2. The refrigerant enters the compressor as saturated vapor at 160 kPa, and exits at 8 and 50 °C, and leaves the condenser as saturated liquid at 800 kPa. In contrast, subcritical refrigeration systems operate at conditions below the critical point where phase change, condensation, occurs. Refrigeration and air conditioning mcq questions converted 1. In a cascade system the high/medium temp refrigerant circuit is used to cool the condenser of the low temp circuit by way of a heat exchanger. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. Multiple Choice Questions on Refrigeration and Air-Conditioning - Set 08 MCQ Refrigeration Edit Practice Test: Question Set - 08. If it is necessary to reduce the ammonia charge, a combination of CO2 and ammonia (as a brine or cascade) can be used as an efficient option to reduce the exposure. Contact us: info@mechanicaltutorial.com, Refrigeration and airconditioning objective Q & A part-1, Production Technology and Manufacturing Process. Dec 16,2020 - Test: Refrigeration And Air Conditioning -1 | 25 Questions MCQ Test has questions of Mechanical Engineering preparation. A cascade system typically operates with evaporator temperatures between –40°F and –150°F (–40°C and –100°C). However, for a refrigerant pair to be suitable in a cascade refrigeration system, several criteria such as temperature range compatibility, performance, system compactness, etc., should be fulfilled. C. One tonne of water can be converted into ice. Refrigeration & Air-Conditioning MCQ with detailed explanation for interview, entrance and competitive exams. Rotary compressor is used in refrigeration when pressure difference between condenser and evaporator pressures is (a) >1.5 bars (b) <1.5 bars (c) >3.5 bars (d) None (Ans:a) Centrifugal compressor is used in refrigeration when pressure difference between condenser and evaporator pressures is (a) >1.5 bars (b) <1.5 bars (c) >3.5 bars (d) None (Ans:b) Refrigeration and Air Conditioning MCQ Questions 1-One ton of refrigeration is equal to (A) 21 KJ/min (B) 105 KJ/min (C) 210 KJ/min (D) 420 KJ/min 2-A low side float valve maintains the level of refrigerant in (A) Flooded evaporator (B If CO2 exerts a major overall impact on global warming, it is because of the large amounts emitted by many industrial applications. Use of CO 2 as a primary or sole refrigerant in a refrigeration system has become a common trend in Europe and is gaining favor in the U.S. CO 2 is primarily used in cascade systems that include ammonia, in booster systems in supermarkets, and as a stand-alone refrigerant for transcritical-configured systems. Aqua ammonia is used as refrigerant in the following type of refrigeration system 60. 11.3 . Explanation are given for understanding. 16. A cascade refrigeration system as in claim 3 containing at least five stages where the fifth stage refrigerant is neon or nitrogen operated at sub-atmospheric pressure. The supercritical portion of the transcritical cycle takes place above 1,067 psia. 6. Refrigerant R143a is used in automobile air conditioning which is trifluoroethane and R22 of room A / C is used for chlorodifluoromethane. ), and the lower-temperature side uses R23, which is an HFC refrigerant. 1: Schematic of a two-stage cascade refrigeration system… Basic Properties of Refrigerants In this paper, the operation of conventional cascade refrigeration system of a typical olefin plant is described first. A cascade system is akin to a two stage system but with a very crucial difference: the refrigerants used in the two stages are different. Jan 15,2021 - Vapour Compression Systems, Refrigerants - MCQ Test 1 | 20 Questions MCQ Test has questions of Mechanical Engineering preparation. Which of the following refrigerant is widely used in domestic refrigeration? During a refrigeration cycle, heat is rejected by the refrigerant in a. Therefore, being environmentally benign and safe, CO2 as a refrigerant has major benefits. One way of accommodating the safety issues is to use ammonia as a refrigerant in combination with CO 2 for medium or high temperatures or in cascade applications for low temperatures. Evaporator. Energies 2020, 13, 2254 2 of 26 The two-stage vapor compression cascade refrigeration system (CCRS) is another commonly used CRS, consisting of two circuits—high-temperature cycle (HTC) and low-temperature cycle (LTC). CO2 systems that operate below the critical point are called “subcritical” and are most commonly applied in a cascade configuration, or a two-stage refrigeration system. The relative coefficient of performance ( C.O.P. The ultra-low temperature refrigerant ASWDC (App, Software & Website Development Center) Darshan A refrigerant should have (a) Tow specific heat of liquid (b) high boiling point (c) high latent heat of vaporisation (d) higher critical temperature (e) low specific volume of vapour. 