2. 1. A standard ice point temperature corresponds of the temperature of :
Ans. – Mixture of ice and water under equilibrium condition
2. The heat transfer takes place according to
Ans. – Second law of thermodynamics
3. Boiling temperature of Freon-22 is :
Ans. – -40.7°C
4. The refrigeration system works on
Ans. – Second law of thermodynamics
5. One tone of refrigeration is equal to
Ans. – 210kJ/min
6. An important characteristic of absorption system of refrigeration is :
Ans. – quiet operation
3. 7. The chemical name of R-134a is :
Ans. – Tetra fluro ethane
8. For the same temperature limits, the COP of a refrigerator is 4, then the
COP of the heat pump equals
Ans. – 5
9. Thermoelectric refrigeration system is based on
Ans. – Peltier effect
10. Which of the following cycles uses air as the refrigerant :
Ans. – Bell-Coleman
11.The capacity of refrigerating machine is expressed as
Ans. – rate of abstraction of heat from the space being cooled
12.Which of the refrigerant is more toxic :
Ans. – Ammonia
4. 13. In vapour compression cycle the condition of refrigerant is dry saturated
vapour :
Ans. – before entering the compressor
14.The boiling point of ammonia is
Ans. – -33.3℃
15.One tone refrigeration corresponds to :
Ans. – 50kcal/min
16.In conventional refrigerants, which element is responsible for ozone
depletion?
Ans. – Chlorine
17.One ton of refrigeration in kW is equivalent to
Ans. – 3.5
18.The domestic refrigerator has a refrigerating load of the order of
Ans. – less than 0.25 ton
5. 19.Ammonium refrigerants is
Ans. – Highly toxic and inflammable
20.The refrigerant for a refrigerator should have :
Ans. – high latent heat
21.Rating of a domestic refrigerator is of the order of :
Ans. – 0.1ton
22.R-114 will have chemical formula as
Ans. – CF2CL-CF2Cl
23.The correct nomenclature for ethylene is
Ans. – R 1150
24.The domestic refrigerator uses following type of compressor :
Ans. – piston type reciprocating
25.Commonly used refrigerant in a domestic vapour compression refrigerator :
Ans. – Freon-12
6. 26.Air refrigeration operates on :
Ans. – Reverse Brayton cycle
27.Large sized industrial air – conditioning plant are
Ans. – water cooled
28.Identify the azeotrope refrigerant from the following :
Ans. – R502
29.The significant advantage of using ammonia as refrigerant is its
Ans. – High latent heat
30.Highly toxic and flammable refrigerant :
Ans. – Ammonia
31.Which of the following refrigerant is an Azeotrope
Ans. – R-502
32.Air refrigeration cycle is used in :
Ans. – gas liquefaction
7. 33.Which one eco-friendly refrigerant out of the following is used in many
domestic and car air conditioners now a day
Ans. – R-134a
34.What is an azeotrope/
Ans. – A mixture of refrigerants without phase separation
35.The Freon group of refrigerants are :
Ans. – halo-carbon refrigerants
36.A Carnot refrigeration cycle has COP of 4. The ratio of higher temperature
to lower temperature will be-
Ans. – 1.25
37.At lower temperatures and pressures, the latent heat of vaporization of a
refrigerant.
Ans. – increases
38.The vapour pressure of refrigerant should be :
Ans. – higher than atmospheric pressure
8. 39.The bank of tubes at the back of domestic refrigerator are :
Ans. – condenser tubes
40.A Bell-Coleman cycle is
Ans. – Reserved Joule Cycle
41.Highest temperature encountered in refrigeration cycle should be :
Ans. – much below critical temperature
42.Which of the following is not a desirable property of refrigerants
Ans. – Low Dielectric strength
43.The recommended material for use with ammonia as a refrigerants is :
Ans. – Steel
44.One TON refrigeration in SI unit is equal to :
Ans. – 3.5kW
45.In an ideal Brayton refrigeration cycle, the refrigerant :
Ans. – Remains as a has throughout
9. 46.The rate at which the heat is absorbed in a cycle from the interior space
to be cooled is called as :
Ans. – Refrigerating effect
47.Kelvin-Plank statement is applicable to
Ans. – Heat Engine
48.In Electrolux refrigerator
Ans. – Ammonia evaporates in hydrogen
49.Which one of the following refrigerants has the highest critical
temperature ?
