An investigation of produce cooling tunnel performance

Abstract

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.

The numerical results from a simple computational fluid dynamic model of a forced air agricultural produce cooling tunnel are compared with experimental measurements made on a full scale tunnel. The experimental tunnel consists of four pallets of produce each holding a number of boxes arranged in a specified, but non-uniform stacking order. The tunnel is located in a large cold storage room while the cold air is drawn at a steady rate through the boxes using a large axial flow fan. The time dependent temperature and pressure values are experimentally determined at a number of strategic locations within the tunnel. The experimentally determined values of the tunnel pressures as well as the produce temperature as functions of time are plotted in a non-dimensional manner. These are then compared with the results of the computational fluid dynamics model. In the model the boxes filled with the agricultural produce, cucumbers in this case, are approximated using porous jumps for the boxes and a non-isotropic porous media model with empirically determined coefficients for the produce. A commercially available finite volume package is used to solve for the time dependent temperature, pressure and flow field. The discrepancies between the experimental and numerical results are discussed and suggestions made for improving the numerical model.