Modeling and simulation of an industrial indirect solar dryer for Iroko wood (Chlorophora excelsa) in a tropical environment

Simo-Tagne, Merlin; Zoulalian, André; Rémond, René; Rogaume, Yann; Bonoma, B.

doi:10.4067/s0718-221x2017005000009

Cited by 13 publications

(8 citation statements)

References 9 publications

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“…This work will demonstrate how the resulting formula for predicting K can predict kiln driers' performance for various operating conditions. Many models have been developed for this purpose [ 76 , 81]. Full models using CFD (computational fluid dynamics) is beyond the extent of this study.…”

Section: Methodsmentioning

confidence: 99%

Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Chanpet

Rakmak

Matan

et al. 2020

Heliyon

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Kiln drying of rubberwood lumbers is a complex transport phenomenon for realistic modeling and simulation. To decouple this complexity, researchers usually divide their research into two parts. The first one is single-lumber drying kinetics to describe how wood lumber responds to its surface conditions. Then they combine this drying kinetics with a lumped transport model or dispersion model or computational fluid dynamics. The mathematical models are then solved numerically to predict the industrial kiln drying behaviors. This work focuses on the drying kinetics of stacked rubberwood lumbers using hot air at different air velocity (0.5, 1.5, 2.5, 3.5, 4.0 m/s), relative humidity (6–67% relative humidity (RH)) and temperature (60–100 °C). The drying kinetics followed the conventional drying theory. However, the two drying periods, namely constant and falling rate (CRP and FRP), were not distinct. As the air velocity increased, the transition from CRP to FRP is faster. The middle of the transition period (at critical moisture content, CMC) moves closer to the fiber saturation point (FSP). The overall mass transfer coefficients in the falling rate period for stacked rubberwood drying were lower than those predicted by the Ananias correlation. Hence, a modified formula was proposed, representing the overall moisture transfer coefficients as a function of air velocity, temperature, relative humidity, and lumbers thickness for the range of variables under investigation satisfactorily. In general, the drying rate and the overall moisture transfer coefficient increased with increasing air velocity, drying temperature, and decreasing RH. Relative humidity directly affects the driving force of moisture transfer rate because higher RH is associated with higher equilibrium moisture content. A lumped parameter model for kiln drying was also developed. After being integrated with the estimated mass transfer coefficient, the model can predict the moisture profiles in lab-scale kiln drying satisfactory, although the model needs more validation data. These kinetic parameters and correlation for stacked rubberwood drying can be used in more complex models and process optimization in future research.

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Section: Methodsmentioning

confidence: 99%

Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Chanpet

Rakmak

Matan

et al. 2020

Heliyon

View full text Add to dashboard Cite

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“…Simo-Tagne et al modeled the drying curve in an indirect solar dryer for industrial wood drying. The model was validated with experimental data for different operating conditions of the dryer [24]. A dynamic prediction model for air heating in an indirect solar dryer with a double-pass parallel flow solar collector without energy storage was validated by [25].…”

Section: Introductionmentioning

confidence: 99%

Reduced Model and Comparative Analysis of the Thermal Performance of Indirect Solar Dryer with and without PCM

2020

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A thermal model is proposed to analyze the performance of an indirect solar dryer (ISD) with latent heat storage using phase change material (PCM). The estimations are compared with experimental data presented in the scientific literature taken in real conditions. The validated thermal model is used in order to address a comprehensive analysis of the performance of the ISDs under the same operation conditions, the model is able to estimate the temperatures of glass cover, absorber plate, PCM, useful heat, thermal and storage efficiencies, and variables that are difficult to measure experimentally such as liquid fraction, heat losses, and accumulated energy of the ISDs. Three study cases are considered: Case 1 consists of two collectors with and without alternating nocturnal and diurnal operation (benchmarking case). Case 2 and 3 consist in a unique collector operating continuously for 24 h with PCM and without PCM, respectively. It was determined that the use of PCM in ISD increased the night thermal performance and extended the operational time of the system. On the other hand, results indicate that the use of two alternating collectors presents similar discharge behavior to using one collector with PCM operating continuously. Concerning the overall thermal performance, cases 1, 2, and 3 obtained thermal efficiencies of 20%, 28%, and 24%, respectively.

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“…In order to solve the system of partial differential equations, the spatial derivatives were approximated by finite volumes, and the resulting set of ordinary differential equations (ODE) was numerically integrated by a fourth‐order Runge‐Kutta method with a variable time step size, simultaneously. Continuing their research, Simo‐Tagne et al modeled a solar dryer for tropical woods, with the mass transfer coefficient based on a literature correlation for wood drying, and the heat transfer coefficients were determined using either the Dittus‐Boelter correlation or a new correlation developed in their own study.…”

Section: Introductionmentioning

confidence: 99%

Modeling, simulation, and optimization of a microalgae biomass drying process

et al. 2019

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Summary The aim of the present work was to develop a transient mathematical model focused on microalgae biomass drying, considering two phases: solid (wet biomass) and gas (drying air). Mass and thermal energy balances were written for each phase producing a system of ordinary differential equations (ODE). The solution of the ODE set delivers the temperature and air humidity ratio and biomass profiles with respect to time. The numerical results were directly compared with temperature experimental measurements—for both phases—and with the biomass humidity content. Data from experiment 1 were used to carry out the mathematical model adjustment, whereas data from experiment 2 were used for the experimental validation of the model. The model was adjusted by proposing a new correlation for the mass transfer coefficient and by calibrating the heat transfer coefficient. The transient numerical results were in good quantitative and qualitative agreement with the experimental results, ie, within the experimental error bars. Then the experimentally validated mathematical model was utilized to optimize the following parameters: (i) the electric heater power ( Q̇res) and the dry air mass flow rate ( ṁda) and (ii) the convection oven length to width ratio (L/W). The goal was to minimize system energy consumption (objective function). The optimization procedure was subject to the following physical constraints: (i) fixed convection oven total volume and (ii) fixed biomass and drying air contact surface area. For the oven original geometry, Q̇italicres,italicopt = 3.0 kW and ṁitalicda,italicopt = 9 g s−1 were numerically found for minimum energy consumption, so that 36.9% and 43.5% energy consumption decreases were obtained, respectively, in comparison with the measurements of experiment 1. Next, the numerical geometric optimization found (L/W)opt = 9, with Q̇italicres,italicopt and ṁitalicda,italicopt, which was capable to reach a 51.6% energy consumption reduction in comparison with the original system tested in experiment 1. The novelty of this work consists of the development and experimental validation of a physically based microalgae biomass drying mathematical model, ie, instead of using empirical correlations to predict the drying time and temperature profiles and then minimize system energy consumption. Therefore, the results show that it is reasonable to state that the model could be used to design, control, and optimize drying systems with configurations similar to the one analyzed in this study.

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Modeling and simulation of an industrial indirect solar dryer for Iroko wood (Chlorophora excelsa) in a tropical environment

Cited by 13 publications

References 9 publications

Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Effect of air velocity, temperature, and relative humidity on drying kinetics of rubberwood

Reduced Model and Comparative Analysis of the Thermal Performance of Indirect Solar Dryer with and without PCM

Modeling, simulation, and optimization of a microalgae biomass drying process

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