The temperature of the air leaving the intercooler depends upon the cooling efficiency of the intercooler. b) high pressure ratio with dry compression gives high compressor discharge temperature It is mandatory to procure user consent prior to running these cookies on your website. To enable use of small cylinders and eliminate problems of unbalanced forces [C]. to increase the turbine outlet temperature (T 4) through reheat of the flow during expansion phase (i.e. Multi-Stage Oil Free and Lubricated Reciprocating Compressors. (b) Compressor work W c can be decreased when multistage compressors with intercooling are used. Temperature of inlet to subsequent stages should be equal to the final temperature [E]. Compressing a gas increases its internal energy which in turn raises its temperature and increases its density. The intercooler pressure is given by Therefore, Total work done per cycle= W = Workdone by L.P cylinder + Workdone by H.P. d) all of the mentioned It improves the volumetric efficiency for the given pressure ratio. This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Vapor Compression Refrigeration Cycle-2”. Multistage Systems – Interstage Desuperheating-Intercooling. The p-v and T-s diagram are shown below( the shaded portion in the p-v diagram shows the work-saving due to Intercooling): When the temperature of the air leaving the intercooling is more than the original atmosphere air temperature, then this is known as incomplete or Imperfect Intercooling. d) none of the mentioned Less Power Required: Less power is required to run a multistage compressor as compared to a single-stage compressor for the same delivery pressure and the same quantity of free air due to intercooling. In fact, it is a way of decreasing the back work ratio in Brayton cycles. b) genetron Advantages of multistage compression with intercooling in vcc Ask for details ; Follow Report by Joyee1140 26.02.2019 Log in to add a comment To minimise the work of compression [D]. In perfect intercooling the point 3 lies exactly on the isothermal curve. In a single-stage compression, the pressure ratio is less. Oil free and lubricated reciprocating compressors realize significant savings from multiple stages of compression. Air is admitted to L.P.(Low-pressure cylinder) and is compressed to some intermediate pressure between the intake and deliver pressure. View Answer, 11. View Answer, 3. The foregoing two sections have isolated for separate analysis the process of flash-gas removal—one of the two major processes that is available in twostage compression. The intercooler may be water cooled or air cooled. d) all of the mentioned The inter-cooling reduces the volume of air which used to increase due to heat. Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs! Plate evaporator is a common type of evaporator. This category only includes cookies that ensures basic functionalities and security features of the website. b) low cost Solution. When volume flow rate of refrigerant is large, which compressor is used? Compression technology specialist, Ingersoll Rand has a long history of supplying single and multistage compressors to a wide range of industries in various configurations … a) using a single stage with high pressure ratio decreases volumetric efficiency b) high pressure ratio with dry compression gives high compressor discharge temperature c) the refrigerant is damaged d) all of the mentioned View Answer c) large installations use air-cooled condenser High temperatures can cause damage to the compressor and its mechanical elements. There are some disadvantages of using a single-cylinder for employing a higher pressure ratio: If we use a single-cylinder then the size of the cylinder will become too large, the final temperature of compressed air increases and the process no longer remains isothermal. Better lubrication: Better lubrication is possible due to lower working temperature and pressure. Less Power Required: Less power is required to run a multistage compressor as compared to a single-stage compressor for the same delivery pressure and the same quantity of free air due to intercooling. Which of the following statement is true? a) rotary compressors are mostly used for small units The other major process is desuperheating of the discharge vapor from the low-stage compressor. Skip to content. Figure-1 Two stage compression with water intercooler Data: T e =-25 oC, T c =47 oC, RC=8 TR and T 3 =14 oC From, P h chart of R 134a, the properties are: h 1 = 383.42 kJ / kg, v= 0.18266 m / kg, h 2 = 412.77 kJ / kg h 3 = 406.65 kJ / kg, h 4 = 427.61 kJ / kg, h 5 = h 6 = 266.93 kJ / kg Intermediate Pressure is, If the compression one stage, the compression process is finalized at state 2\. d) none of the mentioned © 2011-2021 Sanfoundry. The multi stage compressor arrangement facilitates the intercooling of fluid between its stages. Amazon Marketplace Hiring Listing Specialist, Disney+ Hotstar Hiring Software Development Engineer, Goldman Sachs is Hiring For Software Engineer, Motivation: You Can Become a Motivational Speaker, Python And Django Framework For Beginners Complete Course, Python-Introduction to Data Science and Machine learning A-Z, Microsoft Excel -Basic Excel/ Advanced Excel Formulas, Python And Flask Framework Complete Course For Beginners, “Awkward” questions of Women