FUNCTIONS OF A CONDENSER

There are two main functions of a condenser, which are explained below:

1. To reduce the back pressure considerably upon the prime mover, and thereby increasing the work output of steam during expansion.Consider the ideal p−v diagram of a non-condensing steam engine, as shown in Fig. 8.1(a), in which steam is supplied at pressure p₁ and the exhaust takes place at atmospheric pressure p₂. The work output is given by the area 1–2–3–4–5–1. If we reduce the back pressure p₂ to p′₂, which is below the atmospheric pressure, keeping p₁ same, then the work output will be given by the area 1–2–3–4′–5′–1, as shown in Fig. 8.1(b). This work output is obviously greater, than the previous work output. The additional work output is 4–4′–5′–5–4.
2. The condensate condensed from the exhaust steam in the condenser is free from impurities and can be directly used as feed water for the boiler without any treatment. This recovery of feed water is an incidental advantage.

Figure 8.1 Effect of back pressure on work output of a steam engine