10 INTERNAL COMBUSTION ENGINES - RECIPROCATING Heat engine in which the combustion of.fuel takes place in the engine cylinder is known as internal combustion engine. As the combustion takes place inside the engine cylinder, very high temperature is produced in the cylinder. It is therefore, necessary to abstract or remove some of the heat from the cylinder to prevent damage to the metal of the cylinder, by circulating water through jacket, surrounding the cylinder. The cylinder of a motor cycle or an aero-engine is cooled by atmospheric air. It may be noted that the cylinder of a steam engine requires to be heated by supplying steam (from the boiler) in the jacket surrounding the .cylinder to reduce condensation of steam in the cylinder. The thermal efficiency of an internal combustion engine is much higher than that of a steam engine plant, as in I.C. engine there is no apparatus corresponding to boiler and no losses corresponding to the boiler losses. A best modem I.C. engine converts about 30 to 35 per cent of the heat of combustion of fuel into work (i.e. the thermal efficiency is about 30 to 35 per cent), whereas an ordinary steam engine plant converts only 8 to 10 per cent and a best modem steam turbine plant converts .only 15 to 25 per cent of heat of combustion of fuel into work, i.e., the overall efficiency of a modem steam plant (boiler and turbine combined) is about 15 to 25 per cent. Reciprocating internal combustion engines are most , commonly single-acting whereas reciprocating steam engines are nearly always double-acting. All large size I.C.'engines and marine I.C. engines are double-acting. As the combustion of fuel takes place inside the engine cylinder of internal combustion engine, they are relatively smaller in size as compared to steam engine plant. A steam engine plant needs a boiler, a condenser, * and an economiser. Internal combustion engine can be started quickly within a short time, whereas a steam engine plant will require much more time as steam has to be generated in the boiler before the steam engine can be started. Around 1878, many experimental I.C. engines were constructed. The first really successful engine did not appear, however, until 1879, when a German engineer Or. Otto built his famous Otto gas engine. The operating cycle of this engine was based upon principles first laid down in 1860 by a French engineer named Mr. Bea be Rochas. The majority of modem I.C. engines operate according to these principles. The development of the well known Diesel engine began about 1893 by Mr. Rudolf Diesel. Although this engine differs in many important aspects from the Otto engine, the operating cycle of modern high speed Diesel engines is thermodynamically very similar to the Otto engines. 10.1 Introduction
302 ELEMENTS OF HEAT ENGINES Vol.l Internal combustion engines may be classified according to the : - Type of fuel used - Diesel oil engine, Petrol engine, Gas engine, and Light oil (Kerosene) engine.
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- Summer '15
- Combustion, Internal combustion engine, petrol engine, diesel engines