Transient Heat and Reactant Consumption Investigation in a Cylindrical Pipe of Variable Thermal Conductivity

2019 ◽  
Vol 392 ◽  
pp. 178-188
Author(s):  
Ramoshweu Solomon Lebelo
Keyword(s):  
Thermal Conductivity ◽  
Combustion Process ◽  
Reaction System ◽  
Variable Thermal Conductivity ◽  
Heat Generation Rate ◽  
Cylindrical Pipe ◽  
Reactive Material ◽  
Surrounding Environment ◽  
Exothermic Chemical Reaction ◽  
Rate Of Heat Release

This article investigates the transfer of heat with reactant (oxygen) consumption in a stockpile of reactive material. A reactive material is any carbon or hydrocarbon containing component in a stockpile that readily reacts with the oxygen due to exothermic chemical reaction, where self-ignition may take place if heat generation rate during the combustion process within the stockpile, may exceed the rate of heat release to the surrounding environment. The study is modeled in a long cylindrical pipe whose material thermal conductivity varies with the temperature at a given time. The heat and mass transfer partial differential equations governing the problem were solved numerically using the finite difference method (FDM). Kinetic parameters embedded within the reaction system were analyzed to understand their effects on the temperature and the reactant consumption process. The results shew that the parameters that influence the increase in temperature, increase also the consumption rate of the reactant.

scholarly journals Heat loss analysis in a radiating slab of variable thermal conductivity

2018 ◽  
Vol 7 (2.23) ◽  
pp. 228 ◽  
Author(s):  
Ramoshweu S. Lebelo ◽  
Kholeka C. Moloi
Keyword(s):  
Differential Equation ◽  
Thermal Conductivity ◽  
Chemical Reaction ◽  
Combustion Process ◽  
Variable Thermal Conductivity ◽  
Temperature Profiles ◽  
Reactive Material ◽  
Loss Analysis ◽  
Exothermic Chemical Reaction ◽  
Rectangular Slab

This article investigates the transfer of heat in a stockpile of reactive materials, that is assumed to lose heat to the environment by radiation. The study is modeled in a rectangular slab whose materials are of variable thermal conductivity. The stockpile’s reactive material in this context is one that readily reacts with the oxygen trapped within the stockpile due to exothermic chemical reaction. The study of the combustion process in this case is conducted theoretically by using the Mathematical approach. The differential equation governing the problem is tackled numerically by applying the Runge-Kutta Fehlberg (RKF45) method coupled with the Shooting technique. To investigate the heat transfer phenomena, some kinetic parameters embedded in the governing differential equation, are varied to observe the behavior of the temperature profiles during the combustion process. The results obtained from the temperature profiles, are depicted graphically and discussed accordingly. It was discovered that kinetic phenomena such as the reaction rate parameter, accelerates the exothermic chemical reaction. However, the radiation parameter decelerates the exothermic chemical reaction by lowering the temperature profiles.  

On Heat Transfer of a Two-Step Radiating Slab of Variable Thermal Conductivity

2020 ◽  
Vol 987 ◽  
pp. 137-141
Author(s):  
Ramoshweu Solomon Lebelo
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Chemical Reaction ◽  
Combustion Process ◽  
Variable Thermal Conductivity ◽  
Nonlinear Ordinary Differential Equation ◽  
Physical Parameters ◽  
Exothermic Chemical Reaction ◽  
Temperature Levels ◽  
Heat Transfers

An investigation of heat transfers in a combustible stockpile whose materials are of variable thermal conductivity is conducted in this article. The stockpile is modeled in rectangular slap and a two-step exothermic chemical reaction responsible for the combustion process is assumed. The reactive slab is also assumed to lose heat to the ambient by radiation. The Runge-Kutta Fehlberg (RKF45) method coupled with the Shooting technique is applied to tackle numerically the nonlinear ordinary differential equation (ODE) governing the problem. The process of heat transfer during combustion is made easy to understand by investigating effects of selected thermo-physical parameters on the system’s temperature. The results show that some thermo-physical parameters accelerate the exothermic chemical reaction and therefore raise the temperature levels, and that others help to reduce heat release rate to lower the temperature profiles. The graphs for the results are plotted and discussed accordingly.

