17 04 14 sol

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Esercizio 1: Teva = -8 °C Tcond = 40 °C COP = 2.5 Qf = 1000 kWf Eta el comp = 92 % Tamb = 30 °C cp,a = 1 kJ/kg-K MMa = 28.80 kg/kmole Dpa = 0.100 kPa eta vent = 60 % Pel comp = 400 kWe Pfluido = 368 kW Qcond = 1368 kW Taria ex cond = 37 °C <- assunta DTa = 7 °C Ga = 195.4 kg/s rho,a = 1.158 kg/m3 Pvent = 28132 W Tamb* = 20 °C efficacia cond = 0.7 COPid-ref = 5.52 COP/COPid = 0.453 Qcond' = 1368 kW <- assumo inizialmente Qcond invariata DTa' = 7 °C DTmax' = 10 °C Tcond' = 30 °C COPid' = 6.98 COP' = 3.16 Pel comp' = 316.7 kWe Pfluido' = 291 kW Qcond''= 1291 kW <- aggiorno Qcond DTa'' = 6.61 °C DTmax'' = 9.44 °C Tcond'' = 29.44 °C COPid'' = 7.08 COP'' = 3.21 Pel comp'' = 312.0 kWe Pfluido'' = 287 kW Qcond'''= 1287 kW <- sufficientemente vicino a Qcond'' Esercizio 2: xO2-dry = 5 % Combustione stechiometrica: CH4+2(O2+3.76N2) -> CO2+2H2O+7.52N2 Combustione con eccesso d'aria 'e': CH4+2*(1+e)*(O2+3.76N2) -> CO2+2H2O+2*eO2+7.52*(1+e)N2 xO2-dry =2*e/(8.52+2*e+7.52*e) = 0.05 e = 27.95 % fumi: zCO2 = 1 kmole/kmoleCH4 zH2O = 2 kmole/kmoleCH4 zO2 = 0.56 kmoli/kmoleCH4 zN2 = 9.62 kmoli/kmoleCH4 ztot = 13.18 kmoli_fumi/kmoleCH4 xCO2 = 0.0759 kmoli/kmole_fumi xH2O = 0.1517 kmoli/kmole_fumi xO2 = 0.0424 kmoli/kmole_fumi xN2 = 0.7300 kmoli/kmole_fumi cpCO2 = 39.2 kJ/kmole-K cpH2O = 34.3 kJ/kmole-K cpO2 = 30.0 kJ/kmole-K cpN2 = 29.5 kJ/kmole-K cp_fumi = 30.97 kJ/kmole-K aria xO2 = 0.210 xN2 = 0.790 cp_aria = 29.59 kJ/kmole-K alfa = 12.186 kmoliaria/kmoleCH4 LHV CH4 = 50.00 MJ/kg MMCH4 = 16.00 kg/kmole LHV CH4 = 800.0 MJ/kmole Perdite irraggiam = 0.5 % <- assunte Rendim caldaia = 96.0 % Perdite camino = 3.5 % Perdite camino = 28.0 MJ/kmoleCH4 DT fumi camino = 68.6 °C Tamb = 25 °C Tcamino = 93.6 °C Tout eco = 200.00 °C DT fumi prerisc aria = 106.42 Q prerisc aria = 43446 kJ/kmoleCH4…