Ans. – Carbon dioxide
50.An undesirable property of refrigerant is:
Ans. – High boiling point
51.The refrigerating system of passenger aircraft works on reversed
Ans. – Brayton Cycle
10. 52.A Bell-Coleman cycle consist of
Ans. – two isobaric and two isentropic processes
53.What would be the prime consideration in the design of refrigeration
system of an aircraft?
Ans. – low weight of the refrigeration equipment
54.In aircraft, air refrigeration cycle is used because of
Ans. – low unit weight per ton of refrigeration
55. in a refrigerating system, the ratio of refrigeration effect to work done is
known as :
Ans. – Coefficient of Performance
56.Which of the following cycles use in air as the refrigerant
Ans. – Bell-Coleman
57.The fluid, which absorbs heat through evaporation and rejects it by
condensation is known as :
Ans. – Refrigerant
11. 58.The cooling load of a 1 ton AC plant is :
Ans. – 300MJ/day
59.The refrigerants R-12 and R-22 are respectively :
Ans. – CC12F2 and CHC1F2
60.The oil used with 134 A refrigerant is :
Ans. – Polyolester oil
61.Highest pressure encountered in a refrigeration system should be :
Ans. – much below critical pressure
62.Aqua ammonia is used as refrigerant in the following type of refrigeration
system :
Ans. – absorption
63.Crisper temperature of refrigerator is equal to :
Ans. – 8℃
64.Auto defrost operated by :
Ans. – Timer Switch
12. 65.In air conditioning of aeroplanes the refrigerants used is :
Ans. – Air
66.The thermodynamic cycle used in aircraft refrigeration is
Ans. – reversed Brayton
67.The milk is stored at a temperature of :
Ans. – 4℃
68.The lower horizontal line of the refrigeration cycle plotted on pressure-
enthalpy diagram represents :
Ans. – evaporation of the refrigerant vapour
69.For ammonia refrigerating system the tubes of a shell and tube condenser
are made of
Ans. – Steel
70.Convert from CFC 12 to HFC 134 A the compressor displacement will be
Ans. – Slightly larger
13. 71.In an air craft refrigeration system, pressure at the cooling turbine outlet
Ans. – Cabin Pressure
72.The refrigerants enters in the condenser by the :
Ans. – top side
73.Superheating in a refrigeration cycle :
Ans. – decreases COP
74.Dry ice is :
Ans. – solidified carbon dioxide
75.Moisture in Freon refrigerating system causes :
Ans. – freezing automatic regulating valve
76.One ton of refrigeration is equal to :
Ans. –210kJ/min
77.The power per tone of refrigeration is :
Ans. – 3.5/C.O.P.
14. 78.A refrigerant which has the lowest freezing point is :
Ans. – Freon – 22
79.The capacity of a domestic refrigerator is in the range of :
Ans. – 0.1 to 0.3 TR
80.When two refrigerants are mixed in the proper proportions, the mixture
forms a third refrigerant called :
Ans. – an azeotrope
81.Liquid refrigerant collects in the lower coil of condenser and flows through :
Ans. – Capillary tube
82.The cooling capacity of 1 ton of refrigeration is :
Ans. – 12,00 BTU/hr
83.In air-conditioning of aeroplanes, using air as a refrigerant, the cycle is
used :
Ans. – reversed Brayton cycle
15. 84.Which type of valve Reciprocating refrigeration compressor uses :
Ans. – ring plate valve
85.The instrument used for finding the leakage of Freon and Methyl chloride
is :
Ans. – Halide torch
86.Refrigerator door is pulled close by :
Ans. –Magnetic gasket
87.R.717 stands for :
Ans. – Ammonia
88.An ordinary passenger aircraft requires a cooling system of capacity :
Ans. – 8TR
89.For air conditioning the operation theatre in hospital the percentage of
outside air in the supplied is :
Ans. – 100
16. 90.Chemical formula of Freon – 22 :
Ans. – CHClF2
91.The cooling capacity of 1.0 TR is :
Ans. – 12000 BTU/Hr
92.The mechanical fault in refrigerator system is :
Ans. – condenser coil dirty
93.Freon 12 ideal pressure is :
Ans. – 6.0kh/cm2
94.The chemical formula of Freon – 12 is
Ans. – CC12F2
95.Colour code of ammonia refrigerant cylinder :
Ans. – Silver
96.A refrigerant with the highest critical pressure is :
Ans. – Ammonia
17. 97.The material of pipe lines for a system using Freon as a refrigerant should
be
Ans. – copper
98.The freezing point of Sulphur dioxide is :
Ans. – -75.2℃
99.The refrigerant widely used in domestic refrigerators is
Ans. – R-12
100.In larger industrial and commercial reciprocating compression systems,
refrigerant widely used is :
Ans. – ammonia
101. Steam jet refrigeration cycle employs the compressor device called :
Ans. – steam ejector
102.The steam nozzles for steam ejector in case of steam jet refrigeration
system are
Ans. – convergent divergent
18. 103. The refrigerant used for refrigeration purposes in passenger aircraft.
