practice problems
DESCRIPTION
hgfgcgcTRANSCRIPT
Xa Ya Xc Yc Xe Ye0.00 0.00 0.00 0.00 0.00 0.000.10 0.20 0.10 0.20 0.10 0.060.20 0.36 0.20 0.30 0.20 0.150.40 0.61 0.40 0.45 0.42 0.420.55 0.75 0.55 0.55 0.55 0.600.60 0.79 0.60 0.58 0.60 0.680.80 0.90 0.80 0.72 0.80 0.891.00 1.00 1.00 1.00 1.00 1.00
PT 101.3
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.000.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Column CColumn TLinear (Column T)
Xa
Ya
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.000.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Xe
Ye
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.000.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Column IColumn TLinear (Column T)
XcYa
0.00 0.000.13 0.130.25 0.250.38 0.380.50 0.500.63 0.630.75 0.750.88 0.881.00 1.00
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.000.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Column CColumn TLinear (Column T)
Xa
Ya
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.000.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Column IColumn TLinear (Column T)
Xc
Ya
Tank 1 0.45 0.50 0.46Tank 2 0.70 0.80 0.71
kr 0.119
0.20 0.505 2
2.2360679775 1.4142135623731 1.82510.0894427191 0.353553390593274 0.1644901909296670.9105572809 0.646446609406726 0.835509809070333
(CAo-CA)/CAoExpected conversion using hydraulic residence time
Expected conversion using mean residence time
min-1
X 0.7Tau 6.934171 <-- Goal seek to find this valueRHS 0.699811
HRT Tank 2X 0.8Tau 10.37375 <-- Goal seek to find this valueRHS 0.799715
MRT Tank 2X 0.71Tau 7.199785 <-- Goal seek to find this valueRHS 0.709944
a) Reynolds Calc Bernoulli Eqn b)D 0.1016 m u2 12.33u 12.33 m/s u1 0rho 1020 kg/m3 alpha 1mu 1.90E-03 Pa_s KE term 76.01445Reynolds # 672517.1
g 9.81epsilon/D (Cast Iron Diagram) z2 20eps 2.00E-04 z1 0D 0.1016 m height term 196.2 c)eps/D 1.97E-03 m/mf from moody 0.006 Pressure Term
P2 345 kPa gfriction loss from pipes P1 0 kPa g d)f 0.006 rho 1020 kg/m3deltaL 25 m p term -338.2353D 0.1016 mu 12.33 m/s RHS 948.4432Ff 448.9042 m2/s2 LHS -338.2353
Ws -1286.679 J/kgFriction loss from fittingssum of kf 1.7 Convert Wsu 12.33 Ws -1286.679 J/kghf 129.2246 m2/s2 rho 1020
Vol. Flow 0.1 m3/sFf+hf 578.1288 m2/s2 Ws -131.2412 kWHX 10 mg 9.81 m/s2Ff+hf+HX 676.2288 m2/s2
Pmax calcWs -1286.679 J/kgrho 1020 kg/m3Pmax 1312412 PaPmax 1312.412 kPa
accounting for efficiency, pump A or B
increasing roughnessincreases friction factorincreases Ws (check efficiency equation)
if pump goes below vapour pressure of fluidbubbles can form and collapse creating shockwavescausing your pumps damage
2
9.9858D 15 cm
3 deg C
20 deg C
5 deg Calpha 1.04E-07 m2/sr 0.075 m
a) Unaccomplished Temp Change
-2
-17Y 0.117647
t 1.53E+04 st 4.262684 hours
b) New Ambient Temperature
-5 deg C
-10
-25Y 0.4
t 8.72E+03 st 2.421464 hours
Temperature gradient is the driving forceLarger temp gradient means faster heat transfer
c) Dough would freeze on the surface
d) Keep the dough in the freezer until it reaches the temp of the fridge at the surfaceThe overall delta T between freezer and dough is larger so it will reach fridge temperature fasterThen shove it in the fridge.
e) increase surface area
asp
Ksp
Tfridge
Ti
Tideal
Ta-T
Ta-Ti
Tfreezer
Ta-T
Ta-Ti
a) Jetting vs Non-Jetting Regime c)
Increasing flow rate decreases bubble sizeIncreases the number of bubblesResidence time increases (smaller bubbles are less buoyant)More mass transferHTU decreases
b) 2 Mass transfers
High concentration of BA in centre
Low concentration at surface
Concentration gradient from centre to surface
Mass Transfer happens tau
Then concentration of BA at surface is high
Low concentration in water Volume of Kerosene in ColumnConcentration gradient from surface to water tau
Mass Transfer happens
JETTING REGIME NON-JETTING REGIMEVolume of Droplet in Column
r
Number of Droplets#
