Certification Assistance for Marine Engineers
Canadian
First Class ME Applied Heat
In Canada, Transport Canada administers the Marine Engineering
examination process; visit the
Training Page for details on the process. The actual exam consist of nine
(9) questions randomly drawn from a question bank of the various subject. Six
(only) must be answered in a 3.5hrs time frame. The exam questions are similar
to these, presented below, and are drawn heavily from similar question in the
Reed's Marine Engineering series of books.
Disclaimer
Transport Canada has ask us to advise users of this webpage to keep in
mind that these questions are not the exact questions found in their
exams. Martin's Marine Engineering Page -
www.dieselduck.net is not affiliated with
Transport Canada and these questions have been gathered from various
sources.
CR of BC, in March 2010,
reports " BTW just wanted to inform you that I recently wrote my 1st class
Thermodynamic and all 9 questions came form this site."
1. A vessel containing 19.5 kg of water at a temperature of 89oC has
18kg of ice at a temperature of -13oC placed inside. Neglecting the effect
of the containing vessel and loss due
to radiation, Calculate:
1) The equilibrium temperature.
2) The amount of the mixture that
must be removed and heated to 100oC so that when it is replaced, the final
temperature will be 10oC.
note:
Specific heat capacity of water =
4.187 kJ(kgK)-1
Specific heat capacity of ice = 2.11
kJ(kgK)-1
Enthalpy of fusion of ice, = 336
kJ/kg
Ans:4.62oC Ans:2.12 kg
2. Three different liquids each of mass x, y and z have equal volumes,
identical specific capacities and are at temperatures of 49oC, 63oC and
80oC respectively. If x is
mixed with y the resulting temperature is 54oC. If y is mixed with z the resulting temperature is 69oC. Calculate
the final or equilibrium temperature when all three liquids are mixed in
the mass ratios of 2, 3 and 5 respectively
Ans: 62.57oC
Ref DOT2 Ref Reeds p24 ,p284
(similar)
3. The load on a single collar type of thrust block is 250 kN at a
shaft speed of 100 rev/min and the mean diameter of the thrust pads is 480
mm. The coefficient of
friction between collar and pads is 0.03 and the lube oil increases in
temperature by 20oC. Calculate:
1) the power lost due to friction
2) the heat energy generated per
hour
3) the mass flow of oil (kg/h)
required to limit the temperature rise to 20oC
note: specific capacity of oil = 2
kJ(kgK)-1
Ans: 18.85 kW Ref DOT3
Ans: 67.86 MJ Ref Reeds p23 and 288
#4
Ans: 1696.5 kg/h
4. Calculate the equilibrium temperature resulting from the mixture of
41 kg of ice at -25oC, 61 kg of water at 65oC and 64 kg of water at 62oC.
Neglect the effect of the containing vessel.
note: specific heat capacity of
water = 4.187 kJ(kgK)-1
note: specific heat capacity of ice
= 2.11 kJ(kgK)-1
note: enthalpy of fusion of water =
336 kJ/kg
Ans: 24.86oC
5. Calculate the rise in temperature of 4000 l of water at 45oC when
50 kg of dry steam at a pressure of 900 kPa are blown into it.
note: the specific heat capacity of
water = 4.187 kJ(kgK)-1
Ans: 7.6oC Ref DOT5
6. A calorimeter has a water
equivalent of 250 g. and mass of water in the calorimeter is 1.5 kg. When
1.57 g. of fuel are burnt in the calorimeter, the temperatures of the
metal and the water rise by 5.6oC. Calculate
the heating value (calorific value) of the fuel (MJ/kg). Specific heat of water = 4.187 kJ/kg.K.
Ans: 26.1 MJ/kg. Ref. DOT6.
7. The bi-metallic element of a
control device consists of two thin flat strips, one of a nickel and the
other of aluminum, the ends of which are fastend together a distance of 50
mm by means of two brass spacers 2.5 mm long. Calculate the radius of the
curvature of the assembly when the
temperature is increased by 200oC.
note:
alpha Aluminum =(22.5 x 10-6)/K
alpha Nickel =(12.8 x 10-6)/K
alpha Brass =(18.0 x 10-6)/K
Ans: 1296.5 mm
Ans: 1299.11 mm
8. A copper steam pipe of outside diameter 80 mm, inside diameter 65
mm and length 3.85 m is at a temperature of 85oC. Both ends of the pipe
are securly fixed to restrain contraction and expansion. Calculate:
1) the stress in the pipe when it
cools to a temperature of 65oC
2) what total force applied to the
ends of the pipe would cause the same stress
note: linear expansion coefficient
of copper = (16.7)(10-6)K
note: modulus of elasticity = 116
GPa
Ans: 38.744 MPa Ref DOT8
Ans: 66.18 kN
9. A steam pipe has fractured due to the malfunction of and expansion
gland. The operating
temperature of the pipe was 200oC but the pipe had cooled to 22oC when the
crack occured. The length was
measured at this latter temperature and found to be 4.42 m. A temsile test specimen taken from the pipe fractured at 423.4
MPa. Calculate the modulus of elasticity of the pipe material.
note: linear expansion coefficient
of pipe material =(12x10-6)K
Ans: 198.221 GPa Ref DOT9
10. A solid metal sphere at a
temperature of 15oC. is placed in 100 litres of fresh water at a
temperature of 95oC. It was found that when equilibrium conditions
prevailed, the diameter of the sphere had increased by 0.15%. Calculate the original diameter of the sphere.
note: specific heat capacity of
water = 4.187 kJ(kgK)-1
note: specific heat capacity of
sphere = 0.8876 kJ(kgK)-1
Linear expansion coefficient of
sphere = 23(10-6)/K.
Relative density of sphere material
at 15oC. = 2.56.
Ans. 43.07 cm. Ref. DOT10.
11. A glass beaker contains 125 ml
of mercury at a temperature of 20oC. Calculate the quantity of mercury that will overflow when both
beaker and mercury are heated at 80oC.
Note:
Coeff. of linear exp. (glass) alpha
= 8.5(10-6)/K
Coeff. of volumetric exp. (mercury)
beta = 1.8(10-4)/K.
Ans: 1.59 ml.
