Mechanical Engineering
ME 8595 | Thermal Engineering 2 Mcq
1. A steam nozzle is a duct of
a)Constant Cross Section b)Decreasing Cross Section c)Increasing Cross Section d)Bothb&c
2.A steam nozzle converts pressure energy into
a)Hydraulic Energy b)Kinetic Energy c)Potential Energy d)Pneumatic Energy
3.Dry saturated steam has dryness fraction
a)less than1 b)greater than1 c)less than zero d)equal to 1
4.For an isentropic flow,the entropy across nozzle sections are
a)directly proportional b)inversely proportional c)constant d)None
5.Superheated steam has dryness fraction
a)equal to1 b)greater than 1 c)less than 1 d)less than zero
6.Supersaturated flow is a l so called as
a)metastable flow b)isentropic flow c)superheated flow d)None
7.Supersaturation causes specific volume and entropy to
a)decrease b)maintainstability c)increase d)None
8.In a C D nozzle,flow up to throat is___________and flow after throat is___________
a)subsonic&subsonic b)supersonic&subsonic c)supersonic&supersonic d)subsonic&supersonic
9.Pure water has dryness fraction
a)lessthan1 b)equalto1 c)greaterthan1 d)equaltozero
10.Metastable flow will_____________the dryness fraction of steam
a)decrease b)increase c)notchange d)None
11.Nozzle is used in which application?
a)Rockets b)Steam Turbines c)FlowMeasurement d)a&b
12.In a one-dimensional flow, the fluid velocity will______________across crosssection.
a)increase from centre b)remainconstant c)decreasefrom center d)acceleraterandomly
13.Steam flows through a nozzle at a massflowrateof m=0.1 kg/s with a heatloss of 5kW.The enthalpies at inlet and exit are
2500kJ/kg and 2350kJ/kg, respectively. Assuming negligible velocity at inlet (C1=0),the velocity (C2) of steam (inm/s)at the
nozzle exit is
a)457.214m/sec
b)447.214m/sec
c)547.214m/sec
d)557.214m/sec.
14.In a steam nozzle, the steam expands from 4 bar to1 bar.The initial
velocity is 60m/s and initial temperature is 200degreeC. Determine the exit
velocity if the nozzle efficiency is 92%.
a)684.98m/sec
b)712.98m/sec
c)654.98m/sec
d)734.98m/sec
15.Find the nozzle efficiency if the actual enthalpy drop is 2257KJ/Kg and isentropic enthalpy drop is 2527Kj/Kg and the frictional losses is
a)83.915%
b)89.315%
c)87.315%
d)83.715%
16.The critical pressure ratio of a super-heated steam(n=1.3) in a nozzle is
a)0.578
b)0.587
c)0.546
d)0.564
17.If the exit diameter of the divergent portion of the nozzle is 80mm ,throat diameter is 20mm and the length of the divergent portion is 200mm.what is the angle of divergent portion.
a)25.7degree
b)16.7degree
c)10.3degree
d)15degree
18.If the area at the inlet of the nozzle is 0.1sq.metre, the velocity is 60m/sec and the specific volume is 0.187cubic.metre/kg, then the mass flow rateis
a)35.08kg/sec
b)37.08kg/sec
c)32.08kg/sec
d)36.08kg/sec
19.Steam at a pressure of 10.5 bar and 0.95 dry is expanded through a convergent divergen tnozzle. The pressure of steam leaving the nozzle is 0.85bar .(i)Findthevelocityofsteam atthroat
a)547.214m/sec
b)457.214m/sec
c)557.214m/sec
d)447.214m/sec.
20.If the actual enthalpy drop is 4000kJ/kg and isentropic enthalpy drop is 5000kJ/kg, what is the coefficient of velocity?
a)0.8944
b)0.9844
c)0.8644
d)0.6844
21.Steam at 30bar & 350degreeC is supplied to a nozzle, the exit pressure is maintained at 4bar. Determine the degree of under cooling if the flow is supersaturated
a)20.4degreec
b)18.4degreec
c)28.4degreec
d)25.4degreec
22.Steam at 40bar & 400degreec is supplied to a nozzle, the exit pressure is maintained at 6bar. Determine the degree of supersaturation
a)0.97
b)0.78
c)0.87
d)0.79
23.Blow off cock is used to
a)supply water to boiler b)remove water from boiler c)remove impurities from boiler d)remove high pressure steam
24.Super heater is a device used to heat
a)water entering boiler b)steam leaving boiler c)steam leaving turbine d)air entering furnace
25.Steam trap is used to remove
a)remove steam from condensing water b)remove water from steam c)remove dust from emissions d)None
26.Which one of the following is a green house gas?
