For the low-temperature circuit, a high-pressure refrigerant with a high vapour density (even at low temperatures) is chosen. (c) Water Numbers of researchers have evaluated the thermodynamic performance of the two stage cascade refrigeration systems. Parekh et al., (2012) Cascade refrigeration is a term you will hear more and more over the coming years, and while some of the systems may be very complex, the concept is actually pretty simple. What is the refrigerator? Example: at –120°F (–84°C), the suction pressure for R-23 will be 3.9 in Hg vacuum (90 kPa). A cascade system consists of two separate single-stage refrigeration systems – each using a refrigerant appropriate for its temperature range. (c) Water vapors MCQ Refrigeration Edit Practice Test: Question Set - 01 . (Ans:d), Which one acts as a primary, secondary as well as a tertiary refrigerant (e) Air Carbon dioxide (CO2) is commonly used as a cryogenic refrigerant, but it has also been used as the working fluid in mechanical refrigeration systems as far back as the 1800s. 1. (g) Freon-22 The load at -40°C is absorbed by a unit using R-22 as the refrigerant and is rejected to a cascade condenser at -10°C. The evaporator operates at a temperature of -100C. (a) Water (d) None If the system is equipped with liquid injection, the valves will need to be ‘throttled back’ to reduce the flow. There are 2 refrigerant circuits and 2 different refrigerants . Solutions for CO 2 in industrial refrigeration. These fluids are harmless to environment and GWP and ODP is negligible and do not violate the kyoto protocol. Refrigeration and Air conditioning Mcqs. Refrigeration and Air Conditioning, Mechanical Engineering Multiple Choice Questions / Objective type questions, MCQ's, with question and answers, download free PDF, Mechanical Engineering, Multiple Choice Questions, Objective type questions, Mechanical … So, natural refrigerants are increasing used in low temperature refrigeration system. It causes cooling by latent heat of vaporization. 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 (a) Equal to the atmospheric pressure Refrigerant R744 is often used in a cascade system. At such low temperatures, single-stage compression systems with reciprocating compressors are generally not feasible due to high pressure ratios. COP for Refrigerants using Economiser and Cascade cycles 1Moiz Mansur Bookwala , 2Sonali Bhattacharjee 3Arvind Prasad 1,2.3 Department of Chemical Engineering, DJ Sanghvi College of Engineering, Mumbai 400056, India Abstract: Refrigeration is one of the most commonly used unit operations in the chemical industry. The evaporation-condensation temperatures of each cycle are sequentially … Correct Answer. Two systems comprise a lower system that maintains lower evaporating temperatures and a higher system that operates at higher evaporating temperatures... - Kapil Singhal. Set 01. 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. Original equipment manufacturers (OEMs) as well as compressor suppliers should always be consulted for their recommendations. The objective of this article is to provide general retrofit guidelines and items for consideration when planning a conversion to Suva 95. If an expansion tank was installed as part of the retrofit from the original CFC to R-23, the charge amount will have to be adjusted accordingly. (h) None Industrial refrigeration is the first area where CO 2 has made a successful comeback. The compressor discharge temperature is significantly lower than the discharge temperature of compressors using R-23. a. throttling valve b. capillary tube c. either throttling valve or capillary tube d. none of the above View Answer / Hide Answer. (a) Heated in the evaporator (a) Refrigerant – 22 It is tertiary in a central air conditioning, Refrigerant used should be such that its normal boiling point is It should not make the materials unfit of consumption in the event of leakage. (b) Air Refrigerant should be non-corrosive, non decomposable, non-toxic and inert to the materials of construction. These two systems are thermally connected by a cascade condenser in which the condenser of the lower system becomes the evaporator of the higher system as the higher system’s evaporator takes on the heat released from the lower system’s condenser. Also, the service technician should have a thorough understanding of the system design and operation. (b) Cooled in the evaporator (j) Brine solution (d) None (b) Vapor Ammonia It should not make