12. A telemotor system consists of two (2) copper popes each 80
mm long, 15 mm inside diameter, completely filled with hydraulic fluid at
a temperature of 16oC. Calculate
the quantity of fluid (dm3) released to the replenishing tank when the
temperature rises to 40oC. Disregard
the quantity in the hydraulic cylinders.
note: coefficient of linear
expansion (copper) = 1.7 x 10-5/K
note: coefficient of volum expansion
(fluid) = 7.7 x 10-4/K
Ans: 0.4879 Ref DOT12
13. Flue gas at a temperature of 290oC and air at a temperature
of 40oC flow on either side of a metal plate 5 mm thick.
note: The heat transfer coefficient
of the gas is 30.5 Wm-2K-1
note: the thermal conductivity
coefficient of the metal plate is 40 W(mK)-1
Calculate:
1) the overall heat transfer
coefficient
2) for a 1 m2 area, the heat
transfer from gas to air per minute
Ans: 15.59 W/m2K Ref DOT13
Ans: 233.85 kJ/min
14. A spherical vessel of 1 m
diameter, contains a liquified gas at a temperature of -180oC. The vessel is lagged to a thickness of 200 mm with insulating
material having a coefficient of thermal conductivity of 0.05 W(mK)-1.
Calculate the heat transfer per second through the insulation if the
surface temperature is 15oC.
Ans.214.4 Watts or J/s. Ref DOT14
15. Steam at a pressure of 3000 kPa. and a tempeature of 500oC.
flows through a 150 mm. Diameter pipe which is covered with lagging to a
diameter of 300 mm. The
temperature of the
outer surface of the lagging is
50oC. and the thermal conductivity coefficient of the lagging is
0.6W(mK)-1. Calculate the energy lost per second from a 50 metre length of
the pipe.
Ans. 122.373 kW Ref. DOT15.
16. The inner wall of a cold storage chamber is maintained at a
temperature of -2oC when the outside wall temperature is 21oC. The chamber wall is constructed of a 110 mm thickness brick, a 75
mm thickness of corkboard and a 25 mm thickness of wood whick is applied
to the interior wall, the brick forming the interior surface. The thermal conductivities of brick, corkboard and wood are 0.95;
0.043 and 0.17 W(mK)-1 respectively. Calculate:
1) the heat transfer (kJ) through 1
m2 of wall during a 24 hour period
2) the interface temperatures
Ans: 990 kJ/day
Ans: 19.315oC
Ans: -0.673oC
17. The temperatures at the outside surfaces of a furnace wall
are 1120oC and 150oC respectively.
1) Calculate the heat transfer
(kJ/h) through 1 m2 of the wall if it is constructed of refractory brick
and is 340 mm thick.
2) Determine the reduction in the
amount of heat lost if 100 mm of insulating brick are now added to the
wall. In this case the surface temperatures are 1120oC and 23oC
respectively
note: lambda (refractory brick) =
0.7 W(mK)-1
note: lambda (insulating brick) =
0.25 W(mK)-1
Ans: 7189.4 kJ/h Ref DOT17
Ans: 2730.6 kJ/h
18. 1) Two layers of differant
material of thickness L1, and L2 and thermal conductivities lamda1 and
lamda2 are placed in close contact with each other. Deduce from first
principles an expression for the heat transfer through this composite
structure.
2) A wall consists of a external
layer of brick 500mm thick to which is fastened a cork board layer 80mm
thick. The thermal conductivity of the brick is 0.5 W(mK)-1 and the
corkboard, 0.048 W(mK)-1.
Calculate the heat transfer through
1m2 of wall each hour if the temperature difference between the inner and
outer surfaces is 50oC.
Ans: Q = A t (delta T) Sumation ( s ) lambda
Ans: 67.5[kj/hr]
19. A Fortin barometer registers 720
mm Hg, the vacuum gauge
indicates 715 mm Hg and the temperature inside the condenser is 32oC.
Air is extracted from the condenser at the rate of 3.85 m3/min. Calculate:
1) the quantity of air leaking into
the condenser (kg/min)
2) the quantity of steam vapour
associated with the air (kg/min)
note: Assume the standard atmosphere
= 100 kPa
note: R (air) = 0.287 kJ(kgK)-1
Ans: 0.1721 kg/min
Ans: 0.1302 kg/min
20. A tank having an internal volume of 4 m3 contains gas at a
temperature of 20oC, a pressure of 6 kPa and a gas constant, R = 0.27
kJ(kgK)-1. Another gas having
a mass of 0.4 kg, a temperature of 20oC, and a gas constant, R = 0.28
kJ(kgK)-1, is introduced into the tank. Calculate:
1) the mass of gas initially in the
tank
2) the final pressure of the mixture
of the gasses
Ans: 0.3792 kg Ref DOT20
Ans: 12.5632 kPa
21. A condenser has a volume of 20 m3 and contains a mixture of
air and dry saturated steam at a total pressure of 9 kPa and a temperature
of 38oC. Calculate:
1) the mass of steam in the vesse
2) the mass of air in the vessel
3) the mass ratio of the air to
steam
Ans: 0.9246 kg Ref DOT21
Ans: 0.5322 kg
Ans: 0.5756
22. 1) State Daltons
Law of Partial Pressures
2) A closed vessel of 500 cm3 capacity contains a sample of flue gas
at 101 kPa. and 20oC. If the
sample of the flue gas by volume is 10% Carbon Dioxide, 8% Oxygen and 82%
Nitrogen, calculate the partial pressure and mass of each constituent in
the sample. R for CO2, O2 and
N2 = 0.189, 0.26, and 0.297 kJ(kgK)-1 Ans. Partial pressures, CO2 = 10.15 kPa, O2 = 8.12
kPa.
N2. = 83.23 kPa.
Masses: CO2 = 0.09164 g.
O2. = 0.0533 g.
N2. = 0.4782 g.
23. 1) The quantity or amount of a substance is known as the mole
(mol). How has the mol been
defined under the System International d'Unites (S.I.)
2) Calculate the gas constant R for
Oxygen
note: Relative atomic mass of Oxygen
= 16
note: Universal gas constant Ro =
8.3143
Ans: The mole is more commonly
referred to as the kilogram-mole (kg-mol) and defined as a quantity of gas
equivalent to "m" kg of the gas, where "m" is the
molecular weight of the gas. For
example the molecular weight of Oxygen is 32 therefore the mass of one
kg-mol of Oxygen is 32 kg. The
molecular weight of hydrogen is 2. Hence
one kg-mol of hydrogen is a mass of 2 kg. etc.
Ans: 0.26 kJ(kgK)-1 Ref DOT23
24. 1) State Avogadro's law and also
state the approximate number value of Avogadro's number.
