BETC الية التقنية الهندسية المر اسم الطالب. 01: Southern Technical University Engineering Technical College/Basra Department of Thermal Mechanical Eng. Exam of Final Year (2023-2024)-1 Attempt Class: Fourth Year Subject: Power Plants Time: 3 Hour Date: //2024 Note: No need for any table or chart, 40% Full marks (13Marks) Consider a combined gas and steam turbine power plant with the following specifications. Determine: GT plant power (MW). ST plant power (MW), and the thermal efficiency of the combined cycle, Compressor(1-2): Combustion Chamber(2-3) Gas Turbine: (3-4) TRA mair = 104.23- T₁ = 27°C Power 30MW = Misc = 100% Steam Cycle(6-7-8-9): hg=3207kJ/kg Ts = 400°C kg mis.t = 100% kl S = Qin 717.178- kg HRB(4-5): T=450K 02: ha 2066.4kJ/kg he = 151.5kJ/kg Pcon 6kPa; Pboiler = 45bar (9 Marks) A steam power plant of 4075 kW capacity consumes 8 kg/kWh of steam. The steam at 39°C and 0.9 dryne fraction enters into the condenser. The vacuum reading is 68.65 cmlig when the barometer reads 76 cmHg. The temperature of the condensate is 34°C. If the rise in cooling water temperature is 9 K, then determine: (a). The vacuum efficiency. (b). The mass of the leaked air per m³ of condenser shell. (c). The required mass flow rate of cooling water. Help: At steam temperature39°C, then Psat is 5.25cmHg; hy = 163.3kJ/kg; hfg = 2409.3kJ/kg Q3: (9 Marks) An economizer coil is to be used for a boiler. The coil is to be used to heat 7.5 kg/s of pressurized water from 71°C to 182°C(CPwater = 4240J/kg. K). There are 26 kg/s of flue gases available at 426°C (CPflue 1000 J/kg. K). The economizer tubes are of 1.8 cm ID and 2.1 cm OD (kpipe = 111W/m. K). The convective heat-transfer coefficients on the flue gas side is 70,W/m².K and for water sides is 210 W/m²K, Find the total length of economizer pipe required assuming counter flow arrangement. Help: For counter flow HX: 04: € = 1-exp[-NTU(1-c)] 1-c expl-NTU(1-c)] ; C = Cmin Cmax NTU = UAS Cmin (9 Marks) Steam is generated in a boiler at 30 bar 300°C (h = 2995.2 kJ/kg) at the rate of 11 kg/s with feed water entering the economizer at 100°C. During one hour test 5000 kg fuel is used in the boiler. Calorific value of fuel is 35000 kJ/kg. Determine: (a) Boiler efficiency (b) The percentage of energy utilized in the economizer (in kJ/kg of fuel) if the feed water leaves the economizer as a saturated liquid. = Help: at P30bar, h, 1008.3 kJ/kg; h, 2802.3kJ/kg === Dr Safaa H. Faisal Examiner Good Luck Dr. Tahseen Ali Jabbar Head of Department