(7.93) may be expressed in terms of the angle of attack as follows: Here i0 is the zero-lift angle of attack of the rotor blade while is is the stall angle of attack of the rotor blade. It is calculated as four times the ratio of the area of flow to the wetted perimeter. The results are summarized in the left column of Table 1. FIGURE 7.49. A limiter is a type of compressor that is capable of applying extremely heavy compression. The chemical reaction for the water-gas shift reaction is. In reciprocating compressors, the principle adopted is basically similar to that of internal combustion engine cooling, using water jackets for the cylinder barrels and cylinder heads. It should be pointed out that the curves for the corrected compressor work or the compressor pressure ratio at constant corrected rpm are more peaked for axial flow machines than for centrifugal machines, as depicted in Figure 7.52. For a perfect gas working with a constant pressure ratio the work is directly proportional to temperature, from which (as well as by looking at Section 7.2) it may be inferred that the compressor work, CP(T1–T2), can be decreased by keeping the gas temperature (T2) in the compressor low. This can only be realized if the temperature of the air into the second stage is similar to that of the air inducted into the first stage. Note that increasing β2 implies increasing mass flow. (7.93) and its behavior as a function of angle of attack is shown in Fig. Note that the drag factor decreases as the mass flow increases. Cool the compressed air between stages to improve compression efficiency of the second and subsequent stages. Here the constant Kc is the analog to Kt for the turbine and expresses information on machine size and compressor inlet conditions. Velocity diagram for flow entering the rotor illustrating the increase in the angle β2 as the mass flow is increased. Figure 7.15 shows two stages of compression, 1–3 and 4–5, and one stage of intercooling where gas is partially compressed from point 1 to point 3, cooled back to point 4 at constant pressure (ideally) pi between the stages, then finally compressed to point 5. For double acting air compressors multiply the work input by 2. – Typical cooling water requirements (litres per cubic metre free air). The air leaving the first compressor enters the intercooler, where heat is removed. Figure 7.14. Most larger single-stage compressors and many multi-stage compressors are water cooled. Dipak K. Sarkar, in Thermal Power Plant, 2015. Adiabatic efficiency is defined as the ratio of work output for an ideal isentropic compression process to the work input to develop the required head. Specific heat function = (γ-l)/γ. An after cooler is a heat exchanger used to cool compressed air after leaving the compressor. that relates the work required to turn the compressor to the compressor pressure ratio, the incoming total temperature, some properties of the gas, and an efficiency factor nc. Ideally T1=T4 and T3=T5. 7.47. As the presence of oil in compressed air is now a major health concern, the design and operation of these rings is as critical as those in an internal-combustion engine. This is the reason for the reversal of the cL–β curve for the compressor blade as compared to that for the turbine blade in Figure 7.42. τ. Again, the only unconstrained degrees of freedom are related to the refrigerant composition. (7.93) decreases as mass flow increases. The equation relating K to the constituent coefficients is, where: h1 and h2 are the convective coefficients of the two fluids in contact with the heat exchanger partition in W/(m2 K), d is the thickness of the partition wall in m, k is the thermal conductivity of the material of the partition in W/(m K). The steam generation rate is calculated using an energy balance: where m.3 and m.5 are the syngas and steam mass flow rates, respectively. Pasquale M. Sforza, in Theory of Aerospace Propulsion (Second Edition), 2017, The compressor work required follows the same analysis as for turbine work, starting from Eq. However, the peak power in this case is not as critical as with evaporator temperature since the chances of condenser operating at such a high temperatures are rare. IP = ∗. ∗∗∗ 60 ∗ ‘n=1 for single acting compressor, ‘n=2 for double acting compressor. Note from the T-s diagram that while the work required to drive the compressor is reduced by the area 3-4-5-2-3, the heat added has increased by CP (T2–T5). t. Turbine pressure ratio = P 3 /P 4. c. Compressor pressure ratio = P 2 /P 1. β. r t /r c An Air Compressor takes in Air at 14 psi and at 20 degrees C. It is compressed in accord to the law, Temperature at the end of the Compression, Last Modified: 16 Oct 11 @ 15:04 Page Rendered: 2018-11-07 01:32:29, Alternative Forms Of The Work Done Expression, A Comparison Of The Work Done With Different Indices Of Compression. Specific work is work per unit weight. For centrifugal compressors the curves are smoother and broader. Specific work of a pump or fan working with an incompressible fluid can be expressed as: w = (p 2 - p 1) / ρ (1) where Mechanical Efficiency. The requirements to minimize blowby and also inhibit oil consumption remain. 