Effects of the collision integral, thermal diffusion, and the Prater number on maximum temperature in macroporous catalysts with exothermic chemical reaction in the diffusion-controlled regime

2007 ◽  
Vol 62 (3) ◽  
pp. 655-665 ◽  
Author(s):  
Laurence A. Belfiore
Keyword(s):  
Thermal Diffusion ◽  
Chemical Reaction ◽  
Collision Integral ◽  
Maximum Temperature ◽  
Diffusion Controlled ◽  
Exothermic Chemical Reaction

Airbag deployment: Infrared thermography and evaluation of thermal damage

2019 ◽  
Vol 233 (4) ◽  
pp. 424-431 ◽  
Author(s):  
Ehsan Shakouri ◽  
Alimohammad Mobini
Keyword(s):  
Infrared Thermography ◽  
Chemical Reaction ◽  
Direct Contact ◽  
Thermal Damage ◽  
Maximum Temperature ◽  
Time Intervals ◽  
Hot Gas ◽  
Exothermic Chemical Reaction ◽  
Zero Moment ◽  
Airbag Deployment

The performance of airbag and its deployment are based on a fast exothermic-chemical reaction. The hot gas resulting from the chemical reaction which results in airbag deployment can cause thermal damage and skin burning for the car passenger. The thermal burns due to airbags are of two types: burns due to direct contact with the airbag surface and burns resulting from exposure to the hot gas leaving the deflation vents of the airbag. In this research, for experimental study of the burns resulting from exposure of the skin to airbag, using infrared thermography, the extent of temperature rise of the airbag surface was detected and measured from the zero moment of its inflation. Next, using Henriques equation, the extent of thermal damage caused by airbag deployment and its resulting burn degree was calculated. The results indicated that during the inflation of airbag, the maximum temperature of its surface can be 92 °C ± 2 °C. Furthermore, if the vehicle’s safety system functions within the predicted time intervals, the risk of thermal damage is virtually zero. However, if even a slight delay occurs in detachment of the passenger’s head and face off the airbag, second- and third-degree burns could develop.

Interfacial Studies on Cr and Ti Deposited on Benzocyclobutene (BCB) Film

1990 ◽  
Vol 203 ◽  
Author(s):  
Kyung W. Paik ◽  
Herbert S. Cole
Keyword(s):  
Thermal Diffusion ◽  
Chemical Reaction ◽  
Depth Profiling ◽  
Extended Time ◽  
Subsequent Formation ◽  
Metal Diffusion ◽  
Diffusion Controlled ◽  
Time Periods ◽  
Interfacial Characteristics

ABSTRACTInterfacial characteristics such as chemical reaction, metal diffusion, and morphology were investigated for Cr/BCB and Ti/BCB structures. Using Auger and XPS depth profiling, the formation of Ti carbide and Cr oxide was confirmed at the metal/BCB interface. Annealing at 250 °C for extended time periods resulted in diffusion of Cr and Ti into the BCB and subsequent formation of CrSi2 and Ti-Si compound precipitates. The reaction is a thermal diffusion controlled process which was dependent on time and temperature. It was also found that Ar backsputtering treatment on BCB film before metallization was found to roughen the surface resulting in metal spikes which penetrate into the BCB film.

scholarly journals Thermal Stresses in Chemically Hardening Elastic Media With Application to the Molding Process

1974 ◽  
Vol 41 (3) ◽  
pp. 647-651 ◽  
Author(s):  
Myron Levitsky ◽  
Bernard W. Shaffer
Keyword(s):  
Residual Stress ◽  
Chemical Reaction ◽  
Thermal Stresses ◽  
Stress Component ◽  
Elastic Solid ◽  
Molding Process ◽  
Hardening Process ◽  
Exothermic Chemical Reaction ◽  
Component Parallel

A method has been formulated for the determination of thermal stresses in materials which harden in the presence of an exothermic chemical reaction. Hardening is described by the transformation of the material from an inviscid liquid-like state into an elastic solid, where intermediate states consist of a mixture of the two, in a ratio which is determined by the degree of chemical reaction. The method is illustrated in terms of an infinite slab cast between two rigid mold surfaces. It is found that the stress component normal to the slab surfaces vanishes in the residual state, so that removal of the slab from the mold leaves the remaining residual stress unchanged. On the other hand, the residual stress component parallel to the slab surfaces does not vanish. Its distribution is described as a function of the parameters of the hardening process.

scholarly journals Flow Reversal of Fully Developed Mixed Convection in a Vertical Channel with Chemical Reaction

