jj 507 – thermodynamic 2 -unit 1

8/19/2019 Jj 507 – Thermodynamic 2 -Unit 1

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Prepared By :

MUHAMMAD ZUHAIRY BINZULKIFLI

B.Eng(Manufacturing), (Hons), UKMLecturer

Jab. Keuruteraan Me!ani!a"Po"ite!ni! Kota Kinaba"u

JJ #$% & 'HEM*+-M/ 0



1y""abus : 1.0 ADVANCED STEAM POWER PLANT

'2is topic co3ers t2e process in an!ine cyc"e, 1uper2eated an!ine cyc"eand e2eat an!ine cyc"e. 1tudents are re4uire to dra5 '6s diagra7 forsuper2eated an!ine cyc"e and deter7ine t2e super2eated stea7 region.1tudents are re4uire to ca"cu"ate t2e isentropic e8ciency, cyc"ee8ciency, 2eat input, 5or!, speci9c stea7 consu7ption and 5or!ratio.

2.0 STANDARD AIR CYCLE

'2is topic pro3ides understanding of processes in3o"3ed in t2e nterna"/o7bustion Engine and t2e Heat Engine. t re4uires dra5ing of tto and*iese" cyc"e and ca"cu"ation on 2eat e8ciency 7ean eecti3e pressure,co7pression ratio for t2e respecti3e cyc"e.

3.0 INTERNAL COMBUSTION ENGINE

'2is topic e;p"ain t2e 3arious para7eter re"ated to t2e perfor7ance ofinterna" co7bustion engine suc2 as indicated po5er, ndicated 7eaneecti3e pressure, bra!e po5er, friction po5er, engine tor4ue, pistonspeed, speci9c fue" consu7ption, 7ec2anica" e8ciency, t2er7a"e8ciency, co7pression ratio and 3o"u7etric e8ciency. 1tudents arere4uired to ca"cu"ate t2e respecti3e para7eters and to co7p"ete t2e 2eatba"ance s2eet.



4.0 GAS TURBINE

'2is topic e;pose students to t2e operation of open cyc"e gas turbine basedon '6s diagra7, 7et2od to i7pro3e t2er7a" e8ciency and p"ant

5or! ratio using intercoo"er, re2eated and 2eat e;c2anger. ta"so in3o"3es ca"cu"ation of t2e net 5or! output, t2er7a" e8ciency,isentropic e8ciency, 5or! ratio and pressure as 5e"" as gas te7peraturefor open type gas turbine cyc"e, intercoo"er and re2eated.

5.0 REFRIGERATION

'2is topic e;p"ains refrigeration and air conditioning. t s2a"" inc"udes t2eoperation of refrigerated 3apour co7pression cyc"e 52ic2 re4uiresstudents to ca"cu"ate t2e coe8cient of perfor7ance, refrigeratingeect , 2eat "oss, 7ass <o5 rate, refrigerant te7perature, inputpo5er and 5or! done. '2e student needs to dra5 '6s and p62diagra7.

.0 HEAT TRANSFER '2is topic states t2e concepts of 2eat transfer bet5een bodies. '2ree typesof 2eat transfer according to t2e =ourier>s "a5 of conduction ande5ton>s "a5 of coo"ing. '2e student needs to dra5 b"oc! diagra7,e"aborate on t2e genera" e4uations and ca"cu"ate 2eat transfer as 5e""as 5a"" te7perature.



U!"# 1

ADVANCED STEAMPOWER PLANT



1.0 R$!%"!& C'()&

'2ere are 7any syste7s in use today 52ic2con3ert t2er7a" energy into 5or! t2roug2 at2er7odyna7ic cyc"e. n po5er p"ants, genera""y,t2e co7bustion of fossi" fue" for7s t2e 2ig26te7perature source and t2e at7osp2eric air or a"arge body of 5ater for7s t2e "o56te7peraturesin!. n t2e an!ine cyc"e t2e 5or!ing <uidundergoes p2ase c2anges ("i4uid to 3apour or 3ise3ersa) 52i"e going t2roug2 t2e 3arious processesof t2e cyc"e. '2e 5or!ing <uid is in genera" 5ater,

a"t2oug2 <uid suc2 as 7ercury, a77onia ora"co2o" can be used for specia" app"ications.



