This document contains 46 multiple choice questions about thermal engineering concepts. The questions cover topics like Planck's law, heat exchanger fouling factors, refrigeration cycles, steam power plants, nuclear reactors, and cooling towers. The correct answers are not provided.

1. Thermal Engineering MCQs
Correct Answer
Q1. The relation derived for the total emissive power of the blackbody as a function of
wavelength and based of quantum theory is known as
a) Kirchoff'slaw
b) Stefan-Boltzmannlaw
c) Planck'slaw
d) noneofthe above
Q2. Whichmedium of surrounding is better forfin effectiveness?
a) gasmedium
b) liquidmedium
c) finshave sameeffectivenessinboththe gas and liquidmediums
d) noneofthe above
Q3. Fouling factor of a heat exchanger can be calculated by
a) [Thermal resistanceofheatexchangerwithoutscaling] – [Thermal resistanceof
heat exchangerwithscaling]
b) [Thermal resistanceofheatexchangerwithscaling] – [Thermal resistanceofheat
exchangerwithoutscaling]
c) [Thermal resistanceofheatexchangerwithoutscaling] x [Thermal resistanceof
heat exchangerwithscaling]
d) noneofthe above
Q4. When is the arithmetic mean temperature difference of heat exchanger used instead of
LMTD?
a) whenthe temperature profilesoftwo fluidsofheatexchangeraresloping
downwardwithcurve
b) whenthe temperature profilesoftwo fluidsofheatexchangerareslopingupward
with curve
c) whenthe temperature profilesoftwo fluidsofheatexchangerarestraight
d) noneofthe above
Q5. The convectiveheat transfer coefficientin laminar flow over a flatplate
a) Increaseswithdistance
b) Increasesifa higherviscosityfluidisused
c) Increasesifa denserfluidis used
d) Decreaseswithincreaseinfreestream velocity
Q6. Freon group of refrigerants are
a) Inflammable
b) Toxic
c) Non-inflammableandtoxic
d) Nontoxicandnon-inflammable

2. Q7. The boiling point of ammonia is
a) -10.5°C
b) -30°C
c) -33.3°C
d) -77.7°C
Q8. Forobtaining high COP, the pressure range of compressor should be
a) High
b) Low
c) Optimum
d) Anyvalue
Q9. A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigerating
machine withall other conditions unchanged, the coefficientof performance willbe
a) 1.33
b) 2.33
c) 3.33
d) 4.33
Q10. Cooling water is required for followingequipment in ammonia absorption plant
a) Condenser
b) Evaporator
c) Absorber
d) Condenser,absorberandseparator(rectifier)
Q11. The freezing point of sulphur dioxide is
a) -56.6°C
b) -75.2°C
c) -77.7°C
d) -135.8°C
Q12. Mass flow ratio of NH₃ in comparison to Freon-12 for same refrigeration load and same
temperature limits is of the order of
a) 1: 1
b) 1: 9
c) 9: 1
d) 1: 3
Q13. In a refrigeration system, the expansion device is connected between the
a) Compressorandcondenser
b) Condenserandreceiver
c) Receiverandevaporator
d) Evaporatorandcompressor

3. Q14. The vapour compression refrigerator employs the followingcycle
a) Rankine
b) Carnot
c) ReversedRankine
d) ReversedCarnot
Q15. In actual air-conditioning applications forR-12 and R-22, and operating at a condenser
temperature of 40° C and an evaporator temperature of 5° C, the heat rejection factoris
about
a) 1
b) 1.25
c) 2.15
d) 5.12
Q16. Rating of a domestic refrigerator is of the order of
a) 0.1 ton
b) 5 tons
c) 10 tons
d) 40 tons
Q17. A human body feels comfortable when the heat produced by the metabolism of human
body is equal to the
a) Heat dissipatedto the surroundings
b) Heat storedin the humanbody
c) Sum of(A) and(B)
d) Differenceof(A)and (B)
Q18. The bank of tubes at the backof domestic refrigerator is
a) Condensertubes
b) Evaporatortubes
c) Refrigerantcoolingtubes
d) Capillarytubes
Q19. In a lithium bromide absorption refrigeration system
a) Lithiumbromideisused asa refrigerantandwateras an absorbent
b) Water is usedas a refrigerantandlithiumbromideasan absorbent
c) Ammoniaisusedas a refrigerantandlithiumbromideasan absorbent
d) Noneof the above
Q20. The condition of refrigerant after passing through the condenser in a vapour compression
system is
a) Saturatedliquid
b) Wet vapour
c) Drysaturated vapour
d) Superheatedvapour

