Diseño y construcción de un prototipo de deshidratador de frutas de capacidad de 12 kg. con circulación de aire forzado utilizando resistencias eléctricas

Abstract

This paper presents a procedure to build and design a prototype dehydrator with forced hot air circulation that uses electrical resistors, which was applied to the apple slices as raw material. The calculations were performed using experimental formulas of thermodynamics, heat transfer and fluid mechanics, setting the temperature range to be between 50°C to 70 °C to consider for the dehydration of fruits. The chosen analysis parameter of dehydration was set at 65 °C which accommodated for the flow provided by the fan and relative humidity in the air inside of the drying chamber. Using the variables mentioned above we concluded that for a capacity of 12 kg of apple slices, 10 portable trays are needed. As part of the prototype, we implemented a centrifugal fan of 559 CFM and an electrical resistance of 4 kW. The team also included a flow control system of hot air using a thermostat with an on/off switch that maintained the temperature of the operation in the interior of the chamber which ensures better drying. The tests delivered satisfactory data; reaching an initial moisture content of 82.5 % then down to a final moisture content of 20.6 % of the apple slices respectively. The drying time was 3 hours and 30 minutes, with a production of 4.26 kg of dried fruit in an eight hour work day. With it being a prototype, it can be used perfectly by small producers to improve their productivity and participation in the national market, due to the fact that you can dehydrate any type of fruit.