I0N34a THERMODYNAMICA Oefenzitting 4 - bio-ingenieur - home
I0N34a THERMODYNAMICA Oefenzitting 4 - bio-ingenieur - home
I0N34a THERMODYNAMICA Oefenzitting 4 - bio-ingenieur - home
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
<strong>I0N34a</strong> Thermodynamica 2 de studiefase <strong>bio</strong>-<strong>ingenieur</strong>swetenschappen<br />
Oefening 1<br />
Oefening 2<br />
<strong>I0N34a</strong> <strong>THERMODYNAMICA</strong><br />
<strong>Oefenzitting</strong> 4: Machines II<br />
Oplossingen<br />
a) Condensatievat = Low-temperature heat exchanger<br />
Verzadigde vloeistof bij T1 =320K<br />
diagram isobutaan : P1 =0,65 MPa en H1 275 kJ / kg<br />
b) Turbine = adiabatisch/isentroop<br />
Isobutaan dat turbine binnengaat :<br />
T 480 K<br />
3<br />
P 10<br />
MPa<br />
3<br />
<br />
H 780 kJ / kg<br />
<br />
3<br />
3<br />
S 2,26 kJ / kgK<br />
Isobutaan dat turbine verlaat :<br />
<strong>Oefenzitting</strong> 4 - Oplossingen 1/4
<strong>I0N34a</strong> Thermodynamica 2 de studiefase <strong>bio</strong>-<strong>ingenieur</strong>swetenschappen<br />
P 0,65 MPa<br />
4<br />
T 360 K<br />
4<br />
<br />
S 4 2, 26 kJ / kgK<br />
<br />
H 4 660 kJ / kg<br />
c) Energiebalans – steady state<br />
dU<br />
dt<br />
<br />
0 W M in(<br />
H 4 H 3)<br />
<br />
<br />
W <br />
T <br />
43 <br />
H H 780 660 120 kJ / kg<br />
M in<br />
3MW 3000kW 3000<br />
kJ / s<br />
3000 kJ / s<br />
isobutaan M 25 kg / s<br />
120 kJ / kg<br />
e) Compressor : Q=0 (adiabatische omkeerbare compressie)<br />
W <br />
H 2H1 (290 275) kJ / kg 15<br />
kJ / kg<br />
M<br />
<br />
in<br />
W (15 kJ / kg)*(25 kg / s) 375<br />
kJ / s<br />
P<br />
Turbine : adiabatische omkeerbare expansie : -WT/Min =120 kJ/kg<br />
Condensatievat : isobare warmteafgifte<br />
Q<br />
M<br />
C<br />
in<br />
Boiler :<br />
Q<br />
M<br />
<br />
B<br />
in<br />
<br />
H 1H4 (275 660) kJ / kg 385<br />
kJ / kg<br />
<br />
H 3H2 (780 290) kJ / kg 490 kJ / kg<br />
Q 490 kJ / kg *25 kg / s 12,3<br />
MJ / s<br />
B<br />
f) Efficiëntie :<br />
netto arbeid uit 3000 375<br />
kJ / s<br />
0,213 of 21,3%<br />
warmte in boiler 12,3*1000 kJ / s<br />
<strong>Oefenzitting</strong> 4 - Oplossingen 2/4
<strong>I0N34a</strong> Thermodynamica 2 de studiefase <strong>bio</strong>-<strong>ingenieur</strong>swetenschappen<br />
Oefening 4<br />
a)<br />
1→2:<br />
boiler<br />
2 3<br />
1<br />
V1 = 1,917 10 -3 m 3<br />
P1 = 10 5 Pa<br />
T1=300K<br />
condensatievat<br />
V2 =V1/18= 1,065 10 -4 m 3<br />
P2 =P1V1 γ V2 -γ =5,72 10 6 Pa<br />
W = (P1 V1 γ ( 1<br />
) ( 1<br />
)<br />
<br />
V<br />
<br />
2 V1<br />
) <br />
1<br />
1<br />
<br />
PV 2 2<br />
T2 = T1<br />
PV 1 1<br />
2→3:<br />
= 953 K<br />
V3 = 2V2=2,13 10 -4 m 3<br />
P3 =P2= 5,72 10 6 Pa<br />
W =- P ∆V = - 609,2 J<br />
PV 3 3<br />
T3 = T2<br />
= 1906 K<br />
PV<br />
3→4:<br />
2 2<br />
V4 = V1 = 1,917 10 -3 m 3<br />
4<br />
= 1044 J<br />
<strong>Oefenzitting</strong> 4 - Oplossingen 3/4
<strong>I0N34a</strong> Thermodynamica 2 de studiefase <strong>bio</strong>-<strong>ingenieur</strong>swetenschappen<br />
P4 = P3V3 γ V4 -γ = 2,64 10 5 Pa<br />
W = -1781 J<br />
T4 = 792 K<br />
4→1: geen arbeid<br />
Netto arbeid: + 1044 – 609,2 – 1781 = -1346 J in één cyclus.<br />
Warmte opname in stap 2→3:<br />
Q nC T =2123 J (T stijgt van 953 naar 1906 K)<br />
p<br />
Warmte-afgifte in stap 4→1:<br />
Q nC T = - 782 J<br />
v<br />
b)<br />
S2 – S1 = Cp ln (T2/T1) – R ln (P2/P1) = 0<br />
S3 – S2 = Cp ln (T3/T2) – R ln (P3/P2) = + 20 J/(mol . K)<br />
S4 – S3 = 0<br />
S1 – S4 = Cp ln (T1/T4) – R ln (P1/P4) = - 20 J/(mol . K)<br />
<strong>Oefenzitting</strong> 4 - Oplossingen 4/4