Ex 6 DESIGN AND ECONOMIC FEASIBILITY OF A CONCENTRATED SOLAR PLANT Text

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DESIGN AND ECONOMIC FEASIBILITY OF A CONCENTRATED SOLAR PLANT Power production from renewable energy – A.Y. 2020/21 Prof. Paolo Silva – Ing. Dario Alfani Design of collector field A parabolic trough collector is used to heat up 1 kg/s of HTF at Tin to a given Tout. Determine the required collector length and the efficiencies (optical and thermal) for different concentration ratio (CR equal to 50, 80 and 100) assuming a DNI of 900 W/m2 and an ambient temperature of 30 °C. HTF data are reported in Table 1, while collector data are reported in Table 2. Table 1: HTF thermodynamic properties and conditions Synthetic Oil Solar Salts Collector inlet temperature (Tin) 290 °C 290 °C Collector outlet temperature (Tout) 390 °C 550 °C Mean density () 760 kg/m3 1’800 kg/m3 Mean specific heat (cp) 2.5 kJ/kgK 1.5 kJ/kgK Table 2: Collector properties COLLECTOR Mirror Reflectivity (m) 0.905 Absorber Absorptivity (abs) 0.95 Intercept factor () 1-0.001*CR Absorber outer diameter (Dext,abs) 70 mm Glass envelope Trasmittance (g) 0.97 Thermal losses (W/m) 0.00826×T2 - 3.81×T + 554 Design of the CSP plant Figure 1: Simplified parabolic trough CSP plant layout Design a parabolic trough CSP plant with a power block of 50 MWel net power. The solar field has synthetic oil as heat transfer fluid and a solar multiple equal to 2. The selected collectors have the same properties reported in Table 2 and an aperture of 5.75 m. The design DNI is 900 W/m2 and a design ambient temperature of 30 °C. The power block efficiency is 0.66 with respect to the Lorenz efficiency (computed between the HTF source and a heat sink at T=Tamb). Table 3: plant data HTF return T from PB 290 °C p solar field 15 bar HTF collector outlet T 390 °C hydr, SF PUMP 0.85 Collector aperture 5.75 m el-mech, SF PUMP 0.94…