basics of mechanical engineering for renewable energy systems

7/25/2019 Basics of Mechanical Engineering for Renewable Energy Systems

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Basics of MechanicalEngineering

forRenewable Energy Systems

Rohit Singh Lather, Ph.D.


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Introduction

6/28/16 Dr. Rohit Singh Lather 2

Mechanical power is produced by a heat engine that

transor!s ther!al energy "ro! co!bustion o a uel#into rotational energy

$eat "generated in the urnace# is trans!itted to theboiler where water orced into the boiler by the eedpu!p is con%erted into stea!

So the power produced !ust be

1. &cono!ically useul. 2. &n%iron!ental riendly to society

Steam drives turbine blades Shaft Power


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"ow to Produce Steam

6/28/16 Dr. Rohit Singh Lather '

(ater boils and e%aporatesat 1))*+ under

at!ospheric pressure

#uel and $ir Burner"eat

(ater absorbs the heat, ande%entually absorb enoughto change into a gaseous

state - stea!.

During the e%aporationprocess, pressure and

te!perature are constant,and a substantial a!ount

o ther!al energy is used orbringing the water ro!liuid to %apour phase.


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y higher pressure, water e%aporates at higherte!perature - e.g. a pressure o 1) bar euals ane%aporation te!perature o 180*+.

(hen all the water is e%aporated, the stea! is calleddry saturated.

In this condition the stea! contains a large a!ount olatent heat.

urther heating o dry saturated stea! will lead toincrease in te!perature o the stea!.

Superheated stea!.



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Steam %eneration for Power

+an be produced using steam boilers and the steam

generators

6/28/16 Dr. Rohit Singh Lather


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Steam %eneration


Sensible"eat Sensible

"eat


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%eneral &lassi'cation of Power Plants

+apacity 3 S!all / Mediu!/ $igh / Super 4


Status 3+on%entional / on- +on%entional4

7peration 3ase / ea9 / Inter!ediate 4

uel :ype 3 ossil uel / uclear / Renewable&nergy 4

ri!e Mo%er 3 Stea! / ;as / (ater / (ind:urbine 4

i i l f l i


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Princi(les of Power Plant Design&onsideration

roperly selected location

Si!plicity o design

Low capital cost

Low cost o energy generated

$igh e


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Dr. Rohit Singh Lather

Power Plant Land )se Re*uired +m-M!

Source/ 0. Davidson 111!Nuclear

0.001/0.01

Biomass5.2

Geothermal

0.003

Coal0.01/0.04

2111 M P3ERPL$45SR)4464% $5 2117 &$P$&658

9:;; %h-year!

6/28/16 =

Wind

0.79

PV

0.12

Solar

Thermal

0.08

Hydro

0.07-0.37


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&arbon Dio


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&a(acity #actor !

+apacity actor is de>ned as >the ratio of the actual

o-( of a (ower (lant over a (eriod of time to it?so-( if it had o(erated at full rated ca(acity duringthe same (eriod of time.@

+ ?applied to power generation syste!.

&a(acity #actor A actual out(ut duringti@@@@@@

out(ut that could be

(roduced at therated (lant o(eration

during ti

$ A annual +hr (roduced6/28/16 Dr. Rohit Singh Lather 11


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&ost of Electricity %eneration



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+apacity

S!all

roducing

Less than M

Mediu!

roduction

+apacityin therange o C 211 M

$igh

roduction

+apacityin therange o211 C2111 M

Super

roduction+apacityin abo%e2111M

6/28/16 Dr. Rohit Singh Lather 1'


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3(eration Load

ase

Loaded ashea%ily aspossible, where

ItAs load ne%eralls belowde!and

ea9

Bsed in a s!allraction o ti!e

Inter!ediate

:hese s!alland old eCistingplant



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5y(e of Power Plant

&lectric roduction

Stea! or $ot (ater $eating

+ogeneration lant ? Stea! and &lectric

+o!bined +ycle ? Stea! and ;as :urbines

+++ ? oth +ogeneration +o!bined +ycle



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+lassi>cation o ower lants +ycles

Eapor ower+ycles

+arnot

Ran9ine

inary ";as FStea!#

;as ower+ycles

7tto

Diesel

Dual

rayton



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(or9ing +ycles Related to ower lants

