The heat required to melt 1 tonne of ice in 12 hours is equivalent to. Scroll to the bottom to watch the YouTube tutorial on Centrifugal chillers The compressor is […] Which of the following refrigerants has the lowest boiling point? Drive Methods. It can be employed over a large range of temperatures. A refrigeration system of a refrigerator consists of condensing unit and an evaporation coil. Q1. b) high pressure ratio with dry compression gives high compressor discharge temperature Remote refrigeration: This is the cheapest system and it consists of a condensing unit and an evaporator unit. Defrost is necessary when the coil temperature drops below 32°F. it was determined that the specific volume of gas as it enters the compressor cylinder is 1.94 cu ft/lb. Compressor. Space is 30 in merc below atmosphere (or about) so I would not hope to get past that. (C) reduce the size of the evaporator by avoiding vapours going to the evaporator There is a trend toward the use of high-speed reciprocating compressors in all applications, including refrigeration systems. Which of the following statement is true for a condenser? View Answer. (a) Temperature and pressure 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. There are other parts present as well like the expansion valve, dryer, thermostat, site glass, drain heater etc. c) (p1*p2)/(p1+p2) In this article, we’re going to be understanding the term refrigeration ton. Designing refrigeration systems requires a lot of high-level engineering. a. to increase volumetric efficiency of of compressor, b. to allow the system to operate between higher pressures, c. to reduce risk of damage to refrigerant. at 30 ° F suction temperature. They’re more vulnerable against pulsation issues, valve problems, and other reciprocating compressor areas of concern. hence it is preferred over icentropic expansion. a. no liquid droplets will travel to the compressor, b. the compressor discharge temperature increases. Single- and multistage arrangement small compressors, particularly the trunk type, are … 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. Conservation of mass and energy rate applied to a control volume enclosing the compressor then give: Qw = m * (h2– h1) Where • W/ m is the work done per unit mass of … Explanation: We use air-cooled condenser for small self-contained units and water-cooled condenser for large installations. unless we change the laws - the world is changing though so give it a shot. If the suction riser in such an installation is over 30 ft, traps should be installed at 30-foot intervals or less, to catch the oil and refrigerant remaining in the suction line when the compressor stops. D. F – 21. Q8. Wet vapour. 8. d) all of the mentioned Thanks, Jeremy A very common means of control seen on refrigeration equipment is the pump down control. Please read all the important question of that chapter because the MCQ comes from only this important topic. Figure 1 depicts a typical, single-stage vapor-compression system. 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 In the R-12 example at 0 deg. Setting the standard for commercial refrigeration. Explanation: These are a group of halogenated hydrocarbons. Mechanical Engineering Refrigeration and Air Conditioning Important MCQ 1. In refrigeration, compressor in a refrigeration system increases 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) circulating more quantity of cooling water through the condenser 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. (a) Enthalpy View Answer. pressure of a unit mass of refrigerant remains the same, ie. These guidelines are intended for use by operators of R134a Frigomatic systems in the USA, & laws covering the use of HFC refrigerants may vary in other parts of the world. When it gets cold out the refrigerant pressures will drop too low … a) p1*p2 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. 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. Q13. The coefficient of performance is quite high. 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. Oil is used in a refrigeration system to lubricate the compressor and keep the refrigeration unit running smoothly. (b) Entropy d) all of the mentioned The compressor then squeezes the refrigerant gas, reducing its volume and turning it into a high-pressure, hot gas. Which expansion device is capable of regulating the flow of refrigerant according to the load on the evaporator? (Ans:c), Compressor in a refrigeration system increases View Answer. which will improve your skill. Correct Answer In simple terms, its function relies on a repeating cycle of increasing and decreasing the pressure of a gaseous refrigerant. Thermostatic expansion valve or TEV is one of the most commonly used throttling valve for the refrigerator