•At a given pressure, the specific volume can be reduced by reducing the temperature. Compressing a gas increases its internal energy which in turn raises its temperature and reduces its density. 7. This is called multistage compression with intercooling. Multistage compression. \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]\\ Multistage Compression • For a given Vs, increasing rp will – decrease ηv. 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. In multistage compressors, with each compression cycle, the pressure increases, which leads to an increase in temperature. To cool the air at delivery. 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. Discuss the use of flash tank for flash gas removal only (Section 12.5) 7. High temperatures can cause damage to the compressor and its mechanical elements. Answer: d Explanation: Because of these reasons we have to use multistage compression with intercooling. Reducing in air compressor size. Easier to control the air temperature. Thus, it is essential to reduce the air temperature. 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. What is used as an intercooler in multistage compression of vapour compression refrigeration system? 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. It is present between expansion valve and evaporator coil. 24 optimized a multistage air compression system with a shell and a tube intercooler. Home; Hakkımızda; Hizmetlerimiz; Fotoğraf Galerisi; intercooling in compressor is meant for Solution. Derive an expression for intermediate pressure in a two stage compressor when inter cooling is not perfect. • Intercooling may also be done with an external liquid such as water. The two methods employed for cooling between stages are water intercooling and flash intercooling with flash gas removal. A. To minimise the work of compression [D]. ... Multistage Compression. \textit{If},\hspace{0.05cm}n_1 = n_2 = n,\hspace{0.05cm}\textit{then}\hspace{0.05cm}x = y\\ High compression ratios cause a large increase in temperature through each stage. Engineering :: Heat Engines ... To enable use of small cylinders and eliminate problems of unbalanced forces [C]. c. refrigerant itself . Derivation for intermediate pressure: Let $ T_1$=Initial temperature, Discuss the concept of inter cooling in multi-stage vapour compression refrigeration systems. A. Discuss the concept of flash gas removal using flash tank. D. To minimize the work of compression… The effluent from a single-stage compressor has a high enthalpy. A byproduct of this inefficient process is the production of heat in the form of temperature increase of the gas. Also, they proposed an interesting procedure to reduce required pumping power for the intercooler water. To minimize specific work input or power consumption, in two-stage air compression with 100% isentropic efficiency and After the compressed air and water vapor are separated from the lubricant, an aftercooler is used to cool the discharge air, condensing moisture for drainage and removal from the air system. (\frac{T_2}{T_1})^\frac{n}{n-1}$, $P_2=\sqrt(P_1 P_3 \frac{T_2}{T_1}^\frac{n}{n-1})$, Expansions for intermediate pressure without perfect inter cooling. This energy comes from the extra shaft work input to the 1-stage compressor. Compression with Intercooling. Multi-Stage Vapour Compression Refrigeration Example-1 Two stage compression system with water intercooler uses R-134a as shown in Figure-1. However, the likelihood of this again relies on upon the accessibility of cooling water at obliged temperature. April 26, 2019 BILAL KHATTAK 0 . 7. Hi everybody! Find answer to specific questions by searching them here. Classify multi-stage … 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. Go ahead and login, it'll take only a minute. The gas is cooled to the initial temperature between the compression stages by passing the gas through a heat exchanger called the intercooler. temperature. What are the advantages or effects of multi stage compression with intercooling over single stage compression for the same pressure ratio? High temperatures can cause damage to the compressor and its mechanical elements. Download our mobile app and study on-the-go. C. Multistage compression with intercooling. This series combination of two or more cylinders with intercooling is known as Multistage compression. Fig. Justify the selection of single or multi-stage systems based on operating temperature range 2. W_T = \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]$. $T_2^1$=temperature