Measurement of radiative heat transfer coefficient in a high temperature circulating fluidized beds

2009 ◽  
Vol 26 (5) ◽  
pp. 1395-1398 ◽  
Author(s):  
Seung Chul Lee ◽  
Gui Young Han
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
High Temperature ◽  
Transfer Coefficient ◽  
Radiative Heat Transfer ◽  
Fluidized Beds ◽  
Radiative Heat ◽  
Circulating Fluidized Beds ◽  
Radiative Heat Transfer Coefficient

Average Wall Radiative Heat Transfer Characteristic of Isothermal Radiative Medium in Inner Straight Fin Tubes

2021 ◽  
Author(s):  
Wenping Peng ◽  
Min Xu ◽  
Xiaoxia Ma ◽  
Xiulan Huai
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Radiative Heat Transfer ◽  
Calculation Method ◽  
Radiative Heat ◽  
Solid Surfaces ◽  
Design Calculation ◽  
Radiative Heat Transfer Coefficient ◽  
Fin Tubes

Abstract Wall radiative heat transfer in inner straight fin tubes is very complex considering the coupling of heat conduction in fins and radiative heat transfer of medium with solid surfaces, influenced by a number of factors such as fin parameters, radiative pro perties and run conditions. In this study, a simplified method is used.The average radiative heat transfer between radiative medium and solid surfaces is firstly studied by simulation with fins assumed having a constant temperature. Then an approximate correlation of this radiative heat transfer coefficient is proposed using the traditional radiative heat transfer calculation method with a view coefficient, having a error within 15%. A calculation method of average wall radiative heat transfer coefficient is further proposed by fin theory with an average temperature of fin surface used to consider the varying of the temperature along the fin when the conductivity of fins is finite. Using the predicting method proposed, a method for design calculation of fins in tubes to optimize wall radiative heat transfer is also given with three dimensionless numbers of p/n, 2H/D and nt/pD defined. Three cases of are analyzed in detail based on the design calculation method. It is verified that the radiative heat transfer could be enhanced twice by introducing fins. Under the same h0, conductivity and emissivity are two important factors to choose the material for fins.The micro-fins or the special treatments on the tube wall are a best choice for the fin material having a relatively small conductivity.

scholarly journals Determination of Radiative Heat Transfer Coefficient at High Temperatures Using a Combined Experimental-Computational Technique

2015 ◽  
Vol 15 (2) ◽  
pp. 85-91 ◽  
Author(s):  
Václav Kočí ◽  
Jan Kočí ◽  
Tomáš Korecký ◽  
Jiří Maděra ◽  
Robert Č Černý
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Computational Modeling ◽  
Transfer Coefficient ◽  
High Temperatures ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Calculated Data ◽  
Radiative Heat Transfer Coefficient

Abstract The radiative heat transfer coefficient at high temperatures is determined using a combination of experimental measurement and computational modeling. In the experimental part, cement mortar specimen is heated in a laboratory furnace to 600°C and the temperature field inside is recorded using built-in K-type thermocouples connected to a data logger. The measured temperatures are then used as input parameters in the three dimensional computational modeling whose objective is to find the best correlation between the measured and calculated data via four free parameters, namely the thermal conductivity of the specimen, effective thermal conductivity of thermal insulation, and heat transfer coefficients at normal and high temperatures. The optimization procedure which is performed using the genetic algorithms provides the value of the high-temperature radiative heat transfer coefficient of 3.64 W/(m2K).

Analysis of the Heat Transfer Mechanism in High-Temperature Circulating Fluidized Beds by a Numerical Model

2002 ◽  
Vol 124 (1) ◽  
pp. 34-39 ◽  
Author(s):  
Qiao He ◽  
Franz Winter ◽  
Ji-Dong Lu
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Radiative Heat Transfer ◽  
Fluidized Beds ◽  
Radiative Heat ◽  
Total Heat ◽  
Circulating Fluidized Beds ◽  
Total Heat Transfer

A general numerical model is presented here to describe the complex fluid dynamics and the heat transfer process in high-temperature circulating fluidized beds (CFBs). The core-wall concept is used to describe the gas-solid flow in the dilute phase section of CFBs. The variation of the thickness of the wall layer along the height direction is considered in the fluid dynamic model in order to approach the practical conditions. Three components of heat transfer, i.e., the particle-convective heat transfer, the gas-convective heat transfer, and the radiative heat transfer, and their contributions to the total heat transfer coefficient are investigated. The influences of some operating parameters on the total heat transfer and its components are predicted. Detailed information about the mechanism of heat transfer is discussed. The radiative heat transfer accounts for about 30∼60% of the total heat transfer in high temperature CFBs. It gradually increases along the height direction of the furnace. When the contribution of particle convection increases, the contribution of gas convection decreases, and vice versa. Particle size shows a significant effect on the radiative heat transfer and the convective heat transfer. High bed and wall temperatures will primarily increase the radiative heat transfer.

A Correlation for the Suspension-to-Wall Heat-Transfer Coefficient in Circulating Fluidized Beds

1996 ◽  
Vol 35 (10) ◽  
pp. 3822-3823 ◽  
Author(s):  
Xiao S. Wang ◽  
Bernard M. Gibbs ◽  
Martin J. Rhodes ◽  
Derek Geldart
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Fluidized Beds ◽  
Circulating Fluidized Beds ◽  
Wall Heat Transfer

Experimental and theoretical study of total and radiative heat transfer in circulating fluidized beds

1999 ◽  
Vol 54 (17) ◽  
pp. 3749-3764 ◽  
Author(s):  
W. Luan ◽  
C.J. Lim ◽  
C.M.H. Brereton ◽  
B.D. Bowen ◽  
J.R. Grace
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Fluidized Beds ◽  
Radiative Heat ◽  
Theoretical Study ◽  
Circulating Fluidized Beds

Heat-transfer coefficient in viscous liquid-solid circulating fluidized beds

AIChE Journal ◽  
2005 ◽  
Vol 51 (2) ◽  
pp. 671-677 ◽  
Author(s):  
K. S. Shin ◽  
P. S. Song ◽  
C. G. Lee ◽  
S. H. Kang ◽  
Y. Kang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Viscous Liquid ◽  
Fluidized Beds ◽  
Circulating Fluidized Beds
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