INVESTIGATION OF ENGINE PERFORMANCE AND EMISSIONS OF AN SI ENGINE USING BIOGAS-HYDROGEN MIXTURES Bilge Albayrak Ceper*, Mustafa Uysal, Nafiz Kahraman, Selahaddin Orhan Akansu , Erciyes University, Faculty of Engineering, Department of Mechanical Engineering, 38039 Kayseri, Turkey ABSTRACT Currently, fossil fuels such as petroleum, natural gas and coal meet most of the world’ energy demand. However, combustion products of […]