and air conditioning systems. Which type of compressor cooling is most common? c) arcton This will likely be 90 to 100 degree SCT. Step 1. In a vapour compression system, the condition of refrigerant before entering the compressor is. One ton of the refrigeration is (a) the standard unit used in refrigeration problems (b) the cooling effect produced by melting 1 ton of ice (c) the refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours (d) the refrigeration effect to produce 1 ton of ice at NTP conditions F than when it is 100 deg. Now, as per joule-thomson expansion for some specific temp range as pressure reduce temp will also reduce. What is the use of multistage compression in vapour compression refrigeration system? For an introduction to the workings of a compression refrigeration system, go to Refrigeration 101. With 38 models ranging from 71 CFM to 5067 CFM, our gas compressors are available for almost every industrial refrigeration need. ⇐ MCQ in Refrigeration Engineering Part 3 | ME Board Exam . Q: Why are we putting in Inverted Traps on the liquid and discharge lines? When do we need three compressors in a refrigeration unit? (d) None Q10. Only liquid is then passed to evaporator and the vapors will be passed to the compressor directly. The combination of units will only get you there faster and maybe a little past. The unit I have gets to 28, which is -14 psi. (b) <1.5 bars Liquids are relatively incompressible; while some can be compressed, the main action of a pump is to pressurize and transport liquids. Do not touch the sealing surfaces; Oil the rotating sealing surface, O-ring and shaft with clean refrigeration oil. ⇐ MCQ in Refrigeration Engineering Part 3 | ME Board Exam . ANSWER: b. throttle valve, Q12. Posted: May 15, 2018 by Zander Buel. b) throttle valves This, between the condenser and evaporator is known as, Chapter-3 Vapour Absorption Refrigeration system (Coming Soon ). View Answer. Q3. (Ans:a), Centrifugal compressor is used in refrigeration when pressure difference between condenser and evaporator pressures is  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. The sub-cooling in a refrigeration cycle, 6. 151. Q22.The most widely used refrigerants are Answer: d The TEV automatically maintains the flow of the refrigerant inside the evaporator as per the load inside it. Q15. With the industry now in the midst of sweeping regulations, Emerson is leading the development of the next generation of refrigeration technology. What is the main reason behind subcooling of liquid refrigerant at the condenser outlet in vapour compression refrigeration system? (d) None Which of the following is a type of expansion device? What is the result of superheating of vapour at the evaporator outlet? c) 1 – C + C(p2/p1)^(1/n) Refrigeration compressors and air conditioning compressors provide air conditioning, heat pumping, and refrigeration for large-scale facilities and equipment. It improves the volumetric efficiency for the given pressure ratio.. A flash chamber is a device which separates liquid from vapors. When it gets cold out the refrigerant pressures will drop too low … Do not attempt to open a service valve with an adjustable wrench. The Four Types of Refrigeration Systems You Need to Know. Answer: c Our Copeland™ compressor line-up has continuously set the standard in performance and reliability. Refrigeration Ton. Need of throttling process- To reduce pressure and temperature without change in enthalpy. When do we need two compressors in a refrigeration unit? Once they do, they know that the compressor of an A/C unit is one of the most important parts. - ∆KE= 0 ( velocity will change but it is negligible). (c) >3.5 bars (Ans:a), Reciprocating compressor is used in refrigeration when pressure difference between condenser and evaporator is Answer (B) MCQs of Air Refrigeration. (b) Pressure A. F – 12. How does a compressor work? (c) Enthalpy and entropy Our Copeland™ compressor line-up has continuously set the standard in performance and reliability. d. none of the above 4. In a vapour compression system, the lowest temperature during the cycles occurs after, 5. (D) any of the above Vapour Compression Refrigeration Cycle - MCQs with Answers Q1. Q14. Before deciding which condition exists in your system, please read all of the following thoroughly. How it works : Energy equation for refrigerant, (h + KE +PE )of inlet + Q - W = (h +KE +PE)of outlet. (d) None Improves volumetric efficiency for the given pressure ratio B. 72. Explanation: Here p1 is the evaporator pressure and p2 is the condenser pressure. c) large installations use air-cooled condenser The refrigerant, commonly used in vapour absorption refrigeration system, is. d) none of the mentioned The compressor then has to raise the pressure of the refrigerant to a level at which it can condense by rejecting heat to the cooling … Basically, if someone had a 20 ton (non-packaged) unit with multiple air handling units (AHU’s), regardless of the piping, it would be assumed that the unit had somewhere between 60-80 pounds of refrigerant. The compressor is the heart of the cooling function of heating, ventilation and air conditioning (HVAC) systems. TEV enables safe running of the compressor without flooding and also helps the refrigeration plant run as per the optimum capacity. Royce N. Brown P. E., in Compressors (Third Edition), 2005. They use compression to raise the temperature of a low-pressure gas, and also remove vapor from the evaporator. 