2 of these compressors can be mounted on the same shaft to increase capacity and reduce vibration and noise. Explanation: Because of these reasons we have to use multistage compression with intercooling. Q16.For an expansion device, which of the following is true? In 1911 GE released a household refrigeration unit that was powered by gas. Compressor serial number 2. Since our compressors are manufactured in the US, we can ensure compressor and service availability for our customers. d) all of the mentioned Air enters a sealed chamber where it is trapped between two contra-rotating rotors. The common ones are the two-cylinder, four-cylinder and eight-cylinder compressors . An air conditioner works by transforming a refrigerant compound from a gas to a liquid and back again in a continuous cycle. Q13. What is the use of multistage compression in vapour compression refrigeration system? 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. Clean and Quiet Operation. Answer: a Please read all the important question of that chapter because the MCQ comes from only this important topic. A walk in cooler compressor is exactly what you need! Most of the Chemical Process Industries use compressors to achieve the desired Reaction pressure, Refrigeration effect and to transport gases. Multiple Choice Questions with Answers on Refrigeration and Air-Conditioning - Set 07. The compressor may has more than one cylinder which is also known as multicylinder compressor. a) capillary tubes Thanks, Jeremy A very common means of control seen on refrigeration equipment is the pump down control. per ton of refrigeration (d) 2 to 5 h.p. The Vapor Compression Refrigeration Cycle involves four components: compressor, condenser, expansion valve/throttle valve and evaporator. 3.4 Maintaining refrigeration capacity by moving up a frame size when replacing HFC134a with HFO1234ze . b) genetron MCQ No - 1. (B) reduce pressure losses through the evaporator Evaporator. b) 1 – C – C(p2/p1)^(1/n) During a refrigeration cycle,heat is rejected by the refrigerant in a....... 3. We are going to be looking in detail about the operation of the compressor, it’s purpose and why it’s important. Expansion valve. Q1. How is the condensation process in vapour compression refrigeration cycle carried out? We were one of the first to execute rotary screw technology in our air compressors. Why Do We Use The Term “Compression”? Practice Test: Question Set - 07 1. anyways we always put a unit 1.5x the requirement. c) arcton 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. Setting the standard for commercial refrigeration. a) freon a) it can be air-cooled or water-cooled Enerflex refrigeration systems are utilized around the world providing efficient cooling for a variety of applications beyond gas processing, such as CO 2 scrubbing in clean coal power generating facilities. What is the result of superheating of vapour at the evaporator outlet? Rotary screw compressors do not create the same type of air pulses and can deliver large amounts of air when required without the need of a reservoir tank. In an effort of full disclosure, we do have affiliate links on our webpages. Answer: d The more compressed air is cooled inside a compressor's inter-cooler and aftercooler, the more energy-efficient the compressor will be and the more the water vapor will be condensed.A water-cooled compressor installation puts little demand on the compressor room ventilation system, as the cooling water contains, in the form of heat, approximately 90% of the energy taken up by the electric motor. When the time comes to replace your equipment's compressor, it’s important to choose a model that matches the specs of your existing refrigerator or freezer. Air compressors come in two types; the single and two stage.Most prospective buyers ask the difference between single stage vs 2 stage air compressor before making a purchase. Why do we use this rather than just cycling the compressor off and on like a residential HVAC unit? General Electric (GE) was one of the first companies to overcome these challenges. It’s a critical piece for proper and efficient operation of the equipment. It is a compression process, whose aim is to raise the refrigerant pressure, as it flows from an evaporator. Improves volumetric efficiency for the given pressure ratio B. d) none of the mentioned Next . Whereas icentropic expansion is also called Adiabatic expansion. If you deliver in neighborhoods with noise restrictions, the direct-drive line of units offer low noise levels in all operating conditions. Moving up a compressor frame size has an efficiency advantage. One tonne of refrigeration is equal to. A scroll compressor has one fixed scroll which remains stationary and another moving or orbiting scroll that rotates through the use of swing link. Q18. c) large installations use air-cooled condenser Is there a data in the nameplate that you can use as reference? Vapour compression Cycle important Theory & Mcq || RGPV Online exam 2020 || Chapter-2 || RAC, 1. When dealing with refrigeration or air conditioning compressors that employ an oil pump, many service technicians confuse net oil pressure with oil pump discharge pressure. 