Do an Dong Co Dot Trong

8/2/2019 Do an Dong Co Dot Trong

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i hc SPKT Vinh Khoa: C Kh ng Lc

LI NI U

Trong bi cnh ca t nc ta hin nay v ang pht trin mt cch nhanh

chng v ang trn pht trin thnh mt nc cng nghip trong thi gian sp ti,

th vai tr ca ngnh ng c t trong ni chung v nn cng nghip t ni ring

rt l quan trng. C th hn th nn cng nghip t gp phn rt nhiu trong cc

ngnh nng nghip ,cng nghip ,dch v,v c bit l kh nng di chuyn rt linh

ng lm cho phn ln ngi dn Vit Nam chn t xe my lm phng tin

di chuyn qua thc y ngnh cng nghip t pht trin.Hc qua mn kt cutnh ton ng c t trong gip chng ta phn no c th hnh dung ra c cch

tnh ton thit k ra mt ng c t trong.V di y l bn thit k tnh ton ng

c t trong m ti p dng nhng kin thc v tnh ton ng c thit k.Hi

vng bn c c th c gp gip ti ti c th rt kinh nghim trong nhng bn

thit k tip theo.V xin cm n thy Phm Hu Truyn gip em tn tnh

trong qu trnh thc hin bn thit k.

Xin chn thnh cm n thy c!

Vinh,ngy 27 thng 12 nm 2010

Sinh vin thc hin

V nh Cng

CHNG ITNH TON CHU TRNH CNG TC CA NG C T TRONG

n : Mn hc CT SVTH: V nh Cng1


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1.1Trnh t tnh ton:

1.1.1S liu ban u:

1 Cng sut ca ng c Ne = 150 ( m lc

)

2 S vng quay trc khuu n= 3100 ( v/ph )

3 ng knh xi lanh D = 100 ( mm )

4 Hnh trnh piston S= 95 ( mm)

5 Dung tch cng tc Vh = 0.74613 ( dm3 )

6 S xi lanh i= 8

7 T s nn = 6.5

8 Th t lm vic ca xi lanh 1 5 4 2 6 3 7 8

9 Sut tiu hao nhin liu ge = 220

( g/ml.h)

10 Gc m sm xupap np 1 = 31 ( o )

Gc ng mun xupap np 2 = 83 ( o )

11 Gc m sm xupap thi 1 = 67 ( o )

Gc ng mun xupap thi 2 = 47 ( o )12 Chiu di thanh truyn ltt= 185 ( mm )

13 Khi lng nhm piston mpt= 1.187 ( mm )

14 Khi lng nhm thanh truyn mtt= 1.272 ( mm )

1.1.2 Cc thng s cn chn:

1. p sut mi trng : pk= 0.1 ( Mpa)

2. Nhit mi trng: Tk= 297 ( o k )

3. p sut cui qu trnh np: pa = 0.085 ( Mpa)

4. p sut kh thi: pr= 0.105 ( Mpa)

5. Mc sy nng mi cht: T = 6 ( o c)

6. Nhit kh st ( kh thi ): Tr= 1000 ( o k )

7. H s hiu inh nhit: t = 1.1

8. H s qut bung chy: 2 = 1

9. H s np thm: 1 = 1.0210. H s li dng nhit ti z: z = 0.85



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11. H s li dng nhit ti b b = 0.856

12. H s hiu nh th cng: d = 0.929

13. Ch s m a bin: m = 1.45

1.2. Tnh ton cc qu trnh cng tc

1.2.1. Tnh ton qu trnh np:

1.H s kh st r :

H s kh st r dc tnh theo cng thc

2

1

1 2

.( ) 1. .

. . .

k rr

r a mr

t

a

T T p

T ppp

+ =

=

1

1,45

1.(297 6) 0,105 1. .

1000 0,0850,105

6,5.1,02 1,1.1.0,085

r

+=

= 0.0699

Trong : m l ch s gin n a bin trung bnh ca kh st. m = 1,45

1.Nhit cui qu trnh np Ta:

Nhit cui qu trnh np Tac tnh theo cng thc:

1

1,45 1

1,45

( ) . . .

1

0,085(297 6) 1,1.0,0699.1000.

0,105350,5

1 0, 0699

m

ma

k t r r

r

a

r

a

pT T T

pT

T

+ + =

+

+ + = =

+

( oK )

Ta > 310 oK t yu cu

1. H s np v :1

1 2

1. . . . . .

1 ( )

mk a r

v t

k k a

T p p

T T p p

= +

=

1

1,451 297 0,085 0,105. . . 6,5.1,02 1,1.1.

6,5 1 (297 6) 0,105 0,085v

= +

= 0.8116

2. Lng kh np mi M1 :

Lng kh np miM1 c xc nh theo cng thc :



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3

1

432.10 . .

