highest temperature encountered in refrigeration cycle should be
(b) decreases COP (b) NH3 (e) unperdictable. One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice (e) receiver. Ans: c, 70. (a) Freon-11 (c) solid and dry ice (e) none of the above. (d) depends upon the make Ans: b, 2. (d) smaller/bigger depending on capacity (b) before passing through the condenser In vapor compression cycle, the condition of refrigerant is high pressure saturated liquid (d) much below critical temperature (c) increase cooling effect (b) 21 kJ/min (a) lower than atmospheric pressure I'd like to know what temperature the freezer should reach during the defrost cycle. Clapeyron equation is a relation between (c) evaparator C) on a high temperature system. (a) high Objective Type Question Answers For Environmental Engineering 21. Refrigeration load of process cooling: 35 MM Btu/h. ... 36 The refrigerant for a refrigerator should have A high sensible heat. Ans: e, 12. Ans: a, sir, (d) driers (c) more than 10 kg Cascading improves the COP of a refrigeration cycle. (a) Ericsson (b) decrease (e) refrigerant is circulated in a refrigeration system to transfer heat. (b) will be lower The temperature difference varies from one kind of refrigerant to another. (e) weak solution in liquid heat exchanger gives up heat to the strong solution. (a) A refrigerant should have low latent heat (d) more/less depending on rating (c) carnot cycle (c) nearly same work input as for vapour compression cycle (a) ammonia vapour goes into solution Ans: b, 57. (d) S02 (b) it permits complete evaporation in the evaporator (d) metering of the refrigerant liquid For our example, where we need to cool air down to 15.5°C, we will choose T low to be 10°C. (c) refrigerant cooling tubes (d) Superheat and sensible heat of a. refrigerant are same (a) Co2 Moisture in freon refrigeration system causes Ans: a, 49. (d) near critical pressure Ans: c, 17. (c) – 33.3°C (a) high triiscibility with oil But the reverse process (i.e. Choose the wrong statement (a) temperature, pressure and enthalpy Refrigeration in aeroplanes usually employs the following refrigerant (a) suction of compressor (c) 5 But in reality the best systems are around 4.5. In vapor compression cycle, the condition of refrigerant is very wet vapor For better COP of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be, 37. (c) evaporator (c) 50% Most of the domestic refrigerators work on the following refrigeration system (e) temperature, pressure, specific volur and’enthalpy. (a) compression The domestic refrigerator uses following type of compressor (a) ineffective refrigeration (b) non-inflammable (e) 105 kJ/min. Ans: a, 95. F (32 deg. (a) Tow specific heat of liquid (e) none of the above. (c) equal (e) Hydrocarbon refrigerant. (e) 10. The temperature of the condensing refrigerant gas rises as the coolant or ambient air temperature rises. (d) condenser and absorber (a) water at 0°C Cascade cycle is used where a very wide range of temperature between TL and TH is required. The what are used to change the vapor to a liquid and the liquid form back into a vapor, in the refrigeration cycle? In S.J. (e) sensing reduction in pressure. (e) unpredictable. (c) 80 kcal/min Toughness index is defined as the ratio of a) plasticity index to consistency index b) plasticity index to flow index c) ... 91. The value of COP in vapour compression cycle is usually Ans: e, 4. (b) 1 : 9 (b) specific volume and enthalpy Ans: c, 53. (c) after passing through the expansion or throttle valve Ans: b, 48. (c) is equal to 1 (d) reversed Rankine cycle In vapor compression refrigeration system, refrigerant occurs as liquid between Highest temperature encountered in refrigeration cycle should be (a) near critical temperature of refrigerant (b) above critical temperature (c) at critica. (d) gas liquefaction Presence of moisture in a refrigerant affects the working of (e) 100%. heat transfer from low to high temperature) cannot occur by itself (Claussius Definition of Second Law). (b) sulphur sticks which on detection gives white smoke (a) increases COP A household refrigerator is a combination of refrigerator-freezer. The COP of two-stage R718 refrigeration system with two-phase ejectors (Figure 6.9) for air conditioning application, with temperature conditions: Te = 10°C (cooling water 10/15°C) and Tc = 35°C (condensing water 35/30°C), according to the results of numerical experiments is estimated to … (b) If operating temperature of system is low, then refrigerant with low boiling point should be used (e) less for small capacity and more for high capacity. (b) -50°C (c) sublimation temperature The moisture in a refrigerant