Wind tunnel airflow measurements on plastic apple storage bins

During long-term apple cold storage, the fan operation for airflow requires high electrical energy demand to maintain uniform climatic conditions throughout the storage room.
Airflow and heat exchange along apple surface is necessary to remove respiration heat but it has to be minimized in order to limit weight loss due to transpiration to around 2-3% over the period of 6-8 months storage.
In order to develop storage bins for optimizing airflow distribution near the fruit surface, the airflow characteristics inside and around plastic storage bins were studied.
Experiments were performed with dummy apples filled bins centrally arranged in a wind tunnel of 18 m length and 3 m width at ambient temperature.
The air velocity distribution was measured by directional sensitive hot-wire anemometers in the front, at the side and at the rear of the bins with upstream velocity of 2 m s^-1. A newly developed airflow velocity measuring device was used to determine air velocity in the gaps between the fruits.
Experimental data were used to validate velocity distribution model based on CFD approach.
Qualitative comparison of the experimental and simulation results proved a conformal flow behavior.
An upstream velocity of 2 m s^-1 towards the bin caused low air velocity of 0.2 m s^-1 inside the bin.
The velocity distribution inside the bin was mainly influenced by pressure differences inside and outside the bin.
This approach would be useful to optimize the openings on the bin surfaces related to the porosity of the apple bulk.
Thus, improving the flow distribution inside the apple bin and also minimized the energy consumption for ventilation of cold stores with enhanced airflow through the plastic bins.

VIII International Postharvest Symposium: Enhancing Supply Chain and Consumer Benefits – Ethical and Technological Issues

H. Scaar, U. Praeger, M. Spuhler, D.A. Neuwald, I. Truppel, M. Linke, K. Gottschalk, M. König, J.N. Wünsche, M. Geyer

apple storage, plastic bins, air velocity distribution, porosity, bin openings, computational fluid dynamics

https://doi.org/10.17660/ActaHortic.2018.1194.186