Browsing by Author "Nicolai, B. M."

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    CFD model development and validation of a thermonebulisation fungicide fogging system for postharvest storage of fruit
    (Elsevier, 2012-01) Delele, M. A.; Vorstermans, B.; Creemers, P.; Tsige, A. A.; Tijskens, E.; Schenk, A.; Opara, Umezuruike Linus; Nicolai, B. M.; Verboven, P.
    Postharvest treatments of fruits in storage rooms using a fogging system is a recent development that offer a promising means to reduce the use of fungicides in the orchards, where ecological and environmental risks are higher than in the closed environment of the storage room. To investigate the effectiveness of postharvest storage fungicide fogging systems, a computational fluid dynamics (CFD) model was developed and validated. A discrete element (DE) method was applied to generate a random stacking of spherical fruits in a typical bin. The CFD model was then employed to study explicitly the air and fungicide particle flow through the bin vent holes and through the voids of the stack, and to predict the deposition behaviour of the fungicide particle on the products. For model validation purposes, a standardized set-up was used with a single fruit bin positioned in a cold store that was operated at different air flow rates. Good agreement was found between measured and predicted results of deposition profiles of fungicide particles. The deposition on the top layer of the fruit stack was higher than the bottom one, and higher deposition was observed on the top sides than on the bottom sides of the fruit. The effect of air flow rates and different bin handling parameters on fungicide particles flow and deposition were investigated. Air circulation rates of 0 m3 h 1 (no air circulation), 4080 m3 h 1 and 6800 m3 h 1 and 9520 m3 h 1 were used. The highest fungicide deposition on the fruit was observed during fogging without air circulation while the lowest deposition corresponded to fogging with the highest air circulation rate. Covering the top of the bin with foil and removing the bottom plastic foam that is usually placed on the bottom floor of the bin improves the uniformity of fungicide deposition throughout the bin. Removing the bottom plastic liner increased the average deposition of the fungicide particles, while covering the top of the bin decreased the average deposition
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    Investigating the performance of thermonebulisation fungicide fogging system for loaded fruit storage room using CFD model
    (Elsevier, 2012-03) Delele, M. A.; Vorstermans, B.; Creemers, P.; Tsige, A. A.; Tijskens, E.; Schenk, A.; Opara, Umezuruike Linus; Nicolai, B. M.; Verboven, P.
    To study the operation of postharvest storage fungicide fogging systems, a CFD model was used. The modelling was based on an Eulerian–Lagrangian multiphase flow model. The effect of air circulation rate, circulation interval, bin design, stacking pattern and room design on deposition of fungicide was investigated. Air circulation rates of 0 m3 h 1 (no circulation), 2100 and 6800 m3 h 1 were used. Interval circulation of air was also investigated. The highest fungicide deposition was observed during fogging without circulation while the lowest deposition corresponded to fogging with the highest circulation rate. For the considered on/off combination times, the effect of circulation interval on overall average deposition and uniformity was not significantly different from the case of fogging with continuous air circulation. Bin with higher vent hole ratio and the presence of air deflector increased the amount and uniformity of deposition. Good agreement was found between measured and predicted results of deposition of fungicide particles.
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    NIR spectroscopy applications for internal and external quality analysis of citrus fruit - A review
    (Springer, 2012) Magwaza, L. S.; Opara, U. L.; Nieuwoudt, Helene; Cronje, P. J. R.; Saeys, W.; Nicolai, B. M.
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    Prediction of 'Nules Clementine' mandarin susceptibility to rind breakdown disorder using Vis/NIR spectroscopy
    (ELSEVIER SCIENCE BV, PO BOX 211, AMSTERDAM, NETHERLANDS, 1000 AE, 2012) Magwaza, L. S.; Opara, U. L.; Terry, L. A.; Landahl, S.; Cronje, P. J. R.; Nieuwoudt, Helene; Mounem Mouazen, A.; Saeys, W.; Nicolai, B. M.
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    The use of CFD to characterize and design post-harvest storage facilities : past, present and future
    (Elsevier, 2012) Ambaw, A.; Delele, M. A.; Defraeye, T.; Ho, Q. T.; Opara, Umezuruike Linus; Nicolai, B. M.; Verboven, P.
    There has long been an interest on the use of mathematical models for optimization of post-harvest refrigeration systems operation and design. These mathematical models are applied to predict the biophysical phenomena that take place during post-harvest handling of horticultural products. CFD has now become feasible to investigate the flow, heat and mass transfer processes in such details that include complex aspects such as product stacking, gas diffusion and kinetics, and droplet or particle dispersion. This review paper summarizes the advances in the application of CFD applied to post-harvest storage of horticultural products. Due to the geometrical complexity of post-harvest products, packages and systems and limitations due semi-empirical models for turbulence and porous media, new strategies using multiscale methods are starting to be successful.