Applying CFD for Studying the Dynamic and Thermal Behavior of Solar Chimney Drying System with Reversed Absorber
-
Souheyla Khaldi
,
A. Nabil Korti
Abstract
This article provides numerical study of the solar chimney (SC) assembled with a reversed absorber and packed bed for the indirect-mode solar dryer. The present study was designed to determine the effects of using the SC in three configuration and physical proprieties of the packed (thickness and porosity) on the dynamic and thermal behavior of airflow. The results reveal that (1) using SC without storage material can increase the maximum mass flow rate up to 5%. However, integrating a storage material in the SC can improve the mass flow rate up to 32% during nighttime; (2) the use of a packed bed can decrease the crops temperature fluctuation until about 76% and increase the operating time of the solar dryer up to 12.5 hours rather than 10 hours in the case without packed bed; (3) increasing the porosity from 0.1 to 0.8 can increase the maximum temperature by about 10°C.
Appendix
Constant parameters used in the equations are presented in Table 3.
Nomenclature
- Latin letters
mirror surface, m2
- C
inertial resistance factor
empirical coefficients of eq. (16)
empirical coefficients of eq. (16)
- C1
constant for the turbulence model
- C2
constant for the turbulence model
- c
specific heat at constant pressure, J kg−1K−1
constant for the turbulence model
- Dp
particle diameter
- d
air outlet, m
- e
air inlet, m
- Gsun
solar irradiations, W.m−2
- Gk
turbulence model coefficient
- g
gravitational acceleration, m.s−2
- h0
convective heat transfer coefficient due to wind, W.m−2.K−1
- Hb
height of packed bed, m
- K
thermal conductivity, W.m−1.K−1
- k
turbulence kinetic energy
- N
normal coordinate, m
- P
pression, Pa
- Pa
atmospheric pressure, Pa
- Pr
Prandtl number
- R
universal gas constant, J K−1 mol−1
- S
source term
- T
temperature, °C or K
- Vv
wind velocity; m/s
- x
horizontal coordinate, m
- y
vertical coordinate, m
- Greek symbols
- α
coefficient of absorbtion
- β
coefficient of thermal expansio
- vj
velocity magnitude y direction, m.s−1
- va
air velocity, m.s−1
dissipation rate of turbulence energy (m2.s)
- τ
coefficient of transmissivity
- ρ’
coefficient of reflectivity of mirrors
- μt
turbulent dynamic viscosity, kg (m s)-1
- µ
dynamic viscosity, kg (m s)-1
- σ
radiation coefficient
- σt
constant for the turbulence model
- σk
constant for the turbulence model
- σε
constant for the turbulence model
- ϵ
porosity
- θ
coefficient of permeability
- ρ
density, kg.m−3
- Subscripts
- a
ambient
- a1
absorber-1
- a2
absorber-2
- c1
crops in tray-1
- c2
crops in tray-1
- eff
effective
- f
fluid phase in packed bed
- G
glass cover
- m
average
- ref
reference
- s
solid phase in packed bed
- w
wood
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- Development and Evaluation of a Small-scale In-field Integrated Postharvest Citrus Treatment Unit – Part 1
- Unripe Banana Flour Produced by Air-Drying Assisted with Ultrasound – Description of the Mechanisms Involved to Enhance the Mass Transfer in Two Approaches
- Analysis of Operating Conditions on Osmotic Dehydration of Plums (Prunus Domestica L.) and 3D-Numerical Determination of Effective Diffusion Coefficients
- Applying CFD for Studying the Dynamic and Thermal Behavior of Solar Chimney Drying System with Reversed Absorber
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- Drying Kinetics of Continuous and Intermittent Heat Pump Drying of Green Soybean Seeds
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Articles in the same Issue
- Functional and Film-forming Properties of Mechanically Deboned Chicken Meat Proteins
- Development and Evaluation of a Small-scale In-field Integrated Postharvest Citrus Treatment Unit – Part 1
- Unripe Banana Flour Produced by Air-Drying Assisted with Ultrasound – Description of the Mechanisms Involved to Enhance the Mass Transfer in Two Approaches
- Analysis of Operating Conditions on Osmotic Dehydration of Plums (Prunus Domestica L.) and 3D-Numerical Determination of Effective Diffusion Coefficients
- Applying CFD for Studying the Dynamic and Thermal Behavior of Solar Chimney Drying System with Reversed Absorber
- Optimization and In-vitro Evaluation of Coating Process for Film-Coated Tablets
- Drying Kinetics of Continuous and Intermittent Heat Pump Drying of Green Soybean Seeds
- Predicting Storage Conditions for Rice Seed with Thermodynamic Analysis
- Preparation of Melatonin-Loaded Zein Nanoparticles using Supercritical CO2 Antisolvent and in vitro Release Evaluation
- A Simple Method to Prepare Raw Dehydrated Potato Flour by Low-Temperature Vacuum Drying