Investigating Thermal Stability in a Two-Step Convective Radiating Cylindrical Pipe

2021 ◽  
Vol 408 ◽  
pp. 99-107
Author(s):  
Ramoshweu Solomon Lebelo ◽  
Radley Kebarapetse Mahlobo ◽  
Samuel Olumide Adesanya
Keyword(s):  
Differential Equation ◽  
Thermal Stability ◽  
Kinetic Parameters ◽  
Numerical Solutions ◽  
Combustion Process ◽  
Numerical Approach ◽  
Cylindrical Pipe ◽  
Surrounding Environment ◽  
Exothermic Chemical Reaction ◽  
Governing Differential Equation

Thermal stability in a stockpile of reactive materials is analyzed in this article. The combustion process is modelled in a long cylindrical pipe that is assumed to lose heat to the surrounding environment by convection and radiation. The study of effects of different kinetic parameters embedded on the governing differential equation, makes it easier to investigate the complicated combustion process. The combustion process results with nonlinear molecular interactions and as a result it is not easy to solve the differential equation exactly, and therefore the numerical approach by using the Finite Difference Method (FDM) is applied. The numerical solutions are depicted graphically for each parameter’s effect on the temperature of the system. In general, the results indicate that kinetic parameters like the reaction rate promote the exothermic chemical reaction process by increasing the temperature profiles, whilst kinetic parameters such as the order of the reaction show the tendency to retard the combustion process by lowering the temperature of the system.

Radiation and Thermal Decomposition Analysis in a Reactive Slab of Variable Thermal Conductivity.

2018 ◽  
Vol 7 (3.19) ◽  
pp. 27
Author(s):  
RS Lebelo ◽  
KS Moloi ◽  
CC Chitumwa ◽  
SO Adesanya
Keyword(s):  
Thermal Conductivity ◽  
Heat Loss ◽  
Chemical Reaction ◽  
Co2 Emission ◽  
Combustion Process ◽  
Decomposition Analysis ◽  
Variable Thermal Conductivity ◽  
Radiative Heat Loss ◽  
Exothermic Chemical Reaction ◽  
The Impact

In this article, the impact of radiative heat loss in a stockpile of combustible material is investigated. The heat loss is attributed to the exothermic chemical reaction when the carbon containing material of the stockpile reacts automatically with the oxygen trapped within the stockpile. The study is modelled in a rectangular slab of thermal conductivity that varies with the temperature and loses heat to the surrounding environment by radiation. The differential equations governing the problem are solved numerically using the Runge-Kutta-Fehlberg (RKF) method coupled with the Shooting technique. The effect of each embedded kinetic parameter on the temperature, oxygen (O2) depletion and carbon dioxide (CO2) emission, is analyzed and the results are graphically expressed and discussed accordingly. The results show that the kinetic parameters which enhance the exothermic chemical reaction correspondingly increase the temperature and the CO2 emission during the combustion process, and in turn, these parameters also increase the depletion of O2.  

On Thermal Stability Analysis of a Convective and Radiative Slab of Variable Thermal Conductivity with Reactant Consumption

2018 ◽  
Vol 389 ◽  
pp. 195-204
Author(s):  
Ramoshweu Solomon Lebelo ◽  
K.C. Moloi ◽  
C.C. Chitumwa ◽  
M.W.R. Sadiki ◽  
P. Baloyi ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Kinetic Parameters ◽  
Nonlinear Differential Equations ◽  
Combustion Process ◽  
Variable Thermal Conductivity ◽  
Nonlinear Interactions ◽  
O2 Consumption ◽  
Shooting Technique ◽  
Surrounding Environment ◽  
Rectangular Slab

Thermal stability in a stockpile of reactive materials that are assumed to lose heat to the surrounding environment by convection and radiation is studied in this article. The reactant (O2) consumption is also considered and the investigation is modeled in a rectangular slab. The complicated combustion process results with nonlinear interactions and therefore, the nonlinear differential equations governing the problem are solved numerically with the Runge-Kutta Fehlberg Method (RKF45) that is coupled with the Shooting Technique. The behaviors of the temperature and the reactant, due to effects of some embedded kinetic parameters, are depicted graphically and discussed accordingly. The results show that kinetic parameters that increase the temperature of the system, correspondingly increase the reactant consumption.

Thermal Conductivity Impact on Thermal Stability of Reactive Materials

2017 ◽  
Vol 11 ◽  
pp. 1-10 ◽  
Author(s):  
Ramoshweu Solomon Lebelo
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Nonlinear Partial Differential Equations ◽  
Variable Thermal Conductivity ◽  
Spontaneous Ignition ◽  
Combustible Material ◽  
Temperature Oxidation ◽  
Exothermic Chemical Reaction ◽  
The Impact ◽  
Thermal Stability Of

The impact of thermal conductivity on the thermal stability of a combustible material is studied in a stockpile modelled in a long cylindrical pipe. Two combustible material systems, one with constant thermal conductivity, the other one with variable thermal conductivity, are compared to analyse thermal stability in each case. A combustible material is the one that contains carbons or hydrocarbons that readily react with the oxygen of the system. Low-temperature oxidation or exothermic chemical reaction is the primary cause of spontaneous ignition. This is a theoretical study that involves mathematical approach to do the investigation. The nonlinear partial differential equations for heat transfer are solved numerically using the Finite Difference Method (FDM). Effects of embedded kinetic parameters on the temperature of the system are depicted graphically and discussed accordingly.

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