. .

k v

e e k

pM

g p T

=

Trong :

pe l p sut c ch trung bnh dc xc nh theo cng thc:

30. .. .

ee

h

NpV n i

=

Vh l th tch cng tc ca ng c c xc nh theo cng thc:

2 26. . 3,14.100 .95 .10 0, 74613

4 4hD S

V

= = = ( dm3 )

30.150.4

0,71550,74613.3100.8

ep = =

31

432.10 .0,1.0,8116 0,5516220.0.7155.297

M = = ( kmol/kg nhin liu )

2. Lng khng kh l thuyt cn t chy 1 kg nhin liu Mo :

Lng khng kh l thuyt cn t chy 1 kg nhin liu Mo c tnh

theo cng thc :

10,5120

0,21 12 4 32oC H O

M = + =

( kmol/kg nhin liu )

i vi nhin liu ca ng c xng ta c:C = 0,855 ; H = 0,145.

3. H s d lng khng kh :

Trng lng phn t ca xng l nl = 114 nn i vi ng c xng ta c:

1

1 10,5516

114 1,0602

0,5120

nl

o

M

M

= = =

1.2.2 Tnh ton qu trnh nn:

1. T nhit mol ng tch trung bnh ca khng kh:

19,806 0,00209. 19,806 0,00209.297 19,806vmc T= + = + = ( kJ/kmol. )

2. Tnhit mol ng tch trung bnh ca sn vt chy ( = 1).

51'' (17,997 3,504 ) (360,34 252,4 )102v

mc T = + + + =



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51'' (17,997 3,504.1,05) (360,34 252,4.1,05)102v

mc T= + + + =21,74337T

(kJ/kmol.)

3. T nhit mol ng tch trung bnh ca hn hp.

c tnh theo cng thc:'' '

'.'1 2

v r v vv v

r

mc mc bmc a T

+= = +

+

Ta t :

19,806v

a = , 0,02092

vb

=

'' 17,997 3,504. 17,997 3,504.1,0602 21,71197v

a = + = + =

( )''

51 . 360,34 252,4. .10 0,003142 2

vb

= + =

''

' . 19,806 0,0699.21,71191 19,9301 1 0,0699

v r vv

r

a aa

+ += = =

+ +

''

'.

2 2 0,00209 0,0699.0,003140,0216

2 1 1 0,0699

v vr

v

r

b b

b

+ + = = =+ +

Vy ta c t nhit mol ng tch trung bnh ca hn hp' 19,930 0,00216.297 20,5712v

mc = + = ( kJ/kmol. )

4.Ch s nn a bin trung bnh n1:

c tnh theo cng thc:

( )11 '

1'

8,3141

. . 12

nvv a

nb

a T =

+ + ( )1

1 1

8,3141

19,930 0, 00216.350,5. 6,5 1nn

=

+ +

( I )

Ta chn : n1 = 1.375 thay vo hai v ca phng trnh ( I ) ta c

phng

trnh tng ng : 0.375 = 0.3743

Sai s n1 = 0.1929 < 0.2%

5. p sut cui qu trnh nn pc :

p sut cui qu trnh nn pc c xc nh theo cng thc

1 1,375. 0,085.6,5 1,1147nc a

p p = = = ( MPa )



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6.Nhit cui qu trnh nn Tc:

Nhit cui qu trnh nn Tc c tnh theo cng thc :

1 1 1,3750 1. 350,5.6,5 707,2nc a

T T = = = ( oK)

7.Lng mi cht cng tc ca qu trnh nn Mc:

Lng mi cht cng tc ca qu trnh nn Mc c tnh theo cng thc:

Mc = M1 + Mr= M1. ( 1 + r) = 0.5516.( 1 + 0.0699) = 0.590

1.2.3: Tnh ton qu trnh chy :

1. H s thay i phn t l thuyt o :

Ta c tng mol M ca cc loi ng c c xc nh theo cng

thc:

M = 0.21.( 1 ). Mo + 14 32nl

H O

+

Nn h s thay i phan t l thuyt o c xc nh theo cng thc:

( ) o1

0.21. 1 . M4 32

11

.

nl

o

o

nl

H O

M

+ +

= ++

=

( )0,145 1

0.21. 1 1,0602 . 0,5120 4 1141 1.0381

11,0602.0,5120

114

o

+ = + =+

2. H s thay i phn t thc t ( do c kh st ).

c xc nh theo cng thc:

1,0381 0,06991,0356

1 1 0,0699o r

r

+ += = =

+ +

3. H s thay i phn t thc t ti im z ( z ) (do chy cha ht ):Ta c h s thay i thc t ti im z, z c xc nh theo cng thc

:

11 .

1o

z z

r

= +

+

Trong :

0,850,9930

0,856

zz

b

= = =



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1,0381 11 .0,9930 1,0353

1 0, 0699z

= + =

+

4. Lng sn vt chy M2 :

Ta c lng sn vt chy M2 c xc nh theo cng thc:

M2 = M1 + M = o.M1 = 1,0381+ 0,5516 = 0,5726 ( kmol/kg n.l )5. Nhit ti im z Tz :

i vi ng c Xng, nhit ti im z Tz c xc nh bng cch gii

phng trnh chy :

( )' ''.

