INTRODUCTION

“The heat engine, in which the combustion takes place inside the cylinder or the product of combustion (flue gas) directly goes to the cylinder and the heat energy of the flue gas is converted into mechanical energy, is known as Internal Combustion Engine (IC Engine).” The combustion may take place either inside or outside the cylinder, but heat energy of the combustion is directly utilized by the engine to produce into mechanical power. However, in external combustion engines, heat of the combustion is transferred to the intermediate medium like water or air and then the heat energy of that intermediate medium (steam produced from the water or the hot air) is converted into the mechanical energy. The steam engine/turbine and closed cycle gas turbine work on the principle of external combustion engine as the heat of combustion is transferred to water and air, respectively. The steam produced from water in case of steam engine/turbine and hot compressed air in case of closed cycle gas turbine produce mechanical power. While automobile and open cycle gas turbine work on the principle of internal combustion engine as the flue gas produced during combustion produces mechanical power without transferring the heat energy to any intermediate medium.