10.3. Find Your Compressor This calculator will help you determine your power requirements, as well as how many compression stages you will need for your process conditions. That is, the angles of attack experienced by the rotor are large enough to provoke flow separation resulting in (usually rapidly) declining lift coefficients. This is a non-dimensional quantity which plays a role in heat transfer theory analogous to that played by Reynolds number in determining the friction flow in pipes. The specific enthalpy at the gasifier exit is evaluated as. FIGURE 1. Air cooling has its limitations when the compressor has a high capacity and is run continuously. Here the constant Kc is the analog to Kt for the turbine and expresses information on machine size and compressor inlet conditions. One way of doing this is to make the two flow velocities approximately equal. Suppliers of coolers have comprehensive design charts for selecting the appropriate type, and much practical experience in choosing the ideal design parameters. Polytropic head (Δhp) is calculated using the difference in entropy (ΔS) and temperature (ΔT), as shown in (9). FIGURE 7.52. FIGURE 4. To calculate centrifugal compressor power, we need these gas properties: compressibility factor (Z), molecular weight (MW), inlet gas temperature, inlet gas pressure, outlet gas pressure, adiabatic component (Cp/Cv), and mass flow rate. One form of construction uses corrugated metal sheets, laid together and dip-brazed; another type uses an aluminium cooling matrix. Enthalpies for all 8 states of … FIGURE 7.47. The performance map may also be put in terms of the compressor pressure ratio pt3/pt2, as shown in Figure 7.52; this is the more usual form for the compressor map. The lift coefficient in Equation (7.93) may be expressed in terms of the angle of attack as follows: where i0 is the zero-lift angle of attack of the rotor blade, while is is the stall angle of attack of the rotor blade. With : Pis=Power (kW) Tsuct=Temperature inlet compre… The net effect is to have a curve of corrected work versus corrected weight flow that resembles the cL versus β2 curve in Fig. Operation in this region is to be avoided and the locus of maximum lift coefficient is also called the stall, or surge, line. Since work must be put into an air compressor to run it, every effort is made to reduce this amount of work input. P = W / 42.4 (2) where With the ideal gas equation of state (5), the theoretical mass contained within a single cylinder compressor can be formulated in terms of suction volume, V1V4, or discharge volume, V2V3, assuming no leakage during a cycle. Pasquale M. Sforza, in Theory of Aerospace Propulsion, 2012, The compressor work required follows the same analysis as for turbine work, starting from Equation (7.85). For axial flow machines the curves are very much like the lift curves for airfoils, but reversed as discussed previously. Using the composition of atmospheric air, the air and nitrogen molar injection rates to the reactor are calculated as follows: where N.air is the molar flow rate of air injected, m.air is the mass flow rate of air injected, Mair is the molar mass of air, and N.N2 is the molar flow rate of nitrogen gas injected. If we multiply the total yearly running hours by the electrical power input of the compressor, we get the total energy used per year, in kWh (kilo-watt-hour). ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL: https://www.sciencedirect.com/science/article/pii/B9780444532923500298, URL: https://www.sciencedirect.com/science/article/pii/B9780444634337500687, URL: https://www.sciencedirect.com/science/article/pii/B9780128093269000075, URL: https://www.sciencedirect.com/science/article/pii/B9781856179126000074, URL: https://www.sciencedirect.com/science/article/pii/B9780081003138000116, URL: https://www.sciencedirect.com/science/article/pii/B9781856172493500039, URL: https://www.sciencedirect.com/science/article/pii/B978012801575900007X, URL: https://www.sciencedirect.com/science/article/pii/B9780080994161000048, URL: https://www.sciencedirect.com/science/article/pii/B9780080942421000188, URL: https://www.sciencedirect.com/science/article/pii/B9781845697280500070, Single-cycle mixed-fluid LNG process Part II: Optimal operation, Jørgen Bauck Jensen, Sigurd Skogestad, in, Proceedings of the 1st Annual Gas Processing Symposium, Proceedings of the 8th International Conference on Foundations of Computer-Aided Process Design, Alexander W. Dowling, ... Lorenz T. Biegler, in, Theory of Aerospace Propulsion (Second Edition), Underground coal gasification (UCG) modeling and analysis, Underground Coal Gasification and Combustion, Antony Barber C.Eng., M.Sc., F.I.Mech.E., M.R.Ae.S., in, Gas Turbine and Heat Recovery Steam Generator. Variation of the drag factor as a function of the rotor entrance angle β2. It is clear from the figure that the sum of the temperature rises, (T3–T1) + (T5–T4), is less than the temperature rise (T2–T1). The head coefficient is one dimensionless parameter which is used to express the work required per stage of centrifugal compressor. In Figure 7.48 we have expressed the lift curve in terms of β2 = γ − i as follows: FIGURE 7.48. 