a)Nox b)Sox c)CO2 d)CO
27.A steam boiler is an equipment used to
a)produce heat energy b)produce high pressure steam c)produce high velocity steam d)produce coal
28.A fire tube boiler is one in which flame hot gases travel
a)outside the tube b)across the tube c)away from the tube d)inside the tube
29.Economizer is a device used to pre heat
a)air entering furnace b)water entering boiler c)steam entering turbine d)None
30.Moisture content in coal is determined by
a) Ultimate Analysis b)Proximate Analysis c)MoistureAnalysis d)ThermalAnalysis
31.A water tube boiler is one in which flame hot gases travels
a)across the tube b)inside the tube c)outside the tube d)Both a&c
32.Air pre heater is a device used to heat air using
a)High temperature steam b)High pressure steam c)Hot flue gases d)Any
33.Soot removers are fitted in_______________to remove soot particles
a)Economizer b)Airpreheater c)Superheater d)Regenerator
34.Natural Gas is a______________type of fuel
a)Renewable b)Non-renewable c)Low calorific value d)Low quality
35.If the mass of water evaporated is 230kg/hr and the mass of fuel burnt is 0.00556kg/sec, then the actual evaporation rate is
a)12.5kg/kgoffuel
b)10.5kg/kgoffuel
c)11.5kg/kgoffuel
d)9kg/kgoffuel
36.In a steam boiler ,the actual evaporation is 10.5kg/kg of fuel and the factor of evaporation is 1.15 and the equivalent evaporation equals
a)12.125kg/kgoffuel
b)11.075kg/kgoffuel
c)12.15kg/kgoffuel
d)12.075kg/kgoffuel
37.If the actual evaporation rate is 10kg/kg of fuel,enthalpy of steam generated is 2500kJ/kg, feed water enthalpy is 200kJ/kg and the calorific value is 35600KJ/kg then the boiler efficiency is
a)78.4%
b)64.6%
c)81%
d)75.3%
38.The amount of heat evolved when unit mass or unit volume of a fuel is burnt completely in excess supply of oxygen and the biproducts of combustion is all wed to escape in the atmosphere is
a)Net Calorific value
b)Calorificvalue
c)GrossCalorificvalue
d)HigherCalorificvalue
39.The name of gas which is absorbed pyrogallic acid by in an Orsat apparatus is
a)carbondioxide
b)Carbonmonooxide
c)oxygen
d)Nitrogen
40.If the mass of the dry steam is 20kg and the mass of water particles are1 kg then the dryness fraction is
a)0.943
b)0.978
c)0.967
d)0.952
41.The temperature of water entering the economizer is 30degreec ,the temperature of water leaving the economizer is 130 degree c ,the actual evaporation rate is 11kg/kg of fuel and the calorific value of fuel is 34600kJ/kg then the percentage of heat utilized in economizer is
a)15.45%
b)17.45%
c)10.45%
d)12.45%
42.Which of the following statement is wrong
a) Locomotive boiler is a water tube boiler.
b) Watertubeboilersareinternallyfired.
c) La-montboilerisalowpressurewatertubeboiler.