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Habibis Saleh ◽  
Ishak Hashim ◽  
Sri Basriati
Keyword(s):  
Mixed Convection ◽  
Chemical Reaction ◽  
Buoyancy Force ◽  
Vertical Channel ◽  
Critical Values ◽  
Flow Reversal ◽  
Governing Equations ◽  
Reversed Flow ◽  
Exothermic Chemical Reaction

The present analysis is concerned with the criteria for the onset of flow reversal of the fully developed mixed convection in a vertical channel under the effect of the chemical reaction. The governing equations and the critical values of the buoyancy force are solved and calculated numerically via MAPLE. Parameter zones for the occurrence of reversed flow are presented. The exothermic chemical reaction is found to enhance the flow reversal and made flow reversal possible for symmetrical walls temperature.

Transient Heat Analysis in a Two-Step Radiative Combustible Slab

2021 ◽  
Vol 872 ◽  
pp. 15-19
Author(s):  
Ramoshweu Solomon Lebelo ◽  
Kholeka Constance Moloi
Keyword(s):  
Heat Transfer ◽  
Kinetic Parameters ◽  
Chemical Reaction ◽  
Transfer Rate ◽  
Heat Transfer Analysis ◽  
Shooting Technique ◽  
Surrounding Environment ◽  
Article Analysis ◽  
Exothermic Chemical Reaction ◽  
Rectangular Slab

In this article, analysis of heat transfer in a stockpile of reactive materials modelled in a rectangular slab is carried out. A two-step exothermic chemical reaction is assumed and the heat loss to the surrounding environment is by radiation. The ordinary differential equation (ODE) governing the problem is tackled numerically by Runge-Kutta Fehlberg (RKF45) method coupled with Shooting technique. The heat transfer analysis is simplified by investigation some kinetic parameters’ effects on the temperature of the combusting system. It was found out that some kinetic parameters raise the levels of the temperature by encouraging the exothermic chemical reaction, whereas some, reduce the levels of the temperature to slow down the heat transfer rate. The results are depicted graphically and discussed accordingly.

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.  

A Review on Heat Released in early Geopolymerization by Calorimetric Study

2019 ◽  
Vol 967 ◽  
pp. 236-240
Author(s):  
Mohamed Rosnita ◽  
A.R. Razak ◽  
Mohd Mustafa Al Bakri Abdullah
Keyword(s):  
Reaction Kinetics ◽  
Chemical Reaction ◽  
Alkaline Solution ◽  
Curing Temperature ◽  
Calorimetric Study ◽  
Calorimetric Data ◽  
Pozzolanic Material ◽  
Exothermic Chemical Reaction ◽  
Kinetics Of ◽  
Heat Released

An exothermic chemical reaction between cement and water or is called as hydration of cement produced heat in which gives significance impact to the cement or concrete produced. This hydration of cement is similar to geopolymerization as in geopolymerization, heat is liberated when any pozzolanic material mixes with alkaline solution. Heat released for both hydration of cement and geopolymerization can be measured in a form of calorimetric data. This paper reviews on the use of heat released information for a better understanding on the reaction kinetics of geopolymerization and correlating the heat released with several factors including concentration of alkaline solution, mixing designation and curing temperature.

scholarly journals Thermal diffusion and chemical reaction effects on unsteady flow past a vertical porous plate with heat source dependent in slip flow regime

2016 ◽  
Vol 13 (1) ◽  
pp. 51-62 ◽  
Author(s):  
Narasu Siva Kumar ◽  
Rushi Kumar ◽  
A. G. Vijaya Kumar
Keyword(s):  
Fluid Flow ◽  
Heat Source ◽  
Flow Regime ◽  
Thermal Diffusion ◽  
Chemical Reaction ◽  
Slip Flow ◽  
Porous Plate ◽  
Stream Velocity ◽  
Vertical Porous Plate ◽  
Slip Flow Regime

The present study investigates an analytical solution of free convective unsteady fluid flow in presence of thermal diffusion and chemical reaction effects past a vertical porous plate with heat source dependent in slip flow regime. The plate is assumed to move with a constant velocity in the direction of fluid flow, while free stream velocity is assumed to follow exponentially increasing small perturbation law. The velocity, temperature and concentration profiles are presented graphically for different values of the parameters entering into the problem. Finally the effects of pertinent parameters on the skin friction coefficient, Nusselt number and Sherwood numbers distributions are derived and have shown through graphs and tables by using perturbation technique.

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