2) An experiment shows that an
average value for the volume of 1 mol of a permanent gas is 22.4136m3 at
standard atmospheric pressure, 101.325 kPa. and 0oC.
Calculate the Universal Gas
Constant, Ro
note: T=0oC = 273.15 K
Ans: 6.022 (10)23 molecules/mol
Ans: 8.3143 kJ/molK
25. A gas at the start of compression, has a pressure of 100 kPa
a temperature of 20oC and a volume of 9600 cm3. At the end of compression the temperature is 512oC and the volume
is
720 cm3. Calculate:
1) the compression index
"n"
2) the work done during the
compression process (kJ)
3) the change of internal energy
(kJ)
4) the heat transfer during
compression (kJ)
note: specific heat capacity cv =
0.657 kJ(kgK)-1
note: R(gas) = 0.264 kJ(kgK)-1
note: area under compression curve
PVn = (P1V1 - P2V2)/n-1
Ans: 1.38 Ref DOT25
Ans: -4.242 kJ
Ans: 4.011 kJ
Ans: -0.231 kJ
26. Derive the following expression which gives the heat supplied
during a polytropic expansion process. Q. = (gamma - n) W (gamma - 1)
where; Gamma = adiabatic index, n =
polytropic index, W = work done by gas, Q = heat supplied by the gas.
2) Air expands polytropically in a cylinder from a pressure of 1400
kPa, a temperature of 150oC., and a volume of 60 dm3, to a volume of 180
dm3, the index of expansion being, n= 1.2. The adiabatic index for air, gamma = 1.4.
Calculate: a) The air temperature
after expansion.
b) The amount of heat flow through
the cylinder wall.
Ans: 66.56oC Ref DOT 26
Ans: 41.43 kJ
27. 1) Derive an expression for the
external work done by a gas during a steady flow frictionless adiabatic
expansion involving no change of kenetic or potential energy.
2) Oxygen flows at a steady rate of
10 kg/s through a open system, expanding adiabatically from an initial
pressure of 9000 kPa and a temperature of 200oC to a final pressure of
3000 kPa. Assuming frictionless flow and no change in the kinetic and
potential energy of the gas, Calculate:
a) The final temperature of the
oxygen.
b) The work flowing from the system
per minute.
note: Universal gas constant, Ro =
8.3143 kJ(molK)-1, Relative atomic mass of Oxygen = 16, Specific heat
capacity of Oxygen, Cp = 0.917 kJ(kgK)-1
Ans: W= m Cp (T1-T2)
Ans: 346.54K 73.54oC
Ans: 69.58 MJ/min
28. One m3 of air initially at a pressure of 100 kPa at
temperature of 15oC is compressed polytropically to a pressure of 1400 kPa.
Calculate:
1) the volume and temperature at the
end of compression
2) the work done in compressing the
air (kJ)
3) the change in internal energy
(kJ)
4) the heat exchange through the
cylinder walls (kJ)
note: the compression index n = 1.3
note: R(air) = 0.287 kJ(kgK)-1
note: specific heat capacity at
constant pressure Cp = 1.005
Ans: 0.1314 m3 Ref DOT28
Ans: 256.8oC
Ans: -279.86 kJ
Ans: 210.1 kJ
Ans: -69.76 kJ
29. A gasoline engine has a cylinder diameter of 100 mm and a
stroke of 130 mm. The
pressure and temperature at the beginning of compression is 100 kPa and
57oC respectively, and the clearance volume is 230 cm3. The law of compression is PV1.3 = C. Calculate:
1) the temperature at the end of
compression
2) the work done on the gas during
the compression stroke
Ans: 275.5oC Ref DOT29
Ans: -0.276 kJ
30. 1) Derive the following
relationship for a polytropic process: n-1
T2 = (p2) n = (V1)n-1
T1 (p1) (V2)
2) one kg of a certain gas expands
adiabatically in a closed system until its pressure is halved. During the
expansion the gas does 67 kJ of external work and its temperature falls
from 240oC to 145oC. Calculate:
a) the value of the adiabatic index
b) the characteristic gas constant
Ans: See Reeds p73 and p74
Ans: gamma = 1.4194
Ans: 0.2958 kJ(kgK)-1
31. A high speed diesel motor is in the design stage.
It is to be a 6 cylinder, 4 stroke cycle square engine. (cylinder
dia. = stroke). It must develope 76 kW. at 2000 rev/min. with a mechanical
efficiency of 80% and a mean effective pressure of 700 kPa. Calculate the
cylinder dimensions.
Ans: Cylinder diameter and stroke =
120 mm
Ref DOT 31 Ref Reeds p109
32. During a Morse test on a 4 cylinder internal combustion
engine mounted on a test bed, the brake specific fuel consumption is 0.33
kg(kWh)-1 and the enfine developes a brake power of 40 kW. with all
cylinders functioning. The speed is maintained constant at 30 rev/s. and
with each
cylinder cut out in turn, the average torque developed by the three
remaining cylinders is 150 Nm. The
heating value of the fuel used = 40 MJ/kg. Calculate:
a) The indicated power.
b) The specific fuel consumption per
indicated kWh.
c) The indicated themal efficiency.
Ans: 46.92 kW
Ref DOT32
Ans: 0.2813 kg/kWh(ind)
Ans: 31.99%
33. Some modern motor vessels have been fitted with electronic
devices employing a cathode ray oscilloscope for obtaining indicator
diagrams from the cylinders of the main prime mover and displaying the
results in a remote position such for example, as the Chief Engineers
Office. Describe such a
device and state the manner in which it may be used to illustrate certain
important features such as the compustion process etc.
Ans: See "Applied
thermodynamics for Engineering
Technologists" 2nd edition
(1974) pages 700- 704 and 766- 770
Ref DOT33
34. 1) Briefly describe the Morse
Test as a method of obtaining the indicated power of a high speed,
multi-cylinder gasoline engine.
2) An 8 cylinder gasoline engine
operating on a test bed developed 240 kW at 50 rev/s. When one cylinder
was cut out by shorting the spark plug, the brake power reduced to 200 kW.
Calculate the indicated power of
this engine.