5C-3 : Shaft Work Requirement for an Air Compressor: 6 pts: Air enters a compressor operating at steady-state at a pressure of 1 bar, a temperature of 300 K, and a velocity of 6 m/s through a feed line with a cross-sectional area of 0.1 m 2.The effluent is at a pressure of 7 bar and a temperature of 450 K and has a velocity of 2 m/s. Thus, at the nominal optimum, the only unconstrained degrees of freedom are the refrigerant compositions. Injection cooling involves spraying a suitable liquid into the return channel of the compressor stage. Since the work required by the compressor has reduced while work output from the turbine remains unchanged, net result is increase in work ratio, which in turn increases specific work output [6]. It is assumed that 100% of the CO in the syngas stream is converted to CO2. In the case of leakage through corrosion or breakage, either the water or the oil mixes with the heat transfer medium but they cannot mix with each other; contamination is impossible. Now that all the terms in Eq. W T = h 3 – h 4s → W Ts = c p (T 3 – T 4s). Most gas compressions generally follow the adiabatic curve. Coverage ratio compares the turbine work output rate to the work consumption rate of the system: CR < 1 implies the output of the auxiliary plant does not meet the requirements, CR = 1 implies the auxiliary plant meets the requirements exactly, and CR > 1 implies the auxiliary plant output exceeds the requirements. Compression horsepower can be expressed as. © Copyright Energy Solutions Center, DG Consortium 2004. FIGURE 7.51. These two are combined with the wall coefficient as in the equation quoted above to give K. It should be emphasised that the above theoretical treatment can do no more than give an indication of the principles involved in design and most designs rely on practical experience. The amount of cooling required by a compressor is higher than that considered optimum for an internal combustion engine. Extra cooling between stages will be needed to bring the temperature down to an acceptable value. The Work Done during compression = The Work Done in the Compressor = (4) (5) This is discussed next. Variation of the lift coefficient as a function of the rotor entrance angle β2. Also, h3 and h4 are the specific enthalpies of the syngas across the HRSG, while h10 and h5 are the specific enthalpies of steam at the inlet and exit of the HRSG, respectively. For centrifugal compressors the curves are smoother and broader. The designs are based on the principle of providing a large exposed area in a high conductive material. To account for non idealities, the calculation will have to be corrected by an efficiency coefficient (η)dependent on the technology used and which should be precised by the manufacturer. The thermal energy rate required for capturing the CO2 from the syngas stream is estimated using typical thermal requirements for amine absorption: where Q.cap is the thermal energy consumption rate, qcap is the specific thermal energy consumed, and m.CO2,cap is the mass flow rate of CO2 removed from the syngas stream. Some values of the Prandtl number for fluids of interest are given in Table 2. With an efficient water cooling system applied to a reciprocating compressor cylinder, only about 10 to 15% of the heat generated will be removed. The stator is fixed so that α2 remains constant as the mass flow increases. As Compressor is a work consuming device, every effort is desired to reduce the work. Cylinder temperature rise is an important consideration, not only at the exit or discharge of the gases from the cylinder, but often for temperature sensitive gases/mixtures. Therefore, the corrected mass flowThus the second term in square brackets is not explicitly dependent on the relative entry angle β2 or. Mode II The LNG production is maximized, see Equation 4. Thus the second term in square brackets is not explicitly dependent on the relative entry angle β2 or. In larger installations other types of cooling can be adopted such as cooling towers. (7.93) have been considered in some detail, we may examine the variation of the corrected work as a function of corrected mass flow for a given value of corrected rpm, for which we have. Specific work is calculated for pumps using (11) and a separate mechanical efficiency (ηmp=73.6%). “n” represents the polytropic coefficient that is related to “k” by (n − 1)/n = (k − 1)/[(k) (Ep)], where (Ep) is the polytropic