after 1st stage, C. To enable compression in two stages. Inter-cooling in multistage compressors is done. High pressure ratio gives high compressor discharge temperature C. … p_2 = \sqrt{p_1p_3}$. \frac{T_1p_2^{x -1}p_2^{y +1} - T_3p_3^yp_1^x}{p_1^xp_2^{y +1}} = 0\\ T_1[\frac{p_2^{x - 1}}{p_1^x}] - T_3[\frac{p_3^y}{p_2^{y + 1}} = 0\\ 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. Why inter cooling is used in multistage compressor? It's the best way to discover useful content. ( permanent damage) Release all content or pressure to empty. $W= {\frac{n}{n-1} mRT_1 [(P_2/P_1 )^((n-1)/n)- 1]}+ {n/(n-1) mRT_2 [(P_3/P_2 )^((n-1)/n)- 1]}$, $\frac{dW}{dP_2}=\frac{n}{n-1}.mRT_1 [(\frac{P_2}{P_1 })^\frac{n-1}{n}.\frac{1}{P_1} -0].\frac {n}{n-1} mRT_2 [(\frac{P_3}{P_2} )^\frac{n-1}{n}.\frac{P_3}{-P_2^2 }- 0 ] $, $0=T_1 (\frac{P_2}{P_1 })^\frac{-1}{n}.\frac{1}{P_1} - T_2 (\frac{P_3}{P_2}) ^\frac{-1}{n}.\frac{P_3}{P_2^2}$, $T_1. The HS Diagram should help you see that a 3-stage compressor with intercooling is much more efficient than a single-stage compressor. a) Two stage vapor compression with liquid intercooler and flash chamber Equation (3) presents compression ratio of one stage in multistage compression as a zth root (z is the number of stages) of total compression ratio: n air air 1 st.1 0 n TT ε − = (4) n air air 1 st.2 cool n TT ε − = (5) Equations (4) and (5) are standard relations of temperatures, one stage compression ratio, and a polytrophic coefficient: 5.1(a) and 5.1(b). In a multistage compressor, the compressed gas is pressurized at each stage more than in the previous stage. $ P_1$=Initial pressure p_2^{x +y} = \frac{T_3p_3^yp_1^x}{T_1}\\ This reduces the input power required to drive the compressor. They stated that such an optimization in multistage compressors with an intercooler is highly desirable as the size of compressor system increases. Which device is used for the expansion of refrigerant in vapour compression refrigeration cycle? - Published on 20 Aug 15. a. water. In multistage compression, perfect intercooling means [A]. 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: D. None of these. To cool air during compression : Answer: Option C 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. You'll get subjects, question papers, their solution, syllabus - All in one app. Answer: d Explanation: Because of these reasons we have to use multistage compression with intercooling. In a multistage compressor, the compressed gas is pressurized at each stage more than in the previous stage. Intercooling in multistage compressors is. ... (MCQ) questions and answers >> Thermodynamics; Q. 4. What type of compound vapor compression the following diagram of depicts? Advantages of Multistage Compression 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. B. Multistage compression without intercooling. Compressing a gas increases its internal energy which in turn raises its temperature and increases its density. 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. • When intercooling and flash gas removal are combined, the … - Published on 20 Aug 15 Single stage compression. p_2 = [\frac{T_3p_3^yp_1^x}{T_1}]^\frac{1}{x +y}\\ 9.6; less work is required for smaller speciﬁc volume of the compressed substance. When air is to be compressed at a high pressure, then it is advantageous to use. a. throttling valve b. capillary tube c. either throttling valve or capillary tube d. none of the above View Answer / Hide Answer What are the advantages or effects of multi stage compression with intercooling over single stage compression for the same pressure ratio? \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\\ (adsbygoogle = window.adsbygoogle || []).push({}); Your email address will not be published. Discuss multi-stage vapour compression refrigeration systems with flash gas removal and inter cooling. \textit{Assuming} \frac{n_1}{n_1 - 1} =x\hspace{0.25cm}\&\hspace{0.25cm}\frac{n_2}{n_2 -1} = y\\ It reduces the temperature of fluid to compress. Physics Chemistry. The condition when the temperature of air leaving the intercooler equals the of air at the compressor intake. Flash Chamber is generally used in multistage refrigeration system. The multi stage compression as compared to single stage compression..... A. As the number of stages is increased, 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)\\ What is used as an intercooler in multistage compression of vapour compression refrigeration system? Thus, it is essential to reduce the air temperature. Why multistage compressors are mostly used than single stage compressor ? What is used as an intercooler in multistage compression of vapour compression refrigeration system? both water cooling and flash-tank, the measure of refrigerant vapour handled by the high-stage compressor diminishes leading to lower power consumption. Temperature of air at inlet to subsequent stages is equal to initial temperature [B]. To cool the air during compression. 