11 research outputs found
Thermal performance of a solar hybrid dryer for Conilon coffee (Coffea canephora)
The study was aimed at design and development of an energy efficient hybrid solar
dryer suitable for drying of organic Conilon coffee placed in the town of Seropédica, Rio de
Janeiro, Brazil. The energy efficiency and the drying efficiency were the evaluation criteria for
thermal performance of the hybrid solar dryer during the coffee drying. Temperature and relative
humidity (RH) of the drying and ambient air, solar radiation intensity and coffee weight loss were
monitored during the drying process. The process occurred over six consecutive days; the drying
time was from 07:00 to 17:00 h, totalling 120 h of operation with an intermittent period (at night)
of 14 h. During intermittence, the exhaust system kept off and solar collector and drying chamber
sealed. The effective drying period took 60 h, with temperature and RH, respectively, of 38.3 °C
and 60.6% outlet of the solar collector, 32.7 °C and 72.2% outlet drying chamber and 27.8 °C
and 74.5% ambient air. The maximum temperature in the solar collector and drying chamber
reached 54 and 47.7 °C, respectively, with an ambient air temperature of 32 °C at 12:00 h. These
values showing temperature increase 22.2 °C in solar collector and 10 ºC drying chamber. The
mean variation for the reduction in RH between the drying air inside the solar collector and the
ambient air was 28%, while in the chamber obtained in a range of 10.5% at 13:00 h. The solar
collector and dryer chamber efficiency were 29.1 and 40.8%, respectively, while the overall dryer
efficiency 39.7%