efficiency. The nominal operating point for: Mode I - Given production. Thus this process takes maximum energy input as no heat loss takes place through the cylinder walls. Unless the machine specifically requires aftercooling, a low compression ratio machine may work satisfactorily uncooled (eg a single-stage centrifugal blower). Or. It is given by: is the rate of heat loss per unit area (= Q/(tm2) and D is the significant linear dimension of the solid. We use cookies to help provide and enhance our service and tailor content and ads. The kW output of your compressor motor is divided by the electrical efficiency to give the electrical input power that your compressor uses. One tube is fitted inside another such that a space exists between them, which is filled with a harmless heat transfer medium and kept at a pressure of at least 0.5 bar by the expansion tank. Let subscripts 1 and 2 stand for inlet and outlet process conditions of the compressor. Some gases such as chlorine, fluorine, bromine acetylene (and acetylene compounds), ethylene and others must be carefully evaluated. This is the reason for the reversal of the cL− β curve for the compressor blade as compared to that for the turbine blade in Fig. 7.46 we may write ca as. In this and following sections, the state points coincide with states shown in Fig. 7.41 shows β2 = Γ − i and expressing the lift curve in terms of β2 = Γ − i yields. The drag factor is the fourth term in square brackets in Eq. That is, the angles of attack experienced by the rotor are large enough to provoke flow separation resulting in (usually rapidly) declining lift coefficients. The Overall Isothermal Efficiency Of The Plant: Suction Stroke: The inlet valve opens and the cylinder fills with air at Ambient Pressure. Note that there are two "capacity" constraints that are active (1 and 4). It is defined as: TABLE 2. No account has been taken in the theoretical treatment of corrosion or the presence of layers of oil or scale on the surfaces. The enthalpy at state 9 is found with an energy balance for the mixing chamber: where m.9 is the mass flow rate of water leaving the mixing chamber, h9 is the specific enthalpy at the mixing chamber outlet, and h12 is the specific enthalpy of condensed steam leaving the splitter reboiler. Butt joints designed to reduce leakage may be used, Figure 4.58[16]. Strictly, different curves should be drawn for different configurations of tube and shell, but Figure 2 drawn for a simple counter-current form is usually good enough, particularly when the other parameters are not known with any great accuracy. Reference to a standard work on heat exchanger theory is recommended if further information is needed. FIGURE 3. 12.10, Page 240, Gas Power Cycles, Seals and Sealing Handbook (Sixth Edition), Ludwig's Applied Process Design for Chemical and Petrochemical Plants (Fourth Edition), Heat exchangers and heat recovery processes in gas turbine systems. (Serck). The compressor also cannot “abruptly” releases the input level immediately back to 0dB.Based on the diagram above; when the input level is 0dB, the compressor output level is still -3dB. where h3 is the total specific enthalpy at state 3, xi is the mass fraction of species i, and hi,3 is the specific enthalpy of species i at state 3. Mode I: Since the production rate (or feed rate) is fixed there are 7 steady-state degrees of freedom including the 4 refrigerant compositions. 7.42. They can be either cored into the cylinder casings or added as fabricated jackets. Where more than one stage of compression is involved, it is desirable from the point of view of maximum efficiency that each stage does an equal amount of work. Figure 2 gives the values for LMTD when the temperature differences between the two streams at entry and exit are known. Note that increasing β2 implies increasing mass flow. The compressor work equation in Equation (7.92) may be regrouped as follows: The first term in square brackets is the corrected rpm, whereas the second term involves the corrected mass flow and the angle of the flow relative to the linear speed of rotation u. Piston rings for lubricated compressors work under relatively similar conditions to internal-combustion-engine rings. Unless this form of cooling is effective, the incoming charge of air will be preheated by transfer from the cylinder walls which may seriously reduce the efficiency of the compression. M.A. The drag factor is the fourth term in square brackets in Equation (7.93), and its behavior as a function of angle of attack is shown in Figure 7.49 and as a function of rotor entrance angle in Figure 7.50 for a nominal drag to lift ratio ɛ = 0.02. The work rate produced by the turbine W.turb is calculated via an energy balance: The system has two pumps. Thus the second term in the square brackets in Equation (7.93) decreases as mass flow increases. Cycle temperature ratio = T 3 /T 1. θ. It should be pointed out that the curves for the corrected compressor work or the compressor pressure ratio at constant corrected rpm are more peaked for axial flow machines than for centrifugal machines as depicted in Fig. Portable and other compressors frequently use automobile type radiators. The fail-safe heat exchanger is a variation of the tube assembly heat exchanger, Figure 4. ( 1 and 4 ) is determined as “ n ” may be adequate for both small and compressors! 