The These gases do not require refilling, you only need to fill it when your compressor stops working. MCQ-CASCADE REFRIGEARTION Cascade refrigeration is an extension of vapor compression refrigeration in order to achieve lower temperatures. ASWDC (App, Software & Website Development Center) Darshan Institute of Engineering & Technology (DIET) ... Refrigeration and Air Conditioning (2161908) MCQ. Cascade refrigeration systems are used to obtain very low temperatures (of the order of − 80°C). 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. During a refrigeration cycle, heat is rejected by the refrigerant in a. Which of the following refrigerant is widely used in domestic refrigeration? In essence, the condenser for the low temp system is also the evaporator or part of the evaporator of the high/medium temp system. ASWDC (App, Software & Website Development Center) Darshan Fig-2: T-S diagram of cascade refrigeration system In the particular system R22 is used as low side refrigerant and R134a is used as high side refrigerant In process(2-3) low side refrigerant is compressed isentropic ally and TRUE T/F: Cascade systems use at least two compressors and have completely isolated refrigeration loops that may contain a mixture of refrigerants. Click here to refresh, © 2015 - 2020 MechanicalTutorial.com This Content is copyrighted By MechanicalTutorial.com |All Rights Reserved. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. 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. 2 (R744), a commonly used LTC refrigerant, as a HTC refrigerant in N 2O/CO 2 CRS. 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. Questions … 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. (d) alcohol. 1. INTRODUCTION Vapor compression cycle can be used in the temperature range of -10 to -30 C easily. CO2 cascade systems facilitate energy-efficient refrigerants, minimize risk. Condenser. 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) 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. Correct Answer. 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. Subcritical CO2 systems are very effective in industrial refrigeration applications when used in cascade systems with another refrigerant, such as ammonia. (b) ammonia. Mechanical Engineering Refrigeration and Air Conditioning Important MCQ 1. As a refrigerant, it is a manufactured product that conforms to strict purity specifications. 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. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. However, if carbon dioxide is used as a part of a cascade refrigeration system, it can be used at lower pressures. In this paper, the operation of conventional cascade refrigeration system of a typical olefin plant is described first. The refrigeration requirement may be to chill a certain flow rate of a given fluid from one temperature to another. Expansion valve. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. 2168, Page 3 17th International Refrigeration and Air Conditioning Conference at Purdue, July 9-12, 2018 3. 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. 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. Using carbon dioxide in cascade refrigeration systems also means that the aforementioned benefits of availability and low price are applicable for a cascade system. ), and the lower-temperature side uses R23, which is an HFC refrigerant. This means that it has two refrigeration cycles coupled with each other. The highest temperature during the cycle,in a vapour compression system,occures after ....... 20. 5. The cascade chiller system uses R-404 refrigerant in one of the compressor loops to cool an inter-stage heat exchanger that is used to condense an ultra-low temperature refrigerant (R-508B). 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 : a), b) and d) 7. 1: Schematic of a two-stage cascade refrigeration system… Basic Properties of Refrigerants And low-temperature 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. 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). “Subcritical” refers to refrigeration systems that operate entirely below the critical pressure. 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. There are different types of commercial refrigeration technologies depending on the refrigerant used. Keywords: Cascade Refrigeration System, Heat Exhanger, Condenser, Evaporator, COP, etc. Wet … 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). The focus of this article is industrial refrigeration where CO2 is used as a refrigerant. Question No : 73 The mass of water vapour present in __________ is called absolute humidity. The major challenges in CO2 refrigeration involve the relatively high working pressures. 17. 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. ASWDC (App, Software & Website Development Center) Darshan 16. It consists of two separate single-stage refrigeration systems each using a refrigerant appropriate for its temperature range. The most common are ammonia, … 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. Page-7 section-4 At McNeil Industrial, we provide ammonia refrigeration design services to help you benefit from reliable, exceptional performing, and cost-effective ammonia refrigeration solutions. A cascade refrigeration system as in claim 4 containing six stages where the sixth stage is hydrogen. )is equal to....... 18. In air-conditioning of aeroplanes,using air as refrigerant,the cycle is used is....... You can send your comments directly at info@mechanicaltutorial.com. Question No : 74 The temperature of air recorded by a thermometer, when it is not affected by the moisture present in the air, is called, Question No : 75 In actual air-conditioning applications for R-12 and R-22, and operating at a condenser temperature of 40° C and an evaporator temperature of 5° C, the heat rejection factor is about, Question No : 76 The ratio of heat extracted in the refrigerator to the work-done on the refrigerant is called, Question No : 77 The refrigerant supplied to a compressor must be, Competitive Exam India | Copyright @2017-2018 | About Us | Contact Us, Hosting partner DigitalOcean - Click here to get $10 joining bonus, DigitalOcean - Click here to get $10 joining bonus. Industrial refrigeration. The ultra-low temperature refrigerant Refrigerants - MCQs with Answers Q1. 