The condensing pressure for a Rankine engine is 1 bar (hf= 417.4 kJ/kg). Calculate the net work for 1 kg/s of steam and the thermal efficiency when the steam at the beginning of expansion is at 50 bar and (a) saturated (b) 350°C and (c) 640°C. Note the variation of efficiency and the quality at the end of the expansion. 8:35 Ml 67Problem Set on Rankine E...Problem Set on Rankine EngineProblem 1.0A Rankine turbo-generator unit receives 27,000 kg/hof steam at 1.2 MPa and superheat by 122 degrees. Conden-sate leaves at 22°C. For a brake steam rate of 4.74 kg/kwh,mechanical efficiency of 90% and generator efficiency of 94%,determine (a) the ideal cycle thermal efficiency, (b) the indi-cated engine efficiency, (c) the condition of turbine actualexhaust, and (d) the turbo-generator output in Kw. Ans. (a)33%, (b) 85.7%, (c) 87%, (d) 5354.5 kwProblem 2.0The condensing pressure for a Rankine engine is 1 bar.Calculate the net work for 1 kg of steam and the thermalefficiency when the steam at the beginning of expansion is at50 bar and (a) saturated, (b) 350°C, and (c) 640°C.Ans. (a) 627.2 kJ/kg, 26.4%; (b) 727.3 kJ/kg, 27.5%; (c)1079.49 kJkg, 32.35%Problem 3.0There are received 90,000 kg/h of steam at 2.15 MPa,480°C by a Rankine engine; exhaust occurs at 0.10 MPa. Forthe engine find (a) W, (b) m, and (c) e, For the cycle find (a)Work net and (b) thermal efficiency|| ProblemsRankine Cycle and Engine1. In an ideal Rankine cycle, steam is generated at 4.1MPa and 480°C. The condenser is at 32°C. Determine (a) theideal pump work, (b) the cycle thermal efficiency, (c) For anengine with the same end states, determine its thermal efficiency, steam rate, and mep. (d) Considering the engine only,assume the brake engine efficiency to be 78%, the generatorefficiency 92%, the steam flow rate 163,600 kg/hg; computethe output of the combined unit. Ans. (a) 4.12 kJ/kg; (b)38.66%; (c) 38.73%, 2.85 kg/kwh, 51.92 kPa; (d) 41,227 kW2. A Rankine cycle has the following operating condi-tions:Steam pressure, 2.5MPaSteam temperature, 280°CExhaust pressure, 0.026 MPaIndicated steam rate, 5.45 kg/kwhMechanical efficiency, 90%For ideal cycle and engine, calculate (a) the thermal effi•ciency, (b) the engine steam rate), (c) the actual conditionof exhaust steam, and(d) the steam flow rate in kg/h for 1Mw generator output at 94%efficiency. Ans. (a) 28.6%,28.5%;(b) 4.69 kg/kwh; (c) 86.33%; (d) 6447 kg/h3. A Rankine turbo-generator unit receives 27,000 kg/hof steam at 1.2 MPa andsuperheat by 122 degrees. Condensate leaves at 22°C. For a brake steam rate of 4.74 kg/kwh,mechanical efficiency of 90% and generator efficiency of 94%,determine (a) the ideal cycle thermal efficiency. (b) theindi cated enaine efficiency, (c) the condition of turbineactual exhaust, and (d) the turbo-generator output in Kw.Ans. (a) 33'A, (b) 85.7%, (c) 87%, (d) 5354.5 kw4. The condensing pressure for a Rankine engine is 15. There are received 90,000 kg/h of steam at 2.15 MPa,480°C by a Rankine engine; exhaust 0

