ODP of the refrigerant is also considering due to environmental safety. (i) Air It causes cooling by latent heat of vaporization. If the system is equipped with liquid injection, the valves will need to be ‘throttled back’ to reduce the flow. In these systems: A. 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. The schematic view and the P-h diagram of this system are shown below. In a domestic vapour compression refrigerator, the refrigerant commonly used is (A) CO ₂ (B) Ammonia (C) R-12 (D) All of these. It causes cooling by latent heat of vaporization. Capacity and efficiency values are nearly equivalent to R- 503 and superior to R-13. (k) Air (Ans:d), Cp of air is (c) Water (k) Freon-22 A cascade system consists of two separate single-stage refrigeration systems – each using a refrigerant appropriate for its temperature range. There are 2 refrigerant circuits and only 1 type of refrigerant. Because Suva 95 has about 25% higher capacity, the TXV may need to be adjusted or replaced. Two systems comprise a lower system that maintains lower evaporating temperatures and a higher system that operates at higher evaporating temperatures. The application of transcritical R-744 systems is one example and another example is the cascade system. (l) None (Ans:c), Specific heat at constant pressure is highest Air is primary refrigerant in air craft refrigeration, It is a secondary refrigerant in a fridge. a. throttling valve b. capillary tube c. either throttling valve or capillary tube d. none of the above View Answer / Hide Answer. Reciprocating compressors are used with refrigerants with high pressure and small volumes of suction vapour. (d) None (a) Refrigerant – 22 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. Original equipment manufacturers (OEMs) as well as compressor suppliers should always be consulted for their recommendations. © Chary Publications Pvt. 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. (Ans:d), Which is the secondary refrigerant in an ice plant Well today we are going to be doing the same type of post except this time on cascade refrigeration systems. (d) None Ltd. | Cooling India Magazine on HVACR Industry | Powered by: 360digital Hub Pvt. (d) None The R number of a chemical refrigerant is assigned systematically according to molecular structure. What is Cascade refrigeration? (Ans:a), Which is the secondary refrigerant in an ice plant The static charge pressure of Suva 95 will be about 25% LESS than that of R-23 (see Table 2). 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 … This system is employed to obtain temperatures of -40 to -80°C or ultra-low temperatures lower than them. Pick up the wrong statement. 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. 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 … (b) = Cv of air R-23 could be and has been used alone, but Suva 95, an azeotrope of R-23 and R-116, has superior properties. In a Carnot vapor refrigeration cycle refrigerant R - 134a is used as the working fluid. Wet compression is _____. it must be cheap and available in abundance. Lower discharge temperatures may equate to longer compressor life and better lubricant stability. (b) Ammonia These gases do not require refilling, you only need to fill it when your compressor stops working. (c) Cooled by the primary refrigerant A cascade system typically operates with evaporator temperatures between –40°F and –150°F (–40°C and –100°C). During this heat transfer process, the secondary refrigerant ends up with sensible heat change with no phase change. 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. C. One tonne of water can be converted into ice. (c) 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. Set 05. Refrigerant R143a is used in automobile air conditioning which is trifluoroethane and R22 of room A / C is used for chlorodifluoromethane. Fig. (Ans:d), Secondary refrigerant is one which is  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 … (d) None 15. In process (2-3) low side refrigerant is compressed isentropic ally and increases the temperature and pressure. A.Open cycle B.Closed cycle C.Mixed cycle D.Hybrid cycle . (b) Air (j) Water Industrial refrigeration is the first area where CO 2 has made a successful comeback. B. Q. (d) None Set 08. Some refrigerants are well suited for high and medium temperature applications, and some are better suited and for a lower temp applications. Due to the higher operating pressure of Suva 95, the dump valve setting should be increased to about 290 psig. Correct Answer. At such low temperatures, single-stage compression systems with reciprocating compressors are generally not feasible due to high pressure ratios. (d) None 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. Mechanical Engineering Refrigeration and Air Conditioning Important MCQ 1. It consists of two separate single-stage refrigeration systems each using a refrigerant appropriate for its temperature range. Ans: a; Which of the following refrigerants has lowest freezing point (a) Freon-12 (b) NH3 (c) C02 (d) Freon-22 (e) S02. (Ans:b), Pressure of refrigerant in the evaporator should be MCQ Refrigeration Edit Practice Test: Question Set - 01 . (d) None In addition, Suva 95 will maintain a positive suction pressure at lower evaporator temperatures than R-23. Typical refrigerants for the high-temperature system include R-22, and R-404A. 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. (Ans:b), Which is the primary refrigerant in central air conditioning plant (k) Freon-22 … The most commonly used refrigerant in refrigerators is R 134a which is tetrafluoroethylene, which does not deteriorate ozone layers. (Ans:c), Specific heats at constant pressure and at constant volume are equal An example two-stage process is shown at right. Also, the service technician should have a thorough understanding of the system design and operation. (a) Air 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. (d) None Refrigeration and Air conditioning Mcqs. (l) None 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. 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. Example: at –120°F (–84°C), the suction pressure for R-23 will be 3.9 in Hg vacuum (90 kPa). (Ans:c) Set 07. The expansion tank will not have to be replaced. (Ans:c), Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window). Set 04. (Ans:c), Which is the secondary refrigerant in central air conditioning plant 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. (c) Water vapors (d) None These fluids are harmless to environment and GWP and ODP is negligible and do not violate the kyoto protocol. Natural refrigerants with relatively small amount of charge can be used as a refrigerant in the autocascade refrigeration system. (c) Freon- 22 (c) Freon-22 As most of you know each refrigerant has its upsides and downsides. Set 01. (j) Brine solution (a) Vapor Refrigerant – 22 (b) Ammonia CO 2 in industrial refrigeration is used either as the low-stage refrigerant in cascade installations, or as a secondary coolant. Refrigeration Cycle and Input Condition of Natural Gas 03/33. Refrigerant should be non-corrosive, non decomposable, non-toxic and inert to the materials of construction. Solutions for CO 2 in industrial refrigeration. Set 06. (i) Air A cascade refrigeration cycle is a multi-stage thermodynamic cycle. So, natural refrigerants are increasing used in low temperature refrigeration system. 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). The most commonly used refrigeration cycle is the ‘Vapour … Q2. (l) None (Ans:d), Which one acts as a primary, secondary as well as a tertiary refrigerant 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 Because of this, it is difficult to provide detailed retrofit procedures.
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