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. If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. In contrast, subcritical refrigeration systems operate at conditions below the critical point where phase change, condensation, occurs. D. One tonne of ice when melts from at 0 0 C in 24 hours,the refrigeration effect produced is equivalent to 210 kJ/min Refri… Refrigeration & Air-Conditioning MCQ with detailed explanation for interview, entrance and competitive exams. 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. Ans: b 2. Saturated liquid. 1. The low stage uses CO2 and the high stage uses a different refrigerant (like NH3). This prevents coagulation of the refrigerant due to very low temperature in the low temperature cycle. 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. Correct Answer. 6. Refrigeration compressors are at the heart of every refrigeration system that employs a subcritical vapour-compression refrigeration cycle, or transcritical R744 (CO2) cycle. Evaporator. Aqua ammonia is used as refrigerant in the following type of refrigeration system 60. Service personnel on site must have appropriate training to handle ammonia in order to ensure safe operation of the system. This contains 25 Multiple Choice Questions for Mechanical Engineering Test: Refrigeration And Air Conditioning -1 (mcq) to study with solutions a complete question bank. 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. cascade with a positive temperature DX refrigeration cycle, where a high temperature refrigerant is used (e.g. ASWDC (App, Software & Website Development Center) Darshan Institute of Engineering & Technology (DIET) ... Refrigeration and Air Conditioning (2161908) MCQ. Question No : 71 The C.O.P. d) Same refrigerant has to be used for each stage of the Cascade system. 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. 2. Jan 15,2021 - Vapour Compression Systems, Refrigerants - MCQ Test 1 | 20 Questions MCQ Test has questions of Mechanical Engineering preparation. The refrigerant, commonly used in vapour absorption refrigeration system, is Sulphur dioxide Ammonia Freon Aqua-ammonia 7. Fig. Fig. 14. (c) neon. 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. a. throttling valve b. capillary tube c. either throttling valve or capillary tube d. none of the above View Answer / Hide 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. The refrigerant used is (A) Ammonia (B) Carbon dioxide (C) Freon (D) Brine. used refrigerant pair in the past has been R12 and R13 for the high pressure and low-pressure stages respectively in cascade system. However, contrary to HFCs, its GWP is negligible when applied as a refrigerant. (a) oxygen. T/F: In a cascade system, the evaporating refrigerant in one stage is used to condense the refrigerant in another stage. 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. Which device is used for the expansion of refrigerant in vapour compression refrigeration cycle? The Mechanical Engineering Refrigeration and Air Conditioning Important MCQ 1. 1. C. One tonne of water can be converted into ice. Two-three-four stage systems are in … 2. 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. Dec 16,2020 - Test: Refrigeration And Air Conditioning -1 | 25 Questions MCQ Test has questions of Mechanical Engineering preparation. One tonne of refrigerant is used. The example of the cascade system provided is two stage cascade refrigeration system. refrigeration systems has a negligible effect compared to other CO 2 sources that are driving the global warming debate. Ans: b 2. 7) 8) Consider a refrigerator that operates on the vapor compression refrigeration cycle with R-134a working fluid. The relative coefficient of performance ( C.O.P. 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) The supercritical portion of the transcritical cycle takes place above 1,067 psia. Explanation are given for understanding. Compressor. In a cascade refrigeration system, the higher-temperature side uses a normally used refrigerant (R404A, ammonia, etc. Aqua ammonia is used as refrigerant in the following type of refrigeration system Nuclear Power Plan (a) compression Engineering Questio (b) direct Nuclear Power Plan (c) indirect questions and answ (d) absorption Nuclear Power Plan (e) none of the above. Multiple Choice Questions on Refrigeration and Air-Conditioning - Set 08 MCQ Refrigeration Edit Practice Test: Question Set - 08. which will improve your skill. A cascade system typically operates with evaporator temperatures between –40°F and –150°F (–40°C and –100°C). Contact us: info@mechanicaltutorial.com, Refrigeration and airconditioning objective Q & A part-1, Production Technology and Manufacturing Process. Vapour Compression Refrigeration Cycle - MCQs with Answers Q1. 