experimental studies on biogas enrichment and comparative performance evaluation of spark ignition engine with enriched biogas as fuel

Abstract

newline quotThe work focuses on design and development of suitable low-cost biogas enrichment system and to check the performance of the developed biogas enrichment system. It is also aimed to evaluate comparative performance and emission characteristics of spark ignition engine run on fuel like petrol, CNG, and enriched biogas. newline newlineIn order to take advantages of water scrubbing and chemical scrubbing, the combination of water scrubbing method and chemical scrubbing method for biogas enrichment was selected after literature review. The individual performance of water scrubbing and chemical scrubbing was also checked. The packed bed type water scrubber was designed and fabricated for biogas enrichment. While storage type Ca(OH)2, KOH, and NaOH chemical scrubbers were used for biogas enrichment. Iron chips and silica gel was used for removal of H2S and water vapour respectively from biogas. The enriched biogas with 83.05% CH4 coming from water scrubber was then passed through the three reaction chambers arranged in series such as reaction chamber of Ca(OH)2, reaction chamber of KOH and then silica gel. It had given enriched biogas with 95.15% CH4 with 76.04% CH4 rise efficiency. The chemical scrubber could give enriched biogas with maximum CH4 content of 94.05% at lowest biogas flow rate of 0.540 Nm3/h with 74% CH4 rise efficiency. newline newlineThe enriched biogas was used for comparative performance evaluation and emission characteristics study on spark ignition engine. The test was carried out on 4.5 kW variable speed research engine by using fuel as petrol, CNG, and enriched biogas. The engine was run on enriched biogas as fuel with same CNG conversion kit. The engine was operated by using three values of compression ratio (6, 8, and 10), three values of ignition advance (20o, 25o, and 30o), four values of engine speed (1200, 1400, 1600, and 1800 rpm), and two positions of throttle (100% open and 50% open). The performance test results showed that the engine developed maximum power at 10 compression ratio, 25o ignition