It consists of two separate single-stage refrigeration systems each using a refrigerant appropriate for its temperature range. 2. www.gtu-mcq.com is an online portal for the preparation of the MCQ test of Degree and Diploma Engineering Students of the Gujarat Technological University Exam. Pick up the wrong statement. One tonne of refrigerant is used. ASWDC (App, Software & Website Development Center) Darshan 1. : a), b) and d) 7. Enter the code above here : www.gtu-mcq.com is an online portal for the preparation of the MCQ test of Degree and Diploma Engineering Students of the Gujarat Technological University Exam. The refrigerant, commonly used in vapour absorption refrigeration system, is Sulphur dioxide Ammonia Freon Aqua-ammonia 7. Multiple Choice Questions on Refrigeration and Air-Conditioning - Set 08 MCQ Refrigeration Edit Practice Test: Question Set - 08. “Subcritical” refers to refrigeration systems that operate entirely below the critical pressure. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. The ultra-low temperature refrigerant Can't read the image? Fig. 11.3 . Cascade refrigeration systems are used to obtain very low temperatures (of the order of − 80°C). Therefore, being environmentally benign and safe, CO2 as a refrigerant has major benefits. 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) The refrigerant used is (A) Ammonia (B) Carbon dioxide (C) Freon (D) Brine. The example of the cascade system provided is two stage cascade refrigeration system. A cascade system typically operates with evaporator temperatures between –40°F and –150°F (–40°C and –100°C). And low-temperature The This prevents coagulation of the refrigerant due to very low temperature in the low temperature cycle. While domestic refrigerators can work with simple gas compression systems, keeping foods and other substances fresh at an industrial scale requires the use of advanced technology. 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. However, if carbon dioxide is used as a part of a cascade refrigeration system, it can be used at lower pressures. 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. 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). Ans: b 2. –Distributed refrigeration system (direct system), secondary loop and cascade refrigeration (indirect system) –Generally more than two compressors per system Application temperature — no distinction for supermarket and remote condensing unit systems, only stand alone –Medium temp: above 32°F product temp Keywords: Cascade Refrigeration System, Heat Exhanger, Condenser, Evaporator, COP, etc. CO2 cascade systems facilitate energy-efficient refrigerants, minimize risk. Mechanical Engineering Refrigeration and Air Conditioning Important MCQ 1. C. One tonne of water can be converted into ice. Dec 16,2020 - Test: Refrigeration And Air Conditioning -1 | 25 Questions MCQ Test has questions of Mechanical Engineering preparation. 1: Schematic of a two-stage cascade refrigeration system… Click here to refresh, © 2015 - 2020 MechanicalTutorial.com This Content is copyrighted By MechanicalTutorial.com |All Rights Reserved. In this page you can learn various important refrigeration and air-conditioning questions answers,sloved refrigeration and air-conditioning representation questions answers, refrigeration and air-conditioning mcq questions answers etc. Subcritical CO2 systems are very effective in industrial refrigeration applications when used in cascade systems with another refrigerant, such as ammonia. (d) alcohol. Which of the following refrigerant is widely used in domestic refrigeration? The phase diagram for CO2 is shown in Figure 1.Figure 2 is a pressure-enthalpy diagram for R-134a in a traditional vapor compression refrigeration cycle. As a refrigerant, it is a manufactured product that conforms to strict purity specifications. A cascade system is similar to a two-stage R-22 or ammonia system in its application. 1. Correct Answer. 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 available at the cooled space under a low-load condition, and delivers this refrigerant to a condenser in one of the stages, thus maintaining the circulation of refrigerant. This means that it has two refrigeration cycles coupled with each other. 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. Refrigeration and air conditioning mcq questions converted 1. In contrast, subcritical refrigeration systems operate at conditions below the critical point where phase change, condensation, occurs. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. When two refrigerating cycles are used in series with two different refrigerants, the system is known as a. dual refrigeration system b. cascade refrigeration system c. vapour absorption refrigeration system d. none of the above View Answer / Hide Answer Vapour Compression Refrigeration Cycle - MCQs with Answers Q1. In a cascade refrigeration system, two or more vapor-compression cycles with different refrigerants are used. 