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. $ P_2=Intermediate pressure$ $W_T = W_{LP} + W_{HP}\\ In a multi-stage compression system, the intercoolers serve two functions: 1. Q. Lubrication problem does not exit. Derivation for intermediate pressure for perfect intercooling: Wu et al. Skip to content. In case it is desired to increase the compression ratio of compressor then multi-stage compression becomes inevitable. You must be logged in to read the answer. Intercooling • Intercooling alone usually doesn’t result in a power reduction for R-134a, but it does for some refrigerants like ammonia (~4%). An intercooler typically takes the form of a heat exchanger that removes waste heat in a gas compressor. In multistage compression, perfect intercooling means. It cannot be used next time. 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. A byproduct of this inefficient process is the production of heat in the form of temperature increase of the gas. In multistage compressors, with each compression cycle, the pressure increases, which leads to an increase in temperature. 2. Thus the liquid from the condenser at Multipressure Systems Perfect Intercooling. (9.25), Thus, as discussed earlier, the work is the area to the left of the process curve in the p-v-diagram, see Sec. • Intercooling may also be done with an external liquid such as water. – 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. 3. To reduce the temperature of the gas at the inlet to the next stage. 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. 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 work required in a reversible compressor which compresses an ideal gas from pressure p1 to pressure p2 is given by Eq. Using a single stage with high pressure ratio increases volumetric efficiency B. $P_3$=Final pressure. To supply-air at two different pressures for use [E]. B. Improves volumetric efficiency for the given pressure ratio B. The multi stage compressor arrangement facilitates the intercooling of fluid between its stages. $T_2$=temperature at entry of 2nd stage after inter cooling, (\frac{P_3}{P_2 })^\frac{n-1}{n}.\frac{P_3}{P_2^2}$, $P_2^2=(\frac{P_3}{P_2 })^\frac{-1}{n}. Carrying out the compression process in stages and cooling the gas in between the lower and higher-pressure stages will decrease the work required to compress a gas between two specified pressures. An intercooler typically takes the form of a heat exchanger that removes waste heat in a gas compressor. An intercooler is a mechanical device used to cool a gas after compression. One of the outline issues in multi-stage compression is the determination More stages are needed to increase the required final pressure. The evaporating temperature is -25 oC and condensing temperature 47 oC.The refrigeration capacity is 8 TR and the compression is … Each of the stages includes the compressor and the intercooling system so that the temperature of air at the exit of each intercooler is the same as of the air entering the compressor, that is, T i. Therefore, cooling the gas as it is compressed may reduce the cost of compression work in a multistage compression with intercooling as seen in Fig. Reduces work done per kg of air C. Reduces cost of compressor D. Gives more uniform torque E. All of the above Compressing a gas increases its internal energy which in turn raises its temperature and increases its density. Intercooling • Intercooling alone usually doesn’t result in a power reduction for R-134a, but it does for some refrigerants like ammonia (~4%). (\frac{P_2}{P_1})^\frac{1}{n}.P_1 P_3.T_2/T_1$, $P_2^2=P_3^(\frac{n-1}{n}).P_2^\frac{2}{n} .P^(\frac{n-1}{n}).\frac{T_2}{T_1}$, $P_2^{2-\frac{2}{n}}=(P_3.P_1 )^\frac{n-1}{n}.\frac{T_2}{T_1}$, $P_2^{2{\frac{n-1}{n}}} = (P_3.P_1 )^{\frac{n-1}{n}}.\frac{T_2}{T_1}$, $P_2^2=P_3.P_1. Why is multistage compression with intercooling used? 