1) Highest pressure encountered in a refrigeration system should be________________? a. critical pressure of refrigerant b. much below critical pressure c. much above critical pressure d. near critical pressure e. there is no such restriction
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2) If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be________________? a. same b. more c. less d. more/less depending on rating e. unpredictable
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3) Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system ? a. strong solution to weak solution b. weak solution to strong solution c. strong solution to ammonia vapour d. ammonia vapour to weak solution e. ammonia vapour to strong solution
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4) Which of the following is not a desirable property of a refrigerant_________________? a. high triiscibility with oil b. low boiling point c. good electrical conductor d. large latent heat e. non-inflammable
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5) At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant_________________? a. decreases b. increases c. remains same d. depends on other factors e. none of the above
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6) Formation of frost on evaporator in refrigerator ________________? a. results in loss of heat due to poor heat transfer b. increases heat transfer rate c. is immaterial d. can be avoided by proper design e. decreases compressor power
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7) In a refrigeration system, heat absorbed in comparison to heat rejected is_________________? a. more b. less c. same d. more for small capacity and less for high capacity e. less for small capacity and more for high capacity
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8) One of the purposes of sub-cooling the liquid refrigerant is to________________? a. reduce compressor overheating b. reduce compressor discharge temperature c. increase cooling effect d. ensure that only liquid and not the vapour enters the expansion (throttling) valve e. none of the above
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9) Highest temperature encountered in refrigeration cycle should be________________? a. near critical temperature of refrigerant b. above critical temperature c. at critica. temperature d. much below critical temperature e. could be anywhere
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10) Absorption system normally uses the following refrigerant___________________? a. Freon-11 b. Freon-22 c. C02 d. S02 e. ammonia
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11) In a vapor compression cycle, the refrigerant immediately after expansion valve is___________________? a. liquid b. sub-cooled liquid c. saturated liquid d. wet vapour e. dry vapour
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12) Choose the correct statement? a. A refrigerant should have low latent heat b. If operating temperature of system is low, then refrigerant with low boiling point should be used c. Precooling and subcooling bf refrigerant are same d. Superheat and sensible heat of a. refrigerant are same e. Refrigerant is inside the lubes in case of a direct-expansion chiller
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13) Choose the wrong statement ? a. Temperature of medium being cooled must be below that of the evaporator b. Refrigerant leaves the condenser as liquid c. All solar thermally operated absorption systems are capable only of intermittent operation d. frost on evaporator reduces heat transfer e. refrigerant is circulated in a refrigeration system to transfer heat
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14) Pick up the incorrect statement? a. lithium bromide used in vapour absorption cycle is nonvolatile b. lithium bromide plant can’t operate below 0°C c. a separator is used in lithium bromide plant to remove the unwanted water vapour by condensing d. concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator e. weak solution in liquid heat exchanger gives up heat to the strong solution
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