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This study aimed to evaluate the energetic efficiency in coffee drying (Coffee arabica L.) with different combinations of revolving time in a fixed-bed coffee dryer. The experiment was conducted in July 2004 in Jesuítas - Paraná state/Brazil. The dryer featured a mechanic system with rotating blades to revolve of the product at different intervals. The drying air temperature was 75°C ± 5°C. The ventilation and drying was kept constant during the tests. It was observed that the average energy efficiency was 12.3 MJ kg-1 and there was no significant difference between the treatments. For the adopted dryer model, the revolving system is recommended with three-hour intervals and continuous drying. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the temperature reduction in the external parts of a fixed-bed coffee dryer, by means of different combinations of revolving times, using a noncontact thermometer. The experiment was developed in the month of June 2004 at a farm located in Jesuítas, Paraná State, Brazil. Coffee (Coffea arabica L.) variety IAPAR 59 was used. The dryer used was of the fixed-bed model, with metallic drying chamber, with cylindrical format, with an adapted grain revolving system. It was observed that there was a thermal reduction of 156.7°C (79.1%) in the system going from the furnace to the drying chamber. The combination that provided smaller reduction of temperature was with continuous ventilation and 40 minutes revolving interval at every 3 hours until the end of the process. The combination that provided the greatest reduction in temperature was with continuous revolving, with a reduction of 81.09% in the surface temperature of the product. [ABSTRACT FROM AUTHOR]