Adus Amarasinghe

Interpretation of Paste Extrusion Data

Statistical techniques were used to analyse fluctuations in extrusion pressure signals during the isothermal ram extrusion of alumina-based ceramic pastes and an unscented soap. Regions of significant variation were found to correlate with the presence of inhomogeneities in the paste such as air bubbles and agglomerates resulting from poor mixing. Regular surface and bulk fracture of the pastes could be detected using frequency analysis techniques. There is potential for use of these techniques for on-line feedback control where the effect can be distinguished from the homogeneous process noise.

Drying kinetics and mathematical modeling of hot air drying of coconut coir pith

Drying kinetics of coir pith was studied and the properties of compressed coir pith discs were analyzed. Coir pith particles were oven dried in the range of temperatures from 100 to 240xa0°C and the rehydration ability of compressed coir pith was evaluated by finding the volume expansion. The optimum drying temperature was found to be 140xa0°C. Hot air drying was carried out to examine the drying kinetics by allowing the coir pith particles to fluidize and circulate inside the drying chamber. Particle motion within the drying chamber closely resembled the particle motion in a flash dryer. The effective moisture diffusivity was found to increase from 1.18xa0×xa010−8 to 1.37xa0×xa010−8 m2/s with the increase of air velocity from 1.4 to 2.5xa0m/s respectively. Correlation analysis and residual plots were used to determine the adequacy of existing mathematical models for describing the drying behavior of coir pith. The empirical models, Wang and Singh model and Linear model, were found to be adequate for accurate prediction of drying behavior of coir pith. A new model was proposed by modifying the Wang and Singh model and considering the effect of air velocity. It gave the best correlation between observed and predicted moisture ratio with high value of coefficient of determination (R2) and lower values of root mean square error, reduced Chi square (χ2) and mean relative deviation (E%).

Study on small molecular organic compounds pyrolysed from rubber seed oil and its sodium soap

Rubber seed oil (RSO) and its sodium soap were pyrolysed in a batch reactor to obtain low molar mass organic substances. The pyrolitic oil of RSO was redistilled and the distillates were characterized by GC–MS and FTIR. Density, acid value, saponification value and ester values were also measured according to the ASTM standard methods. A similar analysis was done for samples taken out at different time intervals from the reaction mixture. Industrially important low molar mass alkanes, alkenes, aromatics, cyclic compounds and carboxylic acids were identified in the pyrolysis process of rubber seed oil. However, pyrolysis of the sodium soap of rubber seed oil gave a mixture of hydrocarbons in the range of C14–C17 and hence it has more applications as a fuel.

Evaluation of single bed and multi bed dried copra on the quality of extracted coconut oil

Single bed and multi bed drying of copra was evaluated using a hybrid dryer with three compartments. A high percentage (> 75 %) of white copra resulted in single bed drying at low temperatures (