8. (1) Cascade unit (2) Ambient air condenser (3) Low-temperature air evaporator (4) Low-temperature compressor step (5) BPHE desuperheater (6) Hot tap water. Since most refrigeration equipment tends to be located outdoors, it comes down to ambient temperatures and the basic properties of refrigerant we all understand about temperature and pressure and how they can conspire to kill a compressor. What Are the Functions of Compressors on Air Conditioners?. d) 1 + C – C(p2/p1)^(1/n) Two years later, he sold the compressor to the Onondaga Pottery Company of Syracuse, N.Y., for the air conditioning of its lithography plant. This flash chamber between the condenser and evaporator is known as flash intercooling. d) none of the mentioned You can send your comments directly at info@mechanicaltutorial.com. So, During the throttling process, heat absorption capacity at a cons. Which device is used for the expansion of refrigerant in vapour compression refrigeration cycle? In this article we will learn how to locate these on the chiller and briefly what their purpose is. pressure of a unit mass of refrigerant remains the same, ie. From stage 2 to stage 3, heat is put into the system, thus. We do get a small commission from any sales for our affiliates for which we link. WebstaurantStore even has portable walk-in coolers and special walk-in cooler shelving. It has smaller size for the given capacity of refrigeration. (a) 0.1 to 0.5 h.p. We made history by teaming up with Dow Chemical to produce one of the industry’s longest-lasting compressor fluids. 2. This article is written by Jeremy Smith CM, experience refrigeration tech and all-around great dude. b) larger units Commercial and industrial refrigerators may have their compressors located away from the cabinet (similar to split system air conditioners) to reduce noise nuisance and reduce the load on air conditioning in hot weather. In the event that technical assistance or information is required on VZ compressors, please have the following information available when contacting Hasegawa Refrigeration Ltd: 1. Question3: Does a compressor that has 100% Duty Cycle mean that I can run the compressor all the time? Scroll. Reduces work done per kg of air C. Reduces cost of compressor D. Gives more uniform torque E. All of the above For the relatively small, high-speed centrifugal compressors in the 200 to 700 kW th … Only liquid is then passed to evaporator and the vapors will be passed to the compressor directly. In his effort to improve mechanical air-conditioning systems, Willis Haviland Carrier (1876-1950) introduced the first practical centrifugal refrigeration compressor in 1922 … Refrigerators Compressors – Types Of Compressor used in HVAC Introduction To Refrigerator Compressors : A typical refrigeration system consists of several basic components such as compressors, condensers, expansion devices, evaporators, in addition to several accessories such as controls, filters, driers, oil separators etc. Which expansion device is capable of regulating the flow of refrigerant according to the load on the evaporator? View Answer. View Answer. Yes please tell about this rule of thumb i need only an approximate size. Superheated vapour. Hello, I have a question about crankcase heaters and compressors. One tonne refrigareting machine means....... A.One tonne is the total mass of the machine, C.One tonne of water can be converted into ice, D.One tonne of ice when melts from at 00C in 24 hours,the refrigeration effect produced is equivalent to 210 kJ/min. View Answer. The work done per kg of refrigerant is reduced in compound compression with intercooler as compared to single stage compression for the same delivery pressure. At Chicago Pneumatic, we have two different types of compressors. c) 1 – C + C(p2/p1)^(1/n) Their qualification with lower GWP refrigerants make them compliant with refrigerant regulations such as F-Gas in Europe. We have the piston compressors, and then we have our screw compressors. a) p1*p2 Refrigeration may be defined as lowering the temperature of an enclosed space by removing heat from that space and transferring it elsewhere. This is true of both air compressors and refrigeration compressors. 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. All these cooling parts are well integrated in one unit. 4. Q3. Answer: b Explanation: We use air-cooled condenser for small self-contained units and water-cooled condenser for large installations. 