A cylinder, closed by a piston, has a volume of 0.03m and contains air at 1 bar and 15°C. The air is compressed isentropically to one quarter of its original volume. It is then cooled in a reversible constant pressure process until the temperature falls to its initial value. Finally, the air is expanded isentropically back to 1 bar. Find the final temperature and the net work done during the sequence of processes.

A reheat cycle is used to increase the overall efficiency of the power plant.                            

Explanation:

The Reheat cycle is used --

1. to increase the efficiency of the turbine

2. to maintain the quality of the steam

3. to provide higher pressure ratio

The reheat cycle is used to to increase the net work output of the power plant.In reheat cycle, two turbines , one low pressure turbine and one high pressure turbine is used to increase the efficiency. The main purpose of the reheat cycle is to maintain the quality of the steam to 0.85 at the exit of the turbine.

               The figure given below shows a reheat rankine cycle.

In the cycle,

Process 1-2 is high pressure turbine

Process 2-3 is the reheater

Process 3-4 is the low pressure turbine

Process 4-5 is condenser

Process 5-6 is pump

Process 6-1 is boiler

A reheat rankine cycle is 30 -40% efficient than a simple rankine cycle.