Engineering Thermodynamics — Major (End Semester) 2023 question paper

Paper details

• Subject: Engineering Thermodynamics (BME-155)
• Branch: Mechanical Engineering
• Semester: 2
• Exam: Major (End Semester) 2023
• Questions: 24

Questions asked in Engineering Thermodynamics Major (End Semester) 2023

1. Q1. Attempt any Five parts of the following.
2. Q1(a). What do you understand control volume and control surface explain with diagram? [2 marks]
3. Q1(b). Explain the First law of thermodynamics for closed system following a process. [2 marks]
4. Q1(c). Draw the p-v and T-s diagram of Carnot cycle by writing the name of different processes. [2 marks]
5. Q1(d). A heat engine working on Carnot cycle converts one-fifth of the heat input into work. When the temperature of the sink is reduced by 80°C, the efficiency gets doubled. Find the temperature of the source and sink. [2 marks]
6. Q1(e). Derive the formula of entropy change for a reversible isothermal process. [2 marks]
7. Q1(f). Define the following: (i). Brake power (ii). Cut off ratio in diesel cycle. [2 marks]
8. Q1(g). Draw the schematic diagram of a Rankine cycle and write down the formula for its efficiency. [2 marks]
9. Q2. Attempt any Two parts of the following.
10. Q2(a). Define the following: (i). Thermodynamic System and its types. (ii). Concept of Continuum [5 marks]
11. Q2(b). An insulated cylinder of 0.4 m diameter and 0.8 m length contains 10 kg of oxygen. Paddle work is done on the gas to increase its pressure from 3 bar to 6 bar. Determine the change in internal energy, work done on the gas and the change in enthalpy. Also explain PMM-1. [5 marks]
12. Q2(c). One kg of air at 1 bar and 300K is compressed adihatically till its pressure becomes 5 times the original pressure. Subsequently it is expanded at constant pressure and finally cooled at constant volume to return to its original state. Calculate the heat and work interactions and change in internal energy for each process and for the cycle. C_g = 1.005kJ/kg · K and Gas constant R = 0.287 kJ/Kg ·… [5 marks]
13. Q3. Attempt any Two parts of the following.
14. Q3(a). Define the working of Heat Engine and Heat Pump with a neat sketch. [5 marks]
15. Q3(b). In an air compressor air flows steadily at the rate of 0.5 kg/s through an air compressor. It enters the compressor at 6 m/s with a pressure of 1 bar and a specific volume of 0.85 m^3/kg and leaves at 5 m/s with a pressure of 7 bar and a specific volume of 0.16 m^3/kg. The internal energy of the air leaving is 90 kJ/kg greater than that of the air entering. Cooling water in a jacket surrounding… [5 marks]
16. Q3(c). Three Carnot engines E1, E2 and E3 operates between temperature of 1000 K and 300 K. Make calculations for the intermediate temperatures if the work produced by the engines are in the ratio of 4:3:2. [5 marks]
17. Q4. Attempt any Two parts of the following.
18. Q4(a). Define Helmholtz and Gibbs functions and derive the expression for availability for a closed system. [5 marks]
19. Q4(b). If 1kg of ice is at -5°C is exposed to the atmosphere which is at 20°C. The ice melts and comes into thermal equilibrium with the atmosphere. Determine (a). Change in entropy of the universe (b). What is the minimum amount of work necessary to convert the water back into ice at -5°C. Cp of the ice is 2.093 KJ/Kg K and the latent heat of fusion of ice is 333 KJ/Kg. [5 marks]
20. Q4(c). Two identical bodies at constant heat capacity are at the same initial temperature T1. A refrigerator operates between these two bodies until one body is cooled to temperature T2. If the bodies remain at constant pressure and undergo no change of phase. Derive the formula of minimum amount of work needed to do this. [5 marks]
21. Q5. Attempt any Two parts of the following.
22. Q5(a). Define the term critical point triple point of water by giving the numerical values. Steam initially at 1.5 MPa, 300°C expands reversibly and adiabatically in a steam turbine up to 40°C. Determine the ideal work output of the turbine / Kg of steam. Also show the process on T-s and h-s diagram. [5 marks]
23. Q5(b). Solve the following: (a). Draw the T-s and h-s diagram for Rankine cycle for wet dry and superheated steam. (b). A sample of steam at 5 bar is stated to have enthalpy of 2350 KJ/Kg. Make calculations for specific volume, Internal energy and entropy of steam. [5 marks]
24. Q5(c). Explain the working of 4 stroke S I engine with the help of a next sketch. Also explain the different types of efficiencies and power by writing down the expressions of each. [5 marks]