Fuel Feeding Rate Controlling Base on The Temperature Distribution Simulation on Rosella Pod (Hibiscus sabdariffa Linn) Drying Process

Abstract

This paper is concerned to the energy balance analysis of single drying process of rosella pod using solar energy dryer. The study is aimed at determining of the optimum biomass fuel feeding rate in order to retrench the energy consuming of rosella drying. Using first law of thermodynamic, energy balance analysis was performed to estimate the temperature of; drying chamber, product and heat exchanger during drying process; and the impact of fuel feeding rate of biomass to the drying temperature. Temperature is the important parameter of convection drying that influences the dried product quality. The result showed that predicted values of drying chamber temperature are in reasonable agreement with experimental data that is shown by standard deviation value of 2.9o C. Ten scenarios of drying simulation were conducted to reveal the operation conditions of rosella pod drying. The simulation calculation found that drying temperature can be controlled by biomass combustion rate by using biomass feeding adjustment. The drying simulation with air flow rate of 0.39 kg/s, drying temperature of 50oC and drying time of 29 hours and mass of rosella pod of 200 kg needs the average of biomass combustion rate of 5.5 kg/h without adjustment. By adjustment of biomass feeding for 1 kg every 15 minutes, the average of biomass combustion rate can be reduced to 4.3 kg/h, so the energy supply is reduced and the increasing of drying efficiency resulted for the later treatment is about 3 %.