b) small self-contained units use water-cooled condenser Proper division can obtain the relationship between refrigerating ability and volume of gas to be handled by the compressor. Which of the following is a type of expansion device? Pick up the wrong statement. With the industry now in the midst of sweeping regulations, Emerson is leading the development of the next generation of refrigeration technology. When do we need two compressors in a refrigeration unit? ⇐ MCQ in Refrigeration Engineering Part 3 | ME Board Exam . NORCOLD SCQT Icebox Conversion Kits - YouTube. Step 3. (d) None Then, you had a few more options like refrigeration vs air conditioning and whether there was a flooded evaporator or not, etc… but these were minor adjustments. (Ans:a), Reciprocating compressor is used in refrigeration when pressure difference between condenser and evaporator is F and has a specific volume of 1.94 cu ft/lb., the weight of refrigerant that the compressor is able to circulate … 2. b) it regulates the flow of refrigerant to evaporator Another feature of reciprocating compressors that is somewhat unique when compared to the rest of the compressor family is the number of available drive arrangements, which are almost as complex as the cylinder arrangements. I do not think that you can get below 30 in merc. The sub-cooling in a refrigeration cycle, 6. In our example, 40 ° F - 10 ° F = 30 ° F. The unit we want would be shown in a catalog rated at 49,473 BTU/Hr. a) 1 + C + C(p2/p1)^(1/n) 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. Low boiling point. Whereas icentropic expansion is also called Adiabatic expansion. This is the Multiple Choice Questions Part 2 of the Series in Refrigeration Engineering as one of the Mechanical Engineering topic. F than when it is 100 deg. Q20.Why is multistage compression with intercooling adopted? Designing refrigeration systems requires a lot of high-level engineering. First of all, please watch my important question videos of Rac, chapter wise after that you can visit here, where you show the answers to those questions and some MCQ regarding this chapter...... 2. During a refrigeration cycle, heat is rejected by the refrigerant in a. Q21.The intercooler pressure is given by On average you will not need a compressor larger than 1/4hp and anything 1/6hp or better is above average. F. evaporating and 100 deg. (d) None (Ans:d), Compressor in a refrigeration system increases in order to have a leak free seal when the units leave our plant. These units typically draw about 5A @ 12V DC when running, but with a properly insulated box, the average current draw can be as little as 2A. View Answer. Use the right tools! Mechanical Engineering Refrigeration and Air Conditioning Important MCQ 1. d) none of the mentioned C. High … compressors, known as “L” compressors, used refriger-ants 11 and 114 in two frame sizes for air-condi-tioning capacities between 90 and 600 tons. (Ans:a), Centrifugal compressor is used in refrigeration when pressure difference between condenser and evaporator pressures is  This will likely be 90 to 100 degree SCT. During a refrigeration cycle, heat is rejected by the refrigerant in a, 2. (D) any of the above Thermostatic expansion valve or TEV is one of the most commonly used throttling valve for the refrigerator and air conditioning systems. b) throttle valves D. F – 21. Since most refrigeration equipment tends […] Royce N. Brown P. E., in Compressors (Third Edition), 2005. c) the refrigerant is damaged The effect of varying compressor efficiency on the COP of the three GSHP system configurations are presented in Fig. Explanation: Here C is the clearance and p1,p2 are pressures. What is the result of superheating of vapour at the evaporator outlet? (B) using water colder than the main circulating water Q: Why are we putting in Inverted Traps on the liquid and discharge lines? Refrigeration compressors and air conditioning compressors provide air conditioning, heat pumping, and refrigeration for large-scale facilities and equipment. Evaporator: This is the part of the refrigeration system that is doing the actual cooling. (a) Temperature alone The prevention of leakage of the refrigerant is the major problem in vapour compression system. View Answer. (b) Temperature and volume (A) improve overall heat transfer coefficient If compression or expansion of gas takes place with no flow of heat energy either into or out of the gas , the process is said to be isentropic process and it is reversible in nature . F. Assume use of the same compressor with the same fixed displacement as in the example above and that the temperature of the gas entering the compressor cylinder is 80 deg. (d) None b) sqrt(p1*p2) b) 1 – C – C(p2/p1)^(1/n) In a vapour compression system, the condition of refrigerant before entering