Energy Engineering - Power Production from Renewable Energy

Ex 2 - GEOTHERMAL BINARY POWER PLANT - Results

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BINARY GEOTHERMAL CYCLE Power Produc tion from Renewable Energy – A.Y. 20 20 /21 Prof. Paolo Silva – Ing. Dario Alfani Pay attention : the results may slightly differ due to the accuracy of the optimization process (obtained through the parametric approach) and due to the tolerance applied to the solution of the energy balances at the evaporator. These results are obtained with a preliminary optimization step of 0.5 bar (of the evaporation pressure) and a final optimization s tep of 0.05 bar just in proximity of the optimal point . With this approach the optimal evaporation pressure obtained is equal to 8.05 bar, confirming the correctness of the optimal evaporation pressure obtained with the Excel add -in solver optimization tool which is equal to 8.048 bar. Results 1) Cycle with one pressure level – simple cycle Optimal evaporation pressure 8.05 bar Temperature T B 129. 48 °C Mass flow rate isopentane 169.16 kg/s Net electric power 8.41 MWel η I (η cycle ) 11. 14 % η thermal recovery 64.90 % η plant 7.23 % η II (assumed T0=18°C) 28.31 % Mass flow rate cooling water 1967.75 kg/s Area economi zer 764.86 m2 Area condens er 14723 .03 m2 T [°C] p [bar] h [kJ/kg] s [kJ/kgK] x [ -] ρ [kg/m3] 1 30.00 1.12 -321.89 -1.070 0.00 642.05 2 30.65 10.06 -319.90 -1.068 0.00 643.34 3 103.12 8.05 -152. 37 -0.575 0.00 539.47 4l 106.12 8.05 -144.35 -0.554 0.00 533.60 4 106.12 8.05 126.18 0.159 1.00 22.58 5is 57.67 1.12 53.02 0.159 1.00 3.05 5 65.63 1.12 67.65 0.203 1.00 2.97 5v 30.00 1.12 4.47 0.006 1.00 3.36 0 20 40 60 80 100 120 140 160 180 0 10000 20000 30000 40000 50000 60000 70000 80000 Temperature [ °C] Heat exchanged [kW] PHE TQ diagram T,geo T,wf 0 10 20 30 40 50 60 70 0 10000 20000 30000 40000 50000 60000 70000 Temperature [ °C] Heat exchanged [kW] Cond TQ diagram T,wf T,cw Results 2) Cycle with one pressure level – cogenerat ion cycle Area cogeneration exchanger 9401.11 m2 η I 42 .33 % Results 3) Cycle with two pressure levels Evaporation temperature - HP 138.06 °C Corresponding evaporation pressure - HP 14.98 bar Mass flow rate isopentane - HP 133.36 kg/s Mass flow rate isopentane - LP 91.22 kg/s Net electric power 13.34 MW el η I (η cycle ) 12.57 % η thermal recovery 91.23 % η plant 11.47 % η II (assumed T0=18°C) 44.91 % Area E VA HP 2395.82 m2 Area ECO H P 907.62 m2 Area EVA L P 2171.65 m2 Area ECO L P 2103.29 m2 Mass flow rate cooling water 2717.33 kg/s Area condenser 19315.15 m2 T [°C] p [bar] h [ kJ/kg] s [kJ/kgK] x [ -] ρ [kg/m3] 1 30.00 1.12 -321.89 -1.070 0.00 642.05 2 30.65 10.06 -319.90 -1.068 0.00 643.34 3 103.12 8.05 -152.37 -0.575 0.00 539.47 4 104.42 18.73 -149.54 -0.573 0.00 543.97 5 135.06 14.98 -61.59 -0.347 0.00 472.30 6 138.06 14.98 173.29 0.224 1.00 44.84 7is 117.57 8.05 151.05 0.224 1.00 21.44 7 119.59 8.05 155.50 0.235 1.00 21.25 8 106.12 8.05 126.18 0.159 1.00 22.58 9 114.15 8.05 143.59 0.205 1.00 21.76 10is 65.95 1.12 68.24 0.205 1.00 2.97 10 73.98 1.12 83.31 0.249 1.00 2.89 10v 30.00 1.12 4.47 0.006 1.00 3.36 0 20 40 60 80 100 120 140 160 180 0 20000 40000 60000 80000 100000 120000 Temperature [ °C] Heat exchanged [kW] PHE TQ diagram (2 pressure levels) T,geo T,wf 0 10 20 30 40 50 60 70 80 0 20000 40000 60000 80000 100000 Temperature [ °C] Heat exchanged [kW] Cond TQ diagram (2 pressure levels) T,wf T,cw