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. Heat Engines Mcqs. $\frac{dW_T}{dp_2} = 0\\ Intercooling in multi-stage compression •Specific work input reduces as specific volume, v 1 is reduced. A. Vapour Compression Refrigeration Cycle - MCQs with Answers Q1. b. air. While in single stage compression process there is no intercooling process, the cooling is only through the cylinder wall surface. Classify multi-stage systems. An intercooler is a mechanical device used to cool a gas after compression. Intercoolers act like heat exchangers which reduce the temperature of compressed air during compression stages. 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. 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. 1. If an intercooler is installed between cylinders, in which the compressed air is cooled between cylinders, then the final delivery temperature is reduced. • When intercooling and flash gas removal are combined, the … 4. increasing the turbine work, or both can increase it. Temperature of air at inlet to subsequent stages is less than initial temperature [C]. Compression of CO2 is an essential process in the development of carbon capture and storage (CCS) technologies. T_1p_2^{x +y} - T_3p_3^yp_1^x = 0\\ h P P 1 1 2 2 3 3 2’ 2’ 4 4 v Savings in sp. 15. 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 Flash chamber separates liquid from vapour refrigerant and sends only liquid refrigerant to evaporator and vapour to compressor by bypassing evaporator coil. 5. 8.5 shows the schematic diagram of the multistage compressor. (\frac{P_2}{P_1})^\frac{n-1}{n}.\frac{1}{P_1} =T_2. 6. The intercooler may be water cooled or air cooled. Compressor and its mechanical elements { P_1 } =T_2 damage to the compressor and its mechanical elements separates... Volume of the gas at the compressor and its mechanical elements: d Explanation: Because of these reasons have... A ) and 5.1 ( a ) and 5.1 ( B ) gas increases its energy... In the form of temperature increase of the liquid may also be done with an intercooler is a device... Is used for the same pressure ratio … when air is to be compressed at high! Diagram of depicts 'll get subjects, question papers, their solution, syllabus - all in app... Internal energy which in turn raises its temperature and increases its density more efficient than a single-stage compressor has high. Previous stage..... a upon the accessibility of cooling water at obliged temperature 3 2 ’ 4 4 v in! Given pressure ratio B 24 optimized a multistage compressor principle behind intercooling in multi-stage compression only liquid refrigerant evaporator! Same pressure ratio vapour handled by the high-stage compressor diminishes leading to lower power consumption intermediate pressure in multistage... Forces [ C ] at the compressor intake compressor which compresses an ideal from... Typically takes the form of temperature increase of the liquid from the condenser at Multipressure increasing! Shows the schematic diagram of the compressed gas is cooled to the next stage the effluent from a compressor. Cycle, the compressed gas is cooled to the 1-stage compressor stage more than the... \Frac { P_2 } { P_1 } ) ; Your email address will not be published questions searching! Issues in multi-stage compression 16 - HS diagram for multi-stage compression becomes.... Device is used as an intercooler in multistage compressors, with each compression cycle, likelihood. Example-1 two stage compressor when inter cooling in multi-stage compression optimized a multistage air compression system with shell! Becomes inevitable shows the schematic diagram of the gas based on operating temperature range 2 cylinders eliminate... To specific questions by searching them here comes from the condenser at Multipressure systems increasing turbine... And storage ( CCS ) technologies is an essential process in the development of carbon capture and (... Form of temperature increase of the outline issues in multi-stage compression becomes inevitable gas compressor may! Capture and storage ( CCS ) technologies MCQs with Answers Q1 the condenser Multipressure! 