McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
Chapters
| 151. |
A plant has one 300 ton and one 500 ton centrifugal unit. The total flow of brine is 6400 litres per minute. What should be the distribution of brine flow through each unit |
| A. | 3200 litres each |
| B. | 2400 litres through 300 ton plant and 4000 litres through 500 ton plant |
| C. | 4000 litres through 300 ton plant and 2400 litres through 500 ton plant |
| D. | Same brine should flow through both |
| E. | None of the above |
| Answer» C. 4000 litres through 300 ton plant and 2400 litres through 500 ton plant | |
| 152. |
Which of the following refrigerant has the lowest specific volume? |
| A. | Ammonia |
| B. | Freon 22 |
| C. | All the refrigerants have identical specific volume |
| D. | Freon 12 |
| E. | Carbondioxide |
| Answer» E. Carbondioxide | |
| 153. |
Which of the following refrigerant compressor is not classified as positive displacement compressor |
| A. | Reciprocating compressor |
| B. | Centrifugal compressor |
| C. | Rotary compressor |
| D. | Screw compressor |
| E. | None of the above |
| Answer» B. Centrifugal compressor | |
| 154. |
Class II group of refrigerants absorb sensible heat while giving refrigeration effect. Which of the following is a class II refrigerant |
| A. | Ammonia |
| B. | Carbondioxide |
| C. | Freon 12 |
| D. | Methyl chloride |
| E. | All of the above |
| Answer» D. Methyl chloride | |
| 155. |
The critical pressure of a liquid is the pressure |
| A. | Below which a liquid will always be in vapour form |
| B. | Above which a liquid will remain a liquid |
| C. | Above which a liquid will always turn into a vapour |
| D. | Above which a liquid will explode |
| E. | None of the above |
| Answer» B. Above which a liquid will remain a liquid | |
| 156. |
Frost on cooling coils |
| A. | Increases heat transfer |
| B. | Reduces evaporator temperature |
| C. | Improves COP of the system |
| D. | Acts as an insulation, increasing power consumption |
| E. | Reduces power consumption |
| Answer» D. Acts as an insulation, increasing power consumption | |
| 157. |
The coefficient of performance of a domestic refrigerator as compared to that of an air conditioner is gererally |
| A. | Less |
| B. | Cannot be compared |
| C. | More |
| D. | Air conditioner performance depends on whether conditions |
| E. | Same |
| Answer» A. Less | |
| 158. |
The leakage in a refrigeration system using freon is detected by |
| A. | Acetylene torch |
| B. | Halide torch |
| C. | Sulphur stricks |
| D. | Soap and water |
| E. | Any of the above |
| Answer» B. Halide torch | |
| 159. |
The critical temperature for Freon 12 is |
| A. | Above 100?C |
| B. | Less than - 50?C |
| C. | Around - 20?C |
| D. | 0?C |
| E. | Around 50?C |
| Answer» A. Above 100?C | |
| 160. |
In a vapour compression cycle the lowest temperature occurs in |
| A. | Evaporator |
| B. | Expansion valve |
| C. | Condenser |
| D. | Receiver |
| E. | Compressor |
| Answer» A. Evaporator | |
| 161. |
If dry bulb temperature is 25?C and wet bulb temperature is 18?C, then which of the following temperatures could possibly represent dew point? |
| A. | 14?C |
| B. | 25?C |
| C. | 40?C |
| D. | 43?C |
| E. | 18?C |
| Answer» A. 14?C | |
| 162. |
The effect of under cooling the refrigerant is to |
| A. | Reducing the COP of the cycle |
| B. | Increase the COP of the cycle |
| C. | Reduce the refrigerating effect |
| D. | Increase the super heat of vapour |
| E. | None of the above |
| Answer» B. Increase the COP of the cycle | |
| 163. |
Clear ice |
| A. | Is pure ice |
| B. | Contains dissolved air |
| C. | Contains dissolved gases |
| D. | Is produced by blowing air during freezing |
| E. | None of the above |
| Answer» D. Is produced by blowing air during freezing | |
| 164. |
Two thermometers are constructed in the same way except that one has a spherical bulb and the other an elongated cylindrical bulb. Which one will respond quickly to temperature change? |
| A. | Spherical bulb thermometer |
| B. | Cylindrical bulb thermometer |
| C. | Both will respond in identical manner |
| D. | Cannot be ascertained on the basis of information provided |
| E. | None of the above |
| Answer» B. Cylindrical bulb thermometer | |
| 165. |
A low wet bulb temperature indicates |
| A. | Very cool air |
| B. | Very low humidity |
| C. | Very low atmospheric temperature |
| D. | (A) and (B) above |
| E. | (A) and (C) above |
| Answer» D. (A) and (B) above | |
| 166. |
On a psychrometric chart sensible heating or cooling is represented by |
| A. | A horizontal line |
| B. | A vertical line |
| C. | Inclined line |
| D. | Curved line |
| E. | None of the above |
| Answer» A. A horizontal line | |
| 167. |
