The gas is cooled to the initial temperature between the compression stages by passing the gas through a heat exchanger called the intercooler. Why is multistage compression with intercooling used? Ch 8, Lesson C, Page 13 - 2-Stage Compression With Intercooling. 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. This set of Refrigeration Multiple Choice Questions & Answers (MCQs) focuses on “Two/Multi Stage Compression with Water Intercooling, Liquid Subcooling and Flash Chamber – 1”. A byproduct of this inefficient process is the production of heat in the form of temperature increase of the gas. \frac{d}{dp_2}[\frac{1}{x}RT_1[(\frac{p_2}{p_1})^x - 1] \hspace{0.05cm}+\hspace{0.05cm}\frac{1}{y}RT_1[(\frac{p_3}{p_2})^y -1]\\ Why multistage compressors are mostly used than single stage compressor ? (\frac{P_2}{P_1})^\frac{n-1}{n}.\frac{1}{P_1} =T_2. Flash Chamber is generally used in multistage refrigeration system. Temperature of air at inlet to subsequent stages is less than initial temperature [C]. Wu et al. The gas is cooled to the initial temperature between the compression stages by passing the gas through a heat exchanger called the intercooler. What is used as an intercooler in multistage compression of vapour compression refrigeration system? p_2 = [\frac{T_3p_3^yp_1^x}{T_1}]^\frac{1}{x +y}\\ ... (MCQ) questions and answers >> Thermodynamics; Q. Classify multi-stage systems. In a multistage compressor, the compressed gas is pressurized at each stage more than in the previous stage. High pressure ratio gives high compressor discharge temperature C. … A. The intercooler may be water cooled or air cooled. Required fields are marked *. To cool air during compression : Answer: Option C (adsbygoogle = window.adsbygoogle || []).push({}); Your email address will not be published. Find answer to specific questions by searching them here. The two methods employed for cooling between stages are water intercooling and flash intercooling with flash gas removal. B. Ch 8, Lesson C, Page 16 - HS Diagram for Multi-Stage Compression. Single stage compression. 7. Figures 12.4 (a) and (b) show the process of intercooling in two-stage compression on Pressure-specific volume (P-v) and P-h diagrams. Intercooling in multistage compressors is. Hi everybody! High temperatures can cause damage to the compressor and its mechanical elements. 6. An intercooler is a mechanical device used to cool a gas after compression. $T_2^1$=temperature after 1st stage, Derive an expression for intermediate pressure in a two stage compressor when inter cooling is not perfect. Physics Chemistry. W_T = \frac{n_1}{n_1 - 1}RT_1[(\frac{p_2}{p_1})^\frac{n_1}{n_1 - 1} - 1] + \frac{n_2}{n_2 - 1}RT_3[(\frac{p_3}{p_2})^\frac{n_2}{n_2 - 1} - 1] .......(1)\\ 9.6; less work is required for smaller specific volume of the compressed substance. MULTISTAGE COMPRESSION: Multi staging is simply the compression of air or gas in two or more cylinders in place of a single cylinder compressor. temperature. D. None of these. Using a single stage with high pressure ratio increases volumetric efficiency B. In a multistage compressor, the compressed gas is pressurized at each stage more than in the previous stage. Compressing a gas increases its internal energy which in turn raises its temperature and increases its density. What type of compound vapor compression the following diagram of depicts? Intercooling • Intercooling alone usually doesn’t result in a power reduction for R-134a, but it does for some refrigerants like ammonia (~4%). In multistage compressors, with each compression cycle, the pressure increases, which leads to an increase in temperature. Thus, it is essential to reduce the air temperature. Answer: Option C Ch 8, Lesson C, Page 13 - 2-Stage Compression With Intercooling. 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. After the compressed air and water vapor are separated from the lubricant, an aftercooler is used to cool the discharge air, condensing moisture for drainage and removal from the air system. b. air. 4. Answer: d Explanation: Because of these reasons we have to use multistage compression with intercooling. Engineering :: Heat Engines ... To enable use of small cylinders and eliminate problems of unbalanced forces [C]. The amount of air of respiratory importance reaching into alveoli is: In a Diesel engine the duration between the time of injection and time of ignition is called, Agriculture Ecology and General Silviculture Mcqs, Agriculture Genetics Plant Breeding and Biotechnology Mcqs, Fluid Mechanics and Hydraulic Machines Mcqs, Forest Types and Geographical Distribution Mcqs, Temperature Distribution and Ocean Salinity Mcqs. $ P_2=Intermediate pressure$ T_1p_2^{x +y} - T_3p_3^yp_1^x = 0\\ Discuss the use of flash tank for intercooling only (Section 12.6) At the end of the lesson, the student should be able to: 1. It's the best way to discover useful content. As the pressure (atmospheric pressure) and the pressure (required pressure) are constant, intermediate pressure has to be determined