Ans. – water
104. The refrigerant used in small-tonnage commercial machines
(hermetically sealed units) is :
Ans. – Sulphur dioxide
105. The refrigerant R-22 is
Ans. – monochloro difluoro methane
106.The refrigerant R-502 is
Ans. – Azetrope
107.Environment friendly refrigerant R-134 is used in the new generation
domestic refrigerators. Its chemical formula is
Ans. – C2H2F4
108.When there is leakage of ammonia refrigerant, the Sulphur sticks give
Ans. – white smoke
19. 109. The pressure at the inlet of refrigerant compressor is called :
Ans. – Suction Pressure
110. Leakage of halocarbon refrigerants can be best detected by
Ans. – halide torch
111. The function of halide torch is
Ans. – detecting leakage of refrigerant
112. Boiling temperature of ammonia is :
Ans. – -33.33 ℃
113. Boiling temperature of CO2 is :
Ans. – -78.5 ℃
114. Boiling temperature of Fr-12 is :
Ans. – -29.8℃
115. Boiling temperature of Fr-22 is –
Ans. – -40.7℃
20. 116. Clapeyron equation is applicable for region at :
Ans. – Saturation point of vapour
117. The moisture in a refrigerant is removed by :
Ans. – Driers
118. Solar energy can be directly used in
Ans. – Vapour absorption refrigeration system
119. The leakage in a Freon-based refrigeration system can be detected by
using a/an
Ans. – Halide torch
120. The vapour compression refrigeration cycle operates on reversed
Ans. – Rankine Cycle
121. A capillary tube is used in a small refrigerator to serve the purpose of
Ans. – Expansion Valve
21. 120. In the window air conditioner the expansion device used is :
Ans. – Capillary tube
121. During which component of vapour compression refrigeration system,
the enthalpy remains constant?
Ans. – Throttle valve
122. Which part of the vapour compression refrigeration cycle produces the
refrigeration effect?
Ans. – Evaporator
123. Where does the lowest temperature occur in a vapour compression
cycle?
Ans. – Evaporator
124. The type of condenser used in water cooler :
Ans. – Forced draft
125. Liquid charged in thermostatic expansion valves sensing bulb is :
Ans. – Same refrigerant
22. 126. In the absorption refrigeration cycle the compressor of the vapor
compression refrigeration cycle is replaced by
Ans. – Absorber, liquid pump and generator
127. A refrigerant mostly used for household refrigerator is :
Ans. – Freon – 12
128. In an ideal vapour absorption system, the absorber pressure is equal to
the pressure of
Ans. – Evaporator
129. Fitting in ammonia absorption refrigeration system are made of :
Ans. – Cast steel or forgings
130. Brine solution is :
Ans. – Secondary refrigerant
131. Electrolux refrigerator essentially works on
Ans. – Absorption System
23. 132. In a vapour compression system, the condition of refrigerant before
passing through the condenser is
Ans. – Superheated vapour
133. Compressor used in window A/c is :
Ans. – Sealed compressor
134. The most possible leakage spots in the refrigerator is :
Ans. – Brazing tube joints
135. The condenser coil type which used in deep freezer commonly :
Ans. – Force draft
136. The material used to check the tightness of door gasket of a
refrigerator :
Ans. – Paper Sheet
137. Relay is protection device used in :
Ans. – Compressor
24. 138. The condenser in indirect system, condenses :
Ans. – Refrigerant
139. The heart of refrigeration system is :
Ans. – Compressor
140. Defrosting is carried out in :
Ans. – Evaporator
141. Secondary refrigerant is invariably used in
Ans. – Ice plants
142. In milk chilling plants, the usual secondary refrigerant is
Ans. – Brine
143. The pressure at the outlet of a refrigerant compressor is called :
Ans. – Discharge pressure
144. Brine Solution density is checked by :
Ans. – Hydrometer
25. 145. Commonly used liquid absorbent is :
Ans. – Ethylene glycol
146. The component which gives out the heat into atmosphere on a
conventional car A/C system is :
