Authors: Mulugeta A Delele Mduduzi E K Ngcobo Umezuruike Linus Opara Chris J Meyer
Publish Date: 2012/05/30
Volume: 6, Issue: 9, Pages: 2571-2585
Abstract
The flow phenomenon during cooling and handling of packed table grapes was studied using a computational fluid dynamic CFD model and validated using experimental results The effects of the packaging components bunch carry bag and plastic liners and box stacking on airflow heat and mass transfer were analysed The carton box was explicitly modelled grape bunch with the carry bag was treated as a porous medium and perforated plastic liners were taken as a porous jump Pressure loss coefficients of grape bunch with the carry bag and perforated plastic liners were determined using wind tunnel experiments Compared with the cooling of bulk grape bunch the presence of the carry bag increased the half and seven eighth cooling time by 6109 and 9734 respectively The addition of plastic liners over the bunch carry bag increased the half and seven eighth cooling time by up to 16890 and 18522 respectively Nonperforated liners were most effective in preventing moisture loss but also generated the highest condensation of water vapour inside the package For perforated plastic liners cooling with a high relative humidity RH air minimised fruit moisture loss Partial cooling of the grape bunch inside the carry bag before covering it with a nonperforated plastic liner maintained the required high RH inside the package without condensation The stacking of packages over the pallet affected the airflow pattern the cooling rate and moisture transfer There was a good agreement between measured and predicted results The result demonstrated clearly the applicability of CFD models to determine optimum table grape packaging and cooling procedures
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