1. The prevention of leakage of the refrigerant is the major problem in vapour compression system. Not waiting for your compressor to keep up to your work means you can get jobs done faster and complete more jobs in a day. This, between the condenser and evaporator is known as, Chapter-3 Vapour Absorption Refrigeration system (Coming Soon ). Reciprocating compressors have been widely used for over 200 years ever since gases needed to be compressed. work = h 4 – h 3. Refrigeration units for commercial and industrial applications can be made in various sizes, shapes and styles to fit customer needs. 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. The first successful mechanical refrigeration equipment was patented soon after the Civil War, but the large size and high cost of these early machines restricted their use to industrial processes. View Answer. As the rotors intermesh, they reduce the volume of trapped air and deliver it compressed to the proper pressure level. Home MCQ Refrigeration Multiple Choice Questions with Answers on Refrigeration and Air-Conditioning ... Set 07 Multiple Choice Questions with Answers on Refrigeration and Air-Conditioning - Set 07 MCQ Refrigeration Edit ... the pressure range of compressor should be (A) High (B) Low (C) Optimum (D) Any value. Vapour Compression Refrigeration Cycle - MCQs with Answers ... a. one tonne of refrigeration b. two tonne of refrigeration c. half tonne of refrigeration ... a. no liquid droplets will travel to the compressor b. the compressor discharge temperature increases c. both a. and b. As fluid flow through capillary its velocity increase as per continuity eqation (AV=const).hence conversion of pressure energy into kinetic energy takes place. The usual compression, cooling and expansion seen in any refrigeration cycle is accomplished in the ACM by a centrifugal compressor, two air-to-air heat exchangers and an expansion turbine. View Answer. Cold storage room "what you need to know about refrigeration" – part 2 . However, if the refrigerant is R-22, it becomes saturated at approximately 40 degrees. Q23.1. Which of the following statement is true for a condenser? What is the main reason behind subcooling of liquid refrigerant at the condenser outlet in vapour compression refrigeration system? Refrigeration Ton. Q17. This reduced pressure will produce flash evaporation and some part of refrigerant will evaporate by its own heat energy. d) all of the mentioned The refrigerant, commonly used in vapour absorption refrigeration system, is. c) both of the mentioned c) both of the mentioned (A) improve overall heat transfer coefficient RIGID Micro Refrigeration Cooling System includes miniature BLDC inverter mini compressor, driver board, condenser, evaporator, capillary and other refrigeration parts. 1. 9. Explanation: Here p1 is the evaporator pressure and p2 is the condenser pressure. That means that if the compressor removes vapor faster than it can be formed, the pressure will fall and with it the temperature in the evaporator. hence it is preferred over icentropic expansion. Which of the following refrigerant is highly toxic and flammable? Condenser. Ans: c. 87. c. either throttling valve or capillary tube, ANSWER: c. either throttling valve or capillary tube, a. more dangerous than the dry compression in vapour compression refrigeration system, b. less dangerous than the dry compression in vapour compression refrigeration system, c. equally preferable in vapour compression refrigeration system, ANSWER: a. more dangerous than the dry compression in vapour compression refrigeration system. Q9. per ton of refrigeration Questions and Answ (e) 5 to 10 h.p. 5. 2. Now Sullair is part of the Hitachi Industrial Equipment Systems Co., Ltd. compressor portfolio. Learn about the different compressors, how they operate, and when to use them. Answer: c Q21.The intercooler pressure is given by Air behaves like the ideal gas and follows the laws: Boyle’s law (PV=C) and Charles’s law (V/T = C). 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) it increases the pressure of refrigerant We can help you select the refrigeration tools to reduce costs and meet the needs of your customers. Q19.The clearance volumetric efficiency is equal to With more than 150,000,000 Copeland Scroll™ compressors installed, you’re not just choosing a compressor, you’re choosing nearly 30 years of scroll innovation and expertise. These systems rely on the process of absorption and heat, instead of an electrically powered mechanical compressor, to move the refrigerant from the low-pressure side to the high-pressure side. Explanation: Here C is the clearance and p1,p2 are pressures. 