Ans. – Condenser
147. Psychrometer is device which is used to measure
Ans. – Dry bulb and wet bulb temperature simultaneously
148. The uniformly spaced vertical lines on psychometric chart indicates
Ans. – Dry bulb temperature
149. Which is not a factor for comfort air conditioning?
Ans. – Light
150. The mass of water vapour in on m3 of dry air is defined as
Ans. – Absolute ratio
26. 151. In summer A/C, the air is :
Ans. – Cooled and dehumidified
152. The temperature of air recorded by an ordinary thermometer is known
as :
Ans. – Dry bulb temperature
153. Humidity ratio is also called –
Ans. – Specific humidity
154. The amount of moisture in air can be measured by
Ans. – Sling Psychrometer
155. The main process which takes place in a desert cooler is
Ans. – Adiabatic saturation
156. The primary purpose of Boot-strap system is to
Ans. – Provide additional cooling
27. 157. Which is the most suitable type of air-refrigeration system for
supersonic plane with Mach number 3 or above?
Ans. – Boot-strap evaporative
158. Sling Psychrometer is used to measure :
Ans. – Dry and wet bulb temperature
159. The difference between D.B.T and W.B.T is called :
Ans. – Wet bulb depression
160. Dew point temperature is the temperature at which condensation
begins when the air is cooled at constant :
Ans. – Pressure
161. Vertical lines on pressure-enthalpy chart show constant :
Ans. – Total heat lines
162. Presence of moisture in a refrigerant affects the working of :
Ans. – Expansion valve
28. 163. The maximum amount of vapours having no unvapourised liquid as :
Ans. – Saturated Heated vapours
164. An air sample without water vapour is called :
Ans. – Dry air
165. The dry bulb temperature lies on the psychometric chart are :
Ans. – Vertical and uniformly spaced
166. Priming is the process of :
Ans. – Removing the trapped water
167. For saturated air, we bulb depression is :
Ans. – Zero
168. During sensible heating of moist air, enthalpy :
Ans. – increases
169. The psychrometry deals with the study of
Ans. – Moist air
29. 170. Name the temperature at which moisture condenses on a surface :
Ans. – Dew point temperature
171. When air is heated relative humidity :
Ans. – Decreases
172. The thermostat for the window type air-conditioner is set at :
Ans. – 75℉
173. The process of addition of moisture to ar at the constant dry bulb
temperature is known as :
Ans. – Humidification
174. The boiling point of carbon dioxide is :
Ans. – -78.3℃
175. Psychrometric chart :
Ans. – provides plots for moist air conditions
30. 176. Global warming is caused by
Ans. – Carbon dioxide
177. Humidification process involves :
Ans. – an increase in specific humidity
178. Air is normally dehumidified by :
Ans. – Cooling
179. The process of mixing two or more streams of moist air is :
Ans. – Adiabatic
180. The process of removing the moisture from the food product is called :
Ans. – Dehydration
181. The eliminators at the air washes avoid the :
Ans. – Water particles in the air
182. In summer air conditioning relative humidity should not have above :
Ans. – 60%
31. 183. Dew point temperature is always an indication of :
Ans. – Moisture content of the air
184. During the adiabatic cooling of moist air :
Ans. – WBT remains constant
185. In a psychrometric chart, specific humidity (moisture content) lines are
Ans. – Horizontal and uniformly
186. The horizontal and non-uniformly spaced lines on a psychrometric
chart indicates
Ans. – Dew point temperature
187. The saturation temperature of water vapour at its partial pressure is
equal to
Ans. – Dew point temperature
188. The moisture content of air indicated by
Ans. – wet bulb temperature and dew point temperature
32. 189. The process, generally used in winter air-conditioning of warm and
humidity the air, is called :
Ans. – Heating and humidification
190. The human body feels comfortable when the heat stored in the body is :
Ans. – Zero