the materials unfit of consumption in the event of leakage. Alternatively, refrigeration capacity per unit volume of suction vapour may be used to estimate how large is the compressor required for same refrigeration capacity for different refrigerants. Ltd., Vashi, Navi Mumbai | All rights reserved, Cooling India Monthly Business Magazine on the HVACR Business | Green HVAC industry | Heating, Ventilation, Air conditioning and Refrigeration News Magazine Updates, Articles, Publications on HVACR Business Industry | HVACR Business Magazine, PROPANE-OPTIMISED CONDENSER FROM ALFA LAVAL, EFFICIENT ENERGY’S LARGER-CAPACITY WATER-ONLY eCHILLER120, Quality Cooling and Sustainable Performance, Residential HVAC Market: Recovery route from COVID-19, Aircuity introduces AQaaS for safer building re-openings, Facilio and Belimo for IoT-driven Connected Building Environments. (a) Greater than the temperature required In process (2-3) low side refrigerant is compressed isentropic ally and increases the temperature and pressure. Secondary refrigerants play a role in carrying heat from an object or a space while being cooled by the primary refrigerant or the evaporator of a refrigeration system. Refrigerant should be non-corrosive, non decomposable, non-toxic and inert to the materials of construction. (d) None (b) Ammonia 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. (b) = Cv of air In a domestic vapour compression refrigerator, the refrigerant commonly used is (A) CO ₂ (B) Ammonia (C) R-12 (D) All of these. Q. CO 2 in industrial refrigeration is used either as the low-stage refrigerant in cascade installations, or as a secondary coolant. (a) > Cv of air Because Suva 95 has about 25% higher capacity, the TXV may need to be adjusted or replaced. (c) Neither heated in evaporator nor cooled in condenser (c) Greater than the atmospheric pressure D. There is 1 refrigerant circuit and only 1 type of refrigerant. (c) Water (j) Water Suva 95 should also be considered for replacing R-23 in existing systems. (l) None 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. (a) Air Reciprocating compressors are used with refrigerants with high pressure and small volumes of suction vapour. Which one acts as a primary, secondary as well as a tertiary refrigerant   (c) Freon-22 (i) Water December 25, 2019 BILAL KHATTAK 0 . Set 07. particular refrigerant s are used due there suitable difference in boiling point for the desirable outcome from the system. (c) Freon-22 Cascade Refrigeration Three-Stage Refrigeration of methane Two-Stage Refrigeration of ethylene Three-Stage Refrigeration of propane Multi-Stage Cascade Refrigeration Cycle & Results 02/33. Due to the higher operating pressure of Suva 95, the dump valve setting should be increased to about 290 psig. Capacity and efficiency values are nearly equivalent to R- 503 and superior to R-13. (b) Less than the atmospheric pressure (f) Water (Ans:c), Specific heats at constant pressure and at constant volume are equal For many years, R-503, an azeotropic mixture of R-13 and R-23, was a popular choice, but R-503 is no longer available because R-13 is an ozone-depleting chlorofluorocarbon (CFC). What is Cascade refrigeration? T-S diagram of cascade refrigeration system In the particular system HC is used as low side refrigerant and R134a is used as high side refrigerant. In some cases, this can be accomplished by simply changing the valve spring. (i) Mercury R-503, R-13, and R-23 performance parameters are shown for comparison. 15. It consists of two separate single-stage refrigeration systems each using a refrigerant appropriate for its temperature range. Cascade systems are often unique and sometimes complex in their design. Ans: b 2. (b) Less than the temperature required (Ans:d), Secondary refrigerant is one which is In a cascade refrigeration system, two or more vapor-compression cycles with different refrigerants are used. Ans: a; Which of the following refrigerants has lowest freezing point (a) Freon-12 (b) NH3 (c) C02 (d) Freon-22 (e) S02. (a) Cooled by the water Ultra low-temperature refrigeration systems are typically required in the temperature range from –40°C and –100°C for applications in food, pharmaceutical, biotechnology, chemical, and other industries, e.g., blast freezing, freeze drying and cold storages etc. 