the compressor is, 3. Now, having a refrigeration unit in your PC case is hardly the norm, but the VapoChill products have a proven track record of popularity among the extreme overclockers. Step 2. of compressor required will be (A) Same (B) More (C) Less (D) More/less depending on rating. The air conditioner component of a building’s HVAC system essentially is a type of refrigerator that cools and dehumidifies the air in the building, ensuring thermal comfort for the occupants. How is the condensation process in vapour compression refrigeration cycle carried out? The Frick® SGC, SGCH & SGCB bare screw compressors are designed to compress a variety of gases for quality solutions in refrigeration, water chilling, wellhead compression, gas gathering, and vapor recovery. Question: Question 35 When Do We Need Two Compressors In A Refrigeration Unit When Temperature To Be Achieved Is Around 5 0 C When Temperature To Be Achieved Is Around-5 0 C None When Temperature To Be Achieved Is Around -50°c Question 36 COMMON DATA FOR Q36-37 Rihi A Canacity Of 75 TR And Uses As Refrigerant R134a That Evap What is the most common freon gas used in reciprocating compressors? They use compression to raise the temperature of a low-pressure gas, and also remove vapor from the evaporator. (a) Less View Answer. Explanation: Because of these reasons we have to use multistage compression with intercooling. Air trapped in a refrigeration system using a water-cooled condenser is usually indicated by a] unusually high head pressure when compared to the existing temperature of the liquid refrigerant b] higher than normal liquid level in the receiver High critical temperature. B. View Answer. So, During the throttling process, heat absorption capacity at a cons. It has smaller size for the given capacity of refrigeration. We’re going to be covering where the term is used, what the term means, where the term came from, how to calculate it, and also some work examples, as well as how to convert it to other common refrigeration units. (A) circulating more quantity of cooling water through the condenser What is the use of multistage compression in vapour compression refrigeration system? Only liquid is then passed to evaporator and the vapors will be passed to the compressor directly. View Answer: Answer: Option … When do we need three compressors in a refrigeration unit? In evaporation process of vapour compression refrigeration system, a. heat is rejected from refrigerant to surroundings, b. heat is rejected from surroundings to refrigerant, ANSWER: b. heat is rejected from surroundings to refrigerant, Q6. Vapour Compression Refrigeration Cycle - MCQs with Answers Q1. Where a 1/4hp compressor with a small system can do an equal load to say a 1/12hp with twice as large of a system. (b) <1.5 bars Defrost can be as simple as turning the compressor off for a period of time or as elaborate as reversing the flow of refrigerant for the whole system or … a. no liquid droplets will travel to the compressor, b. the compressor discharge temperature increases. Q15. Vapour compression Cycle important Theory & Mcq || RGPV Online exam 2020 || Chapter-2 || RAC, 1. In our example, 40 ° F - 10 ° F = 30 ° F. The unit we want would be shown in a catalog rated at 49,473 BTU/Hr. d) 1 + C – C(p2/p1)^(1/n) As another alternative, the solid sorption refrigeration without compressors has also drawn widespread attention in recent decades (Ge et al., 2018), mainly due to that solid sorption refrigeration systems are driven by low-grade heat such as solar thermal energy, engine waste heat or geothermal energy (Wang and Oliveira, 2006). 4BEngineers allows students to be thorough with their choice of streams or subjects, by enabling them to learn at their comfortable time without losing out on sessions and conveniently access sessions from any given place. In the R-12 example at 0 deg. TEV enables safe running of the compressor without flooding and also helps the refrigeration plant run as per the optimum capacity. 1. A. F – 12. A thermostat controls the system. C. F – 22. (Ans:c), Reciprocating compressor is used in refrigeration when volume to be compressed As gases are compressible, the compressor also reduces the volume of a gas. 1. The difference in these compressors is simply load capacity with system size. 8. Because its function is to absorb heat into the refrigeration system (from where you don't want it), the evaporator is placed in the area to be cooled.The refrigerant is let into and measured by a flow control device, and eventually released to the compressor. Answer: d d. none of the above One of the first things every HVAC/R student learns is that air conditioning units don’t create cool air. (b) Pressure alone Our Copeland™ compressor line-up has continuously set the standard in performance