191. The optimum effective temperature for human comfort is :
Ans. – Lower in winter than in summer
192. The dehumidification process, on the psychrometric chart, is shown by :
Ans. – Vertical line
193. The mixing of two or more streams of moist air in air-conditioning is
Ans. – an adiabatic process
194. In a refrigeration system frosting starts from capillary due to :
Ans. – Drier filter partially blocked
33. 195. In a reversed Brayton cycle, the heat is absorbed by the air during :
Ans. – Constant pressure expansion process
196. The air cooling system mostly used in transport type aircraft is :
Ans. – Boot-strap air cooling system
197. The reduced ambient air cooling system has :
Ans. – Two cooling turbines and one heat exchanger
198. The cooling system used for supersonic aircrafts and rockets is :
Ans. – Regenerative air cooling system
199. In air – refrigeration system, the coefficient of performance is :
Ans. – Low
200. A low side float valve maintains the level of refrigerant in :
Ans. – Flooded evaporator
34. 201. A water cooler uses the refrigerant :
Ans. – R134
202. The maximum possible thermal efficiency of a heat engine is limited by :
Ans. – Second law of thermodynamics
203. The term used to indicate the performance of a refrigeration system is :
Ans. – Coefficient of performance
204. In a vapour compression cycle, the refrigerant immediately after
expansion valve is :
Ans. – Wet vapour
205. The vacuum obtainable in a condenser is dependent upon
Ans. – temperature of cooling water
206. The throttling operation in a refrigeration cycle is carried out in
Ans. – Capillary tube
35. 207. Accumulator is provided for :
Ans. – String of liquid refrigerant
208. Household refrigerators operate on
Ans. – Vapour compression cycle
209. Purging is done :
Ans. – Before gas charging
210. Ammonia absorption refrigeration cycle requirement
Ans. – Very little work input
211. Lithium bromide in vapour absorption refrigeration system is used as :
Ans. – Absorbent
212. The location of freezer in the top portion of a refrigerator results in
Ans. – Quick cooling of entire chamber
36. 213. For obtaining high COP, the pressure range of compressor should be :
Ans. – Low
214. An Electrolux refrigerator uses
Ans. – No pump
215. The COP of a vapour compression plant in comparison to vapour
absorption plant is :
Ans. – More
216. The evolution of heat of solution takes place in ammonia absorption
plant when :
Ans. – Ammonia vapour goes into solution
217. One of the purpose of sub-cooling the liquid refrigerant is to :
Ans. – Ensure that only liquid and not the vapour enters the expansion
(throttling) valve
218. In a vapour absorption refrigerator, heat is rejected in
Ans. – Condenser and absorber
37. 219. Lithium bromide is used as absorbent in
Ans. – Vapour absorption refrigerator
220. The Electrolux refrigerator works on :
Ans. – Absorption refrigeration system
221. A rectifier is fitted in an ammonia absorption plant to
Ans. – Remove the unwanted water vapour by cooling the vapour
mixture and condensing the water vapour
222. Expansion valve is located :
Ans. – Before the evaporator
223. Leaks in brine system can be detected by :
Ans. – Using reagents
224. For ammonia system, the pipe should be of following material :
Ans. – Cast steel or wrought iron
38. 225. Hydrogen is essential in an Electrolux refrigeration system, because
Ans. – It helps in maintaining a low partial pressure for evaporating
ammonia
226. The formation of frost on cooling coils in a refrigerator :
Ans. – Increases power consumption
227. The condition of refrigerant as it leaves the compressor in a vapour
compression system is :
Ans. – Superheated vapour
228. In a pressure enthalpy chart, the space to the left of saturated liquid line
represents :
Ans. – Sub-cooled liquid region
229. The evaporators commonly used in chemical and food processing
industry is
Ans. – Flooded evaporator
39. 230. Refrigerator compressor motor winding burnt out :