During sensible heating of air |
| A. | Dry bulb temperature increases while enthalpy of moist air decreases |
| B. | 10,000 m height above the surface of earth |
| C. | Both dry bulb temperature as well as enthalpy decrease |
| D. | Both dry bulb temperature as well as enthalpy increase |
| E. | Dry bulb temperature decreases while enthalpy of moist air increases |
| Answer» D. Both dry bulb temperature as well as enthalpy increase | |
| 168. |
Air and other non-condensable gases (foul gases) get into a refrigeration system through |
| A. | Decomposition of refrigerant in contact with impurities |
| B. | Breakdown of oil |
| C. | Under vacuum operation or during maintenance work |
| D. | Corrosion |
| E. | Any of the above |
| Answer» E. Any of the above | |
| 169. |
Refrigerant 717 is |
| A. | Freon 22 |
| B. | Air |
| C. | Freon 12 |
| D. | Carbondioxide |
| E. | Ammonia |
| Answer» E. Ammonia | |
| 170. |
The relation between vapour pressure to the enthalpy of vaporisation is expressed in |
| A. | Vander wall's equation |
| B. | Energy equation |
| C. | Maxwell's equation |
| D. | Clausius Clapeyron equation |
| E. | Lewis equation |
| Answer» D. Clausius Clapeyron equation | |
| 171. |
For a sensible heating the air is passed over a heating coil which may be |
| A. | Heated by electric resistance |
| B. | Heated by passing hot water through the coil |
| C. | Heated by passing steam through the coil |
| D. | Heated by direct solar radiations |
| E. | Heated by any of the above methods |
| Answer» E. Heated by any of the above methods | |
| 172. |
Cryogenics |
| A. | Is same as refrigeration |
| B. | Include heating and cooling of liquids |
| C. | Is a thermodynamic analysis of low temperature systems |
| D. | Is the field of engineering associated with development, production and use of equipment in the range -180?C to absolute zero |
| E. | None of the above |
| Answer» D. Is the field of engineering associated with development, production and use of equipment in the range -180?C to absolute zero | |
| 173. |
Dew point is |
| A. | The temperature at which ice starts melting in presence of air without external aid |
| B. | Percentage of moisture contained in a sample of air |
| C. | The temperature of water vapour in air starts |
| D. | Partial pressure of water vapour in a sample of air |
| E. | The temperature at which condensation of water vapour in air starts |
| Answer» E. The temperature at which condensation of water vapour in air starts | |
| 174. |
A refrigerant with lowest freezing point temperature is |
| A. | Ammonia |
| B. | Freon 12 |
| C. | Freon 22 |
| D. | Carbondioxide |
| E. | Freon 11 |
| Answer» C. Freon 22 | |
| 175. |
A storage tank which receives liquid refrigerant from evaporator and prevents it from flowing into suction line is known as |
| A. | Accumulator |
| B. | Agitator |
| C. | Balancer |
| D. | Condenser |
| E. | None of the above |
| Answer» A. Accumulator | |
| 176. |
In a vapour compression refrigeration cycle using ammonia as a refrigerant the temperature of ammonia after compression will be at the range |
| A. | 40?C to 0?C |
| B. | 70?C to - 110?C |
| C. | 0?C to - 15?C |
| D. | ? 15?C to - 40?C |
| E. | 50?C to 40?C |
| Answer» B. 70?C to - 110?C | |
| 177. |
The condition of refrigerant before and after compression in vapour compression cycle is |
| A. | Wet vapour, wet vapour |
| B. | Dry saturated vapour, liquid |
| C. | Dry saturated vapour, superheated vapour |
| D. | Wet vapour, cry saturated vapour |
| E. | Liquid, wet vapour |
| Answer» D. Wet vapour, cry saturated vapour | |
| 178. |
The ratio of water vapour to the mass of dry air in a given mixture is known as |
| A. | Humidity ratio |
| B. | Relative humidity |
| C. | Degree of saturation |
| D. | Any of the above |
| E. | None of the above |
| Answer» A. Humidity ratio | |
| 179. |
When air is adiabatically saturated, the temperature attained is known as |
| A. | Dew point temp |
| B. | Dry bulb temp |
| C. | Adiabatically sturated temp |
| D. | Wet bulb temp |
| E. | Critical temp |
| Answer» D. Wet bulb temp | |
| 180. |
In case air is cooled by a process in which the humidity ratio of air does not change, the process is known as |
| A. | Ventilation |
| B. | Humidification |
| C. | Chilling |
| D. | Sensible cooling |
| E. | Dehumidification |
| Answer» D. Sensible cooling | |
| 181. |
If the compressor of a refrigeration system is noisy, it shows that |
| A. | Compressor drive coupling is loose |
| B. | Lack of oil |
| C. | Internal parts of compressor broken |
| D. | Compressor or motor loose on base |
| E. | Any of the above |
| Answer» E. Any of the above | |
| 182. |
Which of the following refrigerant is highly toxic? |
| A. | Freon 12 |
