Ranz and Marshall correlations limits on heat flow between a sphere and its surrounding gas at high temperature

This paper discusses the characteristics of Birchwood gasification using the simulated results of a Computational Fluid Dynamics (CFD) model. The CFD model is developed and validated with the experimental results obtained with the fixed bed downdraft gasifier available at the University of Agder (UIA), Norway. In this work, several parameters are examined and given importance, such as producer gas yield, syngas composition, lower heating value (LHV), and cold gas efficiency (CGE) of the syngas. The behavior of the parameters mentioned above is examined by varying the biomass particle size. The diameters of the two biomass particles are 11.5 mm and 9.18 mm. All the parameters investigate within the Equivalences Ratio (ER) range from 0.2 to 0.5. In the simulations, a variable air inflow rate is used to achieve different ER values. For the different biomass particle sizes, CO, CO 2 , CH 4 , and H 2 mass fractions of the syngas are analyzed along with syngas yield, LHV, and CGE. At an ER value of 0.35, 9.18 mm diameter particle shows average maximum values of 60% of CGE and 2.79 Nm 3 /h of syngas yield, in turn showing 3.4% and 0.09 Nm 3 /h improvement in the respective parameters over the 11.5 mm diameter biomass particle.

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“…where Re represents the Reynolds number, while the expression Pr expresses the Prandtl number [45,46].…”

Section: Eulerian-lagrangian Methodsmentioning

confidence: 99%

Numerical and Experimental Investigation of Equivalence Ratio (ER) and Feedstock Particle Size on Birchwood Gasification

Jayathilake

Rudra

2017

Energies

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“…Thermal evolution of the particles depends on heat transfer from the surrounding gas to the particle and on solvent evaporation. The empirical Ranz and Marshall correlation defines the heat transfer between a spherical particle and the surrounding gas for a wide range of thermodynamic properties [24,25]. The calculation of the individual particle Nusselt number Nu thereby is given as:…”

Section: Heat Transfermentioning

confidence: 99%

“…m vap,i the resulting enthalpy stream . H vap,i from the gas to the liquid and vapor at the surface of each individual particle is calculated according to Equation (25), where ∆h vap,i (T f,i ) is the temperature-dependent evaporation enthalpy of the liquid and c P,vap,i is the specific heat capacity of the vapor at constant pressure:…”

Section: Mass Transfermentioning

confidence: 99%

Pulsed Multiphase Flows—Numerical Investigation of Particle Dynamics in Pulsating Gas–Solid Flows at Elevated Temperatures

et al. 2020

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Although the benefits of pulsating multiphase flows and the concomitant opportunity to intensify heat and mass transfer processes for, e.g., drying, extraction or chemical reactions have been known for some time, the industrial implementation is still limited. This is particularly due to the lack of understanding of basic influencing factors, such as amplitude and frequency of the pulsating flow and the resulting particle dynamics. The pulsation generates oscillation of velocity, pressure, and temperature, intensifying the heat and mass transfer by a factor of up to five compared to stationary gas flow. With the goal of process intensification and targeted control of sub-processes or even the development of completely new processing routes for the formation, drying or conversion of particulate solids in pulsating gas flows as utilized in, e.g., pulse combustion drying or pulse combustion spray pyrolysis, the basic understanding of occurring transport processes is becoming more and more important. In the presented study, the influence of gas-flow conditions and particle properties on particle dynamics as well as particle residence time and the resulting heat and mass transfer in pulsating gas–solid flows are investigated.

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“…where Re and Pr are Reynolds and Prandtl numbers based on gas properties and the relative velocity of droplets, β c = 0.6 (Ranz and Marshall correlation) and β c = 0.552 (Frossling correlation) (see [30] for a discussion of other similar correlations). An alternative correlation for Nu was suggested by Clift et al [31]:…”

Section: Heating Of Non-evaporating Dropletsmentioning

confidence: 99%

Droplets and Sprays

Basu¹,

Ágarwal²,

Mukhopadhyay³

et al. 2018

Energy, Environment, and Sustainability

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Ranz and Marshall correlations limits on heat flow between a sphere and its surrounding gas at high temperature

Cited by 42 publications

References 13 publications

Numerical and Experimental Investigation of Equivalence Ratio (ER) and Feedstock Particle Size on Birchwood Gasification

Numerical and Experimental Investigation of Equivalence Ratio (ER) and Feedstock Particle Size on Birchwood Gasification

Pulsed Multiphase Flows—Numerical Investigation of Particle Dynamics in Pulsating Gas–Solid Flows at Elevated Temperatures

Droplets and Sprays

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