to find the minimum work done per kg of air delivered. In multistage compressors, with each compression cycle, the pressure increases, which leads to an increase in temperature. (\frac{T_2}{T_1})^\frac{n}{n-1}$, $P_2=\sqrt(P_1 P_3 \frac{T_2}{T_1}^\frac{n}{n-1})$, Expansions for intermediate pressure without perfect inter cooling. As the number of stages is increased, 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 able to find the intermediate pressure only if there'ls only one intercooler,using well known statement: The multi stage compression as compared to single stage compression..... A. c. refrigerant itself . – Increase delivery temperature • To achieve high pressures while avoiding those problems – Do Multistage Compression • At some intermediate pressure Pi, the gas is sent to a smaller cylinder to be compressed further. Compression with Intercooling. A byproduct of this inefficient process is the production of heat in the form of temperature increase of the gas. p_2^{x +y} = \frac{T_3p_3^yp_1^x}{T_1}\\ Multi-Stage Vapour Compression Refrigeration Example-1 Two stage compression system with water intercooler uses R-134a as shown in Figure-1. \textit{If intercooling is perfect},\\ Vapour Compression Refrigeration Cycle - MCQs with Answers Q1. Reduces work done per kg of air C. Reduces cost of compressor D. Gives more uniform torque E. All of the above 4. Multistage Compression • For a given Vs, increasing rp will – decrease ηv. 7. This is called multistage compression with intercooling. Compressing a gas increases its internal energy which in turn raises its temperature and reduces its density. To supply-air at two different pressures for use [E]. According to the equation of total work done per kg of air delivered, the total work done per kg of air for this system is the addition of work done by the low-pressure cylinder and the high-pressure cylinder. Fig. 1. What is used as an intercooler in multistage compression of vapour compression refrigeration system? Multistage compression. Intercooling • Intercooling alone usually doesn’t result in a power reduction for R-134a, but it does for some refrigerants like ammonia (~4%). This reduces the input power required to drive the compressor. Discuss the concept of inter cooling in multi-stage vapour compression refrigeration systems. ( permanent damage) Release all content or pressure to empty. Multistage compression refers to the compression process completed in more than one stage i.e., a part of compression occurs in one cylinder and subsequently compressed air is sent to subsequent cylinders for further compression. Therefore, cooling the gas as it is compressed may reduce the cost of compression work in a multistage compression with intercooling as seen in Fig. • Intercooling may also be done with an external liquid such as water. •This is the principle behind intercooling in multi-stage compression. $P_3$=Final pressure. To reduce the temperature of the gas at the inlet to the next stage. Home; Hakkımızda; Hizmetlerimiz; Fotoğraf Galerisi; intercooling in compressor is meant for To minimize specific work input or power consumption, in two-stage air compression with 100% isentropic efficiency and (\frac{P_3}{P_2 })^\frac{n-1}{n}.\frac{P_3}{P_2^2}$, $P_2^2=(\frac{P_3}{P_2 })^\frac{-1}{n}. An intercooler is a mechanical device used to cool a gas after compression. a. throttling valve b. capillary tube c. either throttling valve or capillary tube d. none of the above View Answer / Hide Answer Compression of CO2 is an essential process in the development of carbon capture and storage (CCS) technologies. Thus, it is essential to reduce the air temperature. It cannot be used next time. Thus the liquid from the condenser at Multipressure Systems 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. Therefore, cooling the gas as it is compressed may reduce the cost of compression work in a multistage compression with intercooling as seen in Fig. In case it is desired to increase the compression ratio of compressor then multi-stage compression becomes inevitable. C. Multistage compression with intercooling. a) Two stage vapor compression with liquid intercooler and flash chamber • When intercooling and flash gas removal are combined, the … If an intercooler is installed between cylinders, in which the compressed air is cooled between cylinders, then the final delivery temperature is reduced. Intercoolers act like heat exchangers which reduce the temperature of compressed air during compression stages. 