BE (2nd Semester)
Basic Mechanical Engineering
1. (a) (i) State three corollaries of first law of thermodynamics.
(ii) Explain flow work.
(b) (i)Derive the steady flow energy equating giving basic assumption.
(ii)Explain system and control volume approach for thermodynamics analysis.
(c) 0.25 kg of air at a pressure of 140 kn/m2 occupies 0.15 m3 and from this condition it is compressed to 1.4 MPa according to the law pvlJ5 =constant Determine.
(i) The change of internal energy of air.
(ii) The work done on or by the air.
(iii)The heat received or rejected by the air.
Take CP =1.005 Kj/kg K, Cv = 0.718 kJ K.
2. (a) (i) State two corollaries of second law of thermodynamics.
(ii) Differentiate between heat engine and heat pump.
(b) (i) Explain the theorem of ‘Clausius Inequality’.
(ii) Describe reversed Cannot cycle taking example of refrigerator and heat pump. Also give their performance parameters.
(c) In a dual cycle, the pressure and temperature at the beginning of compression are 1.03 bar and 303 K. Maximum pressure is 41.4 bar and temperature at the end of heat supply is 1666 K.
(i)The total heat supplied per kg of air.
(ii) The net work done per kg of air.
(iii) Thermal efficiency.
Assume CP = 1.005 kJ/kg K, CV = 0.718 kJ/kgK.
3. (a) (i) Explain the phase transformation of water at 1 atmospheric pressure.
(ii) Discuss Economizer with a neat diagram.
(b) (i) Differentiate between boiler mountings and accessories giving 3 examples of each.
(ii) In Mollier diagram, show following processes adiabatic, isoenthalppic and isothermal process.
(c) 0.9 kg of water vapour, initially at a pressure of 15 bar and a temperature of 250°c, expand reversibly and adia- Bartically to 1.5 bar. Find the final temperature, work done, heat transferred and change of entropy.
4. (a) (i) Discuss the difference in working of a shaper and Planer
(ii) Explain the arc welding process.
(b) (i) Explain quick return mechanism of a shaper.
(ii) Discuss the purpose of Electrode coating giving some important constituents for coating.
(c) Classify different types of Lathe, make a labeled diagram And also explain 3 major operations performed by it.
5. (a) Explain the stress-strain curve of ductile material showing all the specific points.
(b) Explain the testing procedure of material in case of tensile loading.
(c) (i) A load of 4000 N has to be raised at the end of a steel Wire. If the unit stress in the wire must not exceed 80 N/mm2. What is the minimum diameter of wire required? What will be the extensions of 4 meter length of wire? Take £= 2 X io5N/mm2.
(ii) A material has a Young’s Modulus of 1.25 X 105N/mm2 and a poisson’s ratio of 0.25.
Calculate the Modulus of Rigidity and the Bulk Modulus.