Mechanical Engineering MCQs

Page No. 141

The leaks in a refrigeration system using Freon are detected by____________________?


ahalide torch which on detection produces greenish flame lighting

✓


bsulphur sticks which on detection gives white smoke

✖


cusing reagents

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dsmelling

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On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process ________________?


ainvolves no change in volume

✖


btakes place at constant temperature

✖


ctakes place at constant enthalpy

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dtakes place at constant pressure

✓



In vapour compression cycle using NH3 as refrigerant, initial charge is filled at_________________?


asuction of compressor

✖


bdelivery of compressor

✖


chigh pressure side close to receiver

✓


dlow pressure side near receiver

✖



Freon group of refrigerants are___________________?


ainflammable

✖


btoxic

✖


cnon-inflammable and toxic

✖


dnon-toxic and non-inflammable

✓



The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy-diagram represents_____________________?


acondensation of the refrigerant vapour

✖


bevaporation of the refrigerant liquid

✓


ccompression of the refrigerant vapour

✖


dmetering of the refrigerant liquid

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In a refrigeration cycle, the flow of refrigerant is controlled by___________________?


acompressor

✖


bcondenser

✖


cevaporator

✖


dexpansion valve

✓


View Answer expansion valve

If a heat pump cycle operates between the condenser temperature of +27°C and evaporator temperature of – 23°C, then the Carnot COP will be_________________?


a0.2

✖


b1.2

✖


c5

✖


d6

✓


View Answer 6

Aqua ammonia is used as refrigerant in the following type of refrigeration system_________________?


acompression

✖


bdirect

✖


cindirect

✖


dabsorption

✓


View Answer absorption

Efficiency of a Carnot engine is given as 80%. If the- cycle direction be reversed, what will be the value of COP of reversed Carnot cycle_________________?


a1.25

✖


b0.8

✖


c0.5

✖


d0.25

✓


View Answer 0.25

In vapor compression refrigeration system, refrigerant occurs as liquid between_________________?


acondenser and expansion valve

✖


bcompressor and evaporator

✖


cexpansion valve and evaporator

✓


dcompressor and condenser

✖



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