Ans: 320 kW
35. The following data pertains to a 4 cylinder 4 stroke cycle,
single acting compression ignition engine mounted on a test bed
mean effective pressure = 750 kPa brake load
= 6kN
speed ................. = 4 rev/s brake radius = 960mm
cylinder diameter ..... = 320mm
brake cooling water
stroke ................ = 480mm
inlet = 14oC
outlet = 47oC
specific fuel consumption
(indicated) .......... = 49.5 kg/h
heating value of the fuel
...................... = 43.0 MJ/kg
specific heat capacity of cooling
water ... = 4.187 kJ(kgK)-1
mass flow of cooling water
................ = 77.0 kg/min
Calculate:
1) the indicated thermal efficiency
2) the brake thermal efficiency
3) the heat balance diagram for this
engine
Ans: 39.1% Ref DOT35
Ans: 24.49%
Ans:
100%
heat energy supplied by fuel
!
_
!
_
!
!
!
I.P. 39.1%
Cooling water Exhaust gas
!
30.1%
30.8%
_ !
_
!
!
B.P. mechanical
24.49% friction etc.14.61%
36. The following data pertains to a single-cylinder,
single-acting, two stroke cycle, diesel engine mounted on a test bed:
Mean effective pressure = 890 kPa.
Speed
= 2.3 revs/s.
Cylinder diameter = 360 mm.
Stroke
= 780 mm.
Brake load
= 8 kN.
Brake radius
= 1.25 m.
Specific fuel consumption (brake) =
0.251 kg(kWh)-1
Calorific value
= 41.5 MJ/kg.
Calculate:
1) The indicated power.
2) The brake power.
3) The indicated thermal efficiency.
4) The total heat energy lost per
second.
Ans: 162.52 kW
Ref DOT36
Ans: 144.5 kW
Ans: 38.87%
Ans: 255.6 kJ/s
37. A Carnot engine is operated
between two heat resevoirs held at temperatures of 400 K and 300 K
respectively.
1) Calculate the amount of energy
(kJ) rejected to the sink if the engine receives 1200 kJ of energy at 400
K.
2) If the engine is now operated on
the reversed Carnot cycle (refrigerator) and receives 1200 kJ of energy at
300K, calculate the quantity of energy delivered to the resevoir at 400 K.
3) Calculate the work done (kJ) in
driving the compressor of part (2).
Ans. 1) Q = 900 kJ
Ans. 2) 1600 kJ
Ans. 3) 400 kJ
38. A high speed compression ignition engine operating on the
dual combustion cycle receives 2/3 of the total heat energy at constant
volume and the remaining 1/3 of the energy
at constant pressure. Calculate: The
temperatures (K) at the five cardinal points
of the cycle.
NOTE:
Compression ratio........ = 13:1
Maximum cylinder pressure = 5000 kPa
Air intake pressure...... = 100 kPa
Air intake temperature... = 15oC
Specific heat capicity at constant
volume Cv = 0.71kJ(kgK)
Specific heat capacity at constant
pressure Cp = 1.005kJ(kgK)
Ans: 288 K
Ans: 803.5 K
Ans: 1107 K
Ans: 1214 K
Ans: 451.5 K
39. An internal combustion engine
operates on the dual-combustion cycle with a compression ratio of 10.7 :
1. Initially the pressure and temperature of the air at the start of the
compression stroke are 100 kPa and 32oC, and the maximum pressure and
temperature during the cycle are 4200
kPa and 1600oC respectively. Assume
adiabatic compression and expansion. Calculate:
1) The pressures and temperatures at
the remaining cardinal points of the cycle.
2) The ideal thermal efficiency.
note:
Specific heat capacity at constant
volume, Cv = 0.718
kJ (kgK)-1 Specific heat capacity at
constant pressure,
Cp =1.005 kJ (kgK)-1
Ans: 2761.5 kPa 787.2 K (514.2oC)
Ans: 1197.26 K (924.26oC) 284.47 kPa
867.64 K (595oC)
Ans: 58.49%
40. 1) Sketch the pressure - volume
diagram for the ideal Carnot cycle. Describe
the sequence of events in a perfect reciprocating heat engine operating on
the cycle and derive an expression for the cycle efficiency.
2) Determine the Carnot efficiency
of:
a) a gasoline motor operating within
the temperature limits of 80oC and 2080oC
b) Skinner uniflow engine supplied
with steam at a pressure of 2000 kPa and a temperature of 260oC exhausting
to a condenser at a pressure of 7 kPa
Ans: See Reeds p135 - p137
Ans: 85%
Ans: 41.46%
41. An internal combustion engine operates on the constant volume
cycle with a compression ratio of 7:1. Another engine, operating on the diesel cycle, has a compression
ratio of 16:1 the fuel being admitted at constant pressure for 6% of the
stroke. Compare the air
standard efficiencies (A.S.E) of the two engines by means of the following
formulae:
1. constant volume cycle A.S.E. = 1 - 1 /
r(gamma-1)
2. Diesel cycle . = 1-( 1 ) (
1 ) {rho (gamma-1}/(gamma) (r(gamma-1) {rho -1}
note: r = compression ratio
note: rho = fuel cut-off ratio
note: gamma = 1.4 (adiabatic index
for air)
Ans: 54.08%
Ref DOT41
Ans: 61.89%
42. With a internal combustion
engine operating on the constant volume cycle, the pressure, volume, and
temperature at the start of the compression stroke are 99 kPa, 113 dm3 and
48oC respectively, the compression ratio being 10:1. The gas receives 95
kJ of energy during the combustion process, the law of compression is pv
1.37 = C, the specific heat capacity at constant volume is 0.712 kJ (kgK)-1
and the characteristic gas constant R
= 0.29 kJ (kgK)-1. Calculate:
1) The mass of gas compressed during
the cycle.
2) The pressure and temperature at
the end of compression.
3) The pressure and temperature at
the end of combustion.