03 July 2013 To begin our new series, “What you need to know about refrigeration”, we will be taking a look at one of refrigeration’s most important applications, namely the cold storage room. Rotary screw air compressor The rotary screw air compressor has become the most popular source of compressed air for industrial applications. Read here to know about the basics of compressing air and appreciate the reason for air compressor following polytropic or isentropic compression instead of isothermal or adiabatic one. Cascade refrigeration systems may also be implemented using 2 compressors. With the industry now in the midst of sweeping regulations, Emerson is leading the development of the next generation of refrigeration … (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 +10 o C (d) None (Ans:d) Material of the compressor with ammonia refrigerant is (a) Steel (b) Copper (c) Aluminum (d) None (Ans:a) Need of throttling process- To reduce pressure and temperature without change in enthalpy. Only liquid is then passed to evaporator and the vapors will be passed to the compressor directly. q in = h 3 – h 2 = h 3 – h 1. When reefer containers are … a. no liquid droplets will travel to the compressor, b. the compressor discharge temperature increases. We usually recommend a screw compressor. Choose from either heavy-duty refrigerators that give you versatility and storage space, walk-in cooler boxes, or separate walk-in cooler refrigeration units. And, protecting your reputation by selecting a compressor that is of the highest quality in the commercial refrigeration market. Because the refrigeration circuit is closed, equilibrium is maintained. Q20.Why is multistage compression with intercooling adopted? Q24. Compressor model number 3. As the compressor efficiency varies at higher compressor efficiencies, the specific enthalpy at state 3 (compressor exit) for Systems 1, 2, and 3 are identical. Ice Rinks M&M Refrigeration’s series of packaged ice rink chillers are based on our well-known reciprocating compressors, high efficiency evaporators with flooded surge drum, and M&M System’s Ice Rink Control System (IRCS). Nonetheless, I mean if you see a compressor lying around and you need to approximate its cooling capacity, how you will do it? d) (p1+p2)/2 Which of the following refrigerants has the lowest boiling point? When do we need three compressors in a refrigeration unit? (A) circulating more quantity of cooling water through the condenser The two categories of oils commonly used in the compressors are mineral or synthetic oils. Explanation: These are a group of halogenated hydrocarbons. [2] Absorption Refrigeration. Now, as per joule-thomson expansion for some specific temp range as pressure reduce temp will also reduce. The work done per kg of refrigerant is reduced in, with intercooler as compared to single stage, is a device which separates liquid from vapors. The company produces Pro, Built-In and Integrated units for home use. The multi stage compression as compared to single stage compression..... A. The refrigeration compressor in a water cooled refrigeration system is short cycling on the high pressure cutout switch. One reason for this could be the a] system is low on refrigerant b] high pressure cut out is improperly adjusted c] discharge valves are leaking slightly d] discharge valves are leaking excessively If you want to learn more about selecting the highest efficiency and most reliable commercial refrigeration scroll compressor for your applications, please call 833-409-7507. The heat required to melt 1 tonne of ice in 12 hours is equivalent to. which will improve your skill. Which of the following is a type of expansion device? Figure 10.18 Schematic layout of a cascade system. ANSWER: b. throttle valve, Q12. This makes the whole compressor and the motor a single compact and portable unit that can be handled easily. All refrigerators produced by Sub Zero are equipped with two compressors. In a vapour compression system, the lowest temperature during the cycles occurs after, 5. Centrifugal chiller compressor. Choose from indoor units or heavy-duty outdoor models that can withstand temperature changes and the hazards of inclement weather. View Answer. A design without a spring is known as a swing compressor. Explanation: These are the two types of expansion devices. c) the refrigerant is damaged 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 . Danfoss focuses on providing energy efficient, sustainable and smart refrigeration compressors for a varied range of commercial applications such as cold rooms, display windows, ice making machines, glass door merchandizers, process cooling etc. Throttling process can be done by capillary tube.Working fluid is flow through capillary tube. It improves the volumetric efficiency for the given pressure ratio.. A flash chamber is a device which separates liquid from vapors. Refrigeration And Air Conditioning MCQ question is the important chapter for a Mechanical Engineering and GATE students. Typical Compressor Oil & Refrigerants. So, why do I need p-traps for my refrigerant piping? Fewer moving parts and simple rotary motion means less maintenance, lower noise and vibration levels, and of course, lower total …