Sunburn in fruit is caused by excess heat and radiation and has a major economic impact on apple production. Evaporative cooling can be used to keep the apple temperatures below a critical value, but the process needs to be optimised for maximum cooling effect and to avoid excessive use of water. A numerical model was developed to predict the skin and core temperatures of an apple subjected to evaporative cooling. The method makes use of climatic data recorded by a weather station. The model predicted apple skin and core temperatures accurately with a maximum error of 6.4%. The drop in skin temperature when evaporative cooling was applied could be accurately predicted with an error of 5.3%. The results indicate that the model can be used, in combination with a control system and input from a weather station, to control and manage an evaporative cooling system.
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