Ans: 0.1202 kg
Ans: 2320.8 kPa 752.5K
479.5oC
Ans: 5744.2 kPa 1862.5K
1589.5oC
43. A single stage, double acting compressor rotating at 300
rev/min delivers air at the rate of 14 m3/min. The suction conditions are
101.3 kPa and 15oC with delivery pressure of 700 kPa. The clearance volume is 5% of the swept volume and the compression
index n = 1.3. Calculate:
1) the air temperature at delivery
from the cylinder
2) the volume swept out by the
piston (m3)
3) the indicated power (kW)
Ans: 176.9 Ref DOT43
Ans: 0.0281 m3
Ans: 57.58 kW
44. Air is compressed in a single stage reciprocating compressor
from a pressure of 101.3 kPa and a temperature of 15oC to the delivery
pressure of 700 kPa. Calculate
the indicated power required for a free air delivery of 0.3 m3/min when
the compression process is:
1) isentropic
2) reversible isothermal
3) polytropic, with n = 1.25
Ans: 1.31 kW Ref DOT44
Ans: 0.979 kW
Ans: 1.195 kW
45. A three stage single acting compressor having a free air
delivery of 2.83 m3/min operates in a situation where the atmospheric
pressure is 101.3 kPa and the air temperature is 15oC. The suction air pressure and temperature are 98 kPa and 32oC
respectively. The delivery
presssure is 7000 kPa the compression index, n = 1.3 and R(air) = 0.287
kJ(kgK)-1. Calculate the indicated power required for the process assuming
complete intercooling between stages and that the machine is designed for
minimum work. n-1
note: total indicated work = Z _n_ mRT1 [{p2}zn
-1 ]
n-1 [{p1}
]
note: Z = number of stages
note: m = mass air delivered
note: n = compression index
Ans: 24.14 kW
46) A single-acting single-stage,
reciprocating air compressor absorbs 14 kW with a mean piston speed of 3
m/s and a rotation speed of 6.0 rev/s. Air is asperated into the cylinder
at 100 kPa and compressed to 2000 kPa, the compression index, n = 1.32 ,
neglecting the effect of
clearance, Calculate:
1) The stroke of the compressor
piston.
2) The diameter of the compressor
cylinder.
3) The mean effective pressure.
note: For a polytropic operation, W
= P1V1-P2V2 / n-1
Ans: 250mm
Ans: 164.3mm
Ans: 440.33 kPa
47. Air at a pressure of 98 kPa. and a temperature of 18oC is
aspirated into a two stage compressor at the rate of 0.05 kg per stroke.
The air leaves the first stage at a pressure of 295 kPa and is then
passed through an intercooler where it is cooled at constant pressure to
the initial temperature. The air is further compressed in the second stage
to a pressure of 730 kPa and again passed through a cooler where the
temperature is once more reduced to the initial state. Calculate:
1) The % decrease in volume due to
cooling at the end of each stage.
2) The % decrease in volume if
compression had occured in a single stage and then cooled to the initial
temperature.
R (air) = 0.287 kJ(kgK)-1
pVn = Constant, where n = 1.3 for
each stage.
Ans: 22.47%
Ans: 18.87%
Ans: 37.1% Ref. DOT 47.
48. Air is aspirated into the cylinder of a single stage air
compressor at a pressure of 100 Kpa a temperature of 25oC and delivery at
pressure of 600 kPa. The
volume swept out by the
piston amounts to 1440 cm3 and the
clearance volume equals 40 cm3. If the compression index, n = 1.3
Calculate:
1) the fraction of the stroke when
the delivery valves open
2) the fraction of the stroke when
the suction valves open
3) the mean effective pressure
note: for a polytropic operation W =
P1V1 - P2V2, including clearance n-1
Ans: 0.76875 Ref DOT48
Ans: 0.08243
Ans: 203.57 kPa
49. Air is compressed in the cylinder of a compressor according
to the law PVn = C. The
initial condition of the air is 100 kPa 20oC and 0.125 m3 and the final
condition 3800
kPa and 510oC.
note: the specific heat capacity Cp
= 1.005 kJ(kgK)-1 the specific heat capacity Cv = 0.718 kJ(kgK)-1.
Calculate:
1) the compression index
2) the mass of air compressed
3) the work done during compression
4) the change of internal energy
Ans: 1.37 Ref DOT49
Ans: 0.1486 kg
Ans: -56.48 kJ
Ans: 52.28 kJ
50. A single acting,single stage,
air compressor aspirates air at 100 kPa and delivers at 600 kPa. The
cylinder is 300 mm diameter, the stroke 425 mm and it operates at 5 rev/s.
Initially the compressor index was 1.15 but after operating for
some period of time the index was found to be 1.35. Neglecting the effect
of clearance, Calculate:
1) The power absorbed in each case.
2) The % increase in the power
absorbed by the compressor.
n-1
Note: Work per cycle = _n_ P1V1
[{P2} n -1]
n-1 [{P1} ]
Ans: 30.16 kW
Ans: 34.2 kW
Ans: 13.3%
51. The pressure and temperature in
a stream condenser is 9 kPa. and 40oC. The dryness fraction of the steam is 0.86. Find the mass ratio of
steam to air present in the condenser.
NOTE: R(air) = 0.287kJ(kgK)-1.
Ans. 3.3:1 Ref DOT 51
52. A vessel of volume 8.7 m3 contains air and dry saturated
steam at a total pressure of 6.24 kPa and temperature 30oC. Taking R(air)
as 0.287 kJ(kgK)-1 Calculate:
1) the mass of steam in the vessel
2) the mass of air in the vessel
Ans: 0.2642 kg Ref DOT52
Ans: 0.2 kg
53. In a steam turbine plant, the condenser vacuum is equivalent
to 685 mm. of mercury when the atmospheric pressure indicated with a
mercurial barometer is 760mm. The fluid temperature at the extraction
outlet is 39oC. and R(air) = 0.287 kJ(kgK)-1. Calculate:
1) the specific volume of the
extracted air.
2) the quantity of vapour (kg)
removed with each kg. of air extracted with the ejector.
Ans: 29.87 m3/kg Ref DOT53
Ans: 1.45 kg
54. A throttling calorimeter was employed to provide information
upon the quality of steam passing through a pipeline. The following data was recorded: steam pressure in pipeline =
1100 kPa, steam pressure after passing through orifice = 100 kPa.
Calculate the minimum dryness fraction that can be measured for these
particular conditions.
Ans: 0.94786 Ref DOT54
55. A combined throttling / separating calorimeter was employed
to provide information upon the quality of steam passing through a
pipeline. The following data
was recorded:
pipeline pressure................. =
1000 kPa
throttling calorimeter pressure... =
120 kPa temperature = 109.8oC
quantity of water collected after
throttling = 3.03 kg
quantity of water collected in
separator = 0.113 kg
specific heat capacity of
superheated steam at calorimeter
pressure = 2.02 kJ(kgK)-1
Calculate the dryness fraction of
the steam
Ans: 0.9244 Ref DOT55
56. Superheated steam at a temperature of 260oC and a pressure of
1500 kPa is mixed in the mass ratio of 2 to 3 (superheated steam to wet
steam) with steam at the same pressure but of dryness fraction 0.88.
The mixture is then throttled through a reducing valve to a
pressure of 800 kPa.
