Punjab Technical University 2009-1st 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) elaborate similarities and dissimilarities ranging from heat and work?

b) What is reversible process? Also write conditions for reversibility.

c) Why gases have 2 specific heats?

d) What is PMM1 (perpetual motion machine of 1st kind)?

e) How COP of heat pump and refrigerator are related?

f) What is mean effective pressure and what is its role in gas power cycles?

g) List various systems of pulleys.

h) elaborate temperature stresses?

i) What is significance of elastic constant?

j) elaborate the limitations of 1st legal regulations of thermodynamics?

part - B [Marks : eight Each]

Q2) (a) describe and discuss Zeroth legal regulations of thermodynamics? Why it is so called?

(b) A new temperature scale in degrees N is desired with freezing point at 100" N and the boiling point at 4000 N. Establish a correlation ranging from Degrees Celsius and degrees N . What would be the absolute temperature at N?

Q3) Initially at 90 kP a pressure 700K temperature and occupying a quantity of 0.5 m3i s compressed isothermally till the quantity is halved and further it goes compression at constant pressure till the quantity is halved again. Sketch the process on p-V diagram and make computations for total work done and total heat interaction for the 2 processes presume ideal gas behavior for air and
take c- 1.004 kJ/rg K.

Q4) a) discuss and derive steady flow energy formula.

(b) A perfect gas flows through a nozzle where it expands in a reversible adiabatic manner. The inlet conditions are 22 bar, 5000 C, 38 m/s. At the exit the pressure is two bar. Determine the velocity and exit area if the flow rate is a kg/s. Take R : 190 J/kg K and T : 1.35.

Q5) (a) State and discuss Carnot theorem.

(b) Write different statements of 2nd legal regulations of thermodynamics and also. Show their equivalence.

Section- C [ Marks : eight Each]

Q6) A reversible heat engine operates within the higher and least temperature limits of 1400K and 400K respectively. The entire output from this engine is utilized to operate a heat pump. The pump work soon reversed Carnot cycle, extracts heat from a reservoir at 300K and delivers it to the reservoir at 400K. If 100k J/so f net heat is supplied to the reservoir at 400K , compute the heat supplied to the engine by the reservoir at 1400K .

Q7) In an air standard diesel cycle, the compression ratio is 15 and the pressure and temperature of the air at the beginning of the compression are one bar and 288K. The peak temperature in the cycle is 270K. compute

(a) Heat supplied

(b) Work done

(c) Cycle efficiency

(d) Peak pressure of the cycle

(e) Cut-off ratio, and

(f) Mean effective pressure.

Q8) (a) Draw stress- strain diagram and discuss different salient features.

(b) A conical bar tapers uniformly from a diameter of four cm to 15 cm in a length of 40 cm. If an axial force of 80 kN is applied at every end, determine the elongation of the bar. take E =200 GPa.

Q9) (a) describe kinematic link, kinematic pair and kinematic chain.

(b) In a differential wheel and axel, the diameter of the larger axel is 250 mm and that of the smaller is 225 mm. the diameter of the effort wheel is 500mm. obtain the velocity ratio. If an effort of 150 N lifts a load of 3.5 kN. What is the efficiency and effort lost in friction?

Earning:   Approval pending.