d) alloftheabove
43.The boiler power may be defined as
a) the ratio of heat actually used in producing the steam to the heat liberated in the furnace
b) the amount of water evaporated or steam produced in kg per kg of fuel burnt
c) the amount of water evaporated from and at 100degreeC into dry and saturated steam
d) the evaporation of 15.653kg of water per hour from and at 100degreeC
44.The function of a safety valve is
a)to blow offsteam when the pressure of steam inside the boiler exceeds the workingpressure
b)to indicate the water level inside the boiler to an observer
c)to measure pressure of steam inside the steam boiler
d)none of the above
45.Pelton wheel turbine is a
a)constant speed turbine b)reaction turbine c)impulse turbine d)reversible turbine
46.In a steam turbine ,steam ____________in nozzle
a)compresses b)expands c)remains constant d)just flows
47.The heat absorbed by water to raise its temperature upto 100degree Celsius is called
a)Sensible heat b)Latent heat c)Residual heat d)None
48.Water is converted into steam by adding heat energy at
a)constant volume b)constant pressure c)constant temperature d)constant area
49.Reaction turbines has
a)Buckets b)Stator&Rotor c)Diffuser d)Combustion Chamber
50.The need for super heating in steam power plant is
a)to improve steam quality b)To avoid condensation in turbine c)To avoid corrosion of turbine blades d)All the above
51.Mollier steam chart is drawn between
a)Pressure and enthalpy b)enthalpy and entropy c)entropy and pressure d)enthalpy and temperature
52.The SI unit of entropy is
a)KJ/m.K b)KJ/Kg c)KJ/Kg.K d)KJ/m2
53.A turbine is a device used to convert pressure energy into
a)Potential energy b)Heat energy c)Mechanical Energy d)Electrical Energy
54.In a steam turbine ,the velocity of steam _____________through the rotor
a)decreases b)increases c)remains constant d)Botha&b
55.In an impulse turbine,the blades are
a)symmetrical b)increasing area patterned c)decreasing area patterned d)asymmetrical
56.The heat absorbed by 100degreeCelsius water to form water vapour at 100degreeCelsius is called
a)Sensible heat b)Latent heat c)Residual heat d)None
57.Steam at 300kPa and 500 degreeC (h=3486.0kJ/kg) enters a steam turbine and exits at atmospheric pressure and 350degreeC (h=3175.8kJ/kg). Heat losses in turbine are 50 kW and the mass flow rate is 0.25 kg/s.Determine the power output of the turbine if kinetic energy losses are negligible.
a)31.55KW
b)20.7KW
c)27.55kW
d)35.55kW
58.The Rate au turbine belongs to the category of
(a)Pressure compounded turbine
(b)reaction turbine
(c)Velocity compounded turbine
(d)radial flow turbine
59.A steam turbine receives steam steadily at 10bar with an enthalpy of 3000kJ/kg and discharges at 1bar with an enthalpy of 2700kJ/kg. The work output is 250kJ/kg. The changes in kinetic and potential energies are negligible.The heat transfer from the turbine casing to the surroundings is equal to
(a)0kJ
(b)50kJ
(c)150kJ
(d)250kJ
60.Given, Vb=Bladespeed, V=Absolute velocity of steam entering the blade, alpha = Nozzle angle. The efficiency of an impulse turbine is maximum when
a)Vb=0.5Vcosα
b)Vb=Vcosα
c)Vb=0.5V^2cosα
d) Vb=V^2cosα
61.For a single stage impulse turbine with a rotor diameter of 2m and as peed of 3000 rpm, the blade speed is
a)354.159m/sec
b)319.154m/sec
c)314.159m/sec
d)359.154m/sec
62.A turbine is said to have an axial discharge when the steam leaves the blade ti pat__________to the direction of the blade motion.
a)60degree
b)30degree
c)45degree
d)90degree
63.In a De-Laval nozzle expanding super heated steam from 10 bar to 0.1bar,the pressure at the minimum cross-section(i.e. pressure at throat, p2) will be
a)3.3bar
b)5.46bar
c)8.33bar
d)7.64bar
64.In are action turbine,when steam flows through the fixed blades,
a)pressure increases while velocity decreases
b)pressure decreases while velocity increases
c)pressure and velocity both decreases
d)pressure and velocity both increases
65.The process of draining steam from the turbine,at certain points during its expansion and using this steam for heating the feed water in feed water heaters and then supply in gi to the boiler is known as
a)regenerative heating
b)reheating
c)intercooling
d)superheating
66.In a 50% reaction turbine stage, tangential component of absolute velocity at rotor inlet is 537m/s and the blade velocity is 454m/s. The power output in kW of steam will be
a)260
b)302
c)210
d)282
67.In a Topping System Cogeneration plant____________is produced first.
a)HeatEnergy b)Mechanical Energy d)Pressure Energy d)Electrical Energy
68.The advantage of having cogeneration plant is
a)Self reliability b)Grid Stability c)Both a&b d)None
69.Application of heat pipe
a)Chip cooling b)Super heating c)Flow measurement d)Pressure regulation
70.Wetting fluids have contact angles between
a)30 and 60 degrees b)60 and 90degrees c)0and90degrees d)90and180degrees
71.In a Bottoming System Co generation plant____________is produced first.
