Compressor Calc

Compressor Calculations

Compressor calculations can be done in a number of ways. The default calculations is done be specifying pressure and temperature in, and pressure out. THe temperature out will then be calculated assuming an adiabatic compressor. Alternatively we can specify to do an polytrophic calculation using the command:

compressor.setUsePolytropicCalc(true);

Compressor calculations using compressor curves

A compressor curve can be set using the commands:

double[] chartConditions = new double[] { 0.3, 1.0, 1.0, 1.0 };

double[] speed = new double[] {12913, 12298, 11683, 11098, 10453, 9224, 8609, 8200}; double[][] flow = new double[][] { {2789.1285 , 3174.0375 , 3689.2288 , 4179.4503 , 4570.2768 , 4954.7728 , 5246.0329 , 5661.0331 }, {2571.1753 , 2943.7254 , 3440.2675 , 3837.4448 , 4253.0898 , 4668.6643 , 4997.1926 , 5387.4952 }, { 2415.3793 , 2763.0706 , 3141.7095 , 3594.7436 , 4047.6467 , 4494.1889 , 4853.7353 , 5138.7858 }, {2247.2043 , 2799.7342 , 3178.3428 , 3656.1551 , 4102.778 , 4394.1591 , 4648.3224 , 4840.4998 } , {2072.8397 , 2463.9483 , 2836.4078 , 3202.5266 , 3599.6333 , 3978.0203 , 4257.0022 , 4517.345 } , {1835.9552 , 2208.455 , 2618.1322 , 2940.8034 , 3244.7852 , 3530.1279 , 3753.3738 , 3895.9746 } , {1711.3386 , 1965.8848 , 2356.9431 , 2685.9247 , 3008.5154 , 3337.2855 , 3591.5092 } , {1636.5807 , 2002.8708 , 2338.0319 , 2642.1245 , 2896.4894 , 3113.6264 , 3274.8764 , 3411.2977 } };

double[][] head = new double[][] { { 80.0375 , 78.8934 , 76.2142 , 71.8678 , 67.0062 , 60.6061 , 53.0499 , 39.728 }, {72.2122 , 71.8369 , 68.9009 , 65.8341 , 60.7167 , 54.702 , 47.2749 , 35.7471 }, {65.1576 , 64.5253 , 62.6118 , 59.1619 , 54.0455 , 47.0059 , 39.195 , 31.6387 }, {58.6154 , 56.9627 , 54.6647 , 50.4462 , 44.4322 , 38.4144 , 32.9084 , 28.8109 },{52.3295 , 51.0573 , 49.5283 , 46.3326 , 42.3685 , 37.2502 , 31.4884 , 25.598 },{40.6578 , 39.6416 , 37.6008 , 34.6603 , 30.9503 , 27.1116 , 23.2713 , 20.4546 },{35.2705 , 34.6359 , 32.7228 , 31.0645 , 27.0985 , 22.7482 , 18.0113 }, {32.192 , 31.1756 , 29.1329 , 26.833 , 23.8909 , 21.3324 , 18.7726 , 16.3403 }, };

double[][] polyEff = new double[][] { {77.2452238409573 , 79.4154186459363 , 80.737960012489 , 80.5229826589649 , 79.2210931638144 , 75.4719133864634 , 69.6034181197298 , 58.7322388482707 }, { 77.0107837113504 , 79.3069974136389 , 80.8941189021135 , 80.7190194665918 , 79.5313242980328 , 75.5912622896367 , 69.6846136362097 , 60.0043057990909 }, { 77.0043065299874 , 79.1690958847856 , 80.8038169975675 , 80.6543975614197 , 78.8532389102705 , 73.6664774270613 , 66.2735600426727 , 57.671664571658 }, { 77.0716623789093 , 80.4629750233093 , 81.1390811169072 , 79.6374242667478 , 75.380928428817 , 69.5332969549779 , 63.7997587622339 , 58.8120614497758 }, {76.9705872525642 , 79.8335492585324 , 80.9468133671171 , 80.5806471927835 , 78.0462158225426 , 73.0403707523258 , 66.5572286338589 , 59.8624822515064 }, {77.5063036680357 , 80.2056198362559 , 81.0339108025933 , 79.6085962687939 , 76.3814534404405 , 70.8027503005902 , 64.6437367160571 , 60.5299349982342 }, {77.8175271586685 , 80.065165942218 , 81.0631362122632 , 79.8955051771299 , 76.1983240929369 , 69.289982774309 , 60.8567149372229 },{78.0924334304045 , 80.9353551568667 , 80.7904437766234 , 78.8639325223295 , 75.2170936751143 , 70.3105081673411 , 65.5507568533569 , 61.0391468300337 } };

compressor.getCompressorChart().setCurves(chartConditions, speed, flow, head, polyEff);

See: https://github.com/equinor/neqsim/blob/master/src/main/java/neqsim/processSimulation/processEquipment/compressor/CompressorChart.java

Mathematics of compressor calculations using compressor curves

NeqSim will calculate reduced head and efficiency curves based on the functions:

See: https://en.wikipedia.org/wiki/Compressor_characteristic

A second order polynomial is fitted to the reduced curves. This reduced polynomial is used to obtain head and efficiency for any speed and flow combination.