95HE-4
Sr. No.
EXAMINATION OF MARINE ENGINEER OFFICER
Function: Marine Engineering at Operational Level
HEAT ENGINES
INDIA (2001)
CLASS IV
(Time allowed - 3 hours)
Afternoon Paper
Total Marks 100
N.B. - (1) All questions are compulsory.
(2) All questions carry equal marks.
(3) Neatness in handwriting and clarity in expression carries weightage
1. A railway line is laid with 10meters length of the steel when the temperature is 00C. Linear coefficient of expansion of steel is 11 x 10-6 / 0C. If the temperature rises upto 500C, then the space
that must be left between the adjucent steel piece is
a)2.75 mm
b)5.50 mm
c)5.50 m
d)11.00 mm
2. A platinum wire can be sealed through glass but a brass one can not be sealed because
a)Platinum has greater density than brass
b)Platinum and gas have the same value of volume expansion
c)Platinum is an element while brass is an alloy
d)Platinum does not rust
3. The ratio of the densities of the two bodies is 3 : 4 and specific heat in the ratio 4 : 3. The ratio of
their thermal capacities per unit volume is
a)9 : 16
b)2 : 1
c)16 : 9
d)1 : 1
4. 80g of water at 300C are poured on a large block of ice at 00C. The mass of the ice that melts is
a)1600
b)30 gm
c)150 gm
d)8 gm
5. Two blocks of ice when pressed together, form one block because
a)of heat produced during pressing
b)of cold produced during pressing
c)melting point of ice decreases with increase of pressure
d)melting point of ice increases with increase in pressure.
6. A solid ball of metal has a spherical cavity inside it. The ball is heated. The volume of cavity will
a)Decrease
b)Increase
c)Remain unchanged
d)Have its shape unchanged
7. Steam issues from nozzles, inclined at, an angle of 22O to the direction of motion, with a velocity of
680 m/s on to the blades of a single stage impulse turbine. The mean diameter of the blade ring is
1.25m. The blade angles at inlet and exit are the same and equal to 36O. Assuming that the steam
enters the blades without shock and that the flow over the blades is frictionless, determine a)the speed of the turbine rotor in rev/min
b)the absolute velocity of the steam leaving, the blades
c)the torque on the turbine rotor when the flow of steam is 2500 kg/h.
8. One Kilogramme of a certain gas is at 0.11 MN/m2 and 15OC. It is compressed until its volume is
0.1m3. Calculate the final pressure and temperature, if the compression is a)isothermal
b)adiabatic
Calculate, also the work done, change of internal energy and heat transfer in each case. Distinguish
between positive and negative quantities.
Take Cp = 0.92 KJ/kg K; Cv = 0.66 KJ/kg K.
9. In a test on a boiler, the following observations were made
Coal burned per hour, 500kg.
Water evaporated per hour, 4375kg.
Boiler pressure, 20 bar
Feed water temperature, 95OC.
Temperature of steam leaving boiler, 225OC
Calorific value of coal used, 30700 KJ/kg.
Calculate a)the efficiency of the boiler
b)the equivalent evaporation from and at 100OC.
Take Cp of superheated steam as 2.093 KJ/kg K
10. A six cylinder, two stroke cycle heavy oil operated Main Engine has cylinder diameter of 580 mm
and a piston stroke of 1700mm. When the engine speed is 116 rev/min it uses 1204kg of heavy fuel
oil of calorific value 42700 KJ/kg in one hour. The cooling water amounts to 66.62 tonnes/hour
entering at 15OC leaving at 63OC. The torque transmitted at the engine coupling is 583 KNm and the
indicated mean effective pressure is 15 bar. Determine: a)the indicated power
b)the brake power.
c)the percentage of energy supplied/kg of fuel lost to the cooling water.
d)the brake, thermal efficiency.
e)the mechanical efficiency.
f)the brake mean elective pressure.
g)the fuel used/kWh on a brake power basis.
---------------------------X------------------------------
95HE-4
Sr. No.
EXAMINATION OF MARINE ENGINEER OFFICER
Function: Marine Engineering at Operational Level
HEAT ENGINES
CLASS IV
(Time allowed - 3 hours)
Afternoon Paper
INDIA (2001)
Total Marks 100
N.B. - (1) All questions are compulsory.
(2) All questions carry equal marks.
(3) Neatness in handwriting and clarity in expression carries weightage
Answers
Answer For Question No. 1 Answer : b
Answer For Question No. 2 Answer : b
Answer For Question No. 3 Answer : a
Answer For Question No. 4 Answer : b
Answer For Question No. 5 Answer : c
Answer For Question No. 6 Answer : a
Answer for Question No. 7
(a) 4279 rev/min
(b) 264.3 m/s
(c) 304.3 Nm
Answer for Question No. 8
(a) Pressure = 748 MN/m2 Temperature = 150C Work Done = - 143.3 kJ Heat Transfer = -143.3kJ
(b) Pressure = 1591 kN/m2
Temperature = 339.60C Work Done = -214 kJ Heat Transfer = 0 V =
214 kJ (positive)
Answer for Question No. 9
(a) 69.14%
(b) 4703 kg/h
Answer for Question No. 10
(a) 7815 kw
(b) 7083 kw
(c) 55.53 kg/kg of fuel
(d) 49.6%
(e) 90.6%
(f) 13.59 bar
(g) 0.170 kg/kwh