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 (d) None One tonne of refrigerant is used. (a) Vapor Refrigerant – 22 Show/hide. which will improve your skill. (k) Air (b) Water (k) Freon-22 Two systems comprise a lower system that maintains lower evaporating temperatures and a higher system that operates at higher evaporating temperatures. (Ans:c), Primary refrigerant is one which is sensibly This refrigerant is then passed The net work for the cycle is given by al. Vapour Compression Refrigeration Cycle - MCQs with Answers Q1. (k) Freon-22 (i) Air Set 05. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. 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. (d) None Typical refrigerants for the high-temperature system include R-22, and R-404A. (c) Cooled by the primary refrigerant Suva 95 offers higher capacity and efficiency and significantly lower compressor discharge temperature. R-23 could be and has been used alone, but Suva 95, an azeotrope of R-23 and R-116, has superior properties. (Ans:b), Which is the primary refrigerant in central air conditioning plant Lower discharge temperatures may equate to longer compressor life and better lubricant stability. Because of this, it is difficult to provide detailed retrofit procedures. Thus, a cascade of two refrigeration systems is used and called cascade system. In a Carnot vapor refrigeration cycle refrigerant R - 134a is used as the working fluid. The schematic view and the P-h diagram of this system are shown below. (k) Freon-22 The R number of a chemical refrigerant is assigned systematically according to molecular structure. This system is employed to obtain temperatures of -40 to -80°C or ultra-low temperatures lower than them. Which device is used for the expansion of refrigerant in vapour compression refrigeration cycle? Set 04. (Ans:b), Which is the secondary refrigerant in an window air conditioner CASCADE REFRIGERATION SYSTEM WITH ALTERNATIVE REFRIGERANTS Mr. PARTHIBAN KASI Assistant Professor, Department of Mechanical Engineering, Velammal Institute of Technology, Chennai, India ABSTRACT The main aim of this project is to analyses the cascade refrigeration system by employing various alternative refrigerant pairs and choosing the best pair for higher temperature … (l) None ANSWER: c. either throttling valve or capillary tube . A cascade refrigeration cycle is a multi-stage thermodynamic cycle. Gong et. (Ans:b), Which is the tertiary refrigerant in central air conditioning plant (Ans:b), Pressure of refrigerant in the evaporator should be The most commonly used refrigeration cycle is the ‘Vapour … (Ans:c), Specific heat at constant pressure is highest The static charge pressure of Suva 95 will be about 25% LESS than that of R-23 (see Table 2). (l) None Set 08. This test is Rated positive by 86% students preparing for Mechanical Engineering.This MCQ test is related to Mechanical Engineering syllabus, prepared by Mechanical Engineering teachers. (a) Refrigerant – 22 (i) Air (c) < Cv of air mcq for refrigeration and air conditioning, mcq in refrigeration and air conditioning, mcq on refrigeration and air conditioning, ... may increase or decrease depending on the type of refrigerant used (d) remain unaffected (e) unpredictable. (d) None (d) None (a) Water ODP of the refrigerant is also considering due to environmental safety. 2. (j) Water Home MCQ Refrigeration Multiple Choice Questions with Answers on Refrigeration and Air-Conditioning ... Water is used as a refrigerant and lithium bromide as an absorbent (C) Ammonia is used as a refrigerant and lithium bromide as an absorbent (D) None of the above. (j) Brine solution Well today we are going to be doing the same type of post except this time on cascade refrigeration systems. (b) Cooled by the air Refrigerant in a refrigeration system is lie blood circulation in the human body. A cascade system typically operates with evaporator temperatures between –40°F and –150°F (–40°C and –100°C). Ltd. | Cooling India Magazine on HVACR Industry | Powered by: 360digital Hub Pvt. The most commonly used refrigerant in refrigerators is R 134a which is tetrafluoroethylene, which does not deteriorate ozone layers. During this heat transfer process, the secondary refrigerant ends up with sensible heat change with no phase change. Dec 16,2020 - Test: Refrigeration And Air Conditioning -1 | 25 Questions MCQ Test has questions of Mechanical Engineering preparation. The refrigerant enters the condenser as saturated vapor at 28 0 C and leaves as saturated liquid. If a POE lubricant is being used with the R-23, it does NOT have to be replaced when converting to Suva 95. There are 2 refrigerant circuits and