a)Heat Energy b)Mechanical Energy d)Pressure Energy d)Electrical Energy
72.Factors to be considered during establishing cogeneration system are
a)Steam power ratio b)Type of Process c)Fuel availability d)All theabove
73.Wick is a component used in
a)Heat pipe b)Heat Engine c)Heat pump d)Refrigeration system
74.Non-Wetting fluids have contact angles between
a)30and60degrees b)60and90degrees c)0and90degrees d)90and180degrees
75.Cogeneration is simultaneous production of electrical energy and
a)Mechanical Energy b)Thermal Energy c)Potential Energy d)Kinetic Energy
76.Cogeneration system is used in
a)Sugar industries b)Textile industries c)Refineries d)All the above
77.Heat pipe is a device which has_________and_____________at both ends
a)Compressor and Condenser b)Condenser and Evaporator c)Evaporator and Expansion Valve d)Expansion Valve and Condenser
78.Thermosyphon needs_____________to work
a)Pressure difference b)Gravity c)Heat pump d)Compressor
79.The cogeneration plant efficiency nCO if WT, Qi, QH represents turbine work ,heat input, heat output respectively is given by?
a)nCO=(WT+Qi)/QH
b)nCO=(WT–Qi)/QH
c)nCO=(WT+QH)/Qi
d)nCO=(WT+QH)/Qi
80.The electricity fraction of total energy output if W1 and Q1 represents the turbine work and heat output is given by?
a)W1/(W1+Q1)
b)W1/(W1–Q1)
c)W1/(W1Q1)
d)W1/Q1
81.In terms of cost per MW compared to condensing sets of the same power, the back pressure turbines are?
a)more expensive
b)cheaper
c)costly
d)none of the mentioned
82.Which of the following statements is not correct?
a.A topping cycle plant generates electricity or mechanical power first.
b.A bottoming cycle plant generates heat first.
c.A bottoming cycle plant generates electricity or mechanical power first.
d.Both a and b
83.In a glass industry, exhaust gas from the glass melting furnace is used for power generation by installing steam boiler and turbine.Then the type of co-generation is called as:
a)gas turbine
b)diesel generator
c)topping cycle
d)bottom cycle
84.Air compress or alone consumes about-------of the energy generated in a gas turbine
b) a)20-30%
c) b)30-40%
d) c)40-50%
e) d)50-60%
85.The evaporation ratio of a coal-fired boiler is 4.Steam enthalpy is 640kCal/kg; feed water temperature is 55degreeC, Calorific Value of coal is 4000kCal/kg.The boiler efficiency is
a)49%
b)82%
c)58.5%
d)70%
86.Which of the following fuel needs maximum amount of excess air for complete
combustion?
a)Furnace oil
b)Natural gas
c)Pulverised coal
d)Wood
87.In an oil fired heat treatment furnace,which of the following is not required to determine
its efficiency by direct method?
a)Weightofinputmaterial
b)Oxygenpercentageinfluegas
c)Fuelconsumption
d)Calorificvalueoffuel
88.With respect to properties of steam
a)The sensible heat decreases as the pressure increases
b)The latent heat increases as the pressure increases
c)The specific volume increases as the pressure increases
d)The specific volume decreases as the pressure increases
89.Refrigeration is the process of producing and maintaining temperature
a)greater than room temperature b)equal to room temperature c)less than room temperature d)none
90.The output refriger an to f expansion valve is
a)low pressure vapour b)high pressure vapour c)low pressure liquid d)high pressure liquid
91.Pump ,generator ,and absorber are used in____________refrigeration system
a)Vapour compression b)VapourAbsorption c)Air d)Thermoelectric
92.Which one of the following is not a refrigerant?
a)Air b)Water c)Ammonia d)LPG
93.Which component is not available in vapour absorption refrigeration system?
a)Compressor b)Condenser c)Expansion Valve d)Evaporator
94.The output refrigerant from compressor is
a)super heated vapour b)saturated liquid c)low pressure liquid d)None
95.Thermo-electric cooling system uses_________effect to produce temperature differences.
a)Joule b)Seeback c)Peltier d)Newton
96.Air has____% of nitrogen by Mass
a)77 b)78 c)79 d)81
97.1Ton of refrigeration is equal to
a)3.5KJ/min b)3.5KJ/sec c)3.5KJ/Hr d)3.5J/sec
98.Which refrigeration system has highest COP?
a)Air refrigeration system b)Vapour Compression Refrigeration system c)Vapour Absorption Refrigeration System d) Thermoelectric Refrigeration System
99.The output refrigerant of condenser is
a)saturated liquid b)super heated vapour c)low pressure vapour d)low pressure liquid
100.Air has____%of nitrogen by Volume
a)77 b)78 c)79 d)81
Also read : OR 0551 Renewable Energy Sources Mcq
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