'o co7p"ete t2e basic an!ine cyc"e four co7ponents arere4uired. '2ey are t2e boi"er, t2e turbine, t2e condenser

and t2e pu7p, as s2o5n sc2e7atica""y in =igure ?.?.

3

4

1

2

=igure ?.? '2e co7ponents of a basic stea7 p"ant



B*")&+: Here 2eat is supp"ied to 5ater (t2e5or!ing <uid), 52ic2 is con3erted into 2ig26

pressure stea7.

T,+-"!&: Here t2e 2ig26pressure stea7 e;pandto a "o5 pressure and turns t2e turbine rotor togi3e 5or! output.

C*!&!/&+: Here so7e 2eat is reected bycoo"ing and condensing t2e "o56pressure stea7into 5ater.

P,: Here t2e "o56pressure 5ater is pu7pedbac! to t2e boi"er and t2e cyc"e is co7p"eted. '2epu7p needs 5or! input.



'2e basic an!ine cyc"e is 7ade up of four t2er7odyna7icprocesses as i""ustrated in =igure ?.0

=igure ?.0 '2e basic an!ine cyc"e



'2e idea" an!ine cyc"e does not in3o"3e any interna"irre3ersibi"ity and consists of t2e fo""o5ing processes:

4 #* 1: /onstant pressure 2eat addition in aboi"er

1 #* 2: sentropic e;pansion ta!ing p"ace in t2eturbine or engine

2 #* 3: /onstant pressure 2eat reection in t2econdenser

3 #* 4: sentropic co7pression of 5ater in t2efeed pu7p



n t2e an!ine cyc"e, t2e e;2aust stea7 is

co7p"ete"y condensed into 5ater in t2e condenser.t actua""y fo""o5s t2e isentropic e;pansion in t2eturbine. '2is 5ater is t2en pu7ped into t2e boi"erby a boi"er feed pu7p. -fter t2e feed pu7p, sincet2e 5ater is not at t2e saturation te7perature

corresponding to t2e pressure, so7e of t2e 2eatenergy supp"ied in t2e boi"er is ta!en up by t2e5ater as sensib"e 2eat before e3aporation canbegin. '2is resu"ts in t2e boi"er process being no"onger co7p"ete"y isot2er7a"@ t2e process is,

t2erefore, irre3ersib"e, causing t2e an!ine cyc"eto be an irre3ersib"e cyc"e.



'2e stea7 <o5s round t2e cyc"e and eac2 process7ay be ana"ysed using t2e steady <o5 energy

e4uation 52ere c2anges in !inetic energy andpotentia" energy 7ay be neg"ected.

i.e. h1 + Q = h2 + W

n t2is state7ent of t2e e4uation t2e subscripts ? and0 refer to t2e initia" and 9na" state points of t2eprocess@ eac2 process in t2e cyc"e can be consideredin turn as fo""o5s:

S, * $)) #& &!&+' &!#&+"! S, * $)) #&&!&+' )&$6"!



B*")&+7

h4 + Qs = h1 + W

'2erefore, since W A $,

Qs = h1 – h 4 %89%



T,+-"!&7

'2e e;pansion is adiabatic (i.e. QL A $), and

isentropic (i.e. s1 = s2 ), and 20 can beca"cu"ated using t2is "atter fact. '2en

h1 + QL = h2 + W 12

W T = h1 – h2 %89%



C*!&!/&+7

h2 + QR = h3 + W

'2erefore, since W A $

QR = h3 – h2 %89%



P,7

h3 + Q = h4 + W p

'2e co7pression is isentropic ( i.e. s3 = s4 ), and adiabatic( i.e. Q A $ ).