Assume no losses occur, calculate
the dryness fraction of the steam:
1) after mixing but before
throttling
2) after throttling
Ans: 0.96 Ref DOT56
Ans: 0.973
57. Using the following formula, calculate the entropy per kg. of
superheated steam at 1500 kPa and 300oC. taking the mean specific heat of
water and superheated steam as 4.24 and 2.43 kJ(kgK)-1 respectively.
Compare result with the value given in the steam tables. s = C(w)
ln T(sat) + hfg + C(sup)
ln T
273 T(sat)
T(sat)
C(w) = mean specific heat of water
C(sup) = mean specific heat of
superheated steam
T(sat) = saturation temperature
absolute
T = superheated steam temperature
absolute
Ans. s = 6.9172 kJ(kgK)-1
Ref DOT57
Ans: Using A.S.M.E. Steam Tables: s
= 6.9207 kJ(kgK)-1
58. 1 kg of superheated steam at 8000 kPa and 520oC is throttled
to a pressure of 1000 kPa then expanded at constant entropy to a pressure
of 2 kPa. Using the enthalpy
- entropy
(h-s) chart calculate:
1) the change in enthalpy
2) the change in entropy
3) the dryness fraction at 2 kPa
Ans: 1200 kJ(kg)-1 Ref DOT57
Ans: 0.93 kJ(kgK)-1 Ref MAR84
Ans: 0.885
Ref Mc Conkey p424
59. 1) Sketch in diagramatic form, a
simple gas-turbine generator plant showing the compressor, combustor,
turbine and generator.
2) Sketch a temperature/entropy
diagram for this cycle indicating the adiabatic irreversible/isentropic
operations with solid lines and the effect of blade friction (adiabatic
irreversible phenomena),with broken or dotted lines.
3) Air at a temperature of 15oC and
a pressure of 100 kPa enters the compressor of the above plan which has a
maximum cycle temperature of 600oC and a pressure ratio of 6/1.
The isentropic efficiencies of the
compressor and the turbine are 0.82 and 0.85 respectively. Calculate:
a) The actual temperature at the end
of compression.
b) The actual temperature at the end
of expansion.
Note: Adiabatic index, gamma = 1.4
Ans.3a) 523.36K 250.36oC
Ans.3b) 575.7K 302.7oC
60. During a certain type of process dry saturated steam at a
pressure of 4000 kPa is throttled to 500 kPa and then allowed to expand
isentropically to a pressure of 60 kPa. Using the enthalpy - entropy (h-s)
chart calculate:
1. the change in entropy during this
process
2. the final condition of the steam
after the expansion has occured
Ans: 0.871 kJ(kgK)-1 Ref DOT60
Ans: 9.2%
Ref MAY84
61. A turbine is supplied with steam at a pressure of 6000 kPa
and a temperature of 540oC. Isentropic
expansion occurs as the steam passes through the turbine until the exhaust
pressure of 6 kPa is reached. Using the enthalpy-entropy (h-s) chart,
calculate:
1) the dryness fraction at the end
of the expansion process.
2) the Rankine efficiency.
Ans: 0.83
Ref DOT61
Ans: 40.37%
62. 1) Sketch a flow diagram for a
simple saturated steam turbine plant using numbers to denote the cardinal
points of the cycle
2) Illustrate the Rankine cycle for
this process with a pressure / volume (pV) diagram and a temperature /
entropy (Ts) diagram. Use the
same numbers used in part (1) to indicate the main points of these
diagrams.
Ans:? Ref DOT62
63. A double acting compound steam engine develops an indicated
power of 500 kW using dry saturated steam at a pressure of 1400 kPa and
exhausting to atmospheric at pressure of 100 kPa. The overall expansion
ratio is 12:1 and the cut off ratio in the high pressure cylinder is 1:3.
The diagram factor for the engine is 0.8 and the piston speed
is 250 m/min. Assume
hyperbolic expansion in each cylinder. Calculate:
1) the high pressure cylinder
diameter
2) the low pressure cylinder
diameter
Ans: 790 mm Ref DOT63
Ans: 395 mm Ref Mar84
64. A double acting single cylinder
steam engine developes 70 kW at 250 rev/min using dry saturated steam
supplied at a pressure of 1100 kPa and exhausting into a condensor at 75
kPa. The cut off ratio is 0.25 and the stroke/bore ratio is 1.3 / 1. The
mechanical efficiency = 85%, and the affect of the piston rod may be
neglected. ON the basis of a hypothetical diagram, Calculate:
1) The bore and stroke of the engine
assuming a diagram factor of 0.8.
2) The specific steam cosumption of
the engine if the brake thermal efficiency is 15%
Ans. 275 mm 358 mm
Ans.10.02 kg/kWh
65. The travel of a slide valve is 32 cm and the lap is 7 cm.
When the crank has passed through 90o from the dead centre
position, the port opening is 7 cm. Find the lead either graphically or by
calculation.
Ans: 7.5 mm Ref DOT65
66. A steam engine uses steam at the rate of 13.3 Mg/h when
developing an indicated power of 1.5 MW , and uses 18.7 Mg/h when
developing an indicated power of 2.25 MW. Calculate:
1) Willams Law for this engine.
2) the steam consumption (Mg/h) when
developing 2000 kW.
3) the specific consumption, kg(kWh)-1
when developing 2000 kW.
Ans: m = 2.5 + 7.2 P
Ans: 16.9 Mg/h Ref DOT66
Ans: 8.45 kg/kWh
67. Steam is supplied to the high pressure cylinder of an engine
at a pressure of 1500 kPa. and cut-off takes place at 45% of the stroke.
The exhaust pressure is 650 kPa., the clearance volume equals 10%
of the stroke volume, and compression begins when the piston has travelled
88% of the exhaust stroke. Assume isothermal conditions to prevail to the end of the
expansion and compression strokes.
1) Sketch the indicator diagram
showing the given data.
2) Calculate the mean effective
pressure.
Ans. mep = 562.1 kPa
68. An engine is supplied with steam
at a pressure of 1500 kPa and a temperature of 260oC, the exhaust pressure
being 16 kPa. Assumming
isentropic expansion, Calculate:
1) The dryness fraction of the steam
after expansion
2) The Rankine efficiency.
Ans.0.829
Ans.27.6%
69. Dry saturated steam at a
pressure of 1500 kPa is expanded through a turbine nozzle to a pressure of
900 kPa, the expansion following the law PV1.135 = C. Calculate:
1) The dryness fraction of the steam
as it leaves the nozzle.