is removed by (a) compressor (a) compressor Ans: b, 45. (d) 0°C (d) 0.25 (d) compressor and condenser Get shopping advice from experts, friends and the community! The Cannot coefficient of performance of cycle will be (a) 0.2 (b) Refrigerant leaves the condenser as liquid Ans: c, 75. (b) ammonia vapour is driven out of solution The higher temperature in vapour compression cycle occurs at This low pressure and low-temperature refrigerant vapor evaporates in the evaporator taking heat from the cold region. (c) equally. In a vapor compression refrigeration cycle, the temperature of the liquid refrigerant experiences its greatest decrease flowing through what component? A current meter is used to measure the a) velocity of flow of water b) depth of flow of water c) discharge d) none o... 41. (b) high (e) none of the above. (e) unpredictable. (e) depends upon the weather conditions. Question is ⇒ Highest pressure encountered in a refrigeration system should be, Options are ⇒ (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., Leave your comments or Download question paper. Ans: d, 69. Short horizontal lines on pressure-enthalpy chart show (d) anything Ans: d, 13. (b) Rankine cycle (c) 0.5 Ans: d, 21. C. At critical Temperature. Ans: a, 81. (a) increases COP The refrigerant used is (e) refrigerant with high boiling point must be used. (e) before entering the compressor. On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process (a) after passing through the condenser (d) 840 kJ/min (a) involves no change in volume (c) C02 (b) 50 kcal/kr The condenser. (d) weak solution mixes with strong solution Ans: b, 51. (c) non-inflammable and toxic (d) 75% plz send me pdf of this question and answer, sir thanking you for this question answer, Your email address will not be published. (a) after passing through the condenser Ans: b, 76. (a) electrically operated throttling valve (a) 50 kcal/min (c) 2-4 bars (b) evaporator Ans: c, 94. The average cycle is about 30 minutes, but that's only when the refrigerator stays closed. (e) constant volume lines. C. High latent heat of vaporisation. The Cannot coefficient of performance of cycle will be (b) detect liquid in vapour Ans: c, 26. If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. (e) none of the above. (d) higher critical temperature (a) constant pressure lines (b) Carnot (b) takes place at constant temperature an air-conditioning system. (b) condenser (c) much above critical pressure (d) smelling (d) any value (a) 0.1 to 0.5 h.p. Ans: a, 11. (b) is more than 1 Answer: Option D (a) near critical temperature of refrigerant (a) 1.25 It should be observed that the system operates on a closed cycle. Vapour-compression refrigeration or vapor-compression refrigeration system (VCRS), in which the refrigerant undergoes phase changes, is one of the many refrigeration cycles and is the most widely used method for air-conditioning of buildings and automobiles. For better COP of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be A refrigeration cycle operates between condenser temperature of + 27°C and evaporator temperature of- 23°C. (a) after passing through the condenser (c) C02 (c) strong solution to ammonia vapour To cool the refrigerant down it is passed through the expansion valve, this will reduce the pressure of the refrigerant by … (c) equal to atmospheric pressure (e) Reversed Carnot. (c) expansion valve and evaporator Highest temperature encountered in refrigeration cycle should be A. near critical temperature of refrigerant B. above critical temperature C. at critical temperature D. much below critical temperature E. could be anywhere ANSWER: D 12. The leaks in a refrigeration system using Freon are detected by Ans: c, 16. (a) Freon-12 (e) 3 : 1 (b) Freon-22 (d) corrosion of whole system (a) of cooling medium (c) cooling below 0°C (e) increase refrigeration effect. (b) increases heat transfer rate (c) actual COP x theoretical COP (a) saturation point of vapor (c) reversed Camot cycle This is the first in a series of columns addressing advanced basics in the understanding of the refrigeration cycle. (a) condenser Ans: a, 19. (b) evaporator tubes (d) ensure that only liquid and not the vapour enters the expansion (throttling) valve (d) 80 kcal/hr (d) large latent heat Mechanical Engineering Multiple Choice Questions. (c) same (b) high total heat (a) results in loss of heat due to poor heat transfer For obtaining high COP, the pressure range of compressor should be A refrigeration cycle operates between condenser temperature of + 27°C and evaporator temperature of- 23°C. (e) 1000 kcal/day. A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67 kg/cm. (e) none