scholarly journals Three-Dimensional Pore-Scale Simulation of Flow and Thermal Non-Equilibrium for Premixed Gas Combustion in a Random Packed Bed Burner

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6939
Author(s):  
Jinsheng Lv ◽  
Junrui Shi ◽  
Mingming Mao ◽  
Fang He
Keyword(s):  
Flow Simulation ◽  
Local Variation ◽  
Packed Bed ◽  
Surface Radiation ◽  
Discrete Ordinates ◽  
Layer By Layer ◽  
Pore Scale ◽  
Gas Temperature ◽  
Gas Combustion ◽  
Non Equilibrium

Pore-scale studies of premixed gas combustion in a packed bed is conducted to study the flow and thermal non-equilibrium phenomenon in packed bed. The 3D random packed bed is generated using the EDEM software and solid surface radiation is computed using Discrete Ordinates (DO) model. The simulations are carried out using a commercial software package based on the finite volume method. It is shown that the local variation of species mass fraction, reaction rate et al. in pores near the flame front is significant, the radiation heat flux is transferred layer-by-layer. Cold flow simulation without reaction reveals that flow non-equilibrium is one of the essential characteristics of packing bed and increase in flow velocity leads to intensify non-equilibrium phenomenon. The distributions for content of axial velocity and gas temperature are wave-like shape in the burner and vary with time.

Experimental and Pore-scale Analysis of Flow and Thermal Fields in a Packed Bed Channel

2021 ◽  
pp. 1-18
Author(s):  
Mansoureh Khaljani ◽  
Meysam Nazari ◽  
Mahdi Azarpeyvand ◽  
Yasser Mahmoudi
Keyword(s):  
Packed Bed ◽  
Scale Analysis ◽  
Pore Scale ◽  
Thermal Fields

scholarly journals Influence of Gas Temperature in Atmospheric Non-Equilibrium Plasma on Bactericidal Effect

2018 ◽  
Vol 23 (4) ◽  
pp. 167-175 ◽  
Author(s):  
HIROAKI KAWANO ◽  
TOSHIHIRO TAKAMATSU ◽  
YURIKO MATSUMURA ◽  
HIDEKAZU MIYAHARA ◽  
ATSUO IWASAWA ◽  
...  
Keyword(s):  
Bactericidal Effect ◽  
Gas Temperature ◽  
Equilibrium Plasma ◽  
Non Equilibrium

scholarly journals Heat transfer enhancement of the open-type heat recovery unit

2020 ◽  
Vol 177 ◽  
pp. 03019
Author(s):  
Stanislav Davydov ◽  
Rafail Apakashev ◽  
Konstantin Kokarev
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Combustion Products ◽  
Specific Humidity ◽  
Gas Temperature ◽  
Transfer Enhancement ◽  
Gas Combustion ◽  
Open Type ◽  
Heat Transfer Efficiency ◽  
Recovery Unit

An increase in the heat transfer efficiency of the open-type heat recovery unit due to the sequential heat and mass transfer enhancement is considered. The graphs of variances in the water temperature, gas temperature, gas enthalpy and gas specific humidity at the end of each site are presented. The proposed designs of the open-type heat recovery unit can be used for the flue gas disposal, including the disposal of natural gas combustion products in the greenhouse facility.

Heat Transfer to Oil Shale in a Closely Spaced Bundle as an Approximation to a Packed Bed

1981 ◽  
Vol 103 (4) ◽  
pp. 307-317
Author(s):  
K. S. Udell ◽  
H. R. Jacobs
Keyword(s):  
Heat Transfer ◽  
Oil Shale ◽  
Tube Bundle ◽  
Packed Bed ◽  
Cylindrical Sample ◽  
Chemical Processes ◽  
Published Data ◽  
Thermal Processes ◽  
Gas Temperature

The heat transfer to a single cylindrical sample of oil shale in a staggered tube bundle was studied both numerically and experimentally in order to evaluate the thermal and chemical processes associated with the retorting of oil shale in packed beds particular to in-situ processing. The cylinders were subjected to constant gas temperatures and to gas temperature histories experienced in an actual combustion retort. The results of the numerical modeling were compared with the experimental data in order to evaluate the model’s performance. It was found that the model satisfactorily described the thermal processes experienced during the combustion retorting of oil shale within the limits of the accuracy of published data on oil shale thermal properties and chemical kinetics. Net heat transfer to cylindrical oil shale samples in a staggered bundle configuration was also calculated and was shown to nearly duplicate published data related to gas-solid heat transfer in a packed bed combustion retort.

scholarly journals Analysis of Internal Gas Leaks in an MCFC System Package for an LNG-Fueled Ship