2) The change of enthalpy of the
steam during the passage through the nozzle. (kJ/kg)
3) The velocity of discharge.
4) The nozzle exit (mm2) for a mass
flow of 1 kg/s
Ans: 0.961
Ans: 96.95 kJ/kg
Ans: 440.34 m/s
Ans: 469 mm2
Ref Reeds pg234
70. In a reheat turbine cycle, steam, at a pressure of 5000 kPa
and a temperature of 460oC expands through the first stage turbine to a
pressure of 300 kPa. The
steam is then passed through the reheater where the temperature is raised
to its original value while the pressure remains constant at 300 kPa.
The steam now passes through the final stage where it expands
to the condenser pressure of 3 kPa. Calculate
the Rankine efficiency assuming an ideal reheat cycle.
Ans: 41.2% Ref DOT70
71. The theoretical change of
enthalpy of the steam during its passage through the nozzles of an impulse
turbine is 312.5 kJ/kg, and of this, 10% is lost due to friction. The
nozzles are inclined at 20o to the plane of the wheel. The inlet angles of
the blades is 35o and the absolute velocity of the steam leaving the
blades is 204 m/s in the direction of the turbine axis. Assuming steam is supplied to the machine at the rate of 1 kg/s,
Calculate:
1) The blade velocity to avoid shock
at entry.
2) The exit angle of the blades.
3) The power developed (kW)
4) The blade efficiency.
Ans.338.? m/s
Ans.31.076o
Ans.238.6 kW
Ans.84.82%
72. Steam from the nozzle of a single stage impulse turbine
impinges upon the bleads from an angle of 18o to the plane of the wheel
and with a velocity of 900 m/s. The
linear velocity of the blades is 330 m/s and the steam consumption is
0.095 kg/s. The blades are
symmetrical and have a frictional loss of 10%. Calculate:
1) the tangenial force on the blades
(N)
2) the power developed (kW)
3) the axial thrust due to the steam
(N)
Ans: 94.93 N Ref DOT72
Ans: 31.32 kW Ref FEB84
Ans: 2.641 N Ref MAR84
73. Steam is supplied to a turbine at a pressure of 2000 kPa and
a temperature of 440oC. It
exhausts to the condenser at a pressure of 4 kPa. and dryness fraction is
0.85. 14.0% of the steam passing through the turbine is extracted for feed
water heating at a pressure of 150 kPa.
Calculate:
1) the thermal efficiency without
feed heating.
2) the thermal efficiency with feed
heating.
Ans: 35.66%
Ans: 38% Ref DOT 73
74. Air at a pressure of 100 kPa and 20oC is aspirated into a gas
turbine plant operating on the constant pressure cycle and discharged to
the combustion chamber at 600 kPa. The gases entering the turbine are at a
temperature of 900oC and both compression and expansion can be assumed to
be adiabatic. If the specific
heat capacities Cv = 0.718 kJ(kgK)-1 and cp = 1.005 kJ(kgK)-1 calculate:
1) the temperature at the end of
compression
2) the temperature of the exhaust
3) the energy transfer at constant
pressure (kJ/kg)
4) the increase of internal energy
from inlet to exhaust (kJ/kg)
5) the ideal thermal efficiency
Ans: 216oC
Ref DOT74
Ans: 430oC
Ans: 687.4 kJ/kg
Ans: 294.4 kJ/kg
Ans: 40.06%
75. An Orsat apparatus was used to
analyze the exhaust from a gasoline engine. The results, on a volumetric basis, were as follows: CO2= 12.5% ;
O2 = 3.1% ; CO = 0.5%. Convert this analysis to a mass analysis and
determine the mass of 100m3 of the exhaust gas at 15oC and 100 kPA.
Ans: 125.83 kg Ref DOT 75.
76. The coal used for firing a power
station boiler has an analysis by mass of: C = 81% , H2 = 4.5% , and 02 =
3.5%, the remainder being ash. Calculate:
1) The theoretical mass of air
required for complete combustion of 1 kg of this fuel.
2) The percent analysis by mass and
by volume of the flue gases formed when the fuel is burnt with 65% excess
air.
3) The density of the flue gases at
a pressure of 100 kPa and a temperature of 0oC.
Ans: 10.8 kg
Ans: C02 m= 15.88% v=
10.68%
H20 m= 2.16% v=
3.56%
02 m= 8.63%? v=
8.01%
N2 m= 73.33% v= 77.75%
Total =100.00% 100.00%
Ans: 1.308 kg/m3
77. The volumetric composition of air is : Oxygen = 21%, nitrogen
= 79%. The volumetric
composition of a particular gasious fuel is a follows: H2= 48% CH4= 21%
C6H6= 1.5% CO= 19% N2= 6% CO2= 4.5%. The correct quantity of air is supplied so that perfect
combustion takes place. Calculate:
1) the contraction in volume (%
basis) due to combustion.
2) the volumetric air/gas ratio.
3) the volumetric analysis (% basis)
of the combustion products.
Ans: 6.43% Ref DOT77
Ans: 4.13:1
Ans: Products k mol
%k
mol
CO2
53.5 11.14
H2O
94.5 19.69
N2
332.0 69.17
Total 480.0
100.00
78. A 50 ml (millilitre) sample of lake Ontario water required
6.2 ml of a certain reagent to indicate the end point that is the hardness
of the sample. The reqgent is
equivalent to 6.2 mg of Calcium Carbonate (CaCO3). Calculate the hardness
of a 1000 ml sample of this water and express the result in parts per
million (p.p.m.)
Ans: 124 p.p.m. Ref DOT78
79. A two stroke diesel motor develops an indicated power of 3000
kW with a specific fuel consumption (indicated) of 0.225 kg(kWh)-1. The combustion of 1 kg of fuel requires 18 kg of
air. The exhaust gases from the motor pass through a boiler,
entering at a temperature of 330oC and leaving at a temperature of 215oC,
the gasses having a specific heat capacity of 1.05 kJ(kgK)-1. Steam is generated in the boiler at a pressure of 1500 kPa
and a dryness factor of 0.97. The
feed water is at a temperature of 50oC and the boiler efficiency is 0.8.
Calculate the quantity of steam generated per hour.
Ans: 491.2 kg/h Ref DOT79
80. Steam is generated in a boiler at the rate of 50000
kg/h, at a pressure of 4000 kPa and a temperature of 460oC. The daily
consumption amounts to 88 tonnes of fuel having a heating value of 41 MJ/kg.
