Thermal Engineering II Set 6

Mechanical Engineering

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This set of Thermal Engineering 2 Multiple Choice Questions & Answers (MCQs) focuses on Thermal Engineering II Set 6

Q1 | Open cooling system is also called as
  • parallel system
  • once through system
  • air based system
  • non-reversible system
Answer: once through system
Explaination:
open system is also called as once through system, in this system the water is drawn directly from the upstream side of the river pumped through the condenser and discharged to the downstream side of the river at temperature 5 to 10°c in excess of inlet temperature.
Q2 | How many number of spray nozzle does each module on spray pond cooling system contains?
  • 1
  • 2
  • 3
  • 4
Answer: 4
Explaination:
modules in spray pond cooling system contain 4 spray nozzles. the surface area of contact of water is increased when it is sprayed in air. cooling occurs due to the evaporation of water vapours as the spray propels upwards and falls down to the surface.
Q3 | Which of the following is the simplest method of cooling the condenser water?
  • spray cooling pond
  • cooling tower
  • indirect air cooling
  • hyperbolic cooling tower
Answer: spray cooling pond
Explaination:
spray cooling pond is the simplest method of all. the hot water coming out of the condenser is sprayed through the nozzles to expose maximum surface area of water to air for effective cooling. the spray ponds are surrounded with wooden walls to prevent the wind from carrying the water particles.
Q4 | In which type of cooling system are nozzles arranged on different elevation?
  • single deck system
  • double deck system
  • natural flow system
  • direct flow system
Answer: double deck system
Explaination:
in double system of cooling ponds the spray nozzles are arranged at different elevations. cooling effect is more than single deck cooling system as water comes in contact with air at lower temperatures.
Q5 | What are used in the direct flow system to transverse the pond before uniting at intake?
  • separators
  • filters
  • baffle walls
  • porous pipes
Answer: baffle walls
Explaination:
in direct flow system the hot water coming out of the condenser enters the middle channel. on reaching the far end it is divided into two currents being directed by the baffle walls so as to transverse the pond several times before uniting at intake point.
Q6 | What type of cooling system is used in the large power plants?
  • cooling ponds
  • natural flow system
  • cooling towers
  • single deck system
Answer: cooling towers
Explaination:
in large power plants cooling towers are used in the place of cooling ponds. a cooling tower is a wooden or metallic rectangular structure, with packed baffling devices. the hot water is delivered to the top of tower and is made to fall down the tower and is broken into small particles while passing over the baffling devices.
Q7 | How does outside air enter into the wet cooling system?
  • air vents
  • louvers
  • tuyeres
  • vacuum
Answer: louvers
Explaination:
air and water are thoroughly mixed by fill as water splashes down from
Q8 | Why is exhaust steam coming out of turbine is admitted to a steam header?
  • to increase the pressure
  • to decrease the velocity
  • to decrease the pressure drop
  • to control the pollution
Answer: to decrease the pressure drop
Explaination:
exhaust steam from turbine is admitted to a steam header in order to minimize the pressure drop. steam gets condensed as it passes down through the finned tubes arranged in parallel rows.
Q9 | In which system is Cooling of hot water is done on tray as step by?
  • mechanical draught cooling system
  • hyperbolic cooling tower
  • atmospheric cooling tower
  • wet cooling tower
Answer: atmospheric cooling tower
Explaination:
in atmospheric cooling tower, the hot water is delivered at the top most trays and it falls down from one tray to another until it reaches the tank below the tower. the water is cooled by air flowing across the tower.
Q10 | How is air produced in mechanical draught cooling tower?
  • air tuyeres
  • propeller fans
  • air blowers
  • louvre
Answer: propeller fans
Explaination:
in mechanical draught cooling tower the draught of air id produced mechanically by means of propeller fans.
Q11 | Why is induced draught considered better than the forced draught?
  • because power requirement is high for forced draught
  • maintenance of induced draught fan is costlier
  • forced draught is less efficient
  • forced draught produces less amount of speed of air
Answer: because power requirement is high for forced draught
Explaination:
induced draught is considered to be better than forced draught because, the
Q12 | Nozzles are used to control the ___________
  • temperature
  • rate of flow
  • mass flow rate
  • none of the mentioned
Answer: rate of flow
Q13 | A nozzle used to send fluid in coherent stream is called as ________
  • jet
  • high velocity nozzle
  • every nozzle sends fluid in coherent stream
  • none of the mentioned
Answer: jet
Q14 | In fountains the type of nozzle used is _______
  • none of the mentioned
  • turbulent jet
  • high speed nozzle
  • laminar jet
Answer: laminar jet
Q15 | Nozzles used in blast furnaces are called as _______
  • jet
  • hot blast
  • tuyeres
  • none of the mentioned
Answer: tuyeres
Q16 | If mach number is less than one then its flow is ______________
  • subsonic flow
  • turbulent flow
  • laminar flow
  • none of the mentioned
Answer: subsonic flow
Q17 | Nozzle used in rocket engine is __________
  • convergent nozzle
  • divergent nozzle
  • convergent – divergent nozzle
  • none of the mentioned
Answer: convergent – divergent nozzle
Q18 | In rocket engine the flow in the throat of the nozzle is __________
  • subsonic
  • laminar
  • turbulent
  • none of the mentioned
Answer: subsonic
Q19 | When mach number is greater than one the flow is ________
  • subsonic
  • supersonic
  • laminar
  • none of the mentioned
Answer: supersonic
Q20 | In rocket engines the amount of expansion in Nozzle determines the __________
  • exit temperature
  • exit pressure
  • exit temperature & pressure
  • none of the mentioned
Answer: exit temperature & pressure
Q21 | Pressure ratios below 20 are used in _____________ engines.
  • steam turbine
  • aero derivative engines
  • heavy frame engines
  • none of the mentioned
Answer: heavy frame engines
Q22 | Aeroderivative engines have pressure ratios ___________
  • greater than 30
  • lesser than 30 and greater than 20
  • greater than 50
  • none of the mentioned
Answer: greater than 30
Q23 | Aeroderivative engines are used where ____________ power units are required.
  • larger
  • smaller
  • optimum
  • none of the mentioned
Answer: smaller
Q24 | Gas turbines operate at pressures ________ than critical pressure ratio.
  • higher
  • lesser
  • does not depend on pressure ratio
  • none of the mentioned
Answer: lesser
Q25 | Critical pressure ratio is ratios of pressures at _________ discharge.
  • minimum
  • none of the mentioned
  • optimum
  • maximum
Answer: maximum
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