Browsing by Author "Tiamiyu, Nurayn Adewale Tiamiyu"

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    Exploring next generation packaging systems in a refrigerated container using CFD Modelling
    (Stellenbosch : Stellenbosch University, 2020-12) Tiamiyu, Nurayn Adewale Tiamiyu; Coetzee, C. J.; Berry, T. M.; Opara, U. L.; Tsige, A. A.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: The ineffective utilisation of refrigerated container's (RC) space is a pressing problem for the South African fruit industry. Current packaging systems do not optimally make use ofthe refrigeration unit for airflow distribution and cooling efficiency of fruit. This results in heterogeneous airflow circulation and ineffective cooling of fruit. The aim of this research wasto develop a validated computational fluid dynamics (CFD)model. The model was then used to explore novel packaging system for improved RC space utilisation and cooling performance. Both cooling and space utilisation aspects of the container need to be improved simultaneously, as market trends are increasingly demanding higher-quality fresh produce at lower costs. Firstly, a 3D CFD model of a fully packed RC was developed and validated experimentally. Pallets were considered as a porous media, and their directional loss properties were experimentally determined. A functional refrigeration unit was incorporated in the model to account for the dynamic cooling modes of the container. The resulting model predicted acceptable results with respect to airflow and temperature. Modelling prediction error was 17% for airflow distribution and 11% for the temperature prediction. Subsequently, the developed CFD model was used to evaluate conceptual packaging systems for space utilisationand cooling efficiency. Numerical simulations were performed to characterise the airflow distribution and cooling performance of the packaging system in a fully loaded refrigerated container. A multi-parameter approach was used to evaluate the performance of five loading scenarios, namely: Standard A, Standard B, Standard C, Hex and Tes in a fully loaded refrigerated container. The average convective heat transfer coefficient (CHTC)relative standard deviation (RSD) of the Standard packaging system is 47% higher than the Hex design and 51% higher than the Tes design. Overall, Tes design shows significant improved performance for space utilisation and quality preservation of packaged fruit. The results thus highlighted the substantial improvements that are possible concerning shipping costs and quality preservation if alternative packaging system designs are considered in the future.Lastly, the pallet stack ventilation requirements of the Standard packaging system in a refrigerated container was characterised.The influence of packaging system directional loss properties (i.e. the pallets ventilation) on airflow patterns within the pallet stacks was demonstrated. This has significant implications on the cooling uniformity and quality preservation of packaged fruit. The study further provides, for the first time, a benchmark for the design of ventilation in fresh produce packaging towards improved usage of refrigerated containers.