of the above. (c) COP remains unaltered Ans: b, 66. (b) a gas will immediately liquefy High critical temperature and pressure: The critical temperature of the refrigerant should be as high as possible above the condensing temperature in order to have a greater heat transfer at a constant temperature. (a) liquid (c) 420 kJ/min Which of the following cycles uses air as the refrigerant (e) expansion valve (d) other factors decide COP 39. (e) none of the above. (d) may increase or decrease depending on the type of refrigerant used (d) in 12 hours Allowable pressure on high-pressure side or ammonia absorption system is of the order of (d) condenser discharge (b) 1.2 One ton refrigeratiqn corresponds to temperature (d) much below critical temperature (e) could be anywhere. (b) temperature lines Vertical lines on pressure-enthalpy chart show constant (d) before entering the expansion valve (c) saturated liquid (b) Stirling of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will (e) before entering the compressor. Rating of a domestic refrigerator is of the order of The maximum permissible limit for flouride in drinking water is a) ... 21. (d) electrolux refrigerator (a) critical pressure of refrigerant Pick up the wrong statement. (c) thermostatic valve (b) increases Ans: a, 64. rick up the incorrect statement Ans: d, 58. (d) may be higher or lower depending upon the nature of non-condensable gases Ans: c, 78. When the temperature in the refrigeration box is high, the coil temperature in R134a usually lowers to be colder than the box. (a) more (e) mixture of ice and water Under equilibrium conditions. Mass flow ratio of NH3 in comparison to Freon-12 for same refrigeration load and same temperature limits is of the order of (e) unpredictable. (d) wet vapour per ton of refrigeration (e) low sensible heat 22 Highest temperature encountered in refrigeration cycle should be ... 28 Air refrigeration cycle is used in A domestic refrigerators. Ans: b, 67. (b) delivery of compressor (b) 25% (e) before entering the compressor. (c) euqal (c) after passing through the expansion or throttle valve (a) pressure lines (d) absorption (c) it results in high volumetirc and mechanical efficiency C) on a low temperature installation, or 90 deg. The general rule for rating refrigeration systems (excepting for C02 system) is to approximate following h.p. (a) increase Air refrigeration operates on ENGINEERING INTERVIEW QUESTIONS ANSWERS, CIVIL ENGINEERING INTERVIEW QUESTIONS, CIVIL ENGINEERING MCQS, MECHANICAL ENGINEERING INTERVIEWQUESTIONS, MECHANICAL ENGINEERING MCQS, ELECTRICAL ENGINEERING INTERVIEW QUESTIONS AND VIVA SEMINAR INTERVIEW QUESTIONS FOR ALL LAB VIVA QUESTIONS IN CSE, ECE, MECHANICAL ENGINEERING STUDENTS. (d) all of the above (c) after passing through the expansion or thiottle valve ... equal to. (b) 0.5 to 0.8 h.p. (b) of freezing zone In column analogy method, the area of an analogous column for a fixed beam of span L and flexural rigidity El is taken as a) L/E... 31. Ans: c, 54. (c) compression of the refrigerant vapour (a) lowers evaporation temperature (c) 1 to 2 h.p. The C.O.P. (b) more than or equal to 3.65 kg Ans: b, 36. (a) vapour compression (d) zero work input (d) 1-actual COP x theoretical COP Ans: b, 74. Ans: a, 8. Absorption system normally uses the following refrigerant In a vapor compression cycle, the refrigerant immediately after expansion valve is Ans: b, 14. temperature The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases, Reducing suction pressure in refrigeration cycle Ans: d, 35. (b) compressor and evaporator The refrigeration cycle collects this heat by sending the refrigerant at a low temperature and pressure into the evaporator within that room. 11. (b) before passing through the condensei (a) same D. Much below critical temperature. Ans: b, 63. Domestic refrigerator working on vapour compression cycle uses the following type of expansion device 12. 5-5, the condenser for the low temperature refrigerator is used as the evaporator for the high temperature refrigerator. Ans: e, 89. Ans: c, 85. In vapour compression cycle the condition of refrigerant is superheated vapour (a) actual COP/fheoretical COP (b) the cooling effect produced by melting 1 ton of ice (e) takes place at constant pressure. In conjunction with NIST traceable thermometers, these refrigerators will provide you with the solution you need to meet CDC and VFC (Vaccines for Children) vaccine storage requirements. (b) reduce compressor discharge temperature (e) unpredictable. The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will With temperature ranges between 35°F to 46°F, these medical refrigerators will