15. Discuss the concept of flash gas removal using flash tank. When air is to be compressed at a high pressure, then it is advantageous to use. \textit{If},\hspace{0.05cm}n_1 = n_2 = n,\hspace{0.05cm}\textit{then}\hspace{0.05cm}x = y\\ Justify the selection of single or multi-stage systems based on operating temperature range 2. High compression ratios cause a large increase in temperature through each stage. Heat Engines Mcqs. The HS Diagram should help you see that a 3-stage compressor with intercooling is much more efficient than a single-stage compressor. You'll get subjects, question papers, their solution, syllabus - All in one app. Solution. This reduction in temperature means a reduction in internal energy of the delivered air, and since this energy must have come from the input energy required to drive the machine this results in a decrease in input work requirement for a given mass of delivered air. 2. \frac{T_1p_2^{x -1}p_2^{y +1} - T_3p_3^yp_1^x}{p_1^xp_2^{y +1}} = 0\\ To cool the air during compression. - Published on 20 Aug 15 The work required in a reversible compressor which compresses an ideal gas from pressure p1 to pressure p2 is given by Eq. (\frac{P_2}{P_1})^\frac{1}{n}.P_1 P_3.T_2/T_1$, $P_2^2=P_3^(\frac{n-1}{n}).P_2^\frac{2}{n} .P^(\frac{n-1}{n}).\frac{T_2}{T_1}$, $P_2^{2-\frac{2}{n}}=(P_3.P_1 )^\frac{n-1}{n}.\frac{T_2}{T_1}$, $P_2^{2{\frac{n-1}{n}}} = (P_3.P_1 )^{\frac{n-1}{n}}.\frac{T_2}{T_1}$, $P_2^2=P_3.P_1. 5.2.1 Flash Gas Removal In compound compression the throttling expansion of the liquid may also be done in stages as shown in Figs. What are the advantages or effects of multi stage compression with intercooling over single stage compression for the same pressure ratio? The condition when the temperature of air leaving the intercooler equals the of air at the compressor intake. Intercooling in multi-stage compression •Specific work input reduces as specific volume, v 1 is reduced. What is used as an intercooler in multistage compression of vapour compression refrigeration system? A. 5.1(a) and 5.1(b). Compressing a gas increases its internal energy which in turn raises its temperature and increases its density. Easier to control the air temperature. B. Multistage compression without intercooling. Carrying out the compression process in stages and cooling the gas in between the lower and higher-pressure stages will decrease the work required to compress a gas between two specified pressures. April 26, 2019 BILAL KHATTAK 0 . What are the advantages or effects of multi stage compression with intercooling over single stage compression for the same pressure ratio? The effluent from a single-stage compressor has a high enthalpy. p_2 = \sqrt{p_3p_1(\frac{T_3}{T_1})^\frac{1}{x}}\\ - Published on 20 Aug 15. a. water. You must be logged in to read the answer. Reducing in air compressor size. \frac{1}{x}T_1(x)[\frac{p_2^{x -1}}{p_1^x}]\hspace{0.05cm}+\hspace{0.05cm}\frac{1}{y}T_3(-y)[\frac{p_3^y}{p_2^{y+1}}] = 0\\ Why inter cooling is used in multistage compressor? However, the likelihood of this again relies on upon the accessibility of cooling water at obliged temperature. In case of six stage compression of air for minimum work conditions, In six stage compression of air set for minimum work conditions, The compressor used in gas turbine is usually, Intercooling in multistage compressors is done. An intercooler typically takes the form of a heat exchanger that removes waste heat in a gas compressor. • Intercooling may also be done with an external liquid such as water. T_1[\frac{p_2^{x - 1}}{p_1^x}] - T_3[\frac{p_3^y}{p_2^{y + 1}} = 0\\ D. To minimize the work of compression… C. To enable compression in two stages. A.Temperature of air at inlet to subsequent stages is equal to initial temperature B.Temperature of air at inlet to subsequent stages is less than initial temperature C.Temperature of air at inlet to subsequent stages should be zero D.Temperature of inlet to subsequent stages should be equal to the final temperature E.None of the above, Your email address will not be published. The multi stage compressor arrangement facilitates the intercooling of fluid between its stages. One of the outline issues in multi-stage compression is the determination Perfect Intercooling. Discuss the use of flash tank for flash gas removal only (Section 12.5) 7. In multistage compression, perfect intercooling means. Flash chamber separates liquid from vapour refrigerant and sends only liquid refrigerant to evaporator and vapour to compressor by bypassing evaporator coil. It is present between expansion valve and evaporator coil. $ P_1$=Initial pressure Answer: d Explanation: Because of these reasons we have to use multistage compression with intercooling. An intercooler typically takes the form of a heat exchanger that removes waste heat in a gas compressor. 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. 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After compression the input power required to drive the compressor … when air is to be at! { P_2 } { n }.\frac { 1 } { n.\frac! Compression stages MCQs with Answers Q1 the above View answer / Hide answer 4 compression: answer: C! The initial temperature between the compression ratio of compressor system increases to single stage compression the! The of air at the inlet to subsequent stages is increased, you must be logged in to the. Find answer to specific questions by searching them here its internal energy in. Permanent damage ) Release all content or pressure to empty c. either throttling valve or capillary c.!