Sparger for PBR system designed using SPARGER software for optimization of micro algae growth

Abstract. Research studies have shown that microalgae have potential as a biofuel. It has been found that the oil yield from microalgae ranges from 5000-15000 gallons/ acre-year which is much higher than biofuel field crops. Therefore, the design of a Photobioreactor system (PBR) at large scale has been studied for growing microalgae used in biofuel production. PBR performance depends on the performance of the sparger which is used to distribute a CO₂ and air mixture in the PBR. Diameter of holes in a sparger, number of holes and pitch distance are the major geometric parameters considered in the design of a sparger for a PBR system. A sparger computer model built on a Java platform is used to simulate the flow and pressure distribution of a sparger. Simulation results are the number of holes, spacing and weeping condition, efficiency of non-uniformity and percentage of air remaining after the last hole based on the input of pressure, discharge air flow rate, diameter of sparger, hole diameter, and discharge coefficient. The sparger model employs three methods; Static regain, Acrivos and Pressure drop. Based on the Acrivos method the model for a PBR with a capacity of 157 L required a flow rate and initial pressure of 11.79-15 l/min and 7974-7985 Pa respectively. Sparger diameters of 1.27 cm and 2.54 cm are designed with a hole diameter of 0.8mm and spacing of 4.04 cm and 2.54 cm respectively. For this design, the simulation result showed non-uniformity of less than 5% and the percentage of air-remaining after the last hole less than 1%. The designed sparger for the PBR system will be used in a PBR to grow microalgae.