2168, Page 3 17th International Refrigeration and Air Conditioning Conference at Purdue, July 9-12, 2018 3. Cascade refrigeration systems are used to obtain very low temperatures (of the order of − 80°C). At McNeil Industrial, we provide ammonia refrigeration design services to help you benefit from reliable, exceptional performing, and cost-effective ammonia refrigeration solutions. MCQ-CASCADE REFRIGEARTION Cascade refrigeration is an extension of vapor compression refrigeration in order to achieve lower temperatures. Page-3 section-1 Page-3 section-1 Learn Refrigeration And Air Conditioning MCQ questions & answers are available for a Mechanical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. The solved questions answers in this Test: Refrigeration And Air Conditioning -1 quiz give you a … In cascade systems: a) Different refrigerants are used in individual cascade cycles b) There is no mixing of refrigerants and no migration of lubricating oil c) Higher COPs compared to multi-stage systems can be obtained d) Operating pressures need not be too high or too low Ans. cascade with a positive temperature DX refrigeration cycle, where a high temperature refrigerant is used (e.g. This means that it has two refrigeration cycles coupled with each other. 2. Correct Answer. The sub-cooling in a refrigeration cycle .... 19. Expansion valve. For example for attaining temperatures as low as -90 degree C let’s say a suitable refrigerant like R-503 is used. Enter the code above here : Service personnel on site must have appropriate training to handle ammonia in order to ensure safe operation of the system. The high temperature refrigerant (red) condenses in the air condenser and is then separated and evaporated to cool the heat exchanger which condenses the low temperature refrigerant (blue), purple signifies a mixture of both refrigerants. )is equal to....... 18. (d) alcohol. This test is Rated positive by 89% students preparing for Mechanical Engineering.This MCQ test is related to Mechanical Engineering syllabus, prepared by Mechanical Engineering teachers. Question No : 73 The mass of water vapour present in __________ is called absolute humidity. And low-temperature A cascade system consists of two refrigeration circuits, with one higher boiling refrigerant (propane) being used to condense a lower boiling refrigerant (ethane or ethylene). In air-conditioning of aeroplanes,using air as refrigerant,the cycle is used is....... You can send your comments directly at info@mechanicaltutorial.com. ASWDC (App, Software & Website Development Center) Darshan A refrigerant should have (a) Tow specific heat of liquid (b) high boiling point (c) high latent heat of vaporisation (d) higher critical temperature (e) low specific volume of vapour. Two-three-four stage systems are in … THEORETICAL INVESTIGATION OF CYCLES 3.1 Definition of the circuits The cascade system is at present most widely used in industry for applications below -50 °C. The Refrigeration & Air-Conditioning MCQ with detailed explanation for interview, entrance and competitive exams. A cascade refrigeration system for installation where the machinery of the system is remote from the cooled space, in which an insulated bypass conduit withdraws at least some of the refrigerant avail Keywords: Cascade Refrigeration System, Heat Exhanger, Condenser, Evaporator, COP, etc. (a) oxygen. The focus of this article is industrial refrigeration where CO2 is used as a refrigerant. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. CO 2 is generally used in combination with ammonia, either in cascade systems or as a volatile brine Food/retail refrigeration Heat pumps Transport refrigeration Danfoss believes that CO 2 will be the main These gases do not require refilling, you only need to fill it when your compressor stops working. Question No : 71 The C.O.P. Fig. Using carbon dioxide in cascade refrigeration systems also means that the aforementioned benefits of availability and low price are applicable for a cascade system. The refrigerant used is (A) Ammonia (B) Carbon dioxide (C) Freon (D) Brine. TRUE T/F: Cascade systems use at least two compressors and have completely isolated refrigeration loops that may contain a mixture of refrigerants. The refrigerant used in high temperature cycle depends on what refrigerant is used in low temperature cycle, and ultimately on the fact that how low evaporator temperature is required. The major challenges in CO2 refrigeration involve the relatively high working pressures. of compressor ) more/less depending on In essence, the condenser for the low temp system is also the evaporator or part of the evaporator of the high/medium temp system. 1. The most common are ammonia, … The refrigerant, commonly used in vapour absorption refrigeration system, is Sulphur dioxide Ammonia Freon Aqua-ammonia 7. 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Line represents the evaporation process working pressures copyrighted by MechanicalTutorial.com |All Rights Reserved CO2 as a refrigerant such..., is Sulphur dioxide ammonia Freon Aqua-ammonia 7 ( d ) Brine CO2 involve. Vapour present in __________ is called absolute humidity refrigerant before entering the compressor is B ) and d ) refrigerant. Commonly used in the temperature range of -10 to -30 C easily Test: question Set 08! In another stage refrigerant appropriate for its temperature range temperature in the temperature of... An extension of vapor compression refrigeration cycle, in a vapour compression cycle. Conditioning -1 | 25 Questions MCQ Test has Questions of Mechanical Engineering and GATE students using a,... If the evaporator of the evaporator temperature of a plant is lowered, keeping the condenser the. Or more vapor-compression cycles with different refrigerants are used Set 08 MCQ refrigeration Edit Practice Test question. 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