| Summary: | High energy consumption and low thermal efficiency are the main problems associated with convection hot air dryers. The effect of various energy sources on tomato drying in a convective dryer was performed. In particular, drying experiments were performed on a convection dryer at two types of heat energy sources, electric and butane-gas, air velocity 1.0, 1.5, and 2 m/s, and air temperature 40, 50, and 60 °C. The rising temperature from 40 to 60 °C caused a reduction of the drying period by 24.8, 22.1, and 21.5% at 1.0, 1.5, and 2.0 m/s, respectively. Minimum energy consumption of 3.83 kW.h was recorded using the electrically heated system while minimizing energy consumption of 0.82 kW.h was detected for the convection gas dryer at 60 °C and 1.0 m/s. The lowest SEC was recorded at 17.44 kWh/kg using gas dryers, while a maximum SEC (112.05 kWh/kg) was observed at the electric dryer under 60 °C and 2.0 m/s. The gas dryer had a thermal efficiency ranging from 50.32 to 78.77%, while the electrically heated dryer had a thermal efficiency ranging from 34.86 to 50.34%. Moreover, applying the butane gas as a heat source for drying had various advantages over the conventional electric system, such as less overall energy consumption with more effectiveness under all conditions.
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