Set 04. (c) Freon-22 (b) Ammonia In some cases, this can be accomplished by simply changing the valve spring. Capacity and efficiency values are nearly equivalent to R- 503 and superior to R-13. MCQ Refrigeration Edit Practice Test: Question Set - 01 . Industrial refrigeration is the first area where CO 2 has made a successful comeback. Suva 95 offers excellent operating characteristics when compared with R-503 and R-13. CO 2 in industrial refrigeration is used either as the low-stage refrigerant in cascade installations, or as a secondary coolant. R-23 conversions to Suva 95 At such low temperatures, single-stage compression systems with reciprocating compressors are generally not feasible due to high pressure ratios. (b) Less than the atmospheric pressure View All Answers. These fluids are harmless to environment and GWP and ODP is negligible and do not violate the kyoto protocol. Correct Answer. al. Industrial refrigeration is the first area where CO 2 has made a successful comeback. (j) Brine solution (d) None (l) None 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. 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. In process (2-3) low side refrigerant is compressed isentropic ally and increases the temperature and pressure. A cascade system typically operates with evaporator temperatures between –40°F and –150°F (–40°C and –100°C). (l) None 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. Refrigeration and Air conditioning Mcqs. Refrigerant R143a is used in automobile air conditioning which is trifluoroethane and R22 of room A / C is used for chlorodifluoromethane. The estimated operating values of a cascade system running with Suva 95 are shown in Table 1. (d) None (Ans:b), Pressure of refrigerant in the evaporator should be Fig. Correct Answer. Cascade systems are often unique and sometimes complex in their design. The evaporation-condensation temperatures of each cycle are sequentially … Page-1 section-2 So, natural refrigerants are increasing used in low temperature refrigeration system. ODP of the refrigerant is also considering due to environmental safety. Some refrigerants are well suited for high and medium temperature applications, and some are better suited and for a lower temp applications. Refrigerant should be non-corrosive, non decomposable, non-toxic and inert to the materials of construction. B. Q. 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. (i) Mercury It should not make the materials unfit of consumption in the event of leakage. As the world moves away from HFC refrigerants we have also begun to move away from traditional HVAC systems. Thus, a cascade of two refrigeration systems is used and called cascade system. (c) Neither heated in evaporator nor cooled in condenser There are 2 refrigerant circuits and 2 different refrigerants . Reciprocating compressors are used with refrigerants with high pressure and small volumes of suction vapour. (a) Water It should not make the materials unfit of consumption in the event of leakage. Because Suva 95 has about 25% higher capacity, the TXV may need to be adjusted or replaced. Also, the service technician should have a thorough understanding of the system design and operation. (c) Water D. There is 1 refrigerant circuit and only 1 type of refrigerant. Numbers of researchers have evaluated the thermodynamic performance of the two stage cascade refrigeration systems. (b) Cooled in the evaporator (Ans:c), Latent heat is highest for (k) Freon-22 (d) None Mechanical Engineering Refrigeration and Air Conditioning Important MCQ 1. (b) Cooled by the air (Bottom on mobile) The cascade cycle is often employed for devices such as ULT freezers. (a) Equal to the atmospheric pressure (l) None (i) Air C. One tonne of water can be converted into ice. R-503, R-13, and R-23 performance parameters are shown for comparison. (Ans:c), Specific heat at constant pressure is highest It consists of two separate single-stage refrigeration systems each using a refrigerant appropriate for its temperature range. (b) = Cv of air CO 2 in industrial refrigeration is used either as the low-stage refrigerant in cascade installations, or as a secondary coolant. 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. (a) Refrigerant – 22 (d) None Original equipment manufacturers (OEMs) as well as compressor suppliers should always be consulted for their recommendations. 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 … 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. Two systems comprise a lower system that maintains lower evaporating temperatures and a higher system that operates at higher evaporating temperatures. (c) Water Pick up the wrong statement. What is the refrigerator? One Stop Solution Service Provider for all kind of Refrigerant Gas & Motor Capacitor Products. Two systems comprise a lower system that maintains lower evaporating temperatures and a higher system that operates at higher evaporating temperatures... - Kapil Singhal. An example two-stage process is shown at right. (c) Cooled by the primary refrigerant (a) Vapor Refrigerant – 22 Refrigerant should be non-corrosive, non decomposable, non-toxic and inert to the materials of construction. 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. it must be cheap and available in abundance. It causes cooling by latent heat of vaporization. These gases do not require refilling, you only need to fill it when your compressor stops working. (Ans:d), Cp of air is (c) Greater than the atmospheric pressure (c) Water vapors There are 2 refrigerant circuits and only 1 type of refrigerant. (c) Freon-22 (d) None (f) Water Lower discharge temperatures may equate to longer compressor life and better lubricant stability. It causes cooling by latent heat of vaporization. which will improve your skill. One tonne of refrigerant is used. (a) Greater than the temperature required 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 1. (Ans:b), Which is the secondary refrigerant in an window air conditioner (d) None The refrigerant enters the condenser as saturated vapor at 28 0 C and leaves as saturated liquid. Ans: b 2. Q2. Vapour Compression Refrigeration Cycle - MCQs with Answers Q1. Set 03. Ans: a; Which of the following refrigerants has lowest freezing point (a) Freon-12 (b) NH3 (c) C02 (d) Freon-22 (e) S02. (d) None This system is employed to obtain temperatures of -40 to -80°C or ultra-low temperatures lower than them. Due to the higher operating pressure of Suva 95, the dump valve setting should be increased to about 290 psig. 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 cascade refrigeration cycle is a multi-stage thermodynamic cycle. (a) Cooled by the water Set 07. The R number of a chemical refrigerant is assigned systematically according to molecular structure. [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 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. In addition, Suva 95 will maintain a positive suction pressure at lower evaporator temperatures than R-23. 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. Refrigerant R744 is often used in a cascade system. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. The evaporator operates at a temperature of -100C. It consists of two separate single-stage refrigeration systems each using a refrigerant appropriate for its temperature range. (d) None A cascade system typically operates with evaporator temperatures between –40°F and –150°F (–40°C and –100°C). 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 … (Ans:c) (j) Water (c) < Cv of air ANSWER: c. either throttling valve or capillary tube . (Ans:d), Which is the secondary refrigerant in an ice plant (Ans:a), Which is the secondary refrigerant in an ice plant If a POE lubricant is being used with the R-23, it does NOT have to be replaced when converting to Suva 95. (l) None If the system is equipped with liquid injection, the valves will need to be ‘throttled back’ to reduce the flow. 14. Transcritical or subcritical CO2 refrigeration systems are common in Europe and Asia, and they’re gaining popularity in the Americas. Which one acts as a primary, secondary as well as a tertiary refrigerant   © Chary Publications Pvt. (b) Ammonia (a) Heated in the evaporator Refrigerants - MCQs with Answers Q1. (Ans:d), Which one acts as a primary, secondary as well as a tertiary refrigerant 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. (a) Refrigerant – 22 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. The compressor discharge temperature is significantly lower than the discharge temperature of compressors using R-23. 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