W p = ( h3 – h4 ) = -( h4 – h3 )

W p h 4 – h3 %89%

-s 5ater is inco7pressib"e, t2e pu7p 5or! can be ca"cu"atedappro;i7ate"y as:Pu7p 5or! input = v w ( PC & PD)

W p = v f ( P4 : P3;9 1000 %89%

52ere W p A pu7p 5or! input, !J!gv f A speci9c 3o"u7e of 5ater A $.$$? 7D!g

PD A pressure at pu7p entrance, 70

PC A pressure at pu7p e;it, 70



E!&+' B$)$!(& *+ T& C*)&#& P)$!#

F1 G P A ' G F(

F1 6 F( A ' 6 P

<N&# 5 WN&#

52ere F,et A net 2eat added to t2e p"ant,

!J!g

,et A net 5or! output fro7 t2e p"ant,

!J!g



'2e net po5er output fro7 t2e p"ant can beca"cu"ated as:

P = WN&# %W

52ere P A Po5er, !

I A stea7 <o5 rate, !gs

,et A net 5or! output fro7 t2e p"ant,!J!g



an!ine e8ciency or t2er7a"e8ciency of t2e p"ant is de9ned as:

plantthetosuppliedHeat

plantthefromoutput Net work= Rη

S

Net

Q

W =

41

3421 )()(

hh

hhhh

−

−−−

=



'2e 5or! ratio for an!ine cyc"e is de9nedby :

outputworkturbine

outputnet work=

T

Net

W

W =

)(

)()(

21

3421

hh

hhhh

−

−−−

)(

)(v)(

21

34f 21

hh

p phh

−

−−−

or!ratio

i.e. or!ratio A

or or! ratio A



kg/kwh36

Net W

kg/kwh)()(

36

3421 hhhh −−−

-not2er criterion of perfor7ance in stea7 p"ant is t2especi9c stea7 consu7ption. t re"ates t2e po5er

output to t2e stea7 <o5 necessary to produce stea7. '2e stea7 <o5 indicates t2e sie of p"ant 5it2 itsco7ponent part, and t2e speci9c stea7 consu7ptionis a 7eans 52ereby t2e re"ati3e sies of dierentp"ants can be co7pared.

'2e speci9c stea7 consu7ption, (1.1./.) is t2e stea7<o5 in !g2 re4uired to de3e"op ? !,

S&(">( S#&$ C*!/,#"*!

or 1.1./. A

".&. W N&#

? S.S.C. 1 ? 300 %89

i.e. 1.1./. A



E?$)& 1

- stea7 po5er p"ant operates bet5een aboi"er pressure of C0 bar and a condenserpressure of $.$D# bar. /a"cu"ate for t2ese

"i7its t2e a) cyc"e e8ciency, b) t2e 5or!ratio, and t2e c) speci9c stea7consu7ption for a an!ine cyc"e 5it2 drysaturated stea7 at entry to t2e turbine.



Solution:

'2e an!ine cyc"e is s2o5n in t2e 9gurebe"o5.

253.2

26.7



-s in e;a7p"e (use stea7 tab"e) @

h1A 0$$ !J!g and h2 A ?$ !J!g

-"so, h3 = hf at $.$D# bar A ??0 !J!g

v = v f at $.$D# bar



Pu7p 5or! A 6W DC A ν f (p4 – p3 )

A $.$$? ; ( C0 & $.$D#) ; ?$0

A C.0 !J!g

W 12 = h1 – h2 A 0$$ & ?$ A 0 !J!g



)()(

)()(

3431

3421

hhhh

hhhh R

−−−

−−−=η

)2!4()1122"(

)2!4()##2(

−−

−

=

= 0.368 or 36.8 %

a) /yc"ee8ciency,



work gross

net work =

##2

4!2$##2

b) Work ratio

=

= 0.996

=



)()(

36

3421 hhhh −−−

)2!4()##2(

36

−

c) s.s.c. =

= 3.64 kg/kW h

=



1.2 A(#,$) C'()& * #& R$!%"!& C'()&

Pressure drop due frictiona" eects and 2eat"oss to t2e surrounding are t2e 7osti7portant "osses. '2ese cause irre3ersibi"ityand resu"t in t2e production entropy.