to the Gynecologist, Google Free Certification Course | Elements of AI, JPMorgan Chase Virtual Internship | Software Engineering Internship. a) using a single stage with high pressure ratio decreases volumetric efficiency b) high pressure ratio with dry compression gives high compressor discharge temperature c) the refrigerant is damaged d) all of the mentioned View Answer. a) freon a) less than A byproduct of this inefficient process is the production of heat in the form of temperature increase of the gas. Physics Chemistry. d) none of the mentioned As the number of stages is increased, the compression process becomes nearly isothermal at the compressor inlet temperature, and the compression work decreases.1. These all four components run a simple vapour compression refrigeration system. While in single stage compression process there is no intercooling process, the cooling is only through the cylinder wall surface. d) all of the mentioned Work required to be done by a two-stage reciprocating air-compressor with complete intercooling is given by: If the intake pressure and delivery pressure are constant, then the least value of the intermediate or intercooler pressure may be obtained by differentiating the above equation with respect to intercooler pressure. compression is called compound or multistage compression II. a) reciprocating b) larger units The shaded portion in the p-v diagram shows the work-saving due to incomplete intercooling. 8.5 shows the schematic diagram of the multistage compressor. High pressure ratio gives high compressor discharge temperature C. Air at high temperature and pressure is brought to an intercooler( intercooler is a heat exchanger), where the air is cooled down nearly to the temperature of intake air to L.P. cylinder by regulating the supply of cooling water in the intercooler. Ch 8, Lesson C, Page 13 - 2-Stage Compression With Intercooling. c) both of the mentioned In multistage compression, perfect intercooling means [A]. series with intercooling arrangement between them. You also have the option to opt-out of these cookies. b) centrifugal a) using a single stage with high pressure ratio decreases volumetric efficiency This website uses cookies to improve your experience while you navigate through the website. The most widely used refrigerants are The work saving in perfect intercooling off course more than work saving in incomplete intercooling. The compressed air from the first stage enters the intercooler where it is cooled. (a) Regeneration (b) Intercooling and (c) Reheating. Capillary tubes are used in ____ Without intercooling, however, the savings would not exist, and the efficiency would match a single stage machine. Multistage compressors Compressor without clearance volume The Cycle of Operation • The cycle of operation of a reciprocating air-compressor is best shown on a pressure-volume p-V) diagram. Eliminate leaks and improve intercooling performance in heat exchangers used as interstage coolers in multistage gas compression skids, whether: Box-type welded plate heat exchangers. The multistage compressor with intercooler in-between is shown in Figure . Then all that's left is to add up the stage compression work values. View Answer, 12. Intercooling in multistage compressors is. a) high COP b) it regulates the flow of refrigerant to evaporator NEED OF MULTISTAGE REFRIGERATION SYSTEM Simple vapour compression refrigeration system consists of mainly four parts compressor, condenser , expansion valve and evaporator. We write for thermal efficiency of the Brayton cycle as- (a) Q A — the heat added or supplied can be decreased by the process called regenerative heating of gas before entering the combustion chamber. View Answer, 10. But sometimes we require a higher pressure ratio. b) centrifugal Engineering :: Heat Engines @ : Home > Mechanical Engineering > Heat Engines : Intercooling in multistage compressors is done [A]. Which of the following is a type of expansion device? These cookies will be stored in your browser only with your consent. c) equal to Necessity of multistage compression i) As index of compression ‘n’ increases it increases compression work. These cookies do not store any personal information. The work done per kg of air is reduced in multistage compression with intercooler as compared to single stage compression for the same delivery pressure. a) p1*p2 We also use third-party cookies that help us analyze and understand how you use this website. a) 1 + C + C(p2/p1)^(1/n) 2. d) all of the mentioned View Answer. In reciprocating compressors, actual volume of gas drawn in cylinder is ____ the volume displaced by piston. Multistage compression of air as compared to single stage compression offers the advantage of A. To practice all areas of Thermodynamics, here is complete set of 1000+ Multiple Choice Questions and Answers. Total work done is the sum of the work done. The HS Diagram should help you see that a 3-stage compressor with intercooling is much more efficient than a single-stage compressor. Inter-cooling in multistage compressors is done a) To cool the air during compression b) To cool the air at delivery c) To enable compression in two stages d) To minimize the work of compression Compression ratio at each stage is lower when compared to a single-stage machine; Light moving parts usually made of