Introduction. The term engine is applied to any machine that consumes heat energy and converts it into mechanical work at the shaft coupling

STATE EXAM

Diesel engines

Introduction

The term engine is applied to any machine that consumes heat energy and converts it into mechanical work at the shaft coupling. In the marine field of mechanical engineering the internal combustion engine are used.

In the internal combustion engine the fuel is delivered to the engine either in a vaporized or a liquid form. If the fuel is liquid, it must atomized as it is being introduced into the engine cylinder.

Work is done by introducing fuel into a cylinder, burning the fuel to form a gas and heat the gas during formation, forcing a piston from one end of the cylinder to the other by the expansive force of the gas and releasing the expanded gas from the cylinder. Each of these processes is called a phase. Now, if an operation is performed by causing a fluid to go through a complete set of phases, this set of phases constitutes a cycle.

In the engine the phases of fuel combustion, expansion of gases, release and expulsion of gases, filling cylinder with air and compression of air form a complete cycle, and the operation of the engine consists of continued repetitions of this cycle. The operation of any kind involves this continued repetition of some sort of cycle, although the phases that make up the cycle differ in different types of engines.

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