Because of t2e pressure drop in t2e boi"er,t2e 5ater entering t2e boi"er 7ust bepu7ped to a 7uc2 2ig2er pressure t2an t2edesired stea7 pressure "ea3ing t2e boi"er.

'2e e8ciency ratio of a cyc"e is t2e ratio oft2e actua" e8ciency to t2e idea" e8ciency.



n 3apour cyc"es t2e e8ciency ratio co7pares

t2e actua" cyc"e e8ciency to t2e an!ine cyc"ee8ciency,

effi%ien%& 'ankine

effi%ien%& &%le=

E8ciency ratio



=igure ?.D an!ine cyc"e s2o5ing rea" processes on t2e T-s diagram



'2e actua" e;pansion process is irre3ersib"e, ass2o5n by "ine ? & 0> in =igure ?.D. 1i7i"ar"y, t2eactua" co7pression of t2e 5ater is irre3ersib"e, as

indicated by "ine D 6C. '2e isentropic e8ciency of aprocess is de9ned by

workisentropi%

work a%tual=

hh

hh

2$1

2)$1=

worka%tual

work isentropi%=

hh

hh

3$4)

3$4=

sentropic e8ciency for a co7pression process (pu7p)

sentropic e8ciency for an e;pansionprocess (turbine)



E?$)& 2 @+&&+ &?$)& 1;/a"cu"ate t2e a) cyc"e e8ciency, b) t2e 5or!

ratio and c) t2e speci9c stea7 consu7ption52en e;pansion process 2as an isentropic

e8ciency $.



hh

hh

2$1

2$1=

##2

hh 2)$1=

W 12

= h1 – h

2 A 0$$ & ?$ A 0 !J!g

$.

W 12’

=$. (0) A %D.N !J!g

sentropic e8ciency



)()(

)()(

3431

3421

hhhh

hhhh R

−−−

−−−=η

)2!4()1122"(

)2!4()6!*#3(

−−

−

work gross

net work =

*#3!6

4!2$*#3!6

a) /yc"e e8ciency,

A

A $.0C O 0.C

A$.#

b) or! ratio

A



)()(

36

3421 hhhh −−−

)2!4()6!*#3(

36

−

A C.#N !g! 2

A

c) s.s.c.

A



'2e a3erage te7perature at 52ic2 2eat issupp"ied in t2e boi"er can be increased bysuper2eating t2e stea7. Usua""y t2e drysaturated stea7 fro7 t2e boi"er dru7 passedt2roug2 t2e /,&+&$#&+ unti" t2e stea7

reac2es t2e re4uired te7perature. '2e cyc"e e8ciency 2as increased due to

super2eating and t2e i7pro3e7ent in speci9cstea7 consu7ption is e3en 7ore 7ar!eted. '2is

indicates t2at for a gi3en po5er output t2e p"antusing super2eated stea7 5i"" be of s7a""erproportions t2an t2at using dry saturated stea7.

1.3 R$!%"!& C'()& W"# S,&+&$#



=igure ?.Cb 1tea7 p"ant 5it2 super2eat



E?$)& 3 @R&&+ &?$)& 1 )

/o7pare t2e an!ine cyc"e perfor7ance ofE;a7p"e ? 5it2 t2at obtained 52en t2estea7 is super2eated to #$$$ /. eg"ect t2efeed6pu7p 5or!.



442

344+1

−

−h

4+

344+3433

−

−

442

"#!*1

−

− s

4+

"#!*#*+!6

−

−

Solution :

=ro7 super2eated stea7 tab"e, by interpo"ation, at C0 bar (boi"er) and con

By interpo"ation:

2?A DCC0.N !J!g

s0A s

f 0G ;

0s

fg0A $.D? G ;

0.?D A

%.$NN

;

0 A $.0?

20A 2

f 0G ;

02

fg0A ??0 G $.0?(0CD)

A 0??D !J!g

A

A

s?A %.$NN !J!g K

A s0



31

21

hh

hh

−

−

333!6

132#!6=

?0

A 2?&2

0A DCC0.N & 0??D A ?D0.N !J!g

FD?

