The effective thermal conductivity of high temperature particulate beds—II. Model predictions and the implication of the experimental values

1989 ◽  
Vol 32 (3) ◽  
pp. 595-609 ◽  
Author(s):  
J.S.M. Botterill ◽  
A.G. Salway ◽  
Y. Teoman
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Effective Thermal Conductivity ◽  
Model Predictions ◽  
Experimental Values

Effective Thermal Conductivity of the Mushy Region During Solidification of Aqueous Solutions of Ammonium Chloride

1999 ◽  
Author(s):  
Marcus V. A. Bianchi ◽  
Raymond Viskanta
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Ammonium Chloride ◽  
Solidification Process ◽  
Mushy Region ◽  
Diffusion Controlled ◽  
Model Predictions ◽  
Fundamental Understanding ◽  
Two Phases ◽  
Simple Average

Abstract A theoretical and experimental study of the diffusion-controlled solidification process of an aqueous solution of ammonium chloride has been performed to obtain fundamental understanding relevant to metal casting, solidification of alloys, and freezing of biological materials. The effective thermal conductivity of the solidifying system is calculated using different models and the model predictions are compared. The model is validated by comparing the predictions with experimental data. It was found that, for the conditions considered in the present study, the parallel model, which is a simple average of the thermal conductivities of the two phases, leads to acceptable results. The reasons for this are related to the size of the mushy region and the morphology of the crystals during the solidification process.

REVIEW AND APPLICATIONS OF THERMAL CONDUCTIVITY MODELS TO ALUMINUM CELL SIDEWALL REFRACTORIES

2009 ◽  
Vol 23 (06n07) ◽  
pp. 790-795 ◽  
Author(s):  
YUHUA PAN ◽  
STEVEN WRIGHT ◽  
SHOUYI SUN
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Aluminum Electrolysis ◽  
Laser Flash ◽  
Modeling Methods ◽  
Electrolysis Cells ◽  
Model Predictions ◽  
One Step ◽  
Laser Flash Technique ◽  
Multi Phase

Silicon nitride bonded silicon carbide ( Si 3 N 4- SiC ) refractories are commonly used as the sidewall of aluminum electrolysis cells. They have to withstand an extremely corrosive molten electrolyte bath for long periods. The sidewall is normally protected with a layer of solidified electrolyte (called frozen ledge), which is sensitive to the thermal conductivity of the sidewall. In this work, through review of the literature on modeling methods for predicting the effective thermal conductivity of dense composites and porous materials, some selected methods were applied to calculate the effective thermal conductivity of Si 3 N 4- SiC refractories. The model predictions were compared with the thermal conductivity of a commercial Si 3 N 4- SiC refractory measured by using laser flash technique. The present study showed that, due to multi-phase nature and complex microstructure of Si 3 N 4- SiC refractories, most of the selected modeling methods individually do not give satisfactory predictions in one step. Recursive applications of one method or combinations of different methods are capable of giving satisfactory predictions.

scholarly journals Monitor and control test room for investigating thermal performance of panels incorporating phase-change material

2021 ◽  
Vol 10 (2) ◽  
pp. 281-288
Author(s):  
Marwa Othmen ◽  
Radwen Bahri ◽  
Slaheddine Najar ◽  
Ahmed Hannachi
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Test Chamber ◽  
Convection Heat Transfer ◽  
Thermal Characterization ◽  
Composite Panel ◽  
Sensors And Actuators ◽  
Technical Data ◽  
Experimental Values ◽  
And Control

Abstract. This article aims to present equipment designed and developed to study the effective thermal conductivity of composite panels. The composite panel used is a rigid polyurethane foam covered with a layer of aluminum on both sides. The panel is mounted in the test chamber equipped with several sensors and actuators connected via an Arduino platform. Tests have been carried out by applying heat to impose various interior temperatures. Sensors at different locations are used to monitor and record temperatures in and around the composite panel during heating and natural cooling. A model, based on the Fourier equations of thermal conduction and natural convection heat transfer for the steady state, was developed to assess the effective thermal conductivity. The performance of the system was confirmed using temperature signals through the panels for thermal characterization of composite materials. The determined effective thermal conductivity obtained was in agreement with the experimental values reported in the technical data sheets with relative deviations of less than 10 %.

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