ETHYLENE VINYL ACETATE EVA GLASS EVA SAFETY GLASS EVA LAMINATED GLASS COLORED EVA GLASS COLLECTIONS
Eva Cool
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Transcript of Eva Cool
READ!ME
Evaporation cooling Thermocompressor design
Steady state: calculate temperature at the cooling box for given mass flowrate of motion steam
Transient: calculation of time course of temperature in the cooling box
Input parameters are in
Cooling box
Evaporated water
Condenser
Motion steam
Laval nozzle
Strana 1
READ!ME
Thermocompressor design
Steady state: calculate temperature at the cooling box for given mass flowrate of motion steam
Transient: calculation of time course of temperature in the cooling box
blue cells
Strana 2
COOLING-STEADY STATE
Evaporation cooling
Thermocompressor designMotion steam parameters Ambient temperature [C]
p1[MPa]= 0.62 40
T1= 157.7967 Area of cooling box walls [m2]
M [kg/s]= 0.01 100
Condenser (the compressor output), cooling water Heat transfer coef. [W.m-2
.K-1
]
T5[C] 40 30
p5[MPa] 0.007351 Antoine equation lnp=A-B/(C+T) is used
Evaporated water (the compressor suction) Kappa= 1.13 0.11504425
T2[C] p2[MPa] Pe=p1/p2 Pk=p5/p2 fe=Me/Mp fm=Mp/Me Me[kg/s]
30 0.00422 147 1.74 1.86 0.54 0.018609
29 0.00398 156 1.85 1.74 0.58 0.017386
28 0.00375 165 1.96 1.63 0.61 0.016324
27 0.00354 175 2.08 1.54 0.65 0.015390
26 0.00333 186 2.21 1.46 0.69 0.014562
25 0.00314 197 2.34 1.38 0.72 0.013821
24 0.00296 210 2.49 1.32 0.76 0.013153
23 0.00278 223 2.64 1.25 0.80 0.012548
22 0.00262 237 2.81 1.20 0.83 0.011995
21 0.00246 252 2.99 1.15 0.87 0.011489
20 0.00231 268 3.18 1.10 0.91 0.011024
19 0.00217 286 3.39 1.06 0.94 0.010593
18 0.00204 304 3.61 1.02 0.98 0.010194
17 0.00191 324 3.85 0.98 1.02 0.009822
16 0.00179 346 4.10 0.95 1.06 0.009476
15 0.00168 369 4.38 0.92 1.09 0.009151
14 0.00157 394 4.67 0.88 1.13 0.008847
0
10
20
30
40
50
60
70
80
90
20
Q-[
kW
]
Strana 3
COOLING-STEADY STATE
Qchl[kW] Qztraty[kW]
44.662 30
41.727 33
39.178 36
36.937 39
34.949 42
33.171 45
31.568 48
30.114 51
28.789 54
27.574 57
26.457 60
25.423 63
24.465 66
23.574 69
22.742 72
21.963 75
21.233 78
0
10
20
30
40
50
60
70
80
90
20 22 24 26 28 30 32
T-suction [C]
STEADY STATE COOLING
Qchl[kW]
Qztraty[kW]
Strana 4
TRANSIENT
Evaporation cooling : transientMass of water in evaporator M= 100 [kg] Initial temperature of water [C]=
Motion steam parameters Ambient temperature [C]
p1[MPa]= 0.62 40
T1[C]= 157.7967 Area of cooling box walls [m2]
Mp [kg/s]= 0.01 (mass flowrate) 100
Condenser (the compressor output), cooling water Heat transfer coef. [W.m-2
.K-1
]
T5[C]= 40 5
p5[MPa] 0.007351 Antoine equation lnp=A-B/(C+T) is used
Evaporated water (the compressor suction) Kappa= 1.13 0.115044248
Assuming, that the largest mass of water is in the evaporator tank, the analysis of transient start-up or shut-down can be restricted to the heat balance of evaporator
M.cp.dT/dt = - Me.r+S.k.(Te-T), where Me is the mass flowrate of evaporated water and r(T) is the latent heat of water
This is a ordinary differential equation which must be evaluated numerically if the heat of evaporation is not a constant
Nevertheless it will be interesting to compare the numerically obtained results with the analytical solution for r=const.
Its your bussines to find out the analytical solution. The numerical solution in the column A is explicit. Rewrite it to the more precise implicit form.
