Parameters influencing the performance of fluidized bed: A review on thermo-hydraulic properties

ABSTRACT

Owing to its solids handling capacity, closed phases contact with excellent mixing/segregation, heat and mass transfer characteristics, fluidizing beds have been successfully used in various industries for many decades. In this paper, previous studies of fluidization and heat transfer have been critically analyzed concerning the effects of operating parameters. Parametric comparisons of different studies have been done and reported. Detailed reviews of available enhancement techniques used by the researchers for optimum results obtained are presented with a special focus on fluidization and heat transfer studies of sound-assisted binary fluidization. It is clear that, despite the complexity of these processes, the existing methodologies have grown primarily as a result of the efforts of multiple research groups, representing considerable promise for industrial applications and emphasizing the relevance of this research field. The current review covers the various approaches, applications, and discusses their benefits and limitations. Future research opportunities in this area are also identified.

KEYWORDS:

• Fluidized bed
• mixing/segregation
• hydrodynamics
• heat transfer
• binary mixture

Abbreviations

Table

Acknowledgments

The authors wish to thanks Department of Mechanical Engineering School of Engineering, OP Jindal University Raigarh, India for the research grant.

Disclosure statement

There is no conflict of interest.

Highlights

• Extensive review of parametric influence in fluidized bed

• Reviewed and compared operating range effect on performance.

• Review studies on the basis of hydrodynamics effect, heat transfer, sound assisted fluidization, binary mixtures fluidization and CFD studies of fluidization.

Nomenclature

ε	=	Bed voidage
Cps	=	Particle heat capacity (kJ/kg-K)
Cpf	=	Specific heat of air (kJ/kg-K)
Dt	=	Outside diameter of heat transfer tube (m)
dc	=	bottom discharge pipe diameter (mm)
ξ	=	Bulk bed porosity, dimensionless
G	=	Superficial mass fluidizing velocity (kg/m2s)
ϱs	=	Density of solid particles, (kg/m3)
μ	=	Viscosity of the fluidizing gas (N-s/m3)
Kf	=	Thermal conductivity of air (W/m-K)
g	=	Acceleration due to gravity (m/s2)
dsv	=	Mean particle size (µm)
dp	=	Mean particle size (nm)
ρf	=	Fluid density (kg/m3)
Gs	=	Solid flow rate (kg/hr)
T	=	MRT of flotsam (sec)
(1- ε)	=	Flotsam holdup
R-Z	=	Richardson–Zaki equation
H	=	Height of main column (m)
h	=	bed height (mm)
h0	=	initial height of bed (mm)
Wa	=	Coarse bed solids
Wf	=	bed free fines
Δp	=	Pressure drop cross the fluidized bed, (Pa)
Δp0	=	Equilibrium pressure drop (Pa)
Ug	=	Superficial gas velocity (m/s)
Umf	=	Minimum fluidization velocity (m/s)
htc	=	Heat transfer coefficient (kJ/kg-K)
hmax	=	Maximum heat transfer coefficient (kJ/kg-K)
Xf	=	feed composition of flotsam
Ar	=	Archamedes number, dimensionless
Nu	=	Nusselt number, dimensionless
Re	=	Reynolds number, dimensionless
ɸ	=	degree from front stagnation point of tub
Frp	=	Froude number based on particle diameter

Additional information

Funding

This work was supported by the O P Jindal University Raigarh, India.