The dispersion of pollutants in urban environments is a major problem. Because of this fact our study comes to propose prevention and security system against the dispersion of releases and fumes from industrial smokes...The dispersion of pollutants in urban environments is a major problem. Because of this fact our study comes to propose prevention and security system against the dispersion of releases and fumes from industrial smokestacks. The system is modeled by a plume-thermosiphon interaction flow resulting from a vertical cylinder open at both ends with a generating source of the plume centered at the opening of the cylinder. The cylindrical wall heats under the effect of the thermal radiation emitted by the generator source, which causes a flow of thermosiphon around the flow of the thermal plume. In order to determine the radiosity of radiation leaving the wall we have been used the Simpson quadrature and the Gaussian elimination method with a dominant pivot. Numerical simulations have been executed for different positions of the thermosiphon compared to the plume source, and for a number of Rayleigh fixed Ra = 10＋7, and a radius of the hot source corresponds to R＊ = 0.46. The results oftbe numerical model that we have been developed, help first identify the behavior of pollutants from the dynamic and thermal point of view and then explore the different locations of the thermosiphon compared to the source of the plume which causes a major influence on the dispersion of pollutants.展开更多
Hot air producing is one of the most important engineering applications in recent years.It is a technique used in various thermodynamic systems,such as home heating systems,food dryers.One of the main problems impedin...Hot air producing is one of the most important engineering applications in recent years.It is a technique used in various thermodynamic systems,such as home heating systems,food dryers.One of the main problems impeding the spread of hot air producing technology is the lack of homogeneity of the heat flow coming from hot air generators as well as an inadequate flow rate.The most of the existing hot air generators require to be supported by systems that can increase the low volumetric flow and the air temperature of these generators,through increasing the speed of the flow of air emitted or lifting the drawer Heat,which contributes to raising the overall cost.However,to improve the thermal and dynamic quality of the hot air flow produced by the generator,a numerical investigation of the free convection flow inside two different configurations is presented in this thesis.The primary objective of this work is to predict the behavior of the flow inside tow configurations,the first one consists of a vertical cylinder with heated walls,and the second configuration is an open-ended vertical cylinder with a hot disc placed at the entrance(configuration A,configuration B).This work characterizes through the examination of this flow,the variables that control an air emission with high flow rate and a high and homogeneous temperature to represent the appropriate criteria that should be respected to obtain a hot air generator overcoming the previously mentioned constraints.Furthermore;the results of this work show the influence the boundary conditions and Rayleigh number on the resulting flow.展开更多
文摘The dispersion of pollutants in urban environments is a major problem. Because of this fact our study comes to propose prevention and security system against the dispersion of releases and fumes from industrial smokestacks. The system is modeled by a plume-thermosiphon interaction flow resulting from a vertical cylinder open at both ends with a generating source of the plume centered at the opening of the cylinder. The cylindrical wall heats under the effect of the thermal radiation emitted by the generator source, which causes a flow of thermosiphon around the flow of the thermal plume. In order to determine the radiosity of radiation leaving the wall we have been used the Simpson quadrature and the Gaussian elimination method with a dominant pivot. Numerical simulations have been executed for different positions of the thermosiphon compared to the plume source, and for a number of Rayleigh fixed Ra = 10＋7, and a radius of the hot source corresponds to R＊ = 0.46. The results oftbe numerical model that we have been developed, help first identify the behavior of pollutants from the dynamic and thermal point of view and then explore the different locations of the thermosiphon compared to the source of the plume which causes a major influence on the dispersion of pollutants.
文摘Hot air producing is one of the most important engineering applications in recent years.It is a technique used in various thermodynamic systems,such as home heating systems,food dryers.One of the main problems impeding the spread of hot air producing technology is the lack of homogeneity of the heat flow coming from hot air generators as well as an inadequate flow rate.The most of the existing hot air generators require to be supported by systems that can increase the low volumetric flow and the air temperature of these generators,through increasing the speed of the flow of air emitted or lifting the drawer Heat,which contributes to raising the overall cost.However,to improve the thermal and dynamic quality of the hot air flow produced by the generator,a numerical investigation of the free convection flow inside two different configurations is presented in this thesis.The primary objective of this work is to predict the behavior of the flow inside tow configurations,the first one consists of a vertical cylinder with heated walls,and the second configuration is an open-ended vertical cylinder with a hot disc placed at the entrance(configuration A,configuration B).This work characterizes through the examination of this flow,the variables that control an air emission with high flow rate and a high and homogeneous temperature to represent the appropriate criteria that should be respected to obtain a hot air generator overcoming the previously mentioned constraints.Furthermore;the results of this work show the influence the boundary conditions and Rayleigh number on the resulting flow.