aluminum, thus less cost and better maintenance; Refer to the diagram of a multi-stage compressor, where it is evident that the work done by the compressor is less when compared to a single-stage machine for same delivery pressure. Why is multistage compression with intercooling adopted? b) false a) small units Answer: d Explanation: Because of these reasons we have to use multistage compression with intercooling … c) rotary Available Energy, Availability & Irreversibility, Thermodynamic Relations, Equilibrium & Stability, here is complete set of 1000+ Multiple Choice Questions and Answers, Prev - Thermodynamics Questions and Answers – Vapor Compression Refrigeration Cycle-1, Next - Thermodynamics Questions and Answers – Absorption Refrigeration Cycle, Thermodynamics Questions and Answers – Vapor Compression Refrigeration Cycle-1, Thermodynamics Questions and Answers – Absorption Refrigeration Cycle, Heat Transfer Operations Questions and Answers, Steam and Gas Turbines Questions and Answers, Refrigeration and Air Conditioning Questions and Answers, Refrigeration Questions and Answers – Expansion Devices, Thermodynamics Questions and Answers – Simple Steam Power Cycle and Rankine Cycle, Refrigeration Questions and Answers – Multiple Evaporators and Compressor System – 1, Thermodynamics Questions and Answers – Multi-Stage Compression, Refrigeration Questions and Answers – Condensers and Cooling Towers – 2, Thermodynamics Questions and Answers – Rotary Compressor, Refrigeration Questions And Answers – Refrigerant Compressors – 1, Thermodynamics Questions and Answers – Heat Pump System, Thermodynamics Questions and Answers – Work of Compression, Refrigeration Questions and Answers – Two/Multi Stage Compression with Water Intercooling, Liquid Subcooling and Flash Intercooler, Refrigeration Questions and Answers – Performance Characteristics of Refrigerant Reciprocating Compressor, Refrigeration Questions and Answers – Two/Multi Stage Compression with Water Intercooling, Liquid Subcooling and Flash Chamber – 2, Refrigeration Questions and Answers – Two/Multi Stage Compression with Water Intercooling and Liquid Subcooling – 2. View Answer, 7. But opting out of some of these cookies may have an effect on your browsing experience. None of View Answer, 6. a) true So, it deviates from isothermal to polytropic, volumetric efficiency decreases and sometimes, the temperature of the air, at the end of compression, is too high. ii) Increase in pressure ratio (P2/P1) it increases work as well as size of cylinder. Historically, the move toward multistage compression systems in industrial refrigeration applications was rooted in demand for lower operating temperatures. Similar to multistage expansion, there is multistage compression. This series combination of two or more cylinders with intercooling is known as Multistage compression. For financial reasons, the number of compression stages is desired to be restrained to two or three. Here, point 3 doesn’t lie on the isothermal curve. It is often more convenient and less expensive to remove heat from a compression process using a separate heat exchanger instead of a water jacket. View Answer, 2. d) all of the mentioned Multistage compression. a) it can be air-cooled or water-cooled a) it increases the pressure of refrigerant Home; Hakkımızda; Hizmetlerimiz; Fotoğraf Galerisi; intercooling in compressor is meant for Solution. d) none of the mentioned View Answer, 13. When the temperature of the air leaving the intercooler is equal to the original atmospheric air temperature, then this is known as known as Complete or Perfect Intercooling. b) small self-contained units use water-cooled condenser 3. a) small units © Copyright 2020 GeeksGod - All Rights Reserved. View Answer, 8. All Rights Reserved. most important ways to save energy is using multistage compression and intercooling.15–19 The air compressed part ways to the discharge pressure, passed through an intercooler, and then compressed further. At this value of intercooler pressure, the work required to drive the compressor is minimum. View Answer, 9. Temperature of air at inlet to subsequent stages is equal to initial temperature [B]. Tranter SUPERMAX Shell And Plate Heat Exchangers are improving performance as interstage coolers in multistage gas compression. This website uses cookies to improve your experience. That’s why we use the second method in which we provide two or more than two cylinders are provided in series with intercooling arrangement between them. I have a question about intercooling process in compressors Regarding ,for example, a mutli-stage compressor with 3 intercoolers,I'm a little bit confused about finding the intermediate pressures of each intercooler that minimize specific work.I'm … We'll assume you're ok with this, Condition for Minimum Workdone by two-stage Reciprocating Air Compressor, condition for minimum workdone by two stage reciprocating air compressor, what are the advantages of multistage compression, A Pan-India Virtual Hackathon | HackOn |Powered by Google || Github |Devfolio |Matic Fold. View Answer, 14. iii) Increment in pressure ratio (P2/P1) beyond certain limit, volumetric efficiency decreases while it increases leakage loss on either sides the piston and valves. Necessary cookies are absolutely essential for the website to function