Question

The condensing pressure for a Rankine engine is 1 bar (hf= 417.4 kJ/kg). Calculate the net work for 1 kg/s of steam and the thermal efficiency when the steam at the beginning of expansion is at 50 bar and (a) saturated (b) 350°C and (c) 640°C. Note the variation of efficiency and the quality at the end of the expansion. 8:35 Ml 67Problem Set on Rankine E...Problem Set on Rankine EngineProblem 1.0A Rankine turbo-generator unit receives 27,000 kg/hof steam at 1.2 MPa and superheat by 122 degrees. Conden-sate leaves at 22°C. For a brake steam rate of 4.74 kg/kwh,mechanical efficiency of 90% and generator efficiency of 94%,determine (a) the ideal cycle thermal efficiency, (b) the indi-cated engine efficiency, (c) the condition of turbine actualexhaust, and (d) the turbo-generator output in Kw. Ans. (a)33%, (b) 85.7%, (c) 87%, (d) 5354.5 kwProblem 2.0The condensing pressure for a Rankine engine is 1 bar.Calculate the net work for 1 kg of steam and the thermalefficiency when the steam at the beginning of expansion is at50 bar and (a) saturated, (b) 350°C, and (c) 640°C.Ans. (a) 627.2 kJ/kg, 26.4%; (b) 727.3 kJ/kg, 27.5%; (c)1079.49 kJkg, 32.35%Problem 3.0There are received 90,000 kg/h of steam at 2.15 MPa,480°C by a Rankine engine; exhaust occurs at 0.10 MPa. Forthe engine find (a) W, (b) m, and (c) e, For the cycle find (a)Work net and (b) thermal efficiency|| ProblemsRankine Cycle and Engine1. In an ideal Rankine cycle, steam is generated at 4.1MPa and 480°C. The condenser is at 32°C. Determine (a) theideal pump work, (b) the cycle thermal efficiency, (c) For anengine with the same end states, determine its thermal efficiency, steam rate, and mep. (d) Considering the engine only,assume the brake engine efficiency to be 78%, the generatorefficiency 92%, the steam flow rate 163,600 kg/hg; computethe output of the combined unit. Ans. (a) 4.12 kJ/kg; (b)38.66%; (c) 38.73%, 2.85 kg/kwh, 51.92 kPa; (d) 41,227 kW2. A Rankine cycle has the following operating condi-tions:Steam pressure, 2.5MPaSteam temperature, 280°CExhaust pressure, 0.026 MPaIndicated steam rate, 5.45 kg/kwhMechanical efficiency, 90%For ideal cycle and engine, calculate (a) the thermal effi•ciency, (b) the engine steam rate), (c) the actual conditionof exhaust steam, and(d) the steam flow rate in kg/h for 1Mw generator output at 94%efficiency. Ans. (a) 28.6%,28.5%;(b) 4.69 kg/kwh; (c) 86.33%; (d) 6447 kg/h3. A Rankine turbo-generator unit receives 27,000 kg/hof steam at 1.2 MPa andsuperheat by 122 degrees. Condensate leaves at 22°C. For a brake steam rate of 4.74 kg/kwh,mechanical efficiency of 90% and generator efficiency of 94%,determine (a) the ideal cycle thermal efficiency. (b) theindi cated enaine efficiency, (c) the condition of turbineactual exhaust, and (d) the turbo-generator output in Kw.Ans. (a) 33'A>, (b) 85.7%, (c) 87%, (d) 5354.5 kw4. The condensing pressure for a Rankine engine is 15. There are received 90,000 kg/h of steam at 2.15 MPa,480°C by a Rankine engine; exhaust 0<:eurs at 0.10 MPa.For the en,ine find (a) W, (b) m, and (c)•e . For the cyclefind (a)t71th en ne, enters the reheater, and returns at 9 bar, 600°C,expansion then occurs to the condenser pressure of 0.05bar (h,= 138 kJ/kg) on the basis of flow of 1 kg steam.Find (a) W and e of the cycle (b) W, e and m for the idealengine (c)In the actual engine the steam enters thereheater at 10 bar, 300°C and later expands to a saturatedstate at the exhaust to thecondenser, find W, e and m.Ans.: (a) 2226.7 kJ/kg, 48.95%; (b) 2246.7 kJ/kg, 49.17%,1.6 kg;(c)2052.1 kJ/kg, 45.85%, 1.75 kg/kwh.Regenerative Cycle and Engine11. There are received 68,000 kg/h of steam by an ideal« 0.003.5 MPa (a) For the ideal cycle, find e. (b) A60,000 kw turbine operates between the same state pointa except that thesteam enters the reheat.er at 1.95 MPa and 26CFC, departs at 1.8 MPaand MO°C. The steam flow i, 147,000 41hr. generata efficiency is

Accepted Answer

(a) when the expansion is saturated,