gas-vapor power cycles
DESCRIPTION
ME332 IASTATETRANSCRIPT
![Page 1: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/1.jpg)
Gas Turbine Power Plants
Chapter 9.5
![Page 2: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/2.jpg)
Timeline
Week Book Sections Covered1 9.5 – 9.72 9.10, 9.93 9.8 , 9.94 9.1 – 9.4, 9.6.25 9.11 – 9.14
![Page 3: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/3.jpg)
Homework Discussion
• Homework 2 hint: read Section 8.2.3
![Page 4: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/4.jpg)
Simple Gas Turbine
Open System Closed System
![Page 5: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/5.jpg)
Compressors
![Page 6: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/6.jpg)
Turbine Engine
![Page 7: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/7.jpg)
Air-Standard Brayton Cycle
![Page 8: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/8.jpg)
Air-Standard Brayton CycleHeat input
Qin/m + (h2 – h3) = 0
Heat output Qout/m + (h4 – h1) = 0
Note: The book uses different signs for these equation.
![Page 9: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/9.jpg)
Air-Standard Brayton CycleTurbine work
(h3 – h4) - Wt/m = 0
Compressor work(h1 – h2) - Wc/m = 0
Note: The book uses different signs for these equation.
![Page 10: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/10.jpg)
Air-Standard Brayton Cycle
Compressor Pressure Ratio P2/P1
Thermal efficiency η = (Wt/m + Wc/m)/(Qin/m) η = [(h3-h4) + (h1-h2)]/(h2 – h3)
Back Work Ratio (bwr) bwr = (Wc/m)/(Wt/m) (absolute value) bwr = (h1 – h2)/(h3 – h4) (absolute value)
Note: The book uses different signs for these equation.
![Page 11: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/11.jpg)
Air-Standard Brayton CycleTurbine work
Wt/m = h3 – h4
Compressor workWc/m = h1 – h2
Heat input-Qin/m = h2 – h3
Heat output-Qout/m = h4 – h1
Thermal efficiency η = (Wt/m + Wc/m)/(Qin/m) η = [(h3-h4) + (h1-h2)]/(h2 – h3)
Back Work Ratio (bwr) bwr = (Wc/m)/(Wt/m) (absolute) bwr = (h1 – h2)/(h3 – h4) (absolute)
Note: The book uses different signs for these equation.
![Page 12: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/12.jpg)
Irreversibilities and lossesFriction and heat loss cause process inefficiencies in• Compressors (heat loss)• Turbines (heat loss)• Heat exchanger pipes
(pressure drop)
![Page 13: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/13.jpg)
Irreversibilities and lossesPressure drop in heat exchanger pipes <<< heat loss in compressors and turbines<<<Inefficiencies during combustion
![Page 14: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/14.jpg)
Irreversibilities and lossesηt = (Wt/m)/(Wt/m)s
= (h3 – h4)/(h3 – h4s)
ηc = (Wt/m)/(Wt/m)s
= (h3 – h4)/(h3 – h4s)
![Page 15: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/15.jpg)
EXAMPLE 9-6 WITH EES
![Page 16: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/16.jpg)
Regenerative Gas Turbines
![Page 17: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/17.jpg)
Regenerative Gas Turbine CycleThe regenerator preheats the turbine inlet stream using heat from the exhaust gas
This reduces Qin (everything else remains the same)
Note Tx can be higher than Ty
![Page 18: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/18.jpg)
Regenerative Gas Turbine
Regenerator efficiencyηreg = (hx – h2)/(h4 – h2)
![Page 19: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/19.jpg)
Gas Turbine Combined CycleUse rejected heat from the Top cycle as heat input to a Bottom cycle
Improves efficiency
η = (Wgas + Wvap)/(Qin)
Regenerator Energy Balancemv *(h6-h7) + mg*(h4-h5) = 0
![Page 20: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/20.jpg)
Gas Turbines with Reheat
Turbines require temperature control to prevent material deterioration
One strategy is to provide cooling with excess air
Reheat takes advantage of the excess air to burn more fuel
What are some disadvantages?
![Page 21: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/21.jpg)
Gas Turbines with Reheat
![Page 22: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/22.jpg)
Compression with Intercooling
It is easier to compress a cooler gas (think of a hot air balloon)
But… a cooler gas requires additional heat input
Optimization can help select number and temperature of intercooler stages
![Page 23: Gas-Vapor Power Cycles](https://reader034.vdocuments.us/reader034/viewer/2022050720/549158a6b479597a588b54a8/html5/thumbnails/23.jpg)
Integrated Gasification Combined Cycles