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Design, Fabrication and Evaluation of a Direct-Fired Corncob Furnace for Corn Drying

Kevin F. Yaptenco1, Jose D. de Ramos2, Emmanuel Q. Amatorio3


A prototype batch-type hot water tank was developed with a batch capacity of 440 kg of mango fruit. Modifications to earlier models included lighter and cheaper insulation panels filled with rice hull ash, a heat exchange coil for better heat utilization, and improved water circulation. Laboratory tests showed the prototype unit could maintain a water temperature variation of ± 0.5oC or less, was adequately buffered against sudden temperature drops with a fruit-to-water ratio of 1:5, achieved a preheating time of 1.5 hrs, had a circulation rate of one water change every 11 min, and could heat water at a rate of 2,500 kJ min-1. Field tests showed that the hot water tank was capable of treating ‘Carabao’ mango fruits at its design capacity while maintaining water temperature at the recommended range of 52-55oC. Samples of treated fruits ripened at room temperature showed no signs of heat damage; incidence of postharvest disease, specifically anthracnose, was reduced from 72% to 50%, while visual quality improved due to removal of latex stains. Feedback from project cooperators showed no negative reactions from their clients with respect to fruit quality. The estimated cost of fabrication of the hot water tank with accompanying mechanical lifter, temperature control system and LPG burner assembly was US$7,030 (PhP313,035.00).

Keywords: Mango, hot water, postharvest, disease control, anthracnose


Yaptenco, K.F., De Ramos, J.D., and Amatorio, E.Q. (2015). Development of a Batch-Type Hot Water Tank for Postharvest Disease Control for ‘Carabao’ Mango and other Crops.  Philippine Journal of Agricultural and Biosystems Engineering, 11:22-35.