securely store a wide range of vaccines, such as Influenza, rotavirus and MMRV. Ans: d, 83. (e) the refrigeration effect to produce 1 ton of ice in 1 hour time. (b) 0.8 (c) a separator is used in lithium bromide plant to remove the unwanted water vapour by condensing unit, one ton of refrigeration is equal to Optical square is (a) Engineer's square having stock and blade set at 90° (b) a constant deviation prism having the ang... 1. (e) none of the above. (b) expansion valve (e) volume lines. (d) triple point (d) Bell-coleman Ans: a, 80. Critical pressure of a liquid is the pressure Temperature of process fluid: −10°F. Ans: d, 60. Ans: c, 87. (d) can be avoided by proper design (a) Temperature of medium being cooled must be below that of the evaporator (c) equal to unity Ans: d, 79. (b) quiet operation (c) constant total heat lines (b) theoretical COP/actual COP Therefore, for the same cooling load, gas refrigeration cycle machines require a larger mass flow rate, which in turn increases their size. If the- cycle direction be reversed, what will be the value of COP of reversed Carnot cycle (e) there is no such criterion. (e) none of the above. Ans: d, 34. Ans: d, 40. In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to Ans: e, 9. Ans: d, 43. (b) as low as possible (3 to 11°C) (d) refrigerant with lower evaporation temperature should be used (d) before entering the expansion valve (d) highly toxic and inflammable (a) halide torch which on detection produces greenish flame lighting High temperature refrigeration is that produced by. Ans: b, 61. Aqua ammonia is used as refrigerant in the following type of refrigeration system After studying this unit, the reader should be able to • Define high-, medium-, and low-temperature refrigeration. (e) non-inflammable. (a) after passing through the condenser (c) after passing through the expansion throttle valve For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then (c) will remain unaffected (a) atmospheric pressure (e) unpredictable. (d) Air (b) more (b) condenser Ans: c, 90. (b) weak solution to strong solution Ans: a, 23. (a) evaporator (a) domestic refrigerators (d) non-toxic and inflammable 288,000 Btu/24h. In vapour compression cycle, the conditii of refrigerant is saturated liquid (b) smaller (a) 1 : 1 Ans: b, 41. Ans: e, 3. Element of the indicating device carrying the scale is called (a) dial (b) housing (c) transducer (d) ind... 161. (a) high sensible heat A surface gauge is used for (a) levelling the surface plate (b) checking the surface finish (c) laying out the work accu... 21. (d) toxic (d) Erricson cycle Ans: a, 86. Reason R : Higher distribution pressure ca... 21. (d) 2 to 5 h.p. While some people have viewed this method as environmentally harmful and inefficient, the cycle is still applicable in the industrial sphere. Ans: d, 22. (b) vapour absorption (d) takes place at constant enthalpy (c) perfectly tight vapour seal should be used (d) reduces weight displaced by piston In vapour compression cycle using NH3 as refrigerant, initial charge is filled at (d) could be anything Every fridge has a different cycle because it depends on a few various factors. (c) Freon (a) reduce compressor overheating Ans: d, 30. A. Superheating in a refrigeration cycle (a) above which liquid will remain liquid The refrigeration effect in a dry evaporator compared to flooded evaporator in a similar plant is One of the purposes of sub-cooling the liquid refrigerant is to Fig.5-5: A 2-stage cascade refrigeration cycle. Which of the following is not a desirable property of a refrigerant Required fields are marked *. (e) under some conditions small and under some conditions high. (e) none of the above. (d) any value (c) Reversed Rankine (d) 1 : 3 (d) there is no such consideration (e) in 10 hours. (b) increases power required per ton of refrigeration (a) high, of the order of 25° (b) Freon-11 (c) zero • Describe a parallel-flow, plate-and-fin evaporator. Highest pressure encountered in a refrigeration system should be When the door is opened, some of the heavy, cold air slides out of … Ans: a, 77. (e) breakdown of refrigerant. (b) decrease Ans: c, 50. The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P. Ans: e, 33. Choose the correct statement (e) Refrigerant is inside the lubes in case of a direct-expansion chiller. Critical temperature is’ the temperature above which The bank of tubes at the back of domestic refrigerator are So, ultimately, we want a low pressure such that its saturation temperature is below the desired cool air temperature but high enough that the temperature at state one is not too hot.
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