests were conducted on oil-water heat transfer in circumferential overlap trisection helical baffle heat exchangers with inclination angles of 12°, 16°, 20°, 24°, and 28°, and compared with a segmental baffle heat exchanger. The results show that both the shell-side heat transfer coefficient h0 and pressure drop Δp0 increase while the comprehensive index h0/Δp0 decreases with increase in the mass flow rate of all schemes. The shell-side heat transfer coefficient, pressure drop, and the comprehensive index h0/Δp0 decrease with increase in the baffle inclination angle at a certain mass flow rate. The average values of the shell-side heat transfer coefficient and the comprehensive index h0/Δp0 of the 12° helical baffle scheme are above 50% higher than those of the segmental one correspondingly, while the pressure drop is approximate and the ratios of the average values are about 1.664 and 1.596, respectively. The shell-side Nusselt number Nu0 and the comprehensive index Nu0·Euz0-1 increase with the Reynolds number of the shell-side axial Reynolds number Rez0 in all schemes. The correlation equations for the shell-side Nusselt number and axial Euler number are presented varying with the axial Reynolds number, Prandtl number, and with the helical baffle inclination angle; the deviations are within ±10%.
SIMULATION OF HEAT TRANSFER AND CRYSTALLIZATION OF MOLTEN BLAST FURNACE SLAG DROPLETS DURING CONTINUOUS COOLING
361-378
Lei
Gan
School of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, No. 156 Kejia Avenue, Ganzhou, Jiangxi Province, 341000, P. R. China; State Key Laboratory of Advanced Steel Processes and Products, Central Iron and Steel Research
Institute, No. 76 Xueyuannanlu, Haidian District, Beĳ ing, 100081, P. R. China
Fangqin
Shangguan
State Key Laboratory of Advanced Steel Processes and Products, Central Iron and Steel Research
Institute, No. 76 Xueyuannanlu, Haidian District, Beĳ ing, 100081, P. R. China
Jicheng
Zhou
State Key Laboratory of Advanced Steel Processes and Products, Central Iron and Steel Research
Institute, No. 76 Xueyuannanlu, Haidian District, Beĳ ing, 100081, P. R. China
Molten blast furnace slag represents great opportunities for waste heat recovery and natural resource recycling. The use
of slag product depends to a great extent on its mineragraphy, which is closely related to heat transfer and crystallization
during the continuous cooling process. In this paper, in order to predict the heat transfer and crystallization behaviors of
molten blast furnace slag droplets during continuous cooling, the non-Newtonian heat transfer model was coupled with a
continuous cooling crystallization kinetics model under conditions of film boiling, natural convection, and forced convection heat transfer. The effects of droplet size, heat transfer condition, and fluid velocity on heat transfer and crystallization of slag droplets were investigated. The results indicate that the droplet size has a significant influence on the cooling rate and degree of crystallization. The effect of heat transfer condition is obvious, and the effect of fluid velocity is negligible.
With increasing droplet size, the mean cooling rate of a slag droplet decreases exponentially. The critical crystallization
droplet size can be defined under investigated heat transfer conditions. For slag droplets of size less than the critical value, the droplets remain glassy after cooling; while for droplets with larger size, the degree of crystallization increases rapidly with increasing droplet size.