Engineering Thermodynamics - May 2015

Mechanical Engineering (Semester 3)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) Define property. What is meant by intensive and extensive property? State the differences between Microscopic approach and macroscopic approach.(7 marks) 1 (a) Define property. What is meant by intensive and extensive property? State the differences between Microscopic approach and macroscopic approach.(7 marks) 1 (b) State the Steady Flow Energy Equation and explain how this equation can be applied for (i) Nozzle, (ii) Boiler, and (iii) Steam Turbine.(7 marks) 2 (a) The mass flow rate of steam into a steam turbine is 1.5 Kg/s and heat loss from the turbine is 8.5 KW. The steam is entering the turbine at the pressure of 2MPa, temperature 350°C, Velocity 50 m/s, elevation 6 m/s and is leaving the turbine at a pressure of 0.1 MPa, quality of 100%, velocity of 200 m/s, elevation of 3 m/s. Determine power output of turbine.(7 marks)

Answer any one question from Q2 (b) & Q2 (c)

2 (b) State Kelvin-Plank Statement of Second Law of thermodynamics and show that violation of Kelvin-Plank statement leading to violation of Clausius statement.(7 marks) 2 (c) A heat pump is used to heat the house in winter. A house requires 50 KJ/s heat for heating in winter which is delivered by heat pump from outside air. Work required to operate the heat pump is 8 KW. Calculate the Co-efficient of Performance of heat pump and heat abstracted from outside.(7 marks)

Answer any two question from Q3 (a), (b) & Q3 (c), (d)

3 (a) Explain principle of increase of entropy for an isolated system.(7 marks) 3 (b) What is irreversibility? State various types of irreversibilities and explain them.(7 marks) 3 (c) Explain the concept of decrease in available energy when heat is transferred through a finite temperature difference with the aid of T-S diagram.(7 marks) 3 (d) 5 kg of water at 0°C is exposed to reservoir at 98°C. Calculate the change of entropy of water, reservoir and universe. Assume that specific heat of water is 4.187 KJ/Kg-K.(7 marks)

Answer any two question from Q4 (a), (b) & Q4 (c), (b)

4 (a) Draw Rankine cycle on P-v, T-s and h-s diagrams and derive an expression for its thermal efficiency with and without pump work.(7 marks) 4 (b) An engine working on Diesel cycle has cylinder bore of 190 mm and piston stroke of 230 mm. The clearance volume is 290 cm³. The fuel injection takes place at constant pressure for 6% of the stroke. Determine the air standard cycle efficiency.(7 marks) 4 (c) Compare Otto, Diesel and Dual cycle for
i) Same compression ratio and heat supplied
ii) Same Max. Pressure and temperature.(7 marks) 4 (d) Dry and saturated steam at pressure of 10.5 bar is supplied to a turbine and expanded isentropically to a pressure 0.075 bar. Calculate Thermal efficiency of Rankine cycle.(7 marks)

Answer any two question from Q5(a), (b) & Q5 (c), (d)

5 (a) What is regeneration in gas turbine plant? How it improves thermal efficiency of simple open cycle Gas Turbine Plant. Explain it with the help of schematic diagram and T-S Diagram of the cycle.(7 marks) 5 (b) State the statements of Dalton's Law and Gibbs-Dalton Law. Explain in detail Dalton's law of partial pressures.(7 marks) 5 (c) How actual Brayton cycle differes from the theoretical cycle? Explain with the help of T-S diagram.(7 marks) 5 (d) What is the Vander waal's equation of state? State its importance and derive it.(7 marks)