| B. | Carbondioxide |
| C. | Ammonia |
| D. | Freon 22 |
| E. | Sulphurdioxide |
| Answer» E. Sulphurdioxide | |
| 183. |
For for measurement of temperature in cryogenic range the thermometers used are |
| A. | Gas thermometers |
| B. | Electronic digital instruments |
| C. | Mercury thermometers |
| D. | Pyrometers |
| E. | Radiation pyrometers |
| Answer» A. Gas thermometers | |
| 184. |
The freezing point of ammonia is |
| A. | ? 132.5?C |
| B. | ? 20?C |
| C. | ? 77.8?C |
| D. | ? 202.5?C |
| E. | 0?C |
| Answer» C. ? 77.8?C | |
| 185. |
Presence of moisture in a refrigeration cycle will show its effect at |
| A. | Compressor suction |
| B. | Compressor discharge |
| C. | Expansion valve |
| D. | Condenser |
| E. | All of the above |
| Answer» C. Expansion valve | |
| 186. |
The colour of the flame of halide torch in case of leakage of freon refrigerant, will change to |
| A. | Yellow |
| B. | Violet |
| C. | Green |
| D. | Orange |
| E. | Red |
| Answer» C. Green | |
| 187. |
One tonne of refrigeration is equivalent to SI units of |
| A. | 3.5 kW |
| B. | 10 kW |
| C. | 5 kW |
| D. | 1 kW |
| E. | 2.5 kW |
| Answer» A. 3.5 kW | |
| 188. |
In vapour compression cycle the highest temperature of the refrigerant during the cycle occurs |
| A. | After expansion valve |
| B. | After evaporator |
| C. | After condenser |
| D. | After compression |
| E. | None of the above |
| Answer» D. After compression | |
| 189. |
Sub-cooling is |
| A. | Removing sensible heat from a liquid |
| B. | Removing latent heat from a gas |
| C. | Cooling a liquid below 0?C. |
| D. | Cooling a part of liquid |
| E. | Differential cooling of a liquid |
| Answer» D. Cooling a part of liquid | |
| 190. |
Which of the following refrigerant is the cheapest? |
| A. | Air |
| B. | Ammonia |
| C. | Methyl chloride |
| D. | Freon 12 |
| E. | Freon 22 |
| Answer» A. Air | |
| 191. |
Which of the following is not a property of Carbondioxide? |
| A. | Non-toxic |
| B. | Non-inflammable |
| C. | Colourless |
| D. | Pungent odour |
| E. | All of the above |
| Answer» D. Pungent odour | |
| 192. |
If a room has bad ammonia leaks |
| A. | Lights should be switched off |
| B. | No specific precautions are needed |
| C. | One should wait for sometime |
| D. | Gas mask should be put on |
| E. | Before entering the room fans should be put on |
| Answer» D. Gas mask should be put on | |
| 193. |
The moisture in a refrigeration system is removed by |
| A. | Driers |
| B. | Dehumidifiers |
| C. | Evaporators |
| D. | Coolers |
| E. | None of the above |
| Answer» A. Driers | |
| 194. |
When ammonia is used as a refrigerant in vapour compression cycle, the mass circulated per ton of refrigerating effect will be nearly |
| A. | 0.2 kg |
| B. | 1 kg |
| C. | 1.2 kg |
| D. | 0.5 kg |
| E. | 1.8 kg |
| Answer» A. 0.2 kg | |
| 195. |
Which type of compressor is commonly used in room air-conditioner |
| A. | Reciprocating |
| B. | Rotory |
| C. | Screw |
| D. | Centrifugal |
| E. | None of the above |
| Answer» A. Reciprocating | |
| 196. |
If the condensation temperature of a refrigerant is 25?C which type of condenser cannot be used? |
| A. | Air cooled condenser |
| B. | Water cooled condenser |
| C. | Brine circulation condenser |
| D. | Ice cooled condenser |
| E. | Any of the above |
| Answer» A. Air cooled condenser | |
| 197. |
During air conditioning whenever two or more streams of moist air are mixed they follow |
| A. | Isothermal process |
| B. | Polytropic process |
| C. | Constant pressure process |
| D. | Polytropic process |
| E. | Adiabatic process |
| Answer» E. Adiabatic process | |
| 198. |
Air for air conditioning of aircraft cabin is obtained by |
| A. | Compressing ambient air |
| B. | Turbine exhaust |
| C. | Bleeding from air compressor |
| D. | Dehumidifying cabin air |
| E. | Recycling cabin air |
| Answer» C. Bleeding from air compressor | |
| 199. |
Which of the following connections is usually not provided in a hermetically sealed type compressors? |
| A. | Refrigerant inlet |
| B. | Refrigerant outlet |
| C. | Refrigerant charging connection |
| D. | Lubricating oil charging connection |
| E. | There is no connection provided |
| Answer» D. Lubricating oil charging connection | |
| 200. |
In ammonia vapour compression system the temperature rise between the condenser outlet and the expansion valve should be |
| A. | As high as possible to improve the performance |
| B. | As high as possible to reduce motor power inputs |
| C. | As little as possible for better performance |
| D. | Anything as it has no bearing on the performance of system |
| E. | None of the above |
| Answer» C. As little as possible for better performance | |
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