In this article we will discuss about the design of steam engine.
Reciprocating steam engine is a type of heat engines in which heat energy available with the steam is converted into mechanical energy. A steam boiler is required which produces steam supplied to the cylinder which is exhausted either to the atmosphere or to the condenser.
Steam engines are mostly used in locomotives and ships. These run at low speed and their thermal efficiency is very low. It is mostly a case of double acting, i.e., steam pressure acts from both the sides of the piston alternately to reciprocate inside the cylinder. Double acting reciprocating steam engines use a cylinder, piston, connecting rod, crosshead, crank, and crankshaft to obtain rotary motion from reciprocating motion.
In case of such engine, rigid piston rod is used. One end of the piston rod is rigidly fixed with piston and the other end of the piston rod is connected to a cross-head through a pin. The crosshead moves to and fro with the piston rod in a guide. The entire combination of crosshead, connecting rod, and crankshaft converts reciprocating motion into rotary motion (Fig. 4.2).
Reciprocating steam engine was the first prime mover which was developed to obtain mechanical power by the use of steam pressure. It has now become obsolete due to its low efficiency and low-speed operation.