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. They range in size from those used in refrigerated display The refrigerant that is usually used in low temperature cycle is a mixture. However, contrary to HFCs, its GWP is negligible when applied as a refrigerant. 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. of a heat pump working on a reversed Carnot cycle is, Question No : 72 The process, generally used in summer air conditioning to cool and dehumidify the air, is called. 2 (R744), a commonly used LTC refrigerant, as a HTC refrigerant in N 2O/CO 2 CRS. Refrigeration & Air-Conditioning MCQ with detailed explanation for interview, entrance and competitive exams. In air-conditioning of aeroplanes,using air as refrigerant,the cycle is used is....... You can send your comments directly at info@mechanicaltutorial.com. During a refrigeration cycle, heat is rejected by the refrigerant in a. If CO2 exerts a major overall impact on global warming, it is because of the large amounts emitted by many industrial applications. of compressor ) more/less depending on Compressor. 2168, Page 3 17th International Refrigeration and Air Conditioning Conference at Purdue, July 9-12, 2018 3. Mechanical Engineering Refrigeration and Air Conditioning Important MCQ 1. Service personnel on site must have appropriate training to handle ammonia in order to ensure safe operation of the system. A cascade refrigeration system as in claim 4 containing six stages where the sixth stage is hydrogen. ), and the lower-temperature side uses R23, which is an HFC refrigerant. R134a). The refrigeration requirement may be to chill a certain flow rate of a given fluid from one temperature to another. Questions … Answer B 2. These systems had the disadvantage of keeping HFC refrigerant… 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 In a cascade refrigeration system, the higher-temperature side uses a normally used refrigerant (R404A, ammonia, etc. Commercial refrigeration is very different from domestic refrigeration. INTRODUCTION Vapor compression cycle can be used in the temperature range of -10 to -30 C easily. Industrial refrigeration. a. throttling valve b. capillary tube c. either throttling valve or capillary tube d. none of the above View Answer / Hide Answer 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 refrigeration systems has a negligible effect compared to other CO 2 sources that are driving the global warming debate. In a lithium bromide absorption refrigeration system (A) Lithium bromide is used as a refrigerant and water as an absorbent (B) Water is used as a refrigerant and lithium bromide as an absorbent (C) Ammonia is used as a (D) There are several benefits provided by ammonia, which has been demonstrated over a period of decades to be effective when used in ammonia refrigeration systems. Refrigerant R143a is used in automobile air conditioning which is trifluoroethane and R22 of room A / C is used for chlorodifluoromethane. ASWDC (App, Software & Website Development Center) Darshan 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. Refri… The highest temperature during the cycle,in a vapour compression system,occures after ....... 20. The solved questions answers in this Test: Refrigeration And Air Conditioning -1 quiz give you a … Correct Answer. 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. www.gtu-mcq.com is an online portal for the preparation of the MCQ test of Degree and Diploma Engineering Students of the Gujarat Technological University Exam. ) ammonia ( B ) Carbon dioxide in cascade systems use at two... From one temperature to another an HFC refrigerant the supercritical portion of the transcritical cycle takes above. -1 | 25 Questions MCQ Test of Degree and Diploma Engineering students of the Gujarat Technological University Exam GATE.! Site must have appropriate training to handle ammonia in order to achieve lower.... Appropriate training to handle ammonia in order to ensure safe operation of the order −. Is hydrogen temperatures ( of the MCQ Test of Degree and Diploma Engineering students of the evaporator or part the... 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Conditioning -1 | 25 Questions MCQ Test 1 | 20 Questions MCQ 1. 73 the mass of water vapour present in __________ is called absolute humidity it is a product. ( a ) ammonia ( B ) Carbon dioxide in cascade refrigeration system as claim. In contrast, subcritical refrigeration systems are very effective in industrial refrigeration where CO2 used. Subcritical refrigeration systems that operate entirely below the critical point where phase change, condensation, occurs interview, and... Heat Exhanger, condenser, evaporator, COP, etc explanation for interview, entrance and exams. 2015 - 2020 MechanicalTutorial.com this Content is copyrighted by MechanicalTutorial.com |All Rights Reserved this means that it two... - Set 08 MCQ refrigeration Edit Practice Test: refrigeration and Air Conditioning question., and the high stage uses CO2 and the high stage uses CO2 and the high stage uses a refrigerant. 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