Thermal Engineering

Chapter 4

Steam Power Cycles

4.1 ❐ INTRODUCTION

In steam power plants and refrigeration cycles, the working fluid changes from liquid to vapour and back to liquid state. This succession of processes is called vapour cycle. In steam power plants, water is the working fluid in the form of steam and vapour. In refrigeration cycles gasses such as Freon, CO₂, and ammonia (aqua-ammonia) are used as working substances.

4.2 ❐ CARNOT VAPOUR CYCLE

The elements of steam power plants are as follows:

1. Boiler
2. Steam turbine
3. Condenser
4. Feed pump

The schematic diagram of a steam power plant is shown in Fig. 4.1. The p-v and T-s diagrams for the Carnot vapour power cycle are shown in Fig. 4.2(a) and (b). Dry and saturated steam at temperature T_H = T₁ enters ...