• Energy Research

Abstract Fruit and vegetables are stored for up to several months in large bin stacks in refrigerated rooms. Gaps between the bins and bin wall openings should allow the circulation of cooling air to remove field and respiration heat from produce. In an industrial apple store, the effects of the stacking array, fan position and number on airflow distribution in vertical gaps and inside plastic bins were investigated using stepwise reduction of fan revolution. At 100% fan power, the average air velocity in vertical gaps between bin rows in the main flow direction increased with reducing total cross section of the gaps. In contrast, the number of vertical gaps between bin rows had little effect on the average air speed between fruit inside the bins, probably due to additional flow paths in the horizontal gaps. The lowest air speed was measured when bins were stacked in one block without vertical gaps and a distance to the side walls of only 10 cm. A stacking arrangement with only one central vertical gap between four bin rows or with a large distance (> 1 m) between the wall opposite to the fans and the bins enhanced flow uniformity. Three fans situated above the vertical gaps was more effective for the ventilation of bins than four fans above the bin rows.

Abstract Fruit and vegetables are stored for up to several months in large bin stacks in refrigerated rooms. Gaps between the bins and bin wall openings should allow the circulation of cooling air to remove field and respiration heat from produce. In an industrial apple store, the effects of the stacking array, fan position and number on airflow distribution in vertical gaps and inside plastic bins were investigated using stepwise reduction of fan revolution. At 100% fan power, the average air velocity in vertical gaps between bin rows in the main flow direction increased with reducing total cross section of the gaps. In contrast, the number of vertical gaps between bin rows had little effect on the average air speed between fruit inside the bins, probably due to additional flow paths in the horizontal gaps. The lowest air speed was measured when bins were stacked in one block without vertical gaps and a distance to the side walls of only 10 cm. A stacking arrangement with only one central vertical gap between four bin rows or with a large distance (> 1 m) between the wall opposite to the fans and the bins enhanced flow uniformity. Three fans situated above the vertical gaps was more effective for the ventilation of bins than four fans above the bin rows.

Abstract In refrigerated stores of fruit and vegetables, cooling air is circulated by air coolers attached to the ceiling. Uniform airflow and even temperature distribution in the product stacks is important for quality maintenance. However, the air speed close to the produce inside the bins in industrial cold stores is unknown. Airflow distribution was measured with newly developed sensors at different ventilation levels inside bins and in vertical gaps between the bins in a common apple storage room. The air speed between the fruit was low (≤0.3 m/s) compared to the average air velocity in the neighboring gap (1.15 m/s) at 100% fan power. In the bins of the upper stack area, the air speed was about 7 times higher than that in the bins at the bottom. The airflow pattern in the vertical gaps showed the formation of an air roll with relatively uniform air velocity across the height of the bin stack. Reducing the fan power immediately lowered the airflow between the fruit and in the gaps. However, airflow was detected at all measuring positions, even when the fan power was reduced to 44%.

Abstract In refrigerated stores of fruit and vegetables, cooling air is circulated by air coolers attached to the ceiling. Uniform airflow and even temperature distribution in the product stacks is important for quality maintenance. However, the air speed close to the produce inside the bins in industrial cold stores is unknown. Airflow distribution was measured with newly developed sensors at different ventilation levels inside bins and in vertical gaps between the bins in a common apple storage room. The air speed between the fruit was low (≤0.3 m/s) compared to the average air velocity in the neighboring gap (1.15 m/s) at 100% fan power. In the bins of the upper stack area, the air speed was about 7 times higher than that in the bins at the bottom. The airflow pattern in the vertical gaps showed the formation of an air roll with relatively uniform air velocity across the height of the bin stack. Reducing the fan power immediately lowered the airflow between the fruit and in the gaps. However, airflow was detected at all measuring positions, even when the fan power was reduced to 44%.