Chuong 1-2 on tap

7/21/2019 Chuong 1-2 on tap

1/12

TRNG I HC BCH KHOA TPHCM

1

1 Pa = 1 N/m2. (Kpa, Mpa)

1 bar = 105N/m2=750mmHg

1 at = 0,981.105N/m2= 1 kgf/cm2= 10 mH2O = 735,5 mmHg.

1 mmH2O = 9,81N/m

2

.

1 mmHg = 133,32 N/m2.

nvopsut

Ap suat tuyet oi (p)

p = pkq+ pd

p = pkq- pck


2/12


ttdw pdv

wld dpv

dwkt=vdp

k

C

C

v

p

n

1i

iihh CgC

dv > 0W > 0 : hdnnthsinh cng.

dv < 0W < 0 : hnnpthnhncng

dq = Tds= CdtQ > 0 : nulnhitdo hnhnvo.

Q < 0 : nubnthnhtanhit.

C= C = 22,4.C; Cp-Cv=R=8314

Cp-Cv=R

dp < 0Wkt> 0 : hdnnthsinh cngkt.

dp > 0Wkt< 0 : hnnpthnhncngkt

Cng, nhitlng, nhitdung ring


3/12


3

Miquan hgiathnhphnkhilnggivthnhphnthtchri

1

;i ii n

i i

i

gr

g

;ii ig r

Phntlngcahnhp

1

. ;n

i i

i

r

1

1n

i

ii

g

Thtchringvkhilngringcahnhp

1

ni

i i

gv

1

;n

i i

i

r

.ii i i ii

Rp pg pg r p

R

Phnpsutcaccthnhphn

Thnhphnkhilng:

1

1n

i

i

g

Thnhphnthtch, mol:

;i i

i

V n

r V n 11

n

i

i

r


4/12


4

Bng s liu gi tr thc nghim

Kh l tng (c)p

, kcal/kmol. (c)v

, kcal/kmol. k

Loi c 1 nguyn t 5 3 1,667



Kh l tng (c)p, kJ/kmol. (c)v, kJ/kmol. k

Loi c 1 nguyn t 20,9 12,6 1,667

Loi c 2 nguyn t 29,3 20,9 1,4

Loi c 3 nguyn t 37,7 29,3 1,286

Nhm1 nguynt: gmcckh nhAr, Ne, He,

Nhm2 nguynt: gmcckh nhO2, N2, H2, CO, Khngkh,

Nhm3 nguynt: gmcckh nhCO2, SO

2, CH

4, C

2H

2, C

2H

4,

BngNDR kmol camtsloichtkh (kcal/kmol.)

BngNDR kmol camtsloichtkh (kJ/kmol.)


5/12


dq = du + dw; dq = du + pdv

dq = divdp; dq = di + dwkt

2

2

ddq di

V:

du = Cv.dT; di = Cp.dT

Nncc biu thc vit cho L1 c thm cc dng sau

dq = du + pdv = Cv.dT + pdv

dq = divdp = Cp.dTvdp

Cho G kg chtmigii:Q=U+Wtt

Q=I +Wkt

U=GCvT

I=GCpT

nhlutnhitngthnht

Cho 1 kg chtmigii:q=u+Wtt

q=i +Wkt

u=CvT

i=CpT


6/12


p = const 2 2

1 1

v T

v T

w12= p(v2v1) (J/kg) W12= p(V2V1) (J)

wkt12= 0

Qp= GCp(T2T1) (J) ,U=GCvT

(J/K)2

1

lnpT

S GC

T

w12= 0

Wkt12= V(p1p2), (J)

Qv= U = GCv(T2T1), (J)

(J/K)22 1

1

lnvT

S S S GC

T

v = const 2 2

1 1

p T

p T


7/12


7

T = const

(J)

2 1

1 2

p v

p v

1 212 12 1 1

2 1

ln lnktp V

W W GRT p V p V

2 1

1 2

ln lnV p

S GR GRV p

QT = W12, (J)

dq = 0, pvk

= const,

p

v

C

k C

2 1

1 2

;

k

p v

p v

11

2 2 1

1 1 2

;

kk

kT p v

T p v

1 1 2 212 1 2 ---1 -1p V p VGRW T T

k k

1 1

1 1 2 1 212

1 1

1 11 1

k k

k kp V p GRT pW

k p k p

Wkt12=k. W12 , S = 0, i=- wkt12

1/

2 1

1 2

;

k

v p

v p

1

11 2

2 1

;kv T

v T


8/12


Qutrnhabin pvn= const

2 1

1 2

;

n

p v

p v

1

2 1

1 2

;nv p

v p

11 1

2 2 2 1

1 1 1 2

;

nn n

nT p v v

T p v v

1 1

1 1 2 2 1 1 1 1 1 1 1 21 2

2 2 1

1 1 11 1 1 1 1

n n

tt

p V p V p V V GRT V p V T GRW T T

n n n V n V n T

1 21

kt tt

nGRW T T nW

n

Q = GCn (T2T1)

;n p

n v

C Cn

C C

;

p

v

Ck

C

1n v

n kC C

n

2 11

v

n kQ GC T T

n

1

12 1

1 2

;nv T

v T

12 1

1 2

;

n

np T

p T


9/12


9

Biu din cc qu trnh trn th p - v


10/12


10

Biu din cc qu trnh trn th T - s


11/12


V d 1

V d 2


12/12


V d 3

V d 4

Kho st mththngnhitnghlm vic vichtmigii lkh l

tngA, trngthiban unhitcakhlt1= 600oC. Sau khi cho kh

ginntheo qutrnhonnhitthunnghchntrngthi2 cnhitt2

= 220oC ththypsutkhgim10 lnso viban u. Cngsutsinh ra ca

hthngtrong qutrnhginnW = 1455 kW. ChobitlulngkhiquahthngG = 3,5 kg/s.

Xc nh:

1. S m on nhit ca qu trnh,

2. Gi tr nhit dung ring khi lng ng p Cpv ng tch Cvca kh A.

Cho 2,5 kg khMtan(CH4) ginnngita nhncmtcngthay i

thtchl650 kJ. Trong qutrnhginnninngcakhikhgimimtlngl255 kJ. Xcnhnhitlngtrao ivbinthinnhitca

qutrnh.

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Chuong 1-2 on tap