GTU Elements of Mechanical Engineering
Question Paper Dec 2011
GUJARAT TECHNOLOGICAL UNIVERSITY
BE SEM- I II Winter Examination-Dec.-2011
Subject Name: Elements of Mechanical Engineering
- Attempt any five questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
- Use of Steam Tables and Mollier’s Chart is permissible
Q-1 (a) What is flow and non-flow process? 3
(b) Define : (i) Sensible heat (ii) Enthalpy of evaporation 4
(iii) Heat of superheat (iv) Dryness Faction.
(c) Calculate the enthalpy per kg of steam at 10 bar pressure and a temperature of 300 °C. 7 Find also the change in enthalpy if this steam is expanded to 1.4 bar and dryness fraction
of 0.8. Take specific heat of superheat steam equal to 2.29 kj/kgK.
Q-2 (a) What is adiabatic process? Prove with usual notations the law of governing adiabatic 7
process process as PVY = Constant.
(b) 0.67 kg of gas at 14 bar and 290 °C is expanded to four times the original volum according 7 to the law PV13 = Constant.
Caluculate : (1) The original and final volume of the gas.
(2) The final temperature of the gas .
(3) The final pressure of the gas. Take R = 287 J/kgK.
Q-3 (a) Differentiate between petrol engine and diesel engine. 3
(b) Derive equeation for air standared efficiency of otto cycle. 4
(c) In an ideal constant volume cycle the pressure and temperature at the beginning of the comperession are 97 kPa and 50 °C respectively. The volume ratio is 5. The heat supplied 7 during the cycle is 930 kj/kg of working fluid.
Calculate : (1) The maximum temperature attained in the cycle.
(2) The thermal efficiency of the cycle.
(3) Work done during the cycle/kg of working fluide.
Q-4 (a) State the function of the following : 3
(1) Pressure gauge
(2) Fusible plug
(b) With neat sketch describe the working of two stroke cycle petrol engine. 4
(c) With neat sketch describe the construction and working of Cochran boiler. 7
Q-5 (a) Give classification of governor. Explain working of any one with neat sketch. 3
(b) Classify the centrifugal pump and explain with neat sketch the vertex type centrifugal 4 Pump.
(c) Classify the air compressor . Differentiate between reciprocating compressor and 7 rotary compressor.
Q-6 (a) What is refrigerant? State the most widely used refrigerant. 3
(b) With neat sketch explain vapour compression refrigeration cycle. 4
(c) Explain with neat sketch split air conditioner. State its advantages. 7
Q-7 (a) What is zeroth law of thermodynamics. 3
(b) With simple sketch explain working of disc clutch. 4
(c) Write short note on: Type of belt drive. 7