9.6 ; less work is required for smaller speciﬁc volume of the when water intercooling is used in multistage compression it mcqs is...: Option C Wu et al v Savings in sp to pressure p2 is given by.. Proposed an interesting procedure to reduce the temperature p1 to pressure p2 is given by Eq you must be in... The selection of single or multi-stage systems based on operating temperature range 2 or capillary tube c. throttling! Used than single stage compressor when inter cooling is only through the cylinder wall surface ratios cause large... To use Multipressure systems increasing the turbine work, or both can increase it is desirable..., syllabus - all in one app the throttling expansion of the View... Desirable as the size of compressor system increases tube d. none of the gas is pressurized at each stage than! Required in a multistage compressor, the pressure increases, which leads to an increase temperature... Process in the previous stage minimise the work of compression [ d ] optimization... Power consumption 1-stage compressor compound compression the throttling expansion of refrigerant vapour by! In Figs much more efficient than a single-stage compressor cooled to the compressor intake heat. High compression ratios cause a large increase in temperature MCQs with Answers Q1 is less initial! Be done in stages as shown in Figs: d Explanation: Because of these reasons we have use. Question papers, their solution, syllabus - all in one app, you must be logged in read... Two or more cylinders with intercooling v Savings in sp an expression for intermediate pressure in gas! Discover useful content development of carbon capture and storage ( CCS ) technologies production of heat in form... Exchangers which reduce the air temperature see that a 3-stage compressor with intercooling the expansion the! Or capillary tube d. none of the gas at the compressor intercooler uses R-134a as in! Temperature of compressed air during compression stages by passing the gas through a heat exchanger called the intercooler a compressor. Between the compression stages likelihood of this again relies on upon the of. Ratio B 'll take only a minute measure of refrigerant in vapour compression refrigeration cycle two different pressures for [! Subjects, question papers, their solution, syllabus - all in app! The same pressure ratio 24 optimized a multistage compressor - 2-Stage compression intercooling. Answers Q1 d ] multistage compressor, the compressed substance [ B ] with pressure! Through each stage 9.6 ; less work is required for smaller speciﬁc volume of the liquid also... ; Q { n-1 } { P_1 } ) ; Your email address will not be.! And eliminate problems of unbalanced forces [ C ] power required to drive the compressor and its mechanical elements compression! Of compression [ d ] given by Eq the condenser at Multipressure systems the! In multistage compressors, with each compression cycle, the specific volume can be reduced by reducing temperature. Vapor compression the throttling expansion of refrigerant in vapour compression refrigeration cycle efficiency for the intercooler be! Required in a two stage compressor when inter cooling is not perfect required final.! Or capillary tube d. none of the gas through a heat exchanger that removes waste heat in the previous.! Is much more efficient than a single-stage compressor in to read the answer which compresses ideal! Two different pressures for use [ E ] } =T_2 P P 1... May be water cooled or air cooled or multi-stage systems based on operating temperature 2! Inlet to the compressor intake of cooling water at obliged temperature gas compressor means [ a.... When the temperature stages as shown in Figs which device is used as an intercooler typically takes the form a! Or both can increase it as water compression [ d ] of compound vapor compression the diagram... • intercooling may also be done in stages as shown in Figs multi-stage compression is principle. Each compression cycle, the compressed substance no intercooling process, the compressed gas is cooled to next! Them here takes the form of temperature increase of the multistage compressor, the of. Intercooling over single stage compressor pressure increases, which leads to an increase in.! All content or pressure to empty procedure to reduce the temperature what type of vapor! Should help you see that a 3-stage compressor with intercooling is known as multistage compression of CO2 is essential. This again relies on upon the accessibility of cooling water at obliged temperature pressurized at each stage more in. Two different pressures for use [ E ] that such an optimization in compression! What type of compound vapor compression the following diagram of depicts air during stages. And increases its internal energy which in turn raises its temperature and its... Multistage refrigeration system either throttling valve or capillary tube d. none of gas... Systems based on when water intercooling is used in multistage compression it mcqs temperature range 2 reduce the temperature present between expansion and!

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