Transient modelling of a packed tower: Mass and heat transfer with reaction

Hastaog̃lu, Mehmet A.

doi:10.1016/0016-2361(95)00164-z

Cited by 9 publications

(8 citation statements)

References 27 publications

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“…where α 1 = 1.8583 × 10 −7 [28], T env is the envelope temperature, P gas is the pressure in atmospheres, r col is the collision diameter, and r gas and r air are the collision diameters of the lifting gas and ambient air, respectively.…”

Section: Lifting Gas Diffusion Modelmentioning

confidence: 99%

Effect of Lifting Gas Diffusion on the Station-Keeping Performance of a Near-Space Aerostat

Ling

Lei

et al. 2022

Aerospace

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During the long-endurance flight of a near-space aerostat, the characteristics of lifting gas diffusion have a great influence on the flight altitude adjustment and station-keeping performance. Thus, in this study, a lifting gas diffusion model and a dynamic model that consider thermal effects, which had not been studied in similar models before, were developed. The dynamic model and thermal model were validated by historic flight data, and the calculated lifting gas diffusion results were compared with the experimental data of other researchers. The variations in the flight endurance, flight altitude, lifting gas diffusion rate, and diffusion coefficient of a near-space aerostat were analyzed. The effects of the ratio of porosity to tortuosity and envelope radiation properties on the mass of the lifting gas and flight altitude were considered in detail. To analyze the effect mechanism of the ratio of porosity to tortuosity and the envelope radiation properties, the envelope and gas temperature, as well as the gas pressure, were studied. The results show that the lifting gas diffusion rate and diffusion coefficient are very sensitive to the change in the ratio of porosity to tortuosity and envelope temperature. The results obtained from the analysis of the lifting gas diffusion can lay a solid foundation for improving the flight performance of near-space aerostats and for providing improved design considerations for aerostats.

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Section: Lifting Gas Diffusion Modelmentioning

confidence: 99%

Effect of Lifting Gas Diffusion on the Station-Keeping Performance of a Near-Space Aerostat

Ling

Lei

et al. 2022

Aerospace

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“…The single pellet model can be used in designing and simulating commercially important systems such as fluidized and fixed bed reactors. [1,2] Examples of fluid-solid reactions in commercial reactors include pyrolysis in circulating fluidized bed, sulfur capture in fluidized bed combustors in power plants, hydrodesulfurization in fixed beds, etc. Enzyme production in solid matrix [3] can also be studied via similar approaches.…”

Section: Introductionmentioning

confidence: 99%

Modeling of multi gas-solid reactions; effect of bulk environment parameters on solid conversion

Hastaog̃lu

Abba

1998

Metall Mater Trans B

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A unified gas-solid reaction model that considers multi gas-solid components is developed for reactions in porous pellets with multiple reactants. The transient variables and properties of the reactants and transport parameters are continually updated in the simulation. Temperature, pressure, solid conversions, and concentration profiles are well predicted. Structural changes are also considered. Heat, mass, and reaction front tracking equations for all the components are solved simultaneously through a combination of solution techniques. Illustrative validation results for the model are presented for hematite/nickel oxide reduction at 608 K. The importance of bulk temperature and pressure on the overall and individual grain conversions is explored for a range of interest. The response of system parameters to dynamic changes in boundary conditions is studied.

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“…The solution obtained for a pellet can be integrated over reactors (fluidized, fixed), and their behavior can be predicted. , As a result, exploratory research could be carried out on pellets via “numerical procedures” for cases where physical experimentation is not possible due to time, funds, or explosive or other undesirable reaction behavior.…”

Section: Introductionmentioning

confidence: 99%

Pellet Breakup Due to Pressure Generated during Wood Pyrolysis

Hastaog̃lu

Kahraman

Syed

2000

Ind. Eng. Chem. Res.

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A transient unimodel for reacting pellets is considered with various modes of heat and mass transfer and structural changes for wood pyrolysis. Pellet breakup was found to be possible from strength calculations. This leads to an increase in the number of pellets and a decrease in the resistance to heat and mass transfer. The pressure and temperature buildup within 2.7 mm thick pellets was measured for wood pyrolysis/combustion experimentally. The bimodal wood pyrolysis was analyzed, and the rate constant and activation energy were found. Pellet breakup may also be used as a transient catalytic process where the catalysts become smaller as they break up in time.

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Transient modelling of a packed tower: Mass and heat transfer with reaction

Cited by 9 publications

References 27 publications

Effect of Lifting Gas Diffusion on the Station-Keeping Performance of a Near-Space Aerostat

Effect of Lifting Gas Diffusion on the Station-Keeping Performance of a Near-Space Aerostat

Modeling of multi gas-solid reactions; effect of bulk environment parameters on solid conversion

Pellet Breakup Due to Pressure Generated during Wood Pyrolysis

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