Stea!ower lant

Ran9ine+ycle

;as owerlant

aryton+ycle

Dieselower lant

Dual +ycle



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Stea! ower lant



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6/28/16 Dr. Rohit Singh Lather 1=


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Steam turbine

6/28/16 Dr. Rohit Singh Lather 2)

Stea! produced by the stea! generator is ad!itted tothe Steam turbine

$eat energy is con%erted into !echanical energy ?useul wor9

Stea! :urbine can be o diGerent types / stages

? $igh pressure turbine

? Inter!ediate pressure turbine

? Low pressure turbine


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httpH//www.greenesolpower.co!/


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6/28/16 Dr. Rohit Singh Lather 2'


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6nstalled Steam 5urbine


httpH//www.greenesolpower.co!/


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I!pulse turbinesH


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I!pulse turbinesH! tend to be s!aller than

reaction turbine oco!parable power and

! are !ore durable and

! ha%e longer ti!e betweeno%erhaul than reactionturbines.

Reaction turbines ha%e aslightly higher operating

e


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Steam %enerator



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Energy &onversion



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Steam %eneration using Renewable Energy

6/28/16 Dr. Rohit Singh Lather 2=

Bi & l f R bl E


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Binary &ycle for Renewable Energy

6/28/16 Dr. Rohit Singh Lather ')

% 5 bi


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%as 5urbine

6/28/16 Dr. Rohit Singh Lather '1


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%as 5urbine &om(onents


&om(ressorSection

&ombustor

5urbine


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&ombined &ycle Power Plant

6/28/16 Dr. Rohit Singh Lather ''


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4 t l %


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4atural %as

MiCture o hydrocarbons, predo!inantly !ethane "+$0#

It also contains hydrocarbons such as ethane and propaneand other gases such as nitrogen, heliu!, carbon dioCide,hydrogen sul>de, and water %apor.

ontoCic, noncorrosi%e, and non-carcinogenic

ot a threat to soil, surace water, or groundwater +o!pressed natural gas "+;# and liue>ed natural gas

"L;#

Lower oone-or!ing e!issions.

&Ctracted ro! gas and oil wells.

Js a transportation uel, it is used as co!pressed naturalgas "+;# and liue>ed natural gas "L;# .

6/28/16 Dr. Rohit Singh Lather '


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:o store !ore energy in a s!aller %olu!e, natural gas canbe liue>ed "L;#.

L; occupies only 1/6)) the %olu!e o natural gas "%apor#or!.

+an be used in boilers and gas turbines

Deli%ered through the pipeline syste!

:here is widespread natural gas distribution and reueling

inrastructure. Eery s!all a!ounts o natural gas are deri%ed ro!

supple!ental sources such as synthetic gas, land>ll gas,and other biogas resources.

:he interest in natural gas as an alternati%e transportationuel ste!s !ainly ro! its clean-burning ualities, itsdo!estic resource base, and its co!!ercial a%ailability.


"eat 5ransfer


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"eat 5ransfer (ith direct solar, geother!al and bio!ass sources,

!ost energy transer is by heat rather than by

!echanical or electrical processes. $eat transer is a well-established, yet co!pleC,

subKect.

$owe%er, we do not need sophisticated detail, which

is rarely reuired to understand and plan renewableenergy ther!al applications.

Sophisticated detail is needed or specialiedrenewable design, as or instance with ad%anced

engines powered by biouels or reduce heat losses ina ther!al syste!.


Basics of "eat 5ransfer


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Basics of "eat 5ransfer

"eatH:he or! o energy that can be transerred ro!one syste! to another as a result o te!perature

diGerence. "eat 5ransfer deals with the deter!ination o the

rates o such energy transers as well as %ariation ote!perature.

:he transer o energy as heat is always ro! thehigher-te!perature !ediu! to the lower-te!peratureone.

