mechanical engineering MCQs – Page 212

Practise multiple-choice questions from mechanical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

mechanical engineering Mcqs

1. compressors gas turbines and jet engines 2. theory of machines 3. nuclear power plants 4. engineering materials 5. strength of materials mechanical engineering 6. thermodynamics 7. heat transfer 8. i c engines 9. steam boilers engines nozzles and turbines 10. engineering mechanics 11. fluid mechanics mechanical engineering 12. production technology 13. machine design 14. hydraulic machines 15. workshop technology 16. refrigeration and air conditioning

4221. Air refrigeration cycle is used in ____________________?
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A. commercial refrigerators

B. such a cycle does not exist

C. gas liquefaction

D. domestic refrigerators

E. air conditioning

4222. The advantage of dry compression is that________________?
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A. none of the above

B. it permits higher speeds to be used

C. it permits complete evaporation in the evaporator

D. all of the above

E. it results in high volumetirc and mechanical efficiency

4223. For better COP of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be____________________?
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A. high

B. euqal

C. under some conditions small and under some conditions high

D. anything

E. small

4224. In vapor compression cycle the condition off refrigerant is dry saturated vapor________________?
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A. before entering the expansion valve

B. before passing through the condenser

C. before entering the compressor

D. after passing through the condenser

E. after passing through the expansion or throttle valve

4225. Air refrigeration operates on_____________________?
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A. Rankine cycle

B. Reversed Carnot cycle

C. Erricson cycle

D. Brayton cycle

E. Carnot cycle

4226. The vapor compression refrigerator employs the following cycle_________________?
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A. Reversed Carnot

B. Brayton

C. Carnot

D. Reversed Rankine

E. Rankine

4227. In a refrigeration cycle, the flow of refrigerant is controlled by___________________?
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A. condenser

B. all of the above

C. evaporator

D. expansion valve

E. compressor

4228. In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be_________________?
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A. as low as possible (3 to 11C)

B. zero

C. high, of the order of 25

D. none of the above

E. any value

4229. Refrigeration in aeroplanes usually employs the following refrigerant___________________?
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A. Freon-11

B. Freon-22

C. Co2

D. none of the above

E. Air

4230. The higher temperature in vapour compression cycle occurs at____________________?
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A. receiver

B. compressor discharge

C. expansion valve

D. evaporator

E. condenser discharge

4231. The general rule for rating refrigeration systems (excepting for C02 system) is to approximate following h.p. per ton of refrigeration__________________?
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A. 0.5 to 0.8 h.p. per ton of refrigeration

B. 2 to 5 h.p. per ton of refrigeration

C. 0.1 to 0.5 h.p. per ton of refrigeration

D. 5 to 10 h.p. per ton refrigeration

E. 1 to 2 h.p. per ton of refrigeration

4232. The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy-diagram represents_____________________?
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A. metering of the refrigerant liquid

B. none of the above

C. evaporation of the refrigerant liquid

D. compression of the refrigerant vapour

E. condensation of the refrigerant vapour

4233. The domestic refrigerator uses following type of compressor ____________________?
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A. axial

B. none of the above

C. piston type reciprocating

D. centrifugal

E. miniature sealed unit

4234. Super heating in a refrigeration cycle __________________?
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A. decreases COP

B. COP remains unaltered

C. unpredictable

D. other factors decide COP

E. increases COP

4235. The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases ____________________ ?
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A. may be higher or lower depending upon the nature of non-condensable gases

B. will remain unaffected

C. will be higher

D. unpredictable

E. will be lower

4236. Cooling water is required for following equipment in ammonia absorption plant__________________?
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A. evaporator

B. absorber

C. condenser and absorber

D. condenser, absorber and separator (rectifier)

E. condenser

4237. One ton of the refrigeration is_________________?
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A. the standard unit used in refrigeration problems

B. the refrigeration effect to produce 1 ton of ice in 1 hour time

C. the cooling effect produced by melting 1 ton of ice

D. the refrigeration effect to produce 1 ton of ice at NTP conditions

E. the refrigeration effect to freeze 1 ton of water at 0C into ice at 0C in 24 hours

4238. Domestic refrigerator working on vapour compression cycle uses the following type of expansion device____________________?
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A. electrically operated throttling valve

B. capillary tube

C. expansion valve.

D. manually operated valve

E. thermostatic valve

4239. Under-cooling in a refrigeration cycle_________________?
0

A. COP remains unaltered

B. decreases COF

C. increases COP

D. other factors decide COP

E. unperdictable

4240. In vapor compression refrigeration system, refrigerant occurs as liquid between_________________?
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A. compressor and evaporator

B. none of the above

C. compressor and condenser

D. expansion valve and evaporator

E. condenser and expansion valve

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