Power Plant Vapor Power Cycles Chapter Two Vapor

Power Plant Vapor Power Cycles Chapter Two Vapor Power Cycles Power Plant Engineering TUTORIAL SHEET ‐ 1 Thermodynamic Review –ﻴﺮﺻﻨﺘﺴﻤﻼﻫﻌﻤﺎﺟﻼﻫﻴﻜﻴﻨﺎﻛﻴﻤﻼﻫﺴﺪﻧﻬﻼ ﻫﺴﺪﻧﻬﻼﻫﻠﻴﻚ ﻫ ﻣﺴﻖ Carnot cycle 1 - A Carnot cycle works on steam between the pressure limits of 7 MPa and 7 k. Pa. Determine thermal efficiency, turbine work and compression work per kg of steam. Answers: Thermal efficiency = 44. 21%, Turbine work = 969. 57 k. J/kg (+ve), Compression work = 304. 19 k. J/kg (–ve) 2‐ Consider a steady-flow Carnot cycle with water as the working fluid. The maximum and minimum temperatures in the cycle are 350 and 60°C. The quality of water is 0. 891 at the beginning of the heat-rejection process and 0. 1 at the end. Show the cycle on a T-s diagram relative to the saturation lines, and determine (a) thermal efficiency, (b) the pressure at the turbine inlet, and (c) the net work output. Answers: (a) 0. 465, (b) 1. 40 MPa, (c) 1623 k. J/kg 1

Power Plant Vapor Power Cycles 3 - Determine the net work output and thermal efficiency for the Carnot cycle with steam as the working fluid. Steam enters the turbine in both cases at 10 MPa as a saturated vapor, and the condenser pressure is 20 k. Pa. In the Carnot cycle, the boiler inlet state is saturated liquid. Draw the T-s diagrams for this cycle. Answers: 565. 4 k. J/kg , 43% Ideal and actual Rankine cycle 1‐ Consider a 210 -MW steam power plant that operates on a simple ideal Rankine cycle. Steam enters the turbine at 10 MPa and 500°C and is cooled in the condenser at a pressure of 10 k. Pa. assuming an isentropic efficiency of 85 percent for both the turbine and the pump. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a) the quality of the steam at the turbine exit, (b) thermal efficiency of the cycle, and (c) the mass flow rate of the steam. Answers: (a) 0. 874, (b) 34. 1 percent, (c) 194 kg/s 2 - Consider a steam power plant that operates on a simple ideal Rankine cycle and has a net power output of 45 MW. Steam enters the turbine at 7 MPa and 500°C and is cooled in the condenser at a pressure of 10 k. Pa by running cooling water from a lake through the tubes of the condenser at a rate of 2000 kg/s. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a) thermal efficiency of the cycle, (b) the mass flow rate of the steam, and (c) the temperature rise of the cooling water. Answers: (a) 38. 9 percent, (b) 36 kg/s, (c) 8. 4°C 2

Power Plant Vapor Power Cycles 3 - Repeat Prob. 22 assuming an isentropic efficiency of 87 percent for both the turbine and the pump. Answers: (a) 33. 8 percent, (b) 41. 4 kg/s, (c) 10. 5°C 3