![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
Three-dimensional numerical simulation is performed to predict the heat transfer performance in a walking-beam reheating furnace. The furnace uses a mixture of coke oven gas as a heat source to reheat the slabs. The fuel is injected into the furnace at four zones: preheating zone, first heating zone, second heating zone, and soaking zone. This numerical model considers turbulent reactive flow coupled with radiative heat transfer in the furnace; meanwhile, the conductive heat transfer dominates the energy balance inside the slabs. An initial iterative method is proposed to estimate the fuel mass flow rate at each zone of the reheating furnace, while the required heating curve of the slabs is specified. In addition, a simplified two-dimensional numerical model is performed to estimate the fuel mass flow rate for the consideration of computational time consummation. The results of the two-dimensional numerical simulations are compared with those of three-dimensional numerical simulation and the in situ data. Furthermore, velocity and temperature distributions are examined for two cases under different heating curves of the slabs.
Nomenclature
| aϵ,i | = | emissivity weighting factor |
| bϵ,i | = | emissivity factor coefficient |
| c1,c2 | = | turbulent constant |
| cp | = | specific heat, J.kg−1.K−1 |
| COG | = | coke oven gas |
| CSC | = | China steel company |
| f | = | fuel ratio |
| Gκ | = | generation of turbulence kinetic energy J.m−2 |
| h | = | enthalpy, J.k g−1 |
| Ir | = | radiation intensity, W.m−2 |
| Ir,b | = | black body radiation intensity, W.m−2 |
| k | = | thermal conductivity, W.m−1.K−1 |
| Jj | = | diffusion flux of species j, kg.m−2 s−1 |
| Lhv | = | fuel enthalpy, J. kg−1 |
| = | mass flow rate, kg.s−1 | |
| p | = | pressure, Pa |
| Prt | = | turbulent Prandtl number |
| Q | = | heat energy, W |
| qrad | = | heat flux by radiation, W.m−2 |
| = | direction vector | |
| Rφ | = | numerical residual |
| s | = | path length, m |
| = | position vector | |
| T | = | temperature, K |
| u | = | fluid velocity, m.s−1 |
| Yi | = | mass fraction of specie, kg.kg−1 |
| x,y,z | = | space coordinates |
Greek symbols
| δ | = | Kronecker delta |
| ϵ | = | turbulent dissipation rate m2.s−3 |
| ϵe | = | emissivity |
| η | = | efficiency |
| κ | = | turbulent kinetic energy m2.s−2 |
| μ | = | dynamic viscosity, N.s.m−2 |
| μt | = | turbulent dynamic viscosity, N.s.m−2 |
| ρ | = | density, kg m−3 |
| = | Reynolds stress | |
| σa | = | absorption coefficient, m−1 |
| σϵ | = | turbulent Prandtl number for ϵ |
| σκ | = | turbulent Prandtl number for κ |
| σs | = | Scattering coefficient, m−1 |
| Φ | = | Scattering function |
| Ω | = | solid angle (Sr) |
Subscripts
| Avg | = | average value |
| ∞ | = | environment condition |
| i | = | ith specie composition, zone |
Acknowledgment
This research was financially supported by the National Science Council-China Steel Corporation, Taiwan, and the contract MOST103-2622-E006-037 is highly appreciated.
Additional information
Notes on contributors
Chien-Nan Lin
Chien-Nan Lin is a professor of Mechanical Engineering Department at Far East University, Tainan, Taiwan. He received his Ph.D. in Mechanical Engineering from National Cheng-Kung University, Tainan, Taiwan. His main research interests are applications of refrigeration and air condition, computational fluid dynamics, and enhanced heat transfer techniques.
Yi-Ping Luo
Yi-Ping Luo obtained her Mechanical Engineering bachelor's degree in 2013 from National Taiwan University of Science and Technology, Taipei, Taiwan, and then received her master degree in 2015 from National Cheng Kung University, Tainan, Taiwan.
Jiin-Yuh Jang
Jiin-Yuh Jang is a Distinguished Professor in the Department of Mechanical Engineering at National Cheng Kung University, Tainan, Taiwan. He received his Ph.D. in mechanical engineering from the State University of New York at Buffalo, USA, in 1983. His research interests include heat exchanger computer aided design, numerical and experimental studies of heat exchangers, energy conversion, and air conditioning. He is an ASHRAE and ASME fellow.
Chao-Hua Wang
Chao-Hua Wang is a researcher at China Steel Corporation, Kaohsiung, Taiwan. He received his Ph.D. in civil engineering from the State University of New York at Buffalo, USA, in 2003. His research interests include optimization control system for reheating furnaces, mathematical modeling of thermal systems, and energy saving engineering.