Ans. – High voltage
231. A hermetically sealed unit implies :
Ans. – Compressor and motor are sealed
232. The function of brine agitator in ice plant is to :
Ans. – Obtain uniform temperature of brine
233. Which chemical is used for condenser descaling?
Ans. – Hydrochloric acid
234. Convert from CFC 12 to HFC134 appliance, the compressor
displacement will be :
Ans. – Slightly larger
235. The pipes which are used for absorption refrigeration system :
Ans. – Steel
40. 236. The fluids used in Electrolux refrigerator are :
Ans. – Ammonia, water and hydrogen
237. Thermostatic Expansion valve operates on the :
Ans. – Degree of superheat of refrigerant coming out of evaporator
238. The refrigerant supplied to a compressor must be :
Ans. –Superheated vapour refrigerant
239. The reciprocating refrigerant compressors are very suitable for :
Ans. – Small displacement and high condensing pressures
240. The thermostatic expansion valve is also called :
Ans. – Constant superheat valve
241. On psychrometric chart, dry bulb temperature lines are
Ans. – Vertical
41. 242. On a psychrometric chart what does a vertical downward line represent
Ans. – Dehumidification
243. For completely dry air total heat is
Ans. – Total sensible heat
244. The comfort chart is drawn between
Ans. – DBT and WBT
245. the air temperature at which water vapour in the air starts condensing is
known as :
Ans. – Dew point temperature
246. Dew pointy temperature is constant as long as there is :
Ans. – No change in moisture content of the air
247. The comfort air-conditioning and industrial air-conditioning differ in
relation to
Ans. – Indoor requirement
42. 248. The minimum temperature of which water can be cooled in a cooling
tower is :
Ans. – The dew point temperature of air
249. In a psychrometric chart, the vertical lines parallel to the ordinate
indicate
Ans. – Dry bulb temperature
250. The dissipation of heat in a cooling tower is mainly due to
Ans. – Evaporation
43. Domestic refrigerator uses which condenser:- natural convection air cooled
condenser
Low boiling point refrigerator is suitable for:-reciprocating compressor
For summer A/C relative humidity should :-not be less than 60%
For winter A/C relative humidity should:- not be more than 40%
Feeling of coldness & hotness depends upon:- WBT & DBT
Parallel line of WBT in psychrometric chart represent:-enthalpy
The evaporator used in household refrigerator:- frosting refrigerator
Reciprocating compressor suitable for:-small displacement & high condensing
pressure.
During adiabatic saturation process WBT remains:- constant
For unsaturated air dew point temp is:- less than WBT
Material of pipeline using Freon as refrigerant:- copper
In which refrigeration process waste heat is utilized:- vapour absorption
system
In industrial application which refrigerant is mostly used:-Ammonia
Condition of refrigerant as it leaves compressor:-superheated
Superheating causes cop:- to decrease
Subcooling/ undercooling causes cop:- to increase
Alingment circle on chart is marked at:- 26 deg celcius DBT & 50%RH
44. The thermostatic expansion valve uses:- dry type evaporator
Critical temp is the temp:- above which gas never liquefies
Domestic refrigerator uses:-piston type reciprocating compressor( hermetic
sealed comp)
Rating capacity of domestic refrigerator:-0.1 to0.5 TR
For obtaining high cop pressure of compressor must be:- low
Freon group of refrigerant are:- non toxic & non inflammable
Throttle valve/TX valve ensure :- Evaporator is completely filled with refrigerant
Suction pipe diameter as compared to discharge pipe :- always bigger
formation of frost on evaporator:- due to increase in power consumption
Cop of domestic refrigerator & compared to domestic A/C :-less
Refrigerant should have:- high latent heat
Which refrigerant has highest ozone layer depletion:- fluorine
The hydrogen used in Electrolux refrigeration:- increases rate of evaporation.
During sensible heating Relative humidity :- increases
During sensible cooling relative humidity:- increases
During sensible heating & sensible cooling specific humidity :- remains
constant.
During humidification DBT :- remains constant
Wet bulb depression is zero relative humidity:- 1 or 100%
45. Cop of VCR as compared to VAS:- more
The color of halide torch in case of leakage of Freon:- bright green
Cop of reversed carnot cycle mostly depends on :- evaporator temperature
Cop is always greater than:-1
Cop of carnot refrigerator is :- more in winter than summer