2019 ◽  
Vol 9 (11) ◽  
pp. 2330
Author(s):  
Gilltae Roh ◽  
Youngseung Na ◽  
Jun-Young Park ◽  
Hansung Kim
Keyword(s):  
Fuel Cell ◽  
Flow Simulation ◽  
Cell System ◽  
Molten Carbonate Fuel Cell ◽  
Gas Temperature ◽  
Molten Carbonate ◽  
Fuel Cell System ◽  
Gas Leakage ◽  
Gas Leak ◽  
Temperature And Pressure

The airflow inside the housing of a 300-kW molten carbonate fuel cell (MCFC) system is designed to ensure safety in case of a gas leak by applying computational fluid dynamics (CFD) techniques. In particular, gas accumulating zones are identified to prevent damage to vulnerable components from high temperature and pressure. Furthermore, the location of the alarm unit with the gas-leak detector is recommended for construction of safe MCFC ships. In order to achieve this, a flow-tracking and contour field (for gas, temperature, and pressure) including a fuel-cell stack module, balance-of-plant, and various pipes is developed. With the simulated flow field, temperature flow is interpreted for the heating conditions of each component or pipe in order to find out where the temperature is concentrated inside the fuel cell system, as well as the increase in temperature at the exit. In addition, the gas leakage from the valves is investigated by using a flow simulation to analyze the gas and pressure distribution inside the fuel cell system.

Bubble mechanisms and characteristics at pore scale in a packed-bed reactor

2009 ◽  
Vol 64 (13) ◽  
pp. 3179-3187 ◽  
Author(s):  
Daeseong Jo ◽  
Shripad T. Revankar
Keyword(s):  
Packed Bed ◽  
Packed Bed Reactor ◽  
Pore Scale

Simulation of Combustion and Thermal-Flow Inside a Petroleum Coke Rotary Calcining Kiln: Part 2—Analysis of Effects of Tertiary Airflow and Rotation

2009 ◽  
Author(s):  
Zexuan Zhang ◽  
Ting Wang
Keyword(s):  
Natural Gas ◽  
Angular Position ◽  
Air Injection ◽  
Peak Temperature ◽  
Thermal Flow ◽  
Gas Temperature ◽  
Gas Combustion ◽  
Rotational Angle ◽  
Air Jets ◽  
Natural Gas Combustion

A computational model is established to simulate the combustion and thermal-flow behavior inside a petcoke rotary calcining kiln. The results show that peak temperature is located at the tertiary air zone and a cold region that exists between the natural gas combustion zone and the tertiary air zone causes the coke bed to lose heat to the gas stream. The cold tertiary air injections reduce the gas temperature inside the kiln, so preheating the tertiary air using extracted gas or other waste energy is essential to saving energy. The devolatilization rate and location have a pronounced effect on the simulated temperature distribution. As the calcining kiln rotates, the tertiary air injection nozzles will move relative to the coke bed and exert cyclic air-bed interactions. At zero angular position, the air injection nozzles are diametrically located away from the bed, so the interactions between the tertiary air jets and coke bed are minimal. As the kiln rotates to a 180-degree position, the stem of the air injection nozzles are actually buried inside the coke bed with the nozzles protruding outward from the bed. At this position, the tertiary air jets will provide a fresh layer of air just above the coke bed, and the interaction between the air flow and coke bed becomes strong. The 45° rotational angle case shows a better calcination with a 100 K higher bed surface temperature at the discharge end compared to the rest of rotational angles. Without including the coke fines combustion and the coke bed, the lumped gas temperature for the rotational cases shows a peak temperature of 1,400 K at Z/D = 2, which is due to natural gas combustion; the lowest temperature is around 1,075 K at two locations, Z/D = 4 and 8, respectively. The exhaust gas temperature is approximately 1,100K.

Surface Radiation Exchange for Two-Dimensional Rectangular Enclosures Using the Discrete-Ordinates Method

1992 ◽  
Vol 114 (2) ◽  
pp. 465-472 ◽  
Author(s):  
A. Sa`nchez ◽  
T. F. Smith
Keyword(s):  
Weighting Factor ◽  
Heat Fluxes ◽  
Surface Radiation ◽  
Discrete Ordinates ◽  
Two Dimensional ◽  
Discrete Ordinates Method ◽  
Radiation Exchange ◽  
Radiant Exchange ◽  
Irregular Geometries ◽  
Good Agreement

The purpose of this study is to develop a model based on the discrete-ordinates method for computing radiant exchange between surfaces separated by a transparent medium and to formulate the model so that arbitrary arrangements of the surfaces can be accommodated. Heat fluxes from the model are compared to those based on the radiosity/irradiation analysis. Three test geometries that include shadowing and irregular geometries are used to validate the model. Heat fluxes from the model are in good agreement with those from the radiosity/irradiation analysis. Effects of geometries, surface emittances, grid patterns, finite-difference weighting factor, and number of discrete angles are reported.

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