Mass Transfer AreaD
Vk
Vw
Dp
Kc
Vk
Volk
Voldrop
Voldrop
AMT 1 drop
Total AMT
0.05 L/min
2 L/min 0.01 m/s
5 mm 0.03 m2
30 s 4.79 unit conversion
0.01 m/s X 0.03 mol/L 30 mol/m3
0 mol/L 0 mol/m3
Volume of Kerosene in Column 0.04311 mol/s0.5 min
0.05 L/min Convert flow rates
0.025 L rhomW 54.89 kmol/m3rhomK 4.75 kmol/m3
Volume of Droplet in Column rhomBA 8.92 kmol/m3 unit conversion
0.0025 m 0.05 L/min 0.00005 m3/min
6.54E-08 m3 2 L/min 0.002 m3/min
6.54E-05 L 0.2375 mol/min
109.78 mol/minNumber of Droplets
381.97 droplets
Mass Transfer Area0.005 m
7.853975E-05 m2
0.03 m2
NOTE, mk should be mBA
mBA calculation
Kc
Total AMT
Kp
Yi
MBA
Vk
Vw
Mk
Mw
Xi Calculation
2.5866 mol/min
109.78
0.2375
X 0.03
0
10.92095 mol/LY 0.023562 mol/L
MBA
Mw
Mk
Yi
Xi
RunHot Inlet Inlet Cold
(°C) (°C) (GPM) (°C) (°C)1 1 68.9 18.7 3 7 15.83 2 36.1 15.7 3 5.8 13.15 3 29.7 15.6 3 5.4 13.17 3 31.2 26.3 1 5 19.49 3 31 24.3 2 5 17.9
11 3 31.2 22.8 3 5 15.7GPM to m3s 0.0000631
997Di 2.5 cmDo 3.5 cm
pipe thickness 0.5 cm
CoefficientscP waterkJ/(kg·C˚)
4.19
Hot Side: Use a different correlationRun Tm mu (Pa*s) rho (kg/m^3) v (m/s) k (W/m*K) Re
1 27.370306807932 5.66E-04 9.88E+02 1.30E-01 0.64 2.27E+03
3 15.540486394002 1.02E-03 9.98E+02 2.60E-01 0.609 2.54E+03
5 13.141279688679 1.20E-03 9.99E+02 3.90E-01 0.603 3.25E+03
7 16.085131557911 1.55E-03 1.00E+03 3.90E-01 0.595 2.52E+03
9 16.000294582818 1.47E-03 1.00E+03 3.90E-01 0.596 2.65E+03
11 16.623489757232 1.40E-03 1.00E+03 3.90E-01 0.598 2.79E+03
Cold side:Run Tm mu (Pa*s) rho (kg/m^3) v (m/s) k (W/m*K) Re
1 27.370306807932 1.39E-03 1.00E+03 4.00E-01 0.598 7.19E+03
3 15.540486394002 1.45E-03 1.00E+03 4.00E-01 0.597 6.90E+03
5 13.141279688679 1.43E-03 1.00E+03 4.00E-01 0.598 6.99E+03
7 16.085131557911 1.19E-03 9.99E+02 1.30E-01 0.603 2.73E+03
9 16.000294582818 1.24E-03 9.99E+02 2.70E-01 0.602 5.44E+03
11 16.623489757232 1.32E-03 9.99E+02 4.00E-01 0.6 7.57E+03
Overall:U
645.858316281085
734.256574641391
Hot Flow rate (GPM)
Hot Outlet
Cold Flow Rate
Outlet Cold
833.640979093152
485.47559423851
692.786340932194
812.752899881096
Heat Duty
Run Q (kW) Cold Side
1 17.677340271068 17.6773403
3 11.410704307921 11.4107043
5 10.955109266208 10.9551093
7 7.8089388014813 7.8089388
9 11.084785537868 11.0847855
11 13.510789506334 13.5107895
Q (kW) Hot side
Use a different correlationPr Nu hi (W/m^2*K)
3.71E+00 1.65E+01 1055.04272
7.02E+00 2.19E+01 1332.31578
8.34E+00 2.80E+01 1688.60323
1.09E+01 2.48E+01 1473.12553
1.03E+01 2.54E+01 1514.45873
9.81E+00 2.60E+01 1555.50188
Pr Nu ho (W/m^2*K)
9.74E+00 6.96E+01 1665.28368
1.02E+01 6.85E+01 1635.72704
1.00E+01 6.88E+01 1646.49241
8.27E+00 3.00E+01 724.109289
8.63E+00 5.30E+01 1276.90347
9.22E+00 7.09E+01 1702.10758
Bernoulli Equation Friction TermsDn 0.02664 mZt 5.76 m eps/D calculationZdiff 4 m eps 0.00015 mZ2 9.76 m D 0.0525 m
eps/D 0.002857Velocity CalcVdot 11 m3/h SystemDpipe 0.0525 m Re 57003.04CSA 0.002165 m2 fric factor 0.006975u 5081.414 m/h pipe L 6.5
1.411504 m/s Extra H 5.76Ffsystem 6.490617
Reynolds Number Calckin visc 1.30E-06 m2/s Nozzleu 1.411504 m/s eps 0.00015D 0.0525 D 0.02664Re 57003.04 eps/D 0.005631
CSA 0.000557 m2g 9.81 m/s2 u 19734.89 m/h
5.481914 m/sRe 1.12E+05fric factor 8.06E-03L 1 mFfnozzle 18.19447
FittingsKf1 1.1 m2/s2Kf2 0.7 m2/s2Kf3 2.1 m2/s2u 1.411504 m/shf 3.885069 m2/s2
sum of F 28.57016
Ws CalculationsPressure Term 0Height Term 95.7456KE Term 15.02569Friction 28.57016Ws 139.3415 J/kg
Ws Conversionrho 999 kg/m3Vdot 11 m3/hWs 425.3398 W
Particles Unaccomplished Temp Change
8.5 m/s Ta - TK 0.79 W/m2C Ta - Ti
1.8 kJ/kgC Yrho 652 kg/m3
350 deg C Finite CylinderT 160 deg C rcylalpha 6.731425E-07 m2/s rslab
Air
flow rate 2000 cfm
1000 J/kgC
rho 1 kg/m3
2 deg Ct
uterminal
CP
Ti
Ysc = Ys x Yc
acyl
CP kcyl
as
Ta ks
Unaccomplished Temp Change
-158-348
0.454023
Finite Cylinder0.01 m
0.0125 m
1.5811
5.7565
1.2911
2.486122.37146 s
Ysc = Ys x Yc