4. Q.21 Whichis not a boilermounting
a) Airpreheater
b) Safetyvalves
c) Fusibleplug
d) Manhole
Q.22 In thermal powerplants,coal is transferredfrombunkerto the otherplacesby
a) Hoists
b) conveyors
c) cranes
d) lifts
Q.23 A thermal electricpowerplantproduces1000MWof power.If the coal releases
900x 107 kJ/hofenergy,then what is the rate at whichheat is rejected fromthe
powerplant?
a) 500MW
b) 1000MW
c) 1500MW
d) 2000MW
Q.24 Thecorrectsequenceoffactorsin orderofdeceasingimportancefor
locationofathermal powerplantis
a) load,coal,water
b) coal,water, load
c) Water, load,coal
d) water, coal,load
Q.25 TheefficiencyofsuperheatRankinecycleishigherthanthat ofsimpleRankine
cyclebecause
a) Theenthalpyofmain steam is higherforsuperheatcycle
b) Themean temperatureof heat additionishigherforsuperheatcycle
c) Thetemperatureof steam in the condenserishigh
d) Thequalityofstem inthe condenserislow
Q.26 In a Rankinecycle,regenerationresultsinhigherefficiencybecause
a) Pressureinsidetheboilerincreases
b) Heat isadded beforesteamenters the lowpressureturbine
c) Averagetemperatureofheat additioninthe boilerincreases
d) Total workdeliveredbytheturbineincreases
Q.27 For a givenset ofoperatingpressurelimitsofaRankinecycle,the highest,
efficiencyoccursfor
a) Saturatedcycle
b) Superheatedcycle
c) Reheatcycle
d) Regenerativecycle

5. Q.28 In steam and othervapourcycles,the processofremovingnon-condensableis
called
a) Scavengingprocess
b) Deaerationprocess
c) Exhaustprocess
d) Condensationprocess
Q.29 Thereheat cyclein steam powerplantis mainlyadoptedto
a) Improvethermal efficiency
b) Decreasethemoisturecontent inlowpressurestagesto a safevalue
c) Decreasethecapacity ofcondenser
d) Recoversthewaste heat ofboiler
Q.30 Employingsuperheatedsteaminturbinesleadsto
a) Increasein erosionofblading
b) Decreaseinerosionofblading
c) No erosioninblading
d) No changeinerosionofblading
Q.31 A regenerativesteamcyclerenders
a) Increasedworkoutputper unit massof steam
b) Decreasedworkoutputperunit massof steam
c) Increasedthermal efficiency
d) Decreasedworkoutputperunit massof steam aswell as increasedthermal
efficiency
Q.32 In whichone ofthe followingsteamturbines,steamis takenfrom variouspoints
alongthe turbine,solelyforfeedwaterheating?
a) Extractionturbine
b) Bleederturbine
c) Regenerativeturbine
d) Reheatturbine
Q.33 In the bottomingcycleofcogeneration,lowgradewasteheatisused for
a) Processing
b) Powergeneration
c) Feed waterheating
d) noneofthe above
Q.34 A powerplant, whichusesa gasturbinefollowedbysteamturbineforpower
generation,iscalled:
a) Toppingcycle
b) Bottomingcycle
c) Braytoncycle
d) Combinedcycle

6. Q.35 In the Rankinecyclelowerlimitonthe condenserpressureisdueto the
a) Expansionlimitinturbine
b) condensersize
c) Airleakageinto the condenser
d) temperatureof coolingwater
Q.36 Theequivalentevaporation(kg/hr)ofaboilerproducing2000kg/hr ofsteam
with enthalpycontentof 2426kJ/kgfromfeedwater at temperature40°C (liquid
enthalpy= 168kJ/kg,enthalpyofvaporisationofwaterat 100°C =2258kJ/kg)is
a) 2000
b) 2149
c) 1682
d) 1649
Q.37 Boilerratingisusuallydefinedintermsof
a) Maximumtemperatureofsteam in Kelvin
b) Heat transferrate in kJ/hr
c) Heat transferareain m2
d) Steam outputin kg/hr
Q.38 Heat is mainlytransferredbyconduction,convectionandradiationin
a) Insulatedpipescarryinghotwater
b) Refrigeratorfreezer coil
c) Boilerfurnaces
d) condensationofsteamin a condenser
Q.39 MeV is a unitof
a) Energy
b) Power
c) Momentum
d) Noneof the above
Q.40 CANDUisa type of
a) Boiler
b) Turbine
c) Reactor
d) Noneof the above
Q.41 Graphiteisused inPHWR as a
a) Fuel
b) Moderator
c) Coolant
d) Noneof the above

7. Q.42 Calendriaisa part of
a) Boiler
b) Turbine
c) Reactor
d) Noneof the above
Q.43 Peak loadplantsareusuallyoperated
a) Fora higherfractionoftime
b) Fora lessfractionoftime
c) Maybe 1 or2, dependingon thesituations
d) Noneof the above
Q.44 Plant factor(Capacityfactor)is….
a) Ratio ofaverageloadto peakloadforsame time intervals
b) Ratio ofpeak loadto averageloadforsame time intervals
c) Ratio ofaverageloadto rated capacity
d) Noneof the above
Q.45 Plant capacityalwaysdesignedto
a) greaterthan peak load
b) lessthan peakload
c) Maybe 1 or2, dependingonthesituations
d) Noneof the above
Q.46 In a coolingtower,"approach"isthetemperaturedifferencebetweenthe
a) hot inletwater andcoldoutlet water
b) hot inletwater andWBT
c) coldoutletwater and WBT
d) DBT andWBT