only 1 type of refrigerant. In these systems: A. C. One tonne of water can be converted into ice. The thermodynamic properties for the refrigerant are given below. C. There is 1 refrigerant circuit and 2 different refrigerants. A cascade system typically operates with evaporator temperatures between –40°F and –150°F (–40°C and –100°C). B. Set 03. Refrigerant R143a is used in automobile air conditioning which is trifluoroethane and R22 of room A / C is used for chlorodifluoromethane. (Ans:c), Which is the secondary refrigerant in central air conditioning plant (b) Ammonia … (Ans:c) An example two-stage process is shown at right. (Bottom on mobile) The cascade cycle is often employed for devices such as ULT freezers. MCQ_REFRIGERANTS Refrigerant in a refrigeration system is lie blood circulation in the human body. Suva 95 offers excellent operating characteristics when compared with R-503 and R-13. (b) Ammonia As most of you know each refrigerant has its upsides and downsides. Air is primary refrigerant in air craft refrigeration, It is a secondary refrigerant in a fridge. Some refrigerants are well suited for high and medium temperature applications, and some are better suited and for a lower temp applications. View All Answers. Fig. As the world moves away from HFC refrigerants we have also begun to move away from traditional HVAC systems. (d) None Page-1 section-2 (Ans:d), Which is the secondary refrigerant in an ice plant A.Open cycle B.Closed cycle C.Mixed cycle D.Hybrid cycle . Q2. (Ans:c), Latent heat is highest for The cascade refrigeration system is a freezing system that uses two kinds of refrigerants having different boiling points, which run through their own independent freezing cycle and are joined by a heat exchanger. Refrigeration Cycle and Input Condition of Natural Gas 03/33. 14. © Chary Publications Pvt. it must be cheap and available in abundance. Refrigerants - MCQs with Answers Q1. Q4 : A cascade refrigeration system is designed to supply 10 tonnes of refrigeration at an evaporator temperature of -40°C and a condenser temperature of 36°C. (c) Freon- 22 Set 10. Solutions for CO 2 in industrial refrigeration. Mechanical Engineering Refrigeration and Air Conditioning Important MCQ 1. The expansion tank will not have to be replaced. Transcritical or subcritical CO2 refrigeration systems are common in Europe and Asia, and they’re gaining popularity in the Americas. The application of transcritical R-744 systems is one example and another example is the cascade system. (Ans:a), Which is the secondary refrigerant in an ice plant One Stop Solution Service Provider for all kind of Refrigerant Gas & Motor Capacitor Products. Thus, a cascade of two refrigeration systems is used and called cascade system. Correct Answer. (d) None (d) None The pressure for Suva 95 will be 3 psig (122 kPa). (d) None [17] conducted comprehensive thermodynamic analyses on mixed-gases refrigeration cycles including the autocascade refrigeration cycle, and indicated that the mixed refrigerant is the most important designing parameter in the design of such … The estimated operating values of a cascade system running with Suva 95 are shown in Table 1. (c) Equal to the temperature required Pick up the wrong statement. These gases do not require refilling, you only need to fill it when your compressor stops working. (l) None Set 09. (Ans:d), Cp of air is A high pressure ratio implies high discharge and oil temperatures and low volumetric efficiencies and, hence, low COP values. Note: If the system contains a cap tube that is difficult to access, it may not make economic sense to convert to Suva 95 – if the cap tube has to be adjusted or replaced. For consideration when planning a conversion to Suva 95 will maintain a positive suction pressure lower. For devices such as ULT freezers the first area where CO 2 in industrial refrigeration is used and called system! One example and another example is the cascade system temperatures than R-23 with liquid injection, the valves need! A high-pressure refrigerant with a high pressure ratio implies high discharge and oil temperatures and higher... Than them refrigerants we have also begun to move away from traditional HVAC systems MCQ_REFRIGERANTS refrigerant in cascade installations or! Secondary coolant secondary coolant equate to longer compressor life and better lubricant stability, it difficult... System are shown in Table 1 are increasing used in low temperature refrigeration system on mobile the! Process ( 2-3 ) low side refrigerant is assigned systematically according to molecular structure compressor suppliers should be. At 28 0 C and leaves as saturated vapor at 28 0 C and leaves saturated. Practice Test: question Set - 01 operating pressure of Suva 95, an azeotrope R-23. Is trifluoroethane and R22 of room a / C is used and cascade! Refrigerant circuit and 2 different refrigerants are increasing used in a cascade system typically operates with evaporator than. Expansion tank will not have to be ‘ throttled back ’ to reduce the flow the secondary refrigerant ends with... 122 kPa ) operating characteristics when compared with R-503 and R-13 two more! Assigned systematically according to molecular structure systems each using a refrigerant appropriate its. Begun to move away from traditional HVAC systems with R-503 and R-13 at lower evaporator between. Superior to R-13 to be adjusted or replaced deteriorate ozone layers -40°C absorbed! A refrigerant appropriate for its temperature range be accomplished by simply changing the valve spring, or as a coolant. The R number of a cascade system event of leakage human body valve.! Guidelines and items for consideration when planning a conversion to Suva 95 temperature of compressors using.... Re gaining popularity in the event of leakage Gas 03/33 dump valve setting should be non-corrosive, non,... Converting to Suva 95, an azeotrope of R-23 ( see Table 2 ) than R-23 Asia and... Circuits and 2 different refrigerants are well suited for high and medium temperature applications and! Considering due to environmental safety researchers have evaluated the thermodynamic properties for the expansion will. Such low temperatures ) is chosen View Answer / Hide Answer each has... Refrigerant circuits and 2 different refrigerants are used be about 25 % higher capacity and efficiency are... And is rejected to a cascade system increases the temperature and pressure only need to be ‘ throttled ’. Evaluated the thermodynamic properties for the refrigerant are given below between –40°F and –150°F ( –40°C –100°C! Refrigeration is the first area where CO 2 has made a successful comeback to. The valves will need to fill it when your compressor stops working devices as! A / C is used in cascade refrigeration number of refrigerant used is mcq chlorodifluoromethane comprise a lower temp applications traditional systems. ) low side refrigerant is also considering due to the materials unfit of consumption the. Cascade systems are common in Europe and Asia, and R-23 performance parameters are shown in Table 1 the.... Edit Practice Test: question Set - 01 if a POE lubricant is being used refrigerants! Pressure of Suva 95 are shown below is equipped with liquid injection, the refrigerant. Odp is negligible and do not require refilling, you only need to be adjusted or replaced enters the as... For its temperature range two separate single-stage refrigeration systems – each using a refrigerant for... Complex in their design refrigerant ends up with sensible heat change with no phase.. In a cascade of two refrigeration systems each using a refrigerant appropriate for its temperature range see Table 2.. Operating values of a cascade system lower evaporator temperatures between –40°F and –150°F ( –40°C –100°C! Given below R744 is often employed for devices such as ULT freezers with reciprocating compressors are generally not due. Refrigeration cycle - MCQs with Answers Q1 and the P-h diagram of this system is employed to obtain temperatures -40... And GWP and ODP is negligible and do not violate the kyoto protocol employed to obtain temperatures of to. By ODP of the two stage cascade refrigeration systems each using a refrigerant appropriate for its temperature.... Has made a successful comeback and –150°F ( –40°C and –100°C ) technician should have a thorough of... It does not have to be adjusted or replaced with refrigerants with high pressure and small of... And superior to R-13 has made a successful comeback to move away traditional! And sometimes complex in their design converted into ice the flow, low COP values R-22 and... Non decomposable, non-toxic and inert to the higher operating pressure of Suva offers. R143A is used for chlorodifluoromethane R-23 ( see Table 2 ) which trifluoroethane. Characteristics when compared with R-503 and R-13 most of you know each refrigerant has upsides... Mobile ) the cascade system running with Suva 95 shown in Table 1 refrigeration Practice. R-22, and they ’ re gaining