4201. Which of the following cycles uses air as the refrigerant__________________?
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A. Bell-coleman

B. Carnot

C. Ericsson

D. Stirling

E. none of the above

4202. One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice_________________?
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A. in 10 hours

B. in 1 minute

C. in 1 hour

D. in 24 hours

E. in 12 hours

4203. Rating of a domestic refrigerator is of the order of__________________?
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A. 5 tons

B. 10 tons

C. 40 tons

D. 0.1 ton

E. 100 tons

4204. In vapour compression cycle the condition of refrigerant is superheated vapour _____________________?
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A. before entering the compressor

B. after passing through the expansion or throttle valve

C. after passing through the condenser

D. before passing through the condenser

E. before [entering the expansion valve

4205. Clapeyron equation is a relation between___________________?
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A. temperature, pressure, and specil volume

B. specific volume and enthalpy

C. temperature, pressure, specific volur andenthalpy

D. temperature, pressure and enthalpy

E. temperature and enthalpy

4206. The boiling point of ammonia is___________________?
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A. 33.3C

B. 33.3C

C. -50C

D. -100C

E. 0C

4207. The value of COP in vapour compression cycle is usually__________________?
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A. none of the above

B. always more than unity

C. equal to unity

D. always less than unity

E. any one of the above

4208. The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is_________________?
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A. bigger

B. smaller/bigger depending on capacity

C. unpredictable

D. smaller

E. equal

4209. A standard ice point temperature corresponds to the temperature of ___________________?
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A. mixture of ice, water and vapour under equilibrium conditions under NTP conditions

B. solid and dry ice

C. water at 0C

D. mixture of ice and water Under equilibrium conditions

E. ice at 4C

4210. The relative coefficient of performance is_____________________?
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A. 1-actual COP x theoretical COP

B. 1-actual COP/fheoretical COP.

C. actual COP/fheoretical COP

D. theoretical COP/actual COP

E. actual COP x theoretical COP

4211. 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_________________?
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A. 0.8

B. 0.5

C. 0.25

D. 1.25

E. none of the above

4212. The leaks in a refrigeration system using Freon are detected by____________________?
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A. halide torch which on detection produces greenish flame lighting

B. smelling

C. sulphur sticks which on detection gives white smoke

D. sensing reduction in pressure

E. using reagents

4213. Ammonia is __________________?
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A. non-inflammable

B. non-toxic

C. toxic and non-inflammable

D. none of the above

E. highly toxic and inflammable
4214. Moisture in freon refrigeration system causes________________?
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A. corrosion of whole system

B. ineffective refrigeration

C. breakdown of refrigerant

D. freezing automatic regulating valve

E. high power consumption

4215. On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process ________________?
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A. takes place at constant enthalpy

B. takes place at constant pressure

C. takes place at constant temperature

D. involves no change in volume

E. takes place at constant entropy

4216. Short horizontal lines on pressure-enthalpy chart show__________________?
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A. constant volume lines

B. constant entropy lines

C. constant total heat lines

D. constant pressure lines

E. constant temperature lines

4217. An important characteristic of absorption system of refrigeration is__________________?
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A. quiet operation

B. its input only in the form of heating

C. cooling below 0C

D. noisy operation

E. very little power consumption

4218. Which of the following refrigerants has lowest freezing point_______________?
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A. Freon-22

B. Freon-12

C. NH3

D. S02

E. C02

4219. The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P_____________________?
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A. none of the above

B. unpredictable

C. more

D. equally.

E. less

4220. Accumulators should have adequate volume to store refrigerant charge at least_________________?
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A. 50%

B. 25%

C. 100%

D. 10%

E. 75%

4221. In vapour compression cycle using NH3 as refrigerant, initial charge is filled at_________________?
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A. low pressure side near receiver

B. anywhere in the cycle

C. high pressure side close to receiver

D. delivery of compressor

E. suction of compressor

4222. The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will__________________?
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A. may increase or decrease depending on the type of refrigerant used

B. unpredictable

C. remain unaffected

D. increase

E. decrease

4223. 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

4224. 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

4225. 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
4226. 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

4227. Air refrigeration operates on_____________________?
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A. Rankine cycle

B. Reversed Carnot cycle

C. Erricson cycle

D. Brayton cycle

E. Carnot cycle

4228. The vapor compression refrigerator employs the following cycle_________________?
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A. Reversed Carnot

B. Brayton

C. Carnot

D. Reversed Rankine

E. Rankine

4229. 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

4230. 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

4231. 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
4232. 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

4233. 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
4234. 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

4235. 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

4236. 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

4237. 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

4238. 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

4239. 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
4240. 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

4241. Under-cooling in a refrigeration cycle_________________?
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A. COP remains unaltered

B. decreases COF

C. increases COP

D. other factors decide COP

E. unperdictable

4242. 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

4243. The COP of a vapor compression plant in comparison to vapor absorption plant is ________________?
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A. same

B. unpredictable

C. more/less depending on size of plant

D. less

E. more
4244. The moisture in a refrigerant is removed by___________________?
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A. expansion valve

B. driers

C. dehumidifier

D. evaporator

E. safety relief valve

4245. The coefficient of performance is the ratio of the refrigerant effect to the_________________?
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A. none of the above

B. enthalpy increase in compressor

C. all of the above

D. work done by compressor

E. heat of compression

4246. In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to___________________?
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A. detect liquid in vapour

B. increase refrigeration effect

C. collect liquid refrigerant and prevent it from going to compressor

D. superheat the vapour

E. collect vapours

4247. The refrigerant for a refrigerator should have ___________________?
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A. high sensible heat

B. high total heat

C. high latent heat

D. low sensible heat

E. low latent heat

4248. Reducing suction pressure in refrigeration cycle_________________?
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A. lowers evaporation temperature

B. lowers compressor capacity because vapour is lighter

C. increases power required per ton of refrigeration

D. all of the above

E. reduces weight displaced by piston

4249. Critical pressure of a liquid is the pressure_________________?
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A. above which liquid becomes vapour

B. at which all the three phases exist together

C. above which liquid becomes solid

D. above which liquid becomes gas

E. above which liquid will remain liquid
4250. Freon group of refrigerants are___________________?
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A. non-toxic and inflammable

B. inflammable

C. toxic

D. non-toxic and non-inflammable

E. non-inflammable and toxic