Question

A ideal brayton cycle based power plant with optimum reheating condition operates at the pressure ratio 8.0. Maximum temperature after combustion and reheating is 1300k. If the initial conditions to the compressor for air are 1 bar and 300k, find the net-work output, thermal efficiency and work ratio of the cycle

Answer 1

Answer:

Brayton cycle on (a) P-v diagram (b) T-s diagram

Processes: -

1-2: isentropic compression

2-3: constant pressure energy addition

3-4: isentropic expansion

4-1: constant pressure energy rejection

Energy added, Q1= mCp (T3-T2)

Energy rejected, Q2= mCp (T4-T1)

Thermal efficiency,

The pressure ratio of the Brayton cycle, rp is defined as,

Then�

The processes 1-2 and 3-4 are isentropic. Hence,

We get,

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