1

( ). . . .

1

z H Hv c z vz z

r

Q Qmc T m c T

M

+ =

+ ( * )

Trong :

QH : nhit tr thp ca nhin liu ta c, thng thng c th chn

QH = 44000 ( kJ/kgnl ).

QH : nhit lng tn tht do nhin liu chy khng ht khi t 1 kg

nhin liu, thng thng c th xc nh QH theo bng cng

thc sau:

QH = 120.103.(1- )Mo (kJ/kgnl) khi < 1

QH = 0 khi 1 ''. vzm c : L t nhit mol ng tch trung bnh ca sn vt chy c

xc nh theo cng thc:

( )

( )

''

'' '' ''

. . . 1 . .

. .

. 1

ro z v z v

o

vz vz vz z

ro z z

o

m c m c

m c a b T

+ +

= = +

+ +

Ta c:

( )

( )

'' '

''

. . 1 .

. 1

ro v z z v

o

vz

ro z z

o

a a

a

+ +

=

+ +

=



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( )

( )

0.06991, 0381.21, 71197. 0, 9930 1 0, 9930 .19, 930

1, 038121, 70070

0,06991, 0381. 0, 9930 1 0.99301,0381

+ + = =

+ +

( )

( )

'' '

''

. . 1 .2 2

. 1

v vro z z

o

vz

ro z z

o

b b

b

+ +

=

+ +

=

( )

( )

0,06991, 0381.0, 0314. 0, 9930 1 0, 9930 .0, 00216

1,03810,00313

0,06991, 0381. 0, 9930 1 0, 9930

1,0381

+ + = = + +

'' 21, 70070 0,00313.vz z

mc T = + .

Thay vo phng trnh ( * ) ta c:

( )

( )' '' ''.1

( ). . . .

1

z H Hv c z vz vz z z

r

Q Qmc T a b T T

M

+ = +

+( )

( )0, 85. 44000 0

20,5712.707,2 1,0353. 21,70070 0,003130,5516.(1 0,699) z z

T T

+ = =+

20,00324 22,468 83876.71z z

T T + =

( )1

2

2689,1 /

4807, 26( i)( )z

z

T t m

T loa m

=

=

Vy nhit ti im z Tz = 2689.1

6. p sut ti im z pz:

Ta c h s tng p:

. 3,937z

z

c

T

T = =

p sut ti im z pz c xc nh theo cng thc:

pz = .pc = 3,937 . 1,1147 = 4,389 (MPa)1.2.4. Tnh ton qu trnh gin n:



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1. H s gin n sm :.

.

z z

c

T

T

=

i vi ng c xng: = 1

2. H s gin n sau :

Ta c h s gin n sau c xc nh theo cng thc: =

Vi ng c xng : = = 6,5

3. Ch s gin n a bin trung bnh n2 :

Ta c ch s gin n a bin trung bnh n2 c xc nh t phng trnh cn

bng sau:

( )( ) ( )

( )2 *

''''

1

8,3141

. .. 1 . . 2

b z H vzvz z b

r z b

nQ ba T T

M T T

= + + +

+

Trong :

Tb l nhit tr ti im b v c xc nh theo cng thc :

2 21 1

2689,1

6,5z

b n n

TT

= = ( oK )

QH* : Nhit tr tnh ton

i vi ng c xng:QH* = QH - QH= 4400 0 = 4400

( kJ/kg. )

Thay vo phng trnh;

( )

( )2

2

2

1

1

8,314

1 0,856 0,85 .44000 2689,121, 70070 0, 00313. 2689,1

2689,1 6, 50,5516. 1 0,0699 .1, 0356. 2659,1

6,5

n

n

n

= + + + +

Chn n2 = 1.23 thay vo hai v ca phng trnh trn ta c phng trnh

tng ng:

0,223 = 0,2303

4. Nhit cui qu trnh gin n Tb :

Ta c cng thc xc nh nhit cui qu trnh gin n Tb :



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2 1 1.23

2689,10.439

6,5z

b n

TT

= = = ( oK )

5. p sut cui qu trnh gin n pb :

p sut cui qu trnh gin n pb c xc nh theo cng thc :

2 1,234,389 0,4396,5

zb n

pp

= = = ( MPa )

6. Tnh nhit kh thi Trt :

Tnh nhit kh thi c xc nh theo cng thc:

1 1.45 1

1.450.105. 1748. 1121.56

0.4390

m

mr

rt b

b

pT T

p

= = =

( oK )

Sai s ca nhit kh thi tnh ton Trt v nhit kh thi chn

ban u Tr= 1000 khng vt qu 15%, ngha l :

1121,56 1000.100% .100% 0,108% 15%

1121,56rt r

rt

rt

T TT

T

= = =

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