properly. c) lower energy cost To minimize specific work input or power consumption, in two-stage air compression with 100% isentropic efficiency and 100% intercooler effectiveness, is readily … Better mechanical balance: A better mechanical balance is obtained by using two or more stages for compression. c) the refrigerant is damaged In simple vapour compression refrigeration system pressure ration … The … Hi everybody! So, in order to get a large pressure ratio, we can employ a large pressure in a single cylinder or compress the air in two or more cylinders in series. Answer to For a specified pressure ratio, why does multistage compression with intercooling decrease the compressor work, and multistage expansion with reheating increase c) both of the mentioned Using a single stage with high pressure ratio increases volumetric efficiency B. c) both of the mentioned Multistage compression suggests the addition of intercoolers inside the cycle. cylinder. Which of the following statement is true for a condenser? The effluent from a single-stage compressor has a high enthalpy. Why is multistage compression with intercooling adopted? This air is given as input to the second stage where it is compressed again. Throttle valves are used in ____ Temperature of air at inlet to subsequent stages is less than initial temperature [C]. c) (p1*p2)/(p1+p2) d) none of the mentioned å c) arcton Sanfoundry Global Education & Learning Series – Thermodynamics. b) sqrt(p1*p2) Power saving per unit weight of air delivered B. Moisture elimination in the inter-stage cooler Buoyancy and stability of Floating and Submerged body in a fluid. b) throttle valves It is noted that an upsurge in the number of stages causes extra irreversibilities inside the power … use of a multistage turbine with a reheat combustor or with a reheater) to decrease the compressor outlet temperature (T 2) through intercooling of the flow during compression phase (i.e. View Answer, 15. I am very interested in teaching so, I joined Geeksgod as a technical blogging intern. I am pursuing B.tech in mechanical engineering from UIT RGPV, Bhopal. d) all of the mentioned Intercoolers act like heat exchangers which reduce the temperature of compressed air during compression stages. d) (p1+p2)/2 Fig. To cool the air at delivery [B]. • It is known as an indicator diagram for the compressor. View Answer, 5. A. Such an arrangement is known as multistage compassion. d) none of the mentioned Advantages of Multistage Compression. Q20.Why is multistage compression with intercooling adopted? An intercooler is a mechanical device used to cool a gas after compression. Define stage intercooling in multistage compression system Ask for details ; Follow Report by Navaraja6972 13.06.2019 Log in to add a comment Types of compressor include An intercooler typically takes the form of a heat exchanger that removes waste heat in a gas compressor. It is used in reciprocating compressors when pressure of 300 KPa and above are desired, in order to: 1) Save power 2) Limit the gas discharge temperature 3) Limit the pressure differential per cylinder 4) Prevent vaporization of lubricating oil and … c) 1 – C + C(p2/p1)^(1/n) called multistage compression with intercooling. c) both of the mentioned It reduces the temperature of fluid to compress. Ch 8, Lesson C, Page 16 - HS Diagram for Multi-Stage Compression. View Answer, 4. Advantages of Multistage Compression: 1. a) reciprocating Calculations like these can be done very quickly with the help of a computer program like EES. The clearance volumetric efficiency is equal to b) 1 – C – C(p2/p1)^(1/n) Why is multistage compression with intercooling used? b) more than In a multistage compressor, the compressed gas is pressurized at each stage more than in the previous stage. Temperature of air at inlet to subsequent stages should be zero [D]. It is used to reduce the temperature of compressed air during the compression stages. a) capillary tubes Thus, it is essential to reduce the air temperature. In multistage compressors, with each compression cycle, the pressure increases, which leads to an increase in temperature. 15. MULTISTAGE COMPRESSION: Multi staging is simply the compression of air or gas in two or more cylinders in place of a single cylinder compressor. Increased volumetric efficiency; Better mechanical balance: A better mechanical balance is obtained by using two or more stages for compression. Multi-stage compression with intercooling Thread starter exergetic; Start date Nov 10, 2010; Nov 10, 2010 #1 exergetic. c) rotary Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. c) both of the mentioned b) reciprocating compressors are employed in plants with capacity up to 100 tonnes Why is ammonia used in food refrigeration? d) 1 + C – C(p2/p1)^(1/n) Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. Shell and tube heat exchangers. Each of the stages includes the compressor and the intercooling system so that the temperature of air at the exit of each intercooler is the same as of the air entering the compressor, that is, T i. Maximum work is saved in a two-stage reciprocating air compressor with perfect intercooling. 1. It can burn the lubricating oil in the cylinder. This energy comes from the extra shaft work input to the 1-stage compressor.
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