The overall plant efficiency is 16%, and the feed water temperature
is 150oC. Calculate:
1) the boiler efficiency
2) the equivalent power output of
the turbine
3) the boiler evaporation rate
(kg/h) from and at 100oC
4) the equivalent (kg of steam/kg of
fuel) from and at 100oC.
Ans: 90.53% Ref DOT80
Ans: 6681 kW
Ans: 60299 kg/h
Ans: 16.445 (kg steam/kg fuel)
81. Sketch a temperature - entropy (T-s) diagram for a vapour
compression refrigeration system indicating the effect of:
1) isentropic compression to a
superheated state
2) undercooling of the liquid
refrigerant during the condensing process Sketch a pressure - enthalpy
(p-h) diagram for a vapour compression refrigeration system indicating the
effect of :
a) isentropic compression to a
superheated state
b) undercooling of the liquid
refrigerant during the condensing process
Ans: diagram Ref DOT81
82. The pressure and temperatures of the refrigerant entering and
leaving the compressor of an R-12 system are 150.9 kPa and -5oC and 491.4
kPa and 45oC respectively. The refrigerant leaves the condenser as a
saturated liquid at 15oC. Calculate
the coefficient of performance of the
system.
Ans: 5.175 Ref DOT82
83. The pressure and temperature of the refrigerant entering the
compressor of an R-12 system is 182.6 kPa and 0oC, and entering the
condenser, 567.3 kPa and 50oC, respectively. The refrigerant leaves the
condenser as a saturated liquid at a pressure of 567.3. Calculate the coefficient of performance.
Ans: 5.085 Ref DOT83
84. The pressure and temperature of
the refrigerant entering the condenser of an ammonia system is 1470 kPa
and 63oC respectively, and it leaves at the same pressure with no
undercooling. The gas enters the compressor at 207.7 kPa and compression
is isentropic with a flow rate of 0.15 kg/s. Calculate:
1) The refrigerating effect
2) The work transfer in the
compressor
3) The coefficient of performance.
Ans: 140.94 kW
Ans: 36.6975 kW
Ans: 3.84 Ref DOT84
85. The pressure and temperature of the refrigerant entering the
condenser of an R-12 system is 1219 kPa. and 65oC respectively, and it
leaves as a saturated liquid at the same pressure. The gas enters the
compressor at 80.71 kPa and compression is isentropic with a flow rate of
15 kg/min. Calculate:
1) the refrigeration effect.
2) the coefficient of performance.
Ans: 1285.35 kJ/min Ref DOT85
Ans: 1.785
86. A refrigerator is driven by a 2.25 kW motor and yields ice at
the rate of 2.5 tonnes per day. The
ice is at a temperature of -7oC and is produced from water at a
temperature of 18oC. Calculate:
1) the coefficient of performance of
the machine
2) the capacity (tonnes/day) from
and at 0oC
note: specific heat capacity of
water = 4.2 kJ(kgK)-1
note: specific heat capacity of ice = 2.04
kJ(kgK)-1
note: enthalpy of fusion (ice) = 335
kJ/kg
Ans: 5.464 Ref DOT86
Ans: 3.171 tonnes/day
87. A steam engine uses steam at the rate of 13,3 Mg/h when developing an indicated power of 1,5 MW, and uses 18,7 Mg/h when developing an indicated power of 2,25 MW. Calculate:
i) Willan's Law for this engine;
ii) the steam consumption (Mg/h) when developing 2 000 kW;
iii) the specific consumption, (kg/kW-h) when developing 2 000 kW.
88. Steam at a pressure of 3 000 kPa and a temperature of 500C flows through a 150 mm diameter pipe which is covered with lagging to a diameter 300 mm. The temperature of the outer surface of the lagging is 50C and the thermal conductivity coefficient of the lagging is 0,6 W/mK. Calculate the energy lost per second from a 50 m lenght of pipe.
89. Steam is supplied to a turbine at a pressure of 2 000 kPa and a temperature of 440C. It exhausts to the condenser at a pressure of 4 kPa and dryness fraction 0,85. 14,0% of the steam passing through the turbine is extracted for feed water heating at a pressure of 150 kPa. Calculate:
i) the thermal efficiency without feed heating;
ii) the thermal efficiency with feed heating.
90. Superheated steam at a temperature of 260C and a pressure of 1 500 kPa is mixed in the mass ratio 2/3 (superheated steam to wet steam) with steam at the same pressure but of dryness fraction, 0,88. The mixture is then throttled through a reducing valve to a pressure of 800 kPa. Assume no losses occur, calculate the dryness fraction of the steam:
i) after mixing but before throttling;
ii) after throttling.
91. Linear expansion coefficients:
Aluminum = (22,5) (10-6) /K
Nickel = (12,8) (10-6) /K
Brass = (18,0) (10-6) /K
92. A condenser has a volume of 20 m3 and contains a mixture of air and dry saturated steam at a total pressure of 9 kPa and a temperature of 38C. Calculate:
i) the mass of steam in the vessel;
ii) the mass of air in the vessel;
iii) the mass ratio of air to steam in the vessel.
NOTE: R(air) = 0,287 kJ/kgK
93. Air is compressed in the cylinder of a compressor according to the law PVn = C. The initial condition of the air is 100 kPa, 20C and 0,125m3 and the final condition, 3 800 kPa and 510C. The specific heat capacities are:
Cp = 1,005 kJ/kgK
Cv = 0,718 kJ/kgK
Calculate:
(i) the compression index;
(ii) the mass of air compressed;
(iii) the work done during compression;
(iv) the change of internal energy.
94. The following data pertains to a 4 cylinders, 4 stroke cycle, single acting compression ignition engine mounted on a test bed:
Mean effective pressure = 750 kPa
Speed = 4 rev/s
Cylinder diameter = 320 mm
Stroke = 480 mm
Brake load = 6 kN
Brake radius = 960 mm
Brake cooling water, inlet = 14C
Brake cooling water, outlet = 47CSpecific fuel consumption (indicated) = 49,5 kg/h
Heating value of fuel = 43,0 MJ/kg
Specific heat capacity of cooling water = 4,187 kJ/kgK
Mass flow of cooling water = 77 kg/min.
Calculate:
(i) the indicated thermal efficiency;
(ii) the brake thermal efficiency;
(iii) the heat balance diagram for this engine.
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