Time step of numerical integration 100 [s]
T2[C] p2[MPa] Pe=p1/p2 Pk=p5/p2 fe=Me/Mp r[kJ/kg] Me[kg/s]
30 0.00422 147 1.74 1.86 2459 0.018609
20.30 0.00235 263 3.12 1.12 2485 0.011157
16.04 0.00180 345 4.09 0.95 2496 0.009489
13.25 0.00150 414 4.91 0.86 2504 0.008631
11.29 0.00131 472 5.60 0.81 2509 0.008109
9.86 0.00119 520 6.16 0.78 2513 0.007764
8.81 0.00111 559 6.62 0.75 2515 0.007525
8.01 0.00105 590 7.00 0.74 2518 0.007354
7.41 0.00101 615 7.29 0.72 2519 0.007229
6.96 0.00098 635 7.53 0.71 2520 0.007136
6.61 0.00095 651 7.71 0.71 2521 0.007067
6.34 0.00094 663 7.86 0.70 2522 0.007015
6.14 0.00092 673 7.97 0.70 2522 0.006975
5.98 0.00091 680 8.06 0.69 2523 0.006945
5.86 0.00090 686 8.13 0.69 2523 0.006922
5.76 0.00090 690 8.19 0.69 2523 0.006904
5.69 0.00089 694 8.23 0.69 2524 0.006890
5.64 0.00089 697 8.26 0.69 2524 0.006880
5.59 0.00089 699 8.29 0.69 2524 0.006872
5.56 0.00089 700 8.30 0.69 2524 0.006865
5.53 0.00088 702 8.32 0.69 2524 0.006861
5.51 0.00088 703 8.33 0.69 2524 0.006857
5.50 0.00088 703 8.34 0.69 2524 0.006854
5.49 0.00088 704 8.35 0.69 2524 0.006852
5.48 0.00088 704 8.35 0.69 2524 0.006850
5.47 0.00088 705 8.36 0.68 2524 0.006849
5.47 0.00088 705 8.36 0.68 2524 0.006848
0
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10
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20
25
30
35
0
T [
C]
START UP
Strana 5
TRANSIENT
5.46 0.00088 705 8.36 0.68 2524 0.006847
5.46 0.00088 705 8.36 0.68 2524 0.006846
5.46 0.00088 706 8.37 0.68 2524 0.006846
Strana 6
TRANSIENT
30 cp[J/kg/K]= 4.2
Assuming, that the largest mass of water is in the evaporator tank, the analysis of transient start-up or shut-down can be restricted to the heat balance of evaporator
M.cp.dT/dt = - Me.r+S.k.(Te-T), where Me is the mass flowrate of evaporated water and r(T) is the latent heat of water
This is a ordinary differential equation which must be evaluated numerically if the heat of evaporation is not a constant
Nevertheless it will be interesting to compare the numerically obtained results with the analytical solution for r=const.The numerical solution in the column A is explicit. Rewrite it to the more precise implicit form.
Qcool[kW] Qlosses time [s] T Q [kW]
45.760 5 0 30 45.760
27.727 9.852 100 20.29519 27.727
23.689 11.980 200 16.03936 23.689
21.611 13.374 300 13.25164 21.611
20.346 14.355 400 11.29045 20.346
19.509 15.068 500 9.864078 19.509
18.928 15.597 600 8.806755 18.928
18.513 15.993 700 8.01349 18.513
18.210 16.293 800 7.413488 18.210
17.986 16.521 900 6.957082 17.986
17.817 16.696 1000 6.608489 17.817
17.690 16.829 1100 6.341444 17.690
17.594 16.932 1200 6.136417 17.594
17.521 17.011 1300 5.978744 17.521
17.464 17.071 1400 5.857336 17.464
17.421 17.118 1500 5.763762 17.421
17.388 17.154 1600 5.691589 17.388
17.363 17.182 1700 5.635892 17.363
17.343 17.204 1800 5.592891 17.343
17.328 17.220 1900 5.559681 17.328
17.316 17.233 2000 5.534027 17.316
17.307 17.243 2100 5.514205 17.307
17.300 17.251 2200 5.498887 17.300
17.295 17.256 2300 5.487049 17.295
17.291 17.261 2400 5.477899 17.291
17.288 17.265 2500 5.470826 17.288
17.285 17.267 2600 5.465359 17.285
0
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50
1000 2000 3000 4000
Q [
kW
]
t [s]
START UP - COOLING T
Q [kW]
Strana 7
TRANSIENT
17.283 17.269 2700 5.461132 17.283
17.282 17.271 2800 5.457865 17.282
17.281 17.272 2900 5.455339 17.281
Strana 8
GRAPHS
0
10
20
30
40
50
60
70
80
90
20 22 24 26 28 30 32
Q-[
kW
]
T-suction [C]
STEADY STATE COOLING
Qchl[kW]
Qztraty[kW]
0
5
10
15
20
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30
35
40
45
50
0
5
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25
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35
0 500 1000 1500 2000 2500 3000 3500
Q [
kW
]
T [
C]
t [s]
START UP - COOLING
T
Q [kW]
Strana 9