Numerical Analysis of Heat and Mass Transfer on Collision Dominated Particles Flow in a Vessel

Author(s):  
T. Yamaguchi ◽  
K. Kanemaru ◽  
S. Momoki ◽  
T. Shigechi ◽  
T. Yamada

Though the solid-gas multiphase flow has been studied experimentally and numerically, the transport phenomena have not been cleared due to its complexity, computational time required and economical costs for hardwares. In this study the heat and mass transfer of solid-gas collision dominated flow in a rectangular vessel is analyzed by the Discrete Particle Simulation (DPS), a kind of the Dispersed Element Methods (DEM)[1]. This method describes the discrete phase and continuous phase by the Lagrange and the Euler methods respectively, and has been used to simulate the multiphase flows of various geometrical systems. In order to analyze the thermal field we took account of the energy equation and heat conduction between colliding particles. We treated the continuous phase as a pseudo two dimensional flow, and the interaction between continuous and discrete phases as two way coupling. The positions, the momenta and the temperature information of particles and velocity and temperature distribution of fluid were obtained as functions of time from results of these numerical simulations. When the hot air flowed from bottom to top in the vessel of packed bed, we traced the particles and got the temperature distribution of fluid. The particles at the surface of the packed bed jumped first and made the void areas at the middle of vessel. We found the void areas that rise in the dispersed particles.

Author(s):  
Tomohiko Yamaguchi ◽  
Kuniyasu Kanemaru ◽  
Satoru Momoki ◽  
Toru Shigechi ◽  
Ryo Fujiwara

The solid-gas or liquid-gas two phase flow has many industrial applications such as spray drying, pollution control, transport systems, fluidized beds, energy conversion and propulsion, material processing, and so on. Though the solid-gas multiphase flow has been studied experimentally and numerically, the transport phenomena have not been cleared due to its complexity, computational time and economical costs for the hardware. In this study the heat and mass transfer of solid-gas collision dominated flow is analyzed by the Discrete Particle Simulation (DPS), a kind of the Dispersed Element Method (DEM)[1]. This method describes the discrete phase and the continuous phase by Lagrange and Euler methods respectively, and has been used to simulate the multiphase flow of various geometrical systems. In order to analyze the thermal field we took account of the energy equation and heat conduction between colliding particles. The heat transfer rate is summation of conductive heat transfer and convective heat transfer. Furthermore, the fluid flow has a two dimensional velocity profile, because the void fractions are analyzed as two dimensions. But momentum space has not been resolved by the two dimensional simulation. We call this method, the quasi two-dimensional simulation in this paper. To obtain the temperature distribution of the continuous phase the energy equation is solved in addition to the momentum equations. We treated the interaction between continuous and discrete phases as one and two way couplings. The positions, the momentum and the temperature information of particles and the velocity and the temperature distribution of the fluid were obtained as functions of time from results of these numerical simulations. When the hot air that is suspending small glass particles flows in a duct from bottom up, we traced the particles and got the temperature distribution of fluid and compared with the former results of one-dimensional flow. At the beginning, the cooler particles decrease the fluid temperature near the bottom of the vessel. The temperature profile of the particles obtained by the one-dimensional simulation is as same as quasi two-dimensional simulation. After 0.5 second the particles cool the downstream air. At 1.2 second, particles do not decrease the air temperature because the temperatures of particles are close to the inlet temperature of the air.


Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 1017 ◽  
Author(s):  
Mateusz Korpyś ◽  
Anna Gancarczyk ◽  
Marzena Iwaniszyn ◽  
Katarzyna Sindera ◽  
Przemysław J. Jodłowski ◽  
...  

Optimization of structured reactors is not without some difficulties due to highly random economic issues. In this study, an entropic approach to optimization is proposed. The model of entropy production in a structured catalytic reactor is introduced and discussed. Entropy production due to flow friction, heat and mass transfer and chemical reaction is derived and referred to the process yield. The entropic optimization criterion is applied for the case of catalytic combustion of methane. Several variants of catalytic supports are considered including wire gauzes, classic (long-channel) and short-channel monoliths, packed bed and solid foam. The proposed entropic criterion may indicate technically rational solutions of a reactor process that is as close as possible to the equilibrium, taking into account all the process phenomena such as heat and mass transfer, flow friction and chemical reaction.


2000 ◽  
Vol 33 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Eri Yamamoto ◽  
Koichi Katsurayama ◽  
Fujio Watanabe ◽  
Hitoki Matsuda ◽  
Masanobu Hasatani

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