Elements of Mechanical Engineering — Summer 2019

What is refrigeration? Explain working of vapour compression refrigeration cycle. Name the basic components of VCRC

What is Adiabatic process? Prove with usual notations the governing equation for adiabatic process PVγ = Constant

Calculate the enthalpy per kg of steam at 10 bar pressure and a temperature of 300 ºC. 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.

Define (i) Hardness (ii) Creep (iii) Resilience (iv) Toughness (v) Sensible heat (vi) Latent heat (vii) Dryness fraction.

With usual notations derive an expression for work done for single stage single acting reciprocating air compressor by considering clearance volume.

State the function of (i) Fusible Plug (ii) Economiser (iii) Safety valves (iv) water level indicator (v) Superheater (vi) Pressure gauge (vii) Air pre-heater

Define the following terms related to belt drive: (i) Velocity ratio (ii) Initial Tension (iii) Slip (iv) Creep (v) Power transmitted in belt drive

In ideal constant volume cycle the pressure & temperature at the beginning of compression are 97 KPa & 50° Crespectively. The volume ratio is 8. The heat is supplied during the cycle is 930 kJ/kg of working fluid. Calculate: (i) The maximum temperature attained in the cycle. (ii) The thermal efficiency of cycle. (iii) Work done during the cycle /kg of working fluid.

List various liquid fuels. State their merits over solid fuels.

What is priming? Why it is required in centrifugal pump?

Explain with neat sketch construction and working of two stroke petrol engine

Differentiate between Fire tube and Water tube boiler.

Explain working of Hartnell Governor with neat sketch

Following readings were taken during test of single cylinder four stoke oil engine. (i) Cylinder diameter = 250 mm (ii) Stroke length = 400 mm (iii) Main effective pressure = 6.5 bar (iv) Engine speed = 250 r. p .m. (v) Net load on brake = 1080 Newton (vi) Effective diameter of brake = 1.5 meter (vii) Fuel used per hour = 10 Kg (viii) Calorific value of fuel = 44300 KJ/Kg Calculate (1) Indicated power, (2) Brake power, (3) Mechanical efficiency and (4) Indicated thermal efficiency.

Define Zeroth law, First law and Second law of thermodynamics. Give limitations of first law of thermodynamics

Discuss construction, Specification and working of Cochran boiler with sketch.1