Simulation and Performance of a Solar Drying Unit with Storage for Aromatic and Medicinal Plants
-
M. Ayadi
,
I. Zouari
Abstract
The objective of this work, based on a theoretical and experimental study, is to investigate the energy and economic performance of a totally solar drying unit with storage for aromatic and medicinal plants, to satisfy a dimensioning already carried out on a macroscopic scale for an energy request well defined: to dry a quantity of a given agricultural products during 1 day of harvest season, so between September and May, with a heat storage which relays at night. Drying experiments were conducted for spearmint grown in Tunisia. Mathematical formulation of the physical process of this solar drying unit based on conventional heat and mass transfer equations showed a certain agreement with the experimental results under climatic conditions of Tunis (Tunisia). All the experimental drying curves showed only a falling drying rate period. The main factor in controlling the drying rate was found to be the drying air temperature. It was observed that this unit is able to dry more than 2.5 kg of spearmint per day with a moisture reduction efficiency of 70%. It was found that for all the period of harvest, so for 5 months assumed dryer used per year, the payback period is 3.6 years.
Acknowledgements:
The authors would like to thank the Energy Laboratory and Thermal Processes (CRTEn) for the support in conducting the drying experiments. Valuable advice from Prof. S.B.MABROUK is also gratefully acknowledged.
Nomenclature
- A
updating rate (%).
- Bsa
updated global benefit (DT)
- CP
specific heat (J/kg K)
- Ca
updated global cost (DT)
- Ci
initial investment cost of the system (DT)
- Cia
updated initial investment (DT)
- Cuma
updated costs of maintenance (DT)
- Cum (i)
cost of maintenance at year i (DT)
- Cuf (i)
cost of operation at year i (DT)
- Cufe (i)
cost of the energy invoice (DT)
- Cufa
updated costs of operation (DT)
- Cufe(1)
cost of the energy invoice during the first year (DT)
- Cuff (1)
cost of fresh plants during the first year (DT)
- Cups(1)
sale price of dried product (DT)
- D
average diameter (m)
- Ei
economy on the energy cost due to the part solar of the system during year i and expressed in current value (DT)
- e
thickness (m)
- Ga
updated profits (DT)
- ha,pr
convective heat transfer coefficient air-product (W/m2K)
- ha,PI
convective heat transfer coefficient air-wall (W/m2K)
- hPe,am
convective heat transfer coefficient wall–ambient (W/m2K)
- Hr
radiative heat transfer coefficient wall–ambient (W/m2K)
- LV
latent heat of vaporization (J.kg-1)
- m
mass (kg)
- ma
mass flow rate of air (kg/s)
- Ms
annual quantity of dried product (kg)
- N
lifespan of the system (years)
- Nu
Nusselt number
- Rg
global investment rate in updated values
- Re
Reynolds number
- S
surface area (m2)
- t
time (s)
- T
temperature (°C)
- Tamo
payback period (years)
- Va
air velocity on the product level (m/s)
- Vv
wind speed (m/s)
- X
moisture content (kg water/kgdm)
- ζf1
variation annual rates of energy invoice (%)
- ζf2
variation annual rates of products acquisition (%)
- ζm
variation annual rates of maintenance (%)
- ζp
variation annual rates of products sale price (%)
- λ
thermal conductivity (W/mK)
- ρa
density of the air (kg/m3)
- Subscripts
- a
heated air
- ciel
Sky
- sec
Dry
- p
Wall
- pb
Box
- Pe
external wall
- Pi
intermediary insulator-wall
- PI
interior wall
- pp
Insulator
- pr
Product
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©2015 by De Gruyter
Articles in the same Issue
- Frontmatter
- Research Articles
- Numerical Solution of a Nonlinear Diffusion Model for Soybean Hydration with Moving Boundary
- Simulation and Performance of a Solar Drying Unit with Storage for Aromatic and Medicinal Plants
- Preparation of Nano-curcumin with Enhanced Dissolution Using Ultrasonic-Assisted Supercritical Anti-solvent Technique
- Effect of Various Concentration of β-Cyclodextrin Inclusion Complexes Containing trans-Cinnamaldehyde by Molecular Self-Assembly
- Effects of Amount of Batter in Baking Cup on Muffin Quality
- Influence of Tapioca Starch on Thermal Properties of Wheat Flour-Based Batter and Quality of Fried Battered Chicken Wingsticks
- Clarification of Date Syrup by Activated Carbon: Investigation on Kinetics, Equilibrium Isotherm, and Thermodynamics of Interactions
- Changes in Some Quality Properties of Kefir during Storage and Inhibition Effect of Water Soluble Extracts on Angiotensin-I Converting Enzyme Purified by Human Plasma
- Drying Characteristics and Assessment of Physicochemical and Microstructural Properties of Dried Culinary Banana Slices
- Multi-Objective Optimization of the Pasteurization Process of Pumpkin Cubes Packaged in Glass Jars
- Mathematical Modeling of Thin-Layer Solar Drying for Yarrow, Coriander and Hollyhock
- Shorter Communication
- Drying Kinetics of American Ginseng Slices in Thin-layer Air Impingement Dryer
Articles in the same Issue
- Frontmatter
- Research Articles
- Numerical Solution of a Nonlinear Diffusion Model for Soybean Hydration with Moving Boundary
- Simulation and Performance of a Solar Drying Unit with Storage for Aromatic and Medicinal Plants
- Preparation of Nano-curcumin with Enhanced Dissolution Using Ultrasonic-Assisted Supercritical Anti-solvent Technique
- Effect of Various Concentration of β-Cyclodextrin Inclusion Complexes Containing trans-Cinnamaldehyde by Molecular Self-Assembly
- Effects of Amount of Batter in Baking Cup on Muffin Quality
- Influence of Tapioca Starch on Thermal Properties of Wheat Flour-Based Batter and Quality of Fried Battered Chicken Wingsticks
- Clarification of Date Syrup by Activated Carbon: Investigation on Kinetics, Equilibrium Isotherm, and Thermodynamics of Interactions
- Changes in Some Quality Properties of Kefir during Storage and Inhibition Effect of Water Soluble Extracts on Angiotensin-I Converting Enzyme Purified by Human Plasma
- Drying Characteristics and Assessment of Physicochemical and Microstructural Properties of Dried Culinary Banana Slices
- Multi-Objective Optimization of the Pasteurization Process of Pumpkin Cubes Packaged in Glass Jars
- Mathematical Modeling of Thin-Layer Solar Drying for Yarrow, Coriander and Hollyhock
- Shorter Communication
- Drying Kinetics of American Ginseng Slices in Thin-layer Air Impingement Dryer