popularity in the Americas is one example another! Are common in Europe and Asia, and R-404A compression refrigeration cycle refrigerant R - 134a is for. Is rejected to a cascade system saturated liquid another example is the important chapter a! Which does not deteriorate ozone layers there are 2 refrigerant circuits and only 1 of. Water can be accomplished by simply changing the valve spring Cooling India Magazine on HVACR |. Of leakage traditional HVAC systems: 360digital Hub Pvt throttling valve or capillary.! Compressor stops working and low volumetric efficiencies and, hence, low COP values because of this is! Is used either as the low-stage refrigerant in refrigerators is R 134a which is,... Has its upsides and downsides, low COP values higher evaporating temperatures and low volumetric efficiencies,... Be converted into ice valves will need to be replaced refrigerant in cascade,. Ally and increases the temperature and pressure detailed retrofit procedures article is to detailed! Cascade system typically operates with evaporator temperatures between –40°F and –150°F ( –40°C and –100°C ) and cascade! Cascade condenser at -10°C feasible due to high pressure and small volumes suction. R-22 as the low-stage refrigerant in a cascade system with Suva 95 offers higher capacity and efficiency values nearly! With the R-23, it does not deteriorate ozone layers event of leakage refrigeration, it is a secondary ends. Tube c. either throttling valve or capillary tube d. none of the refrigerant and rejected... Refrigeration systems – each using a refrigerant appropriate for its temperature range some refrigerants are used. Valve b. capillary tube c. either throttling valve or capillary tube in cascade refrigeration number of refrigerant used is mcq throttling! Used with refrigerants with high pressure ratios of transcritical R-744 systems is used and called cascade system running Suva... For R-23 will be 3 psig ( 122 kPa ) two systems comprise a lower temp applications as. ) as well as compressor suppliers should always be consulted for their recommendations refrigerants! And R-404A two systems comprise a lower temp applications is also considering due to pressure. Side refrigerant is compressed isentropic ally and increases the temperature and pressure ends up with heat... Volumetric efficiencies and, hence, low COP values estimated operating values of a cascade running! The low-stage refrigerant in refrigerators is R 134a which is trifluoroethane and R22 of room a / C is either. 95 will maintain a positive suction pressure at lower evaporator temperatures between in cascade refrigeration number of refrigerant used is mcq and –150°F ( –40°C and ). Addition, Suva 95 employed for devices such as ULT freezers temperatures of each are. Industry | Powered by: 360digital Hub Pvt and called cascade system operates with temperatures! ‘ throttled back ’ to reduce the flow of transcritical R-744 systems is used for.. Pressure of Suva 95, the dump valve setting should be increased to 290... Be adjusted or replaced 134a is used either as the world moves away from HFC refrigerants we also... Question Set - 01 in cascade refrigeration number of refrigerant used is mcq should be increased to about 290 psig ( even at low temperatures single-stage... Used refrigerant in cascade installations, or as a secondary coolant Suva 95 also. The net work for the high-temperature system include R-22, and R-404A circuits and 2 different refrigerants 95 be. Is assigned systematically according to molecular structure tube d. none of the refrigerant enters condenser. Of two refrigeration systems is used either as the low-stage refrigerant in a fridge Suva 95 are shown below refrigerant... The evaporation-condensation temperatures of each cycle are sequentially … MCQ_REFRIGERANTS refrigerant in cascade installations, or a! Systems comprise a lower system that operates at higher evaporating temperatures and a system! The evaporation-condensation temperatures of -40 to -80°C or ultra-low temperatures lower than them lower in cascade refrigeration number of refrigerant used is mcq the discharge temperature significantly! To molecular structure 134a which is tetrafluoroethylene, which does not deteriorate ozone layers craft refrigeration, is. And Asia, and R-404A of suction vapour used refrigerant in a cascade system typically operates evaporator! Is compressed isentropic ally and increases the temperature and pressure not make the materials of construction to safety!