Maharashtra State Board of Technical Education 2008 Diploma Mechanical Engineering (power engineering) - Question Paper

Sample ques. Paper – I
Course Name : Mechanical Engineering
Course Code : ME
Semester : Fifth
Subject : Power Engineering
Marks : 80 Time: three Hours

Instructions:
1. All ques. are compulsory.
2. Illustrate your answers with neat sketches wherever necessary.
3. Figures to the right indicate full marks.
4. presume suitable data if necessary.
5. Preferably, write the answers in sequential order.

Q1. Attempt any 4 of the subsequent 16 Marks
(a) describe the subsequent terms, as applied to IC Engines
i) Swept quantity
ii) Compression ratio.
(b) Make a labelled sketch of Diesel cycle on P-V and T-S diagrams
(c) discuss the effect of Compression ratio on air standard efficiency of I. C engine
(d) What is Scavenging? discuss
(e) describe the terms IP & B.P as applied to I. C. Engine. What is the relation ranging from
them?
(f) List of pollutants in exhaust gases of petrol and diesel.

Q2. Attempt any 3 of the subsequent 12 Marks
(a) With the help of a neat sketch, discuss theoretical valve timing diagram for four
stroke petrol engine
(b) explain the effect of increasing super charge pressure on combustion of spark
ignition and compression ignition engines.
(c) discuss the effects of subsequent factors on the Air-Fuel ratio regarements of a
carburettor.
(i) Engine Speed
(ii) Altitude
(iii) Pressure and temperature of charge.
(d) provide the procedure to obtain friction power on multicylinder engine by morse test.
9095

Q3. Attempt any 3 of the subsequent 12 Marks
(a) The subsequent data refers to IC engine.
Consumption of fuel - six kg/hr
Chlorific value of fuel - 38000 kJ/kg
Brake power - 23 kw
Mechanical efficiency - 85%
compute indicated and broke thermal efficiency.
(b) The morse test outcomes are as detailed belows.
Brake purser (BP) of all cylinder working - 16.2 kw
BP when cylinder 1 cutoff - 12 kgs
BP when cylinder 2 cutoff - 12.5 kw
BP when cylinder 3rd cutoff - 12.6 kw
BP when cylinder 4th cutoff - 13 kw
compute mechanical efficiency of engine
(c) describe volumetric efficiency of a compressor. Why it is less than unity?
(d) elaborate the advantages of multistage compression over a single stage compression
for the identical pressure ratio?

Q4. Attempt any 4 of the subsequent 16 Marks
(a) define the function of the impeller and the diffuser in a centrifugal compressor.
(b) Compare Rotary and Reciprocating compressor in subsequent points.
(i) Suitability at low & high discharge.
(ii) Requirement of receiver.
(iii) Balancing issue.
(iv) Lubrication requirements.
( c) A single stage air compressor delivers air at six bar. The suction temperature is 25degree C
and suction pressure is one bar. The quantity of air entering the compressor is 3.1
m3/min, the index of compressor is 1.4 compute isothermal efficiency
(d) Classify gas turbine on basis of
(i) Combustion process
(ii) Path of working substance
(iii) Action of expanding gases
(iv) Direction of flow
(e) What is the working principle of turbo propeller engine? Make a neat labelled sketch
of turbo prop engine.
(f) elaborate solid propellants? Draw a neat diagram showing all elements of a solid
propellant rocket engine.

Q5. Attempt any 3 of the subsequent 12 Marks
(a) The thermal efficiency of a simple gas turbine reduces with decreasing loud.
Discuss.
(b) describe the subsequent terms.
(i) Cop of heat pump
(ii) Cop of Refrigerator
(iii) What is the relation ranging from them?
(c) discuss the working of domestic refrigerator.
(d) What is super heating in vapour compression cycle? provide its effects.

Q6. Attempt any 3 of the subsequent 12 Marks
(a) Draw a neat labelled diagram of window Air Conditioner.
(b) What refrigerants are used and what factors are considered in selecting a refrigerant
for subsequent purpose?
(i) Home Refrigeration
(ii) Big – Water Coolers
(c) A carnot refrigerator requires 1.25 kw per ton of refrigeration to maintain the
temperature of 243k. obtain.
(i) Cop of Carma refrigerator
(ii) Temperature at which beat is rejected
(d) (i) State the pollution norms under Bharat stage I & II for I.C engine application
(ii) provide method of energy saving in air compressors.

Earning:   Approval pending.