Punjab Technical University 2010-2nd Sem B.Tech Elements of Mechanical Engineering, B Tech ester, Regular , , - Question Paper

Time: three Hours
Maximum Marks: 60

Instruction to Candidates:
1) Section- A is Compulsory.
2) Attempt any 5 ques. from Section- B & C
3) choose at lowest 2 ques. from part - B & C

part – A [Marks 2*10=20]

Q1) a) describe enthalpy of the system. How it is related to internal energy?

b) describe compression ratio.

c) Is it possible net Work done not equals zero even if dv = 0? If so provide an example.

d) What is entropy principal?

e) Draw P-V and T-S diagrams for brayton cycle.

f) What is PMM1?

g) provide the relation ranging from COP of heat pump and refrigerator.

h) Differentiate ranging from machine and mechanism.

i) State the uses of Oldham coupling.

j) describe temperature stresses and strains.

part - B [Marks : eight Each]

Q2) Differentiate ranging from temperature heat and internal energy. A non-flow reversible process occurs for which pressure and quantity are correlated by the expression P = (Vt + 5V), where P is in bar and V is in m3. What amount of work will be done when quantity modifications from three to 6m3?

Q3) What is throttling process? Point out its salient aspects. The centrifugal pump delivers 50kg of water per second. The inlet and outlet pressures are one bar and 4.2bar respectively. The suction rs2.2m beneath the center of the pump and delivery is 8.5m above the center of the pump. The suction and delivery pipe diameters are 20cm and 10cm respectively. Determine the capacity of the electric motor to run the pump.

Q4) Draw P-V diagram for isobaric, isochoric and isothermal process 0.2m3 of an ideal gas at a pressure of 2MPa and 600 K is expanded isothermally to five times the initial quantity. It is then cooled to 300K at constant quantity and then compressed back polytropically to its initial state. Determine the network done and heat transfer during the cycle principle of dual cycle with the help of P-V and T-S expression for the air standard efficieny of the dual compression ratio pressure ratio cut off ratio.

Q5) State Kelvin-Planck and Clausius statements of 2nd legal regulations of thermodynamics. discuss the equivalence of Kelvin-Planck and Clausius statements.

part - C [Marks: eight Each]

Q6) discuss the working diagrams. Derive an cycle in terms of the adiabatic index.

Q7) (a) discuss the working of elliptical mamrnel.

(b) A machine raised a load of 300N through a distance of 300ntrn effort of 50N moved 2.7m during the process. Determine

(i) Mechanical advantage.

(ii) Velocity Ratio.

(iii) Efficiency.

(iv) Effect of friction.

Q8) (a) Derive the relation ranging from Bulk modulus (K), Youngs modulus (E) and Poissons ratio (1/m).

(b) In order to evaluate different mechanical properties a steel specimen of 20mm diameter and 20cm length was tested in a standard tension test and data collected are yield load = 150kN maximum load = 225kN fracture load = 175kN gauge length at fracture = 25cm extension at load of 30kN = 0.08mm. Determine

(i ) Yield point stress.

(ii) Ultimate tensile stress.

(iii) Percentage elongation.

(iv) Modulus of elasticity.

(v) Breaking strength.

Q9) Write short notes on the subsequent :

(a) Reversible processes.

(b) Carnot cycle.

(c) Creep.

(d) Working of 4 stroke diesel engine

Earning:   Approval pending.