| The purposes of the thesis is to explain the microalgae cultivation in a photobioreactor system; demonstrate the light activity in a flat-plate photobioreactor; and design the light channeling system.;Generally, microalgae are cultivated in open ponds and in closed photobioreactor systems. In open ponds, the productivity of microalgal biomass is very low, due to lack and improper use of carbon and energy sources. In photobioreactor systems, all required inputs can be supplied effectively to the microalgae which in turn increases the biomass productivity. However, these systems are expensive to build and to maintain in a large-scale basis. In a photobioreactor, the supply of carbon source can be controlled easily, but not the supply of energy. The main energy source in a photobioreactor is light. Controlling light activity in a photobioreactor can be a big challenge.;Since light plays a vital role in microalgal growth, studying light activity in a photobioreactor is crucial. The fundamentals of light behavior is also presented. An experiment has been carried out to analyze the interaction of light with all the factors like growth medium, gas bubble flumes, biomass concentration, and the light path length in the photobioreactor system. These experiments are used to determine the light penetration in to a photobioreactor system.;It is concluded that the light attenuates 15.80% to 44.83% across the light pathlength (101mm to 305mm); 7.045 to 36.6% with gas bubble flow rates (1 to 10 l/min); and 64.18% to 99.2% with the biomass concentration of (0 to 1 kg/m3) in a photobioreactor system. The equations were developed to show the relation between output light intensity with three design factors. Therefore, the extinction coefficient is found to be 2m-1 for light path length, 0.41 min/m4 for gas bubbles, and 58.44 m2/kg for biomass concentration.;Different types of light guides were designed and tested for their photon transmission efficiency. Diameter, length and output taper angles are taken as design factors. The highest transmission efficiency of 90.17% is found in simple light guide of 102mm long and 50.8 mm diameter with 90° exit surface whereas the lowest transmission efficiency of 51.97% is found in light guide of 203 mm long and 9.53 mm diameter with a 60° exit surface. |