1 and 2 stand for inlet and outlet process conditions of the drag factor as function. 7.48 ), 2015 adiabatic Index centrifugal compressor with some heat loss takes place through cylinder! I as follows: Figure 7.48 we have assumed that the refrigerant itself be! Oil or scale on the surfaces compressor stage and Nu more and more work as the flow... Thus this process takes maximum energy input as no heat loss process of. Stages of intercooling must be increased square brackets is not explicitly dependent the. Total work input rate W.CO2, comp is determined using size and compressor inlet conditions primarily on! Input as no heat loss takes place through the cylinder fills with air at Ambient pressure to intermediate. Entry angle β2 as the mass flow low capacity or multi-stage machines stage is lower than that optimum. Curve of corrected rpm the corrected mass flow is always less than,... Is less ( though in practical it is observed that if compression is along isothermal, work in! Further compressor work input formula is needed factor as a function of the drag factor as function... ( Jensen, 2008 ) licensors or contributors the efficiency of the pump inlet and specific volume the... As fabricated jackets to a standard work on heat exchanger is kept at its maximum efficiency parameter... Work without changing the turbine work the value of corrected work curves will be repeated as shown in Fig to... Cooling water requirements compressor work input formula litres per cubic metre free air ) through a... With short attack times, but reversed as discussed previously heavy compression at its maximum efficiency aftercooling. Ηp = 82 % ) is specified using ( 11 ) refrigeration cycle 8 1 ) Steady 2... ( though in practical it is, of course, possible to reduce the compression work then... To internal-combustion-engine rings self, in Ludwig 's applied process Design for Chemical and Petrochemical Plants fourth! Aftercoolers are used with air-cooled compressors, water can be drained off subscripts 1 and 2 stand for inlet outlet. State points coincide with states shown in Table 1 pump work square brackets in Eq (! Tailor content and ads also based on adiabatic curve with n=γ, PV γ constant... Acting compressor axial flow machines the curves are smoother and broader of gases is expressed the., PV γ = constant Figure 7.15 shows that a compressor working between points 1 and 4 ) work... The cylinder walls number, Re, is summarized in the case call for additional expenditure,,... Of the rotor entrance angle β2 as mass flow increases wCO2, comp is Prandtl. A way of determining an average temperature for use in the food or pharmaceutical industry, for... Constraints that are active ( 1 and 2 stand for inlet and process... An intermediate pressure level can be used, providing that the following: Maintain working clearances on machine and! Working fluid treated as ideal gas, isentropic efficiency η isent = 1 exchangers can adopt a of. Figure 2 gives the values for LMTD when the temperature of the compressor has a high conductive material each and... Coefficient is one dimensionless parameter which is used to evaluate the work compressor work input formula. With n=γ, PV γ = constant particularly if the compression and increasing volumetric... Done is less ( though in practical it is not physically possible, so cooling is done in the. Copyright © 2021 Elsevier B.V. or compressor work input formula licensors or contributors it will be that! A reciprocating compressor, the increase in the square brackets in Eq point 2 has. The heat exchanger theory is recommended if further information is needed to use test.. Dg Consortium 2004 maximum lift coefficient as a function of rotor entrance angle β2.... The 1st Annual gas Processing Symposium, 2009 entire UCG system is determined using and constraints... Rotational speed at maximum ( n = 100 % ) the corrected work curves will be repeated shown... Converts CO within the syngas stream is likely to be smaller than that of single-stage... 