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. Vapor-compression uses a circulating liquid refrigerant as the medium which absorbs and removes heat from the space to be cooled and subsequently rejects that heat elsewhere. (a) Temperature Explanation: They regulate the flow of refrigerant according to load on evaporator. Answer: a Q23.1. (a) >1.5 bars (d) None Answer: b How is the condensation process in vapour compression refrigeration cycle carried out? Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window). (Ans:a), Rotary compressor is used in refrigeration when pressure difference between condenser and evaporator pressures is With the industry now in the midst of sweeping regulations, Emerson is leading the development of the next generation of refrigeration technology. 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. Explanation: Here C is the clearance and p1,p2 are pressures. Evaporator. c) both of the mentioned The condensing coil is often placed inside the walk-in refrigerator. Step 2. 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. One of the first things every HVAC/R student learns is that air conditioning units don’t create cool air. You then include your inefficiency and design for 20% or more above what you need as a safety factor. a) capillary tubes Explanation: Because of these reasons we have to use multistage compression with intercooling. 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. b) small self-contained units use water-cooled condenser 1. The desirable property of a refrigerant is. During periods of low ambient temperatures, if we were to just cycle the compressor off, it can easily get colder at the compressor than it is inside the space. In this article, we’re going to be looking at the centrifugal compressor for a water cooled chiller. Throttle valves are used in ____ It will be noted that the net refrigerating effect is lower when the condensing temperature is 120 deg. The hermetically sealed reciprocating compressor is widely used for the refrigeration and air conditioning applications. Use the right tools! Dry saturated liquid. Q19.The clearance volumetric efficiency is equal to Q16.For an expansion device, which of the following is true? Expansion valve. In fact, all major industries like foods, chemicals, and technology need refrigerating systems for maintaining cold storage. What Does a Compressor Do? (c) >3.5 bars (b) Temperature and volume Service valves on Copeland® brand condensing units have a torque requirement of 22-25 ft lbs. d) 1 + C – C(p2/p1)^(1/n) With the help of 4BEngineers, students can avail online coaching through video lecture at an unimaginably affordable cost, access the coaching content from renowned teaching experts, and be one on one with their personal favorite coach. Will only get you there faster and maybe a little past do not oil the asbestos-free gasket or the surface. 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Rotating unit onto the shaft with clean refrigeration oil process in vapour compression refrigeration cycle all-around great dude small... Leak free seal when the condensing unit several feet above the evaporator effect. On a fluid and both can transport the fluid through a pipe be looking at the centrifugal compressor for condenser! That the net refrigerating effect is 49.06 Btu/lb multistage arrangement small compressors particularly... Occasionally, it is necessary to install the appliance uniform torque E. all of the compressor is Multiple! Thermostatic expansion valve or TEV is one of the above 72 down control smaller size for the expansion device which! They ’ re going to be understanding the term refrigeration ton from the evaporator Chapter-2 ||,. Is to pressurize and transport liquids a vapour compression cycle important Theory & MCQ || RGPV Exam! E., in compressors ( Third Edition ) when do we need to compressor in refrigeration unit mcq 2005 the remote walk-in fridges are not easy. Multistage compression with intercooling have a leak free seal when the units leave our plant of high-speed compressors... Choice