scholarly journals Determining the heat transfer coefficient during the continuous casting process using stochastic particle swarm optimization

2021 ◽  
pp. 101439
Author(s):  
Ruan Zhao-Hui ◽  
Gao Xiu-Yan ◽  
Yuan Yuan ◽  
Tan He-Ping
Keyword(s):  
Heat Transfer ◽  
Particle Swarm Optimization ◽  
Heat Transfer Coefficient ◽  
Continuous Casting ◽  
Transfer Coefficient ◽  
Casting Process ◽  
Continuous Casting Process ◽  
Swarm Optimization ◽  
The Heat Transfer Coefficient ◽  
Stochastic Particle

Measurement of Kinetic Zone Temperature and Heat Transfer Coefficient in the Lost Foam Casting Process

2004 ◽  
Author(s):  
X. J. Liu ◽  
S. H. Bhavnani ◽  
R. A. Overfelt
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Casting Process ◽  
Lost Foam Casting ◽  
Foam Pattern ◽  
Lost Foam ◽  
The Heat Transfer Coefficient ◽  
Zone Temperature

A thermometric technique has been developed to study the thermal characteristics of the foam-metal interaction in the lost foam casting process. A cylindrical foam pattern and heated steel block have been used to estimate the endothermic losses associated with the thermal degradation of the expanded polystyrene at the metal front. Thermocouple readings have been analyzed to determine the temperature of the kinetic zone between the advancing metal front and the receding foam pattern. The heat transfer coefficient between the metal front and the foam pattern has been calculated from the thermal data at the simulated metal front. The results confirmed that the endothermic degradation of the polystyrene pattern at the metal front introduced a steep thermal gradient in the metal and a consistently increasing heat flux. It is found that the heat transfer coefficient, initially 150 W/m2·K increases to 220 ~ 300 W/m2·K during the process. Foam density has marginal effect on the heat flux and heat transfer coefficient, whereas the increase of simulated metal front velocity enhances the heat transfer at the metal front. The kinetic zone temperature is measured to be in the range of 150 to 290°C with an average of 200°C and a gaseous gap size of 1 to 4 cm.

Thermal-Economic Optimization of Moving Packed Bed Particle-to-SCO2 Heat Exchanger Using Particle Swarm Optimization

2021 ◽  
Author(s):  
Yanjie Zheng ◽  
Kelsey B. Hatzell
Keyword(s):  
Heat Transfer ◽  
Particle Swarm Optimization ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Entropy Generation ◽  
Heat Exchangers ◽  
Packed Bed ◽  
Payback Period ◽  
Swarm Optimization

Abstract Low cost (< $150 kWt−1) and high heat-transfer coefficient particle heat exchangers may enable high temperature operation of high efficiency power cycles (supercritical CO2/air Brayton) [1–3]. Currently, these heat exchangers are cost-prohibitive and require large surface areas due to ineffective particle-particle and particle-CO2 heat transfer. Particle heat transfer media are examples of complex material systems that can display a re-configurable mesostructure during flow or shearing processes. This deformation or rearrangement in the underlying active material can cause a decrease in the thermal transport properties and limit the heat-transfer coefficient. For future adoption, it is critical that we gain a greater understanding of how local (particle-particle) thermophysical properties are affected by system architecture/design. Traditional heat exchanger optimization approaches are limited and often lead to non-feasible design approaches. Here, we employ a stochastic and evolutionary method, particle swarm optimization (PSO), to perform a multi-objective optimization for the particle-to-sCO2 shell-and-plate heat exchanger for two state-of-the-art particulate materials (i.e., Accucast ID50K and CARBO HSP). The objective function for optimization considers the minimum payback period (economics), entropy generation (thermodynamics), and volume (engineering). The results suggest that Accucast ID50K is preferable for a packed bed heat exchanger from the perspective of minimizing payback period and volume, while at a larger entropy generation rate than CARBO HSP.

Evaporation of lignin-lean black liquor

TAPPI Journal ◽  
2015 ◽  
Vol 14 (7) ◽  
pp. 441-450
Author(s):  
HENRIK WALLMO, ◽  
ULF ANDERSSON ◽  
MATHIAS GOURDON ◽  
MARTIN WIMBY
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Black Liquor ◽  
Salt Content ◽  
Solubility Limit ◽  
Lignin Removal ◽  
Kraft Black Liquor ◽  
Black Liquors ◽  
The Heat Transfer Coefficient

Many of the pulp mill biorefinery concepts recently presented include removal of lignin from black liquor. In this work, the aim was to study how the change in liquor chemistry affected the evaporation of kraft black liquor when lignin was removed using the LignoBoost process. Lignin was removed from a softwood kraft black liquor and four different black liquors were studied: one reference black liquor (with no lignin extracted); two ligninlean black liquors with a lignin removal rate of 5.5% and 21%, respectively; and one liquor with maximum lignin removal of 60%. Evaporation tests were carried out at the research evaporator in Chalmers University of Technology. Studied parameters were liquor viscosity, boiling point rise, heat transfer coefficient, scaling propensity, changes in liquor chemical composition, and tube incrustation. It was found that the solubility limit for incrustation changed towards lower dry solids for the lignin-lean black liquors due to an increased salt content. The scaling obtained on the tubes was easily cleaned with thin liquor at 105°C. It was also shown that the liquor viscosity decreased exponentially with increased lignin outtake and hence, the heat transfer coefficient increased with increased lignin outtake. Long term tests, operated about 6 percentage dry solids units above the solubility limit for incrustation for all liquors, showed that the heat transfer coefficient increased from 650 W/m2K for the reference liquor to 1500 W/m2K for the liquor with highest lignin separation degree, 60%.

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