An Open cycle and Closed cycle Gas Turbine Engines. Methods to improve the performance of simple gas turbine plants

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Deborah Ford
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An Open cycle and losed cycle Gas ubine Engines Mehods o impove he pefomance of simple gas ubine plans I egeneaive Gas ubine ycle: he empeaue of he exhaus gases in a simple gas ubine is highe

exchange called a egeneao, heeby educing he amoun of hea supplied fom an exenal souce and also he amoun of hea ejeced Figue shows a single sage egeneaive gas ubine cycle Ai is dawn fom he

eaches he combusion chambe, less amoun of fuel will be equied o aain he designed ubine inle empeaue of he poducs of combusion Afe combusion a consan pessue in he combusion chambe, he gas enes

1 An Open cycle and losed cycle Gas ubine Engines Mehods o impove he pefomance of simple gas ubine plans I egeneaive Gas ubine ycle: he empeaue of he exhaus gases in a simple gas ubine is highe han he empeaue of he ai afe compession pocess he of he Bayon cycle can be inceased by uilizing pa of he enegy of he exhaus gas fom he ubine in heaing up he ai leaving he compession in a hea exchange called a egeneao, heeby educing he amoun of hea supplied fom an exenal souce and also he amoun of hea ejeced Figue shows a single sage egeneaive gas ubine cycle Ai is dawn fom he amosphee ino he compesso and is compessed isenopically o sae I is hen heaed a consan pessue in he egeneao o sae x by he ho bun gases fom he gas ubine Since he empeaue of he ai inceases befoe i eaches he combusion chambe, less amoun of fuel will be equied o aain he designed ubine inle empeaue of he poducs of combusion Afe combusion a consan pessue in he combusion chambe, he gas enes he ubine a sae and expands isenopically o sae in he ubine I hen enes he coune-flow egeneao as saed ealie, whee i gives up a poion of is hea enegy o he compessed ai fom he compesso and leaves he egeneao a sae y

2 In an ideal cycle, he empeaue of he ai leaving he egeneao is equal o he empeaue of he bun gases leaving he ubine, ie, x Bu in pacice, he empeaue of he ai leaving he egeneao is less han x In -S diagam, x is he empeaue of he ai leaving he egeneao in an acual plan Effeciveness of a egeneao is x x ε when is consan In an ideal egeneao, hea loss by he bun gases is equal o he hea gained by he ai in he egeneao, ie, y x, Whee x and y and hence H L h Q Q Fo an ideal egeneaive gas ubine cycle, Q L ( y ) ( ) and Q H ( x ) ( ) ( ) ( ) h Since and h ie, h I is eviden ha he h of an ideal egeneaive gas ubine cycle depends no only on he pessue aio bu also on he aio of he wo exeme empeaues Fo a fixed aio of /, he cycle dops wih inceasing pessue aio In pacice he egeneao is cosly, heavy and bulky, and causes pessue losses which bings abou a decease in cycle II Ideal egeneaive cycle wih ine cooling and ehea: a) Gas ubine cycle wih ehea and mulisage expansion:

3 Inceased wok oupu due o eheaing Wok oupu of he ubine is inceased by mulisage expansion wih eheaing In he above illusaion, wo-sage expansion is done in low pessue ( ) and high pessue ( ) ubines wih eheaing he ai in beween sages Opimum wok oupu fo a wo-sage ehea cycle:

4 Assumpions: he ai afe one sage of expansion is eheaed back o is oiginal empeaue ie, Le aio empeaue imum cycle and max,, Ne wok oupu is W N ( ) ( ) ( ) we have N W bu / N W Fo given values of, and, W N is maximum if d dw N d dw ie,

5 o ( ) O ie, Fo maximum wok oupu, Similaly if he cycle has N sages of expansion, wih eheaing, hen fo maximum wok oupu, pessue aio fo each (compession pessue aio) /N Advanages: By employing mulisage expansion wih eheaing in beween he sages, he ne wok oupu fom he gas ubine cycle can be inceased his is illusaed on he -S diagam shown fo a -sage expansion wih eheaing in beween he sages Disadvanages: Bu disadvanage of eheaing is due o he fac ha addiional hea has o be supplied in ode o ehea he ai afe each sage of expansion his may esul in a decease in he hemal efficiency of he cycle his is shown in figue below I can be seen ha fo a given value of, he hemal of he ehea cycle inceases wih incease in and fo a given value of, he hemal inceases wih incease in Howeve, he hemal of a ehea cycle will be less han ha of a simple cycle fo a given value of b) Gas ubine cycle wih mulisage compession wih ine cooling in beween he sages:

Lecture 18: Kinetics of Phase Growth in a Two-component System: general kinetics analysis based on the dilute-solution approximation

Lecture 18: Kinetics of Phase Growth in a Two-component System: general kinetics analysis based on the dilute-solution approximation Lecue 8: Kineics of Phase Gowh in a Two-componen Sysem: geneal kineics analysis based on he dilue-soluion appoximaion Today s opics: In he las Lecues, we leaned hee diffeen ways o descibe he diffusion