91C-20 |
Modeling of cooling of strawberries with a computational fluid dynamics solver |
A. SARKAR1, F. Erdogdu2, B. A. Anderson1, and R. P. Singh1. (1) Biological and Agricultural Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, (2) Food Engineering Department, Mersin University, Ciftlikkoy - Mersin, 33342, Turkey Faster cooling rates are of primary importance for higher quality and less post harvest losses in strawberries. But, there is a lack of scientific and technical information on such cooling studies and related modeling attempts. The objective of the present work was to do laboratory scale tests for industrial cooling of strawberries to determine the typical cooling times. Attempts were also made to model the cooling with Fluent V.5, three dimensional, computational fluid dynamics (CFD) solver. Cooling tests were done for strawberries at an initial temperature of 20°C packed in polystyrene packages (number 6) placed in cardboard trays. Trays were stacked three high. Two trays were stacked across the direction of airflow. Airflow rate was kept at 0.009 to 0.012 m³/kg (0.15 to 0.2 ft³/lb) of product per minute. Temperature of inlet airflow was monitored to be 0°C. Cooling was done till seven-eighth cooling was achieved for the strawberries. Cooling was monitored at various places in the stack using single and averaging type T-thermocouples. Three-dimensional models for the polystyrene packages were developed with spherical shapes representative of the strawberries. All the models were developed and meshed using Gambit V.1.3. The inlet and outlet boundaries were defined and the volumes were imported into Fluent V.5.5 solver. Pressure conditions as measured during the cooling tests were defined and the fluid flow and heat transfer were modeled. Typical cooling times were noted to be between 50 to 60 minutes for standard packages for seven-eights cooling under the given conditions for the variability in the setup. The modeling results suggested that there is considerable scope for lowering cooling time by changing shape of the packages. The work suggests that cooling experiment coupled with CFD modeling can result in much better industrial scale cooling applications.
Session 91C, Food Engineering: Food process engineering
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