Question

Q1 (a)Describe why the Carnot cycle not considered suitable for practical purposes. (3 marks) (b)An ideal reheat-regenerative steam power plant with two open feedwater heater generates 150000 kW energy from the electric generator directly couple to steam turbine. The boiler pressure is 10 MPa and 600°C and leaves the low pressure turbine as saturated vopour at 7.5 kPa. Steam is extracted from the turbine at 1.8 MPa and 0.3 MPa, and reheated to 550°C at a pressure of 1 MPa. Water leaves both feedwater as saturated liquid. By neglecting all the pumps works, determine the thermal efficiency of the cycle and the mass flow rate of steam through the boiler.

Answer 1

According to our guidelines,we should answer any one question..so I choose A to answer...

Two main reasons for carnot cycle is not used in practical purposes:-

1. All processes that happen in nature are IRREVERSIBLE.But the process that are in carnot cycle are REVERSIBLE..

2. In carnot cycle there are 4 processes.They are:-

1. Reversible isothermal expansion

2. Reversible adiabatic expansion

3. Reversible isothermal compression

4 Reversible adiabatic compression..

So there are two adiabatic processes and two isothermal processes in carnot cycle..We know that Adiabatic process is VERY FAST process whereas Isothermal process is VERY SLOW process..In nature,a fast and slow process CANNOT WORK SIMULTANEOUSLY...

So carnot cycle is not considered as practical purposes.....