CENTRIFUGAL COMPRESSOR 6 manual VI. ← Turbine isentropic efficiency – Samarth Mittal → Polytropic efficiency of Turbine Calculator – Samarth Mittal. Discharge conditions can also be determined from: (13) η P is the polytropic efficiency Example #3 19 Leave a Reply Cancel reply. The total feed gas volumetric flow rate was 101 MMSCFD (2.86×10 6 Sm 3 /d). However, in short to calculate the discharge temperature T2=T1*r^((n-1)/n) where r is the pressure ratio As you have the mass flow calculate the density at suction conditions from P1/(Z1*R*T1) where R is the Gas Constant. Centrifugal compressors are best discussed by going through a calculation procedure and discussing each part. Support WINGS OF AERO. Polytropic efficiency per stage of 85% is normal for quantity constant. Polytropic efficiency of the compressor is defined by the formula given as: It is defined for the polytropic processes. Also compute the power developed if the number of cycles executed per minute is 300. Polytropic Head It means that the calculated power of the compressor will be (1/0.76=1.32) 32% higher when calculated with the 13 th edition compared to the 12 th. Advanced Polytropic Calculation Method of Centrifugal Compressor Jiri Oldrich. First, the required head is calculated. Either the polytropic or adiabatic head can be used to calculate horsepower as long as the polytropic or adiabatic efficiency is used with the companion head. Presentation on Calculation of Polytropic and Isentropic Efficiency of natural gas compressors 1. The gas mixture with the composition shown in Table1 at 105 °F (40.6 °C) and 115 Psia (793 kPa) is compressed using a single-stage centrifugal compressor with the polytropic head and efficiency curves shown in Figures 1 and 2 at a speed of 7992 rpm. It seems to be a very huge difference for the same compressor! Jiri Oldrich ... new method is based on numerical solution of basic definition equation of polytropic change in form edH = Vdp where “polytropic efficiency” e has constant value along the whole polytropic path. A chart is then used to calculate the polytropic coefficient of the gas, then the discharge temperature calculated and then the actual power needed thanks to the formula 1 above. For a centrifugal compressor for example, the polytropic efficiency is often close to 76%. Compressor efficiencies Reversible adiabatic(or isentropic efficiency), η IS: (11) W s is determined from eqn (4) Centrifugal compressors’ efficiency given by polytropic efficiency, η P: (12) Polytropic efficiency > adiabatic efficiency. Sketch the cycle on a p-V diagram. COMPARISON OF POLYTROPIC AND ISENTROPIC EFFICIENCY OF NATURAL GAS COMPRESSOR CALCULATED USING ASPEN HYSYSAND USING MANUAL CALCULATIONS MUHAMMAD WAQAS MANZOOR PROCESS ENGINEER Contact: engr.waqasmanzoor@gmail.com 2. Reply. Sep 26, 2013 … Selection Of A Reciprocating Or Centrifugal Compressor a. Parameters …. A polytropic process is a thermodynamic process that obeys the relation: … within a "polytropic compression" process like gas through a centrifugal compressor. Volumetric flow at suction conditions is … Table 1. Centrifugal compressors : η is calculated from the polytropic efficiency given by the manufacturer. is to be brought back to its initial state what should be the polytropic index? We ask you, humbly: don’t scroll away. ⋅ the polytropic efficiency of the compressor is identical, i.e T 3 is determined from T3 p3 pc the polytropic efficiency that is the same as the two stages = since polytropic efficiency approaches isentropic efficiency for pressure ratio ~ T1 p1 1, this is the same as saying that for a compressor … To determine adiabatic and polytropic efficiency, use the following chart and equations. calculate the network interaction of this cycle. 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