7/29/2019 THERMA IN-II EXAM L
1/2
CMS COLLEGE OF ENGINEERINGNAMAKKAL-637 003INTERNAL TEST-II
Year/Sem: III/V Branch: MECHSubject Code& Title: Thermal
Engineering Date: 21.08.2012Time: 1.30 Hours Max.Marks: 50Prepared
by: Approved by:
(Mr.P.Muthusamy) (Prof.M.MUTHUKUMARAN)
AP / Mech HOD / Mech
PART-A (5X2=10)
(Answer All the Questions)
1.Define Free Ain Delivered with regard to a compressor2.State
the effect of clearance on work done in a reciprocating
compressor3. What are the advantages of multistage compression over
single stage compression?
4.How is the inter cooler used to reduce the power consumption
of compressor?5.Draw the valve timing diagram for a CI engine.
PART-B
6.Describe the working of Diesel fuel pump.(8)7.(a) (i) Derive
an expression for workdone in single stage compressor wihout
clearence volume. (6)
(ii)A single acting single stage compressor is belt driven from
an electric motorat 400rpm. The cylinder diameter is 15 cm and the
stroke 17.5 cm. The air is
compressed from 1 bar to 7 bar and the law of compression PV1.3
= constant.
Find the power of the motor, if transmission efficiency is 97%
and the
mechanical efficiency of the compressor 90%. Neglect clearance
effects. (10)
(or)
(b) (i) Explain with suitable sketches the working of two stage
air compressor with
actual p - v diagram. (6)
(ii)A Single stage, single acting reciprocating air compressor
has a bore of 20cm and a stroke of 30 cm. The compressor runs at
600 rpm. The clearance
volume is 4% of the swept volume and index if expansion and
compression
is 1.3.Thesuction conditions are 0.97 bar and 27C and delivery
pressure is
5.6 bar. The atmospheric conditions are at 1.01 bar and 17C.
Determine (i)
the free air delivered inm3/min (ii) the volumetric efficiency
referred to the
free air conditions (iii) the indicated power. (10)
8.(a) (i)Derive an expression for the minimum work required for
a two-stage recipro--cating air compressor with perfect
intercooling and neglecting clearance. (8)
(ii)A two stage air compressor compresses air from 1 bar and 20C
to 42 bar. Ifthe law of compression is pV1.35= constant and the
intercooling is perfect.
Find per kg of air (1) the work done in compression (2) the mass
of cooling
water necessary for abstracting the heat in the intercooler, if
the temperature
rise of the cooling water is 25C. (8)
(or)
(b) (i)With a neat sketch describe any one type of rotary
compressor. (8)(ii)The free air delivery of a single stage
reciprocating air compressor is
2.5m3/min. The ambient air is at condition and the delivery
pressure is 7 bar.
The clearance volume is 5% of stroke volume and law of
compression and