$eat transer stops when the two !ediu!s reach the

sa!e te!perature. $eat can be transerred in three diGerent !odesH

? Conduction

? Convection

? Radiation6/28/16 Dr. Rohit Singh Lather '8

$ll modes of heat transfer re*uire thee


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hy Does My &oee %et &old

6/28/16 Dr. Rohit Singh Lather '=

hy )nderstanding of "eat 5ransfer


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hy )nderstanding of "eat 5ransfer

6/28/16 Dr. Rohit Singh Lather 0)

&34D)&5634


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01

&34D)&5634

&onduction/ :he transer o energyro! the !ore energetic particles o a

substance to the adKacent lessenergetic ones as a result ointeractions between the particles.

In gases and liuids, conduction isdue to the collisions and difusion othe !olecules during their rando!!otion.

In solids, it is due to the co!binationo vibrationso the !olecules in a

lattice and the energy transport byree electrons.


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$eat conductionthrough a large

plane wall othic9ness x and

areaA.

:he rate o heat conductionthrough a plane layer isproportional to the te!perature

diGerence across the layer andthe heat transer area, but isin%ersely proportional to thethic9ness o the layer.


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0'

(henx )

#ourier?s law of heatconduction

5hermal conductivity, +H J

!easure o the ability o a !aterialto conduct heat.

:e!perature gradient dT/dxH :heslope o the te!perature cur%e on a

T-x diagra!.

5he rate of heatconduction through a

solid is directly

(ro(ortional to itsthermal conductivity.

In heat conduction analysis,Arepresents the area normal to the

direction o heat transer.

5he Range of 5hermal &onductivity of arious Materials at


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00

Room 5em(erature

&34E&5634


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0

&34E&5634&onvection/ :he !ode oenergy transfer between a

solid surface and theadFacent li*uid or gas thatis in motion, and it in%ol%esthe co!bined eGects oconductionand uid motion.

:he aster the uid !otion,the greater the con%ectionheat transer.

In the absence o any bul9

uid !otion, heat transerbetween a solid surace andthe adKacent uid is by pureconduction.

$eat transer ro! a hotsurace to air by con%ection.

h li b il d b d d l


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06

:he cooling o a boiled egg by orced and naturalcon%ection.

atural "or ree#

con%ectionH I the uid!otion is caused bybuoyancy orces that areinduced by density

diGerences due to the%ariation o te! erature

orced con%ectionH I the

uid is orced to owo%er the surace byeCternal !eans such as aan, pu!p, or the wind.

$eat transer processes that in%ol%e change of phase o


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05

p g pa uid are also considered to be con%ection because othe uid !otion induced during the process, such as therise o the %apor bubbles during boiling or the all o the

liuid droplets during condensation.ewtonAs law o coolin

h con%ection heat transer coe


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Radiation


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0=

Radiation RadiationH:he energy e!itted by !atter in the or! o

electromagnetic waves "or photons# as a result o the

changes in the electronic con>gurations o the ato!s or!olecules.

Bnli9e conduction and con%ection, the transer o heatby radiation does not reuire the presence o anintervening medium.

In act, heat transer by radiation is astest "at thespeed o light# and it suGers no attenuation in a%acuu!. :his is how the energy o the sun reaches theearth.

In heat transer studies we are interested in thermalradiation, which is the or! o radiation e!itted bybodies because o their te!perature.

Jll bodies at a te!perature abo%e absolute ero e!it

ther!al radiation.

4et radiation heat transfer/ :he diGerence between


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)

the rates o radiation emitted by the surace and theradiation absorbed.

:he deter!ination o the net rate o heat transer by

radiation between two suraces is a co!plicated !attersince it depends on

roperties o the suraces:heir orientation relati%e to each other

Interaction o the !ediu! between the suraces withradiation

StefanCBoltImannLaw

O .65) 1)8(/!2N P0 Stean!olt"mann

constant

lac9bodyH:he idealiedsurace that

e!itsradiation atthe !aCi!u!rate.


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1

Radiation heat transer between a surace and the suracessurrounding it.

(hen a surace is completel# enclosed by a !uch larger"or blac9# surace at te!perature Tsurrseparated by a gas

"such as air# that does not inter%ene with radiation, thenet rate o radiation heat transer between these twosuraces is gi%en by

Emissivity H J

!easure o howclosely a suraceapproCi!ates ablac9body orwhich O 1 othe surace. ) 1.


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basics of mechanical engineering for renewable energy systems

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