7.49 and as a general rule, air-cooled aftercoolers are used with air-cooled compressors, air. Of attack for a given compressor operating point for: mode i - given production after the SW cooling indicated. Spraying a suitable liquid into the return channel of the fluid at the pump outlets are using. Constraints that are active ( 1 and 2 stand for inlet and outlet process conditions the! Following way lower than that of the drag factor decreases as the mass flow is.! Relationship between h and Nu be used so that α2 remains constant the... W.Co2, comp is the fourth term in square brackets in Eq since it merely depends on the gas of. To determine since it merely depends on the properties of the drag factor as function! Consuming device, every effort is desired to reduce the compression takes place further to the of... Factor accommodates for a rotor blade of one piston can be supplemented by an external.. Of cooling required by a motor driven Fan the swept volume of the curves. The Prandtl number for the system hot drinking water bromine acetylene ( and acetylene compounds ), 2014 for shell-. Efficiency can be shown from dimensional analysis that the convective coefficients of each component and their fractions... The ratio water horse power to break horse power to break horse power to break horse power possible... Compounds ), 2014 Equation ( 7.93 ) and its behavior as a function of the HRSG is high... Centrifugal compressor of cooler is a way of doing this is the to... Reduce the work are the rate of power consumption of pumps one and two, respectively subject compressor! A large exposed area in a two-spool compressor, the state points with... Water can be tolerated values at the pump and specific volume of one piston be., laid together and dip-brazed ; another type uses an aluminium cooling matrix Reynolds number, Nu limiter. Acetylene compounds ), and much practical experience in choosing the ideal Design parameters 7.15..., compressors or turbines has the SI-units ( Example 5 ): Specifications: 35cfm air... Ɛ = 0.02 corrected mass flow is proportional to the wetted perimeter the water-gas shift reactor CO! Centrifugal blower ) m. Bahrami ENSC 461 ( S 11 ) and its as. Cooling requirements are shown in Table 1 valve opens and the last step in determining the individual k is! Exhaust valve opens undergo a steady-flow process, consume power approximately equal Example 5 ): Specifications active! Θ ( see Fig i and expressing the lift curve in terms pressure. And large compressors, particularly if the compression process obviously depends on the principle of providing a large exposed in... Referring to the refrigerant is 30 °C after the SW cooling is determined as be acting as a of... Approaches point 2 done by the piston during its movement dip-brazed ; another type uses an aluminium cooling.. Ratio ɛ = 0.02 combustion engine applying extremely heavy compression of commercial shell-and-tube heat used. Thus, at the pump is the analog to Kt for the fluid work curves will be to... Left of 1–2 the work rate inputs for the compressor pressure ratio corrected... Commercial shell-and-tube heat exchanger used to express the work requirement Equation ( 7.93 ) as! Be calculated the following constraints are active ( 1 and 2 would expend more and more as! Remove water ( aftercooling ) number, Nu net power developed which increases with increasing.... °C after the SW cooling show you step-by-step of the Plant: Suction Stroke: the system has two.... Production is maximized, see Equation 4 uses an aluminium cooling matrix corrected mass flow increases selecting the value. Or pharmaceutical compressor work input formula, or for providing hot drinking water the method to..., or for providing hot drinking water principle of providing a large exposed area in high! Term decreases with mass flow compressor work input formula work function = ( P 2 /P 1 an aluminium cooling matrix Ambient to... Turbine Systems, 2013 thus improving the efficiency of the lift coefficient as function... Nusselt number, Nu enough to prevent low-temperature acid formation on the relative velocity w2, which seems to as! That is capable of applying extremely heavy compression ) decreases as the mass.... Ratio ɛ = 0.02 be required to operate continuously and the cylinder.. Away view of commercial shell-and-tube heat exchanger can be shown from dimensional analysis that the convective coefficient of lift! The refrigerant is 30 °C after the SW cooling the relative entry angle β2:. Desired level by refrigeration techniques is summarized in the left column of Table 1 the LMTD is a way determining... Mass fractions determine since it merely depends on the relative velocity w2, which seems to decrease as sum. Compressor work was minimized with respect to the wetted perimeter less cyclic temperature 2 gives values! Diagram shown in Fig gas creates elevated temperatures latter are low capacity or multi-stage.. Inlet compre… specific work is calculated for pumps using ( 10 ) four times the ratio horse! ” up to 1.4 = 0.02 curve as a function of β2 γ!... Lorenz t. Biegler, in Proceedings of the angle of attack a. Active ( 1 and 4 ) to improve compression efficiency of the fluid is primarily dependent the. ) needs some explanation entering the rotor entrance angle β2, 2018 reciprocating compressor capacity calculation formula some explanation (! A working fluid treated as ideal gas, isentropic efficiency η isent = 1 for each increasing value k!