and reliability. When it gets cold out the refrigerant pressures will drop too low … Only liquid is then passed to evaporator and the vapors will be passed to the compressor directly. (c) >3.5 bars What is the main reason behind subcooling of liquid refrigerant at the condenser outlet in vapour compression refrigeration system? (d) None Ans: b 2. unless we change the laws - the world is changing though so give it a shot. Answer: b Do not oil the asbestos-free gasket or the flange surface. a) small units 1. As the evaporator temperature lowers down, the required compression ratio, a. becomes lower for a given condensation temperature, b. becomes higher for a given condensation temperature, c. becomes steady for a given condensation temperature, ANSWER: b. becomes higher for a given condensation temperature. A. Explanation: Here p1 is the evaporator pressure and p2 is the condenser pressure. 01) full size refrigerator: compressor probably about 1/8 - 1/6hp 02) full size refrigerator freezer combo: compressor typically 1/6 - 1/3hp 03) chest freezer: compressor typically 1/4 - 1/2hp 04) full size freezer: compressor typically 1/5 - 1/3hp 05) mini fridge: compressor range 1/20 - 1/8hp 06) mini freezer: compressor range 1/10 - 1-6hp 9. The cut out is adjusted for the lowest end of normal operating SCT. Evaporator. 9, based on the results of previous investigations [24,49].The compressor isentropic efficiency is varied from 65% to 100% for each of the heat pump systems, following the range given by Cengel et al. (C) reduce the size of the evaporator by avoiding vapours going to the evaporator Choose the letter of the best answer in each questions. 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It can be employed over a large range of temperatures. (c) >3.5 bars (a) When temperature to be achieved is around  -25 0 C, (b)  When temperature to be achieved is  around –50 0 C, (c)  When temperature to be achieved is around  +10oC, Material of the compressor with ammonia refrigerant is, Material of the compressor with Freon refrigerant is. The purpose of installing a flash chamber in the refrigeration circuit is to Our Copeland™ compressor line-up has continuously set the standard in performance and reliability. (D) all of the above, Q25.The process of undercooling is generally brought about by Most of the Chemical Process Industries use compressors to achieve the desired Reaction pressure, Refrigeration effect … With the industry now in the midst of sweeping regulations, Emerson is leading the development of the next generation of refrigeration technology. 151. View Answer. Remote refrigeration: This is the cheapest system and it consists of a condensing unit and an evaporator unit. If … [54] for low to high efficiency compressors. (c) Volume alone Page-1 section-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. Why do we use this rather than just cycling the compressor off and on like a residential HVAC unit? The drive pin must be located in … These compressors are very sensitive to off-design operation. Q13. Dry saturated liquid. (b) <1.5 bars c) both of the mentioned (C) employing a heat exchanger Answer: d What is used as an intercooler in multistage compression of vapour compression refrigeration system? Q18. High-speed compressors. c) both of the mentioned a) using a single stage with high pressure ratio decreases volumetric efficiency Latest Hvac questions and answers for interview Refrigeration and air conditioning 2 marks questions and answers free Basic air conditioning test questions free for your. A: Whenever a condenser is located above the compressor, an inverted trap or check valve should be installed at the condenser inlet to prevent liquid refrigerant from flowing backwards into the compressor during off cycles. Which type of compressor cooling is most common? (b) <1.5 bars 4. This reduced pressure will produce flash evaporation and some part of refrigerant will evaporate by its own heat energy. Condenser. Improves volumetric efficiency for the given pressure ratio B. The L compressors were remark-able in that they required only one stage of compres-sion to do what two or three stages had done in all previous centrifugal air-conditioning machines. In fact, all major industries like foods, chemicals, and technology need refrigerating systems for maintaining cold storage. Explanation: The expansion device reduces the pressure of refrigerant. c) arcton (a) When temperature to be achieved is around  5 0 C, (b)  When temperature to be achieved is  around –5 0 C, (c)  When temperature to be achieved is around  –50oC. c) both of the mentioned Q14. a. throttling valve b. capillary tube c. either throttling valve or capillary tube d. none of the above View Answer / Hide Answer View Answer: Answer: Option … Throttle valves are used in ____