Effects of thermal and rheological properties of biodiesel from microalgae and feedstocks

Comparative investigation and assessment of thermal and rheological properties of biodiesel fuels from micro algae and other second generation feedstocks were carried out with the aim of assessing micro-algal technology as a viable biodiesel production option. Chlorella vulgaris and Synedesmus spp were collected, cultured and cultivated in the open pond and in photobioreactor differently and inoculated with Agar broth media for twenty-three and sixteen days respectively for biomass production/accumulation. Thermal parameters and rheological properties were studied. Viscosity is one of the most critical features of a fuel or biofuel. It plays a dominant role in fuel spray, fuel-air mixture formation and the combustion process. Fuels are sprayed into compressed air and atomised into small droplets near the nozzle exit in any diesel engine. In the combustion chamber, fuel forms cone-shaped spray at the nozzle exits which impacts the viscosity and also affects the atomisation quality, penetration and size of fuel droplets. Density is an important fuel property that influences the amount of fuel injected into the engine cylinder. Changes in fuel density influences engine output power due to different mass of the fuel being injected, and this directly affects engine performance characteristics and emissions. TGA conducted reveals stability of algal oil and biodiesel after thermal treatment. With studies of viscosity and shear stress at varying speeds and temperature being evaluated, the interaction of viscosity at different torque presented in this study decreases from 20 rpm to 60 rpm but increases in shear stress at temperatures of 40°C and 60°C. Across temperature was a general initial decrease and later increase from lower temperatures to higher temperatures. The general conclusion is that shear stress increases with increase in temperature and torque while viscosity generally decreases along the trends.