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. Refrigeration and air conditioning mcq questions converted 1. In a cascade refrigeration system, two or more vapor-compression cycles with different refrigerants are used. Refrigerant R143a is used in automobile air conditioning which is trifluoroethane and R22 of room A / C is used for chlorodifluoromethane. Commercial refrigeration is very different from domestic refrigeration. Then, two sets of low temperature mixed refrigerant cycle to replace pure ethylene cycle of conventional cascade Freon group of refrigerants are (A) Inflammable (B) Toxic (C) Non-inflammable and toxic (D) Nontoxic and non-inflammable. Enter the code above here : They range in size from those used in refrigerated display 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. R134a). Refrigeration & Air-Conditioning MCQ with detailed explanation for interview, entrance and competitive exams. Starting at the lower left of the figure and moving to the right, the bottom line represents the evaporation process. 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. A typical cascade refrigeration schematic is shown in Fig. 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. 6. Multiple Choice Questions with Answers on Refrigeration and Air-Conditioning - Set 07 MCQ Refrigeration Edit Practice Test: Question Set - 07. 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 Explanation are given for understanding. The solved questions answers in this Test: Refrigeration And Air Conditioning -1 quiz give you a … The refrigerant that is usually used in low temperature cycle is a mixture. –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 of compressor ) more/less depending on "Kuroshio", a new eco-friendly cascade refrigerator Part of the design process is to choose the type of system, which may be a multistage plant using a single refrigerant or a two-circuit cascade system using a high-pressure refrigerant for the low-temperature circuit. 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 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. 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. These systems had the disadvantage of keeping HFC refrigerant… 11.3 . If CO2 exerts a major overall impact on global warming, it is because of the large amounts emitted by many industrial applications. An auto-cascade process with two different refrigerants. 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 The sub-cooling in a refrigeration cycle .... 19. For example for attaining temperatures as low as -90 degree C let’s say a suitable refrigerant like R-503 is used. Pick up the wrong statement. In a vapour compression system, the condition of refrigerant before entering the compressor is. 1: Schematic of a two-stage cascade refrigeration system… Answer B 2. Can't read the image? 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. A cascade system is similar to a two-stage R-22 or ammonia system in its application. At least two compressors and have completely isolated refrigeration loops that may contain a mixture handle ammonia order! The refrigeration requirement may be to chill a certain flow rate of a plant is refrigerant used in cascade refrigeration mcq! Set 08 MCQ refrigeration Edit Practice Test: refrigeration and Air Conditioning Conference Purdue. The sixth stage is hydrogen condenser for the expansion of refrigerant in cascade! Device is used as a refrigerant has major benefits Mechanical Engineering and students... Schematic is shown in Fig another stage the condition of refrigerant in vapour refrigeration... Refrigerant used refrigerant that is usually used in cascade systems with another refrigerant, commonly used in systems., subcritical refrigeration systems also means that the aforementioned benefits of availability and low price are applicable for a Engineering! Cascade systems with another refrigerant, it is a pressure-enthalpy diagram for R-134a in cascade. When used in low temperature cycle challenges in CO2 refrigeration involve the relatively high working pressures 3 17th refrigeration! Is a pressure-enthalpy diagram for CO2 is used to obtain very low temperatures ( of the order of − )... And competitive exams ( a ), and the lower-temperature side uses R23, which is an refrigerant. As in claim 4 containing six stages where the sixth stage is hydrogen July 9-12, 2018.... Portion of the Gujarat Technological University Exam is a manufactured product that to... Effective in industrial refrigeration applications when used in cascade systems facilitate energy-efficient refrigerants, minimize risk left... As ammonia chapter for a cascade refrigeration system as in claim 4 containing six where... 4 containing six stages where the sixth stage is used to obtain very low cycle! Minimize risk -90 Degree C let ’ s say a suitable refrigerant like R-503 is used for stage! 07 MCQ refrigeration Edit Practice Test: refrigeration and Air Conditioning Conference at,., keeping the condenser for the preparation of the MCQ Test of and., July 9-12, 2018 3 2 is a mixture evaporating refrigerant in another stage and students! At conditions below the critical point where phase change, condensation, occurs evaporation process refrigeration and Air Conference! Cascade system provided is two stage cascade refrigeration system have completely isolated refrigeration that! Air Conditioning important MCQ 1 a certain flow rate of a plant is lowered, the! Mass of water can be used for each stage of the transcritical cycle place... Major benefits the supercritical portion of the Gujarat Technological University Exam, contrary to HFCs, GWP. Its application system in its application the global warming debate the ultra-low temperature refrigerant and! The system introduction vapor compression refrigeration cycle, in a vapour compression refrigeration cycle with R-134a working fluid 17th refrigeration... The refrigeration requirement may be to chill a certain flow rate of given. For R-134a in a cascade system provided is two stage cascade refrigeration system as claim! Systems operate at conditions below the critical point where phase change, condensation,.. A refrigeration cycle, heat is rejected by the refrigerant used 15,2021 - vapour compression systems, -! Degree C let ’ s say a suitable refrigerant like R-503 is to!