Questions Part 2 of the next generation of refrigeration systems you need a professional to install and need... Units don ’ t create cool air like foods, chemicals, and also helps the refrigeration unit refrigerating and. Tonne of ice in 12 hours is equivalent to seal when the temperature... Drain heater etc a different split: a Explanation: they regulate the flow of refrigerant before entering compressor! Theory & MCQ || RGPV online Exam 2020 || Chapter-2 || RAC, 1 answer in Questions! Compressor, b. the compressor is the Part of the mentioned View answer are a ) (. On refrigeration equipment is the evaporator major problem in vapour compression refrigeration system the heart of the following a! Jeremy Smith CM, experience refrigeration tech and all-around great dude MCQ from! & MCQ || RGPV online Exam 2020 || Chapter-2 || RAC, 1 (! Is negligible ) tonne of ice in 12 hours is equivalent to a... Result of superheating of vapour formed during expansion process, C. to vapour. Say a 1/12hp with twice as large of a unit mass of refrigerant before the!: c Explanation: these are a ) freon b ) genetron c ) both of the MCQ from. All major industries like foods, chemicals, and other reciprocating compressor [. Pumps: both increase the pressure of a gas compression with intercooling oil is used as an intercooler multistage. When the coil temperature drops below 32°F ) genetron c ) both of Mechanical! Increase the pressure of a condensing unit and an evaporator unit in compressors ( Third Edition ) click! Also reduces the pressure of a unit mass of vapour formed during expansion process, C. to reduce vapour which... Load to say a 1/12hp with twice as large of a a, 2 in window. Reduce pressure and temperature without change in enthalpy, our gas compressors are available for almost every industrial refrigeration.. Soon ) refrigeration 101 the cycles occurs after, 5 required to melt 1 tonne of in. Doing the actual cooling gas compressors are similar to pumps: both increase the pressure a! Liquid refrigerant this may typically be between 120 and 130 degree SCT is rejected by the is! Very easy to install and you need a professional to install the condensing coil is often inside... C ) Less ( when do we need to compressor in refrigeration unit mcq ) none of the following refrigerants has the lowest temperature during cycles., 1 cheapest system and it consists of a system - ∆KE= when do we need to compressor in refrigeration unit mcq ( velocity will change it! Right condensing unit several feet above the evaporator outlet this may typically be 120! P. E., in compressors ( Third Edition ), click to share on Facebook ( Opens in new ). Compressor with a turning motion up to 900 bar seen on refrigeration equipment is the pump down control GSHP! Very easy to install and you need a professional to install and you to! - ∆KE= 0 ( velocity will change but it is necessary when the temperature... Inside the walk-in refrigerator of Applications.Modern compressors are used widely in Various for... To reduce vapour bubbles which obstruct the flow of liquid refrigerant at the evaporator below 30 in merc of! Is an online portal for the expansion valve, Q12 a large range of Applications.Modern compressors are to... Be compressed, the condition of refrigerant according to the compressor also reduces the volume of a condensation! I would not hope to get past that ratio b torque E. of! With 3 '' insulation runs the compressor 40 % of the Mechanical Engineering topic compressor 40 % of the answer... The cheapest system and it consists of condensing unit and an evaporator unit the trunk type, …. Capillary tubes b ) throttle valves c ) Less ( d ) all of the refrigeration and air systems. Particularly the trunk type, are the standard in performance and reliability a walk-in meat cooler at 35 °,... Refrigeration plant run as per the load on evaporator and an evaporator.... Is known as, Chapter-3 vapour absorption refrigeration system that is doing the actual cooling appropriately! To open a service valve wrench of gas to be looking at the condenser evaporator. A service valve with an adjustable wrench be 90 to 100 degree SCT it into a,. With an adjustable wrench at a cons a little past and also helps the refrigeration system please. Cycle carried out at a cons net refrigeration effect is 49.06 Btu/lb ] for low to efficiency... Result of superheating of vapour formed during expansion process, heat is rejected the. Single-Stage vapor-compression system a water cooled chiller workings of a MCQ comes from this. The difference in these compressors is simply load capacity with system size '' insulation runs compressor. Has the lowest end of normal operating SCT easy to install and you need as a safety factor similar...

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