Wan Ramli

A Cross-Flow Model for Continuous Plug Flow Fluidized-Bed Cross-Flow Dryers

Plug flow fluidized bed cross-flow dryers have been used in drying of particulate solids such as paddy and other grains for many years. However, simulation of the performance of any particular design of the dryer has always been problematic due to the inadequate overall empirical models used that are too inflexible and too specific to the particular design. In addition, previous theoretical models of the plug flow fluidized bed cross-flow dryer did not model the gas cross flow properly and had difficulty in modeling the moving solid bed. A new steady-state cross-flow model of the dryer that models the gas cross-flow is proposed. The profiles for the solids and air moisture contents and temperatures were found to be dependent on the gas-solid flow ratio, G/F, the specific heat demand, C PY (T I − T A )/(Y E − Y I ), the total number of a transfer units, N T = Gϵ/KφaSL and the specific drying load, (X I − X P )/ (Y E − Y I ). The model was validated by comparing the simulated data with experimental data that were obtained by drying paddy in a plug flow fluidized bed cross-flow dryer pilot plant. The model was found to estimate very well the solids moisture content and temperature, the gas moisture content and temperature profiles, and the driving force profile.

Effect of different substrate on performance of microbial fuel cell

Microbial fuel cells are new technology for the production of bioelectricity. The electrons liberated by microorganisms during consumption of organic substrate are transferred from the anode to the cathode linked by an external circuit and produce electricity under anaerobic conditions. In this study, palm oil mill effluent anaerobic sludge was used as active biocatalyst for bioelectricity generation. Several substrates such as glucose, fructose, sucrose and molasses were examined as electron donors by mixed culture of microorganisms in an anaerobic anode compartment. The maximum open circuit voltage achieved was 460 mV and the highest power and current density were 55.25 mW/m 2 and 208.55 mA/m 2 , respectively.