A 2?&2

DA DCC0.N & ??0 A DDD$.N !J!g (feed

pu7p is neg"ected)

/yc"e e8ciency A

A $.DD OD.

)(

36

21 hh −

6!132#

36

s.s.c. A

A 0.%? !g!2 O $.$$$%#0 !g!s

A



'2e condenser 2eat "oad for dierent p"ants can beco7pared by ca"cu"ating t2e rate of 2eat re7o3a" in

condenser, per unit po5er output.

/ondenser 2eat "oad A s.s.c ; (206 2

D)

2ere (206 2

D) is t2e 2eat re7o3ed in condenser by t2e

coo"ing 5ater

=or e;a7p"e ? (saturated stea7 at entry to turbine):/ondenser 2eat "oad A $.$$?$? (?$ 6 ??0)

A ?.%?D ! per K5 po5er output

=or e;a7p"e D (super2eated stea7 entry to turbine):/ondenser 2eat "oad A $.$$$%#0 (0??D 6 ??0) A ?.#$# ! per ! po5er output



Ent2a"py6 entropy c2art can be use to ana"ye stea7po5er p"ant in addition of 1tea7 'ab"e.

E!#$)' E!#+*' C$+#



t is desirab"e to increase t2e a3eragete7perature at 52ic2 2eat is supp"ied to t2estea7, and a"so to !eep t2e stea7 as dry aspossib"e in t2e "o5er pressure stage of

turbine. '2e e;2aust stea7 condition canbe i7pro3ed 7ost eecti3e"y by re2eatingt2e stea7 being carried out in t5o stages

1.4 T& R&&$# C'()&



2631

6*12

QQ

W W

+

+

)()(

)()(

2631

*621

hhhh

hhhh

−+−

−+−=

'2e ana"ysis is as fo""o5s:

Heat supp"ied A FD? G F0N A (2? & 2D) G (2N 6 20), t2e feedpu7p 5or! is neg"ected

or! output A ?0

G N%

A (2?& 2

0) G (2

N& 2

%)

,

'ycle e((icie!cy =



E?$)& 4 @R&&+ E?$)& 3;

/a"cu"ate t2e ne5 cyc"e e8ciency and speci9cstea7 consu7ption if re2eat is inc"uded in t2ep"ant of E;a7p"e D. '2e stea7 condition at in"et tot2e turbine are C0 bar and #$$$ /, and t2econdenser pressure is $.$D# bar as before. -ssu7e

t2at t2e stea7 is ust dry saturated on "ea3ing t2e9rst turbine at 0.D bar, and is re2eated to its initia"te7perature. eg"ect t2e feed6pu7p ter7.



Solution:

t is con3enient to read o t2e 3a"ues of ent2a"py fro7 h-s

c2art, i.e. 2? A DCC0.N !J!g@2

0A 0%?D !J!g (at 0.D bar)@ 2

NA DC% !J!g (at 0.D bar and

#$$$ /), 2%A 0#D# !J!g.

=ro7 tab"es

2D A??0 !J!g



41+

16"2

16"2

1

/yc"e e8ciency A

A $.C? or

C?

A $.$$$##!g !s A 0.?C !g!2

ssc A

/o7paring t2ese ans5ers 5it2 t2e resu"t of E;a7p"e D itcan seen t2at t2e speci9c stea7 consu7ption 2as been

i7pro3ed considerab"y by re2eating (i.e. reduced fro70.%?!g!2 to 0.?C !g!2. '2e e8ciency is greater (i.e.increased fro7 D. to C? ). '2e cyc"e e8ciency 5i"" beincreased on"y if t2e 7ean te7perature of t2e 2eat supp"yis increased, t2is 5i"" not be t2e case if t2e re2eat

jj 507 – thermodynamic 2 -unit 1

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