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DRYER HOPPER DESIGN
Yearly Total Capacity: CTotal 1 107
kg
Total Production Hours: DTotal 365 24 hr
Mass Flow Rate: mrate_chip
CTotal
DTotal
mrate_chip 1.142 103
kg
hr
ASUMPTIONS:Particle Shape is oval
Chip inlet temperature is 20C Chip is dried at 80CAvarage values
for CP's are usedVaporization is assumed to take place at 50C (Mean
value)For drying diffusive drying is assumed since PET is
hydroscopic. No constant drying period
FEEDSTOCK CHARACTERIZATION
Particle Small Diameter: D1 2.3 mm Wp 0.018 gParticle
Weight:
Particle Big Diameter: D2 2.7 mm solid 1380kg
m3
Bulk Density: bulk 750
kg
m3
True Density:
Particle Length: Lp 2.4 mm
Elipse Parameter a: aD1
2 Elipse Parameter b: b
D2
2
HEAT TRANSFER CALCULATIONS
CPsolid 1400joule
kg K CPwater 4185
joule
kg K CPvapour 1872
joule
kg K CPair 1009
joule
kg K
Specific Heat of Substances:
Feedstock Moisture: Hin1000
1000000 Hin 1 10
3
Inlet Air Density: air_70C 1.05kg
m3
Product Moisture: Hout20
1000000 Hout 2 10
5
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Feedstock Temperature: Tchip_in 20C Product Temperature:
Tchip_out 30.6 C Heat of Vaporization: vap 2270joule
kg
Dry Air Inlet Temperature: Tair_in 70C Dry Air Outlet
Temperature: Tair_out 63C Mean Temperature of Vaporization: Tv
30C
THERMODYNAMIC BALANCE EQUATIONqT mrate_chip CPsolid Tchip_out
Tchip_in Hin CPwater Tv Tchip_in Hin Hout vap Hout CPwater
Tchip_out Tv Hin Hout CPvapour Tchip_out Tv
qT 4.72 kWRequired Heat Power:
Required Hot Air at 120C:
mrate_air
qT
CPair Tair_in Tair_out mrate_air 0.668
kg
s Vrate_air
mrate_air
air_70C
Vrate_air 2.291 10
3
m3
hr
PRESSURE DROP CALCULATIONS
gc 32.174Kinematic Viscosity of Air at 80C: air_80C 2.075
105
kg
m s
Newtons Propotinality Constant:
Cp a b( ) 1 3
a b
a b
2
10 4 3a b
a b
2
Cp 7.867 mmCircumferential of the sphere:
Surface Area of the Particle: Sp Cp Lp 2 a b( ) Volume of a
Particle: Vp a b Lp
Sp 28.634 mm2
Vp 11.706 mm
3
Sphericity of a Particle: p
6
D2
Sp
Vp
p 0.908 Porosity of the Particle Pile: p 1bulk
solid
p 0.457
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TRIAL VARIABLES:
Ddryer 2.9 m Ldryer 2.41 Ddryer
Adryer_cross
Ddryer2
4Volume of the Cylinderical Part of the Dryer:Vdryer
Ddryer2 Ldryer
4
Vdryer 46.164 m3
Total Mass of the Pile: mdryer Vdryer bulk mdryer 3.462 104
kg
Total Residance Time of The Chips: Tresidance
mdryer
mrate_chip
Tresidance 30.33 hr
Artificial Velocity of Air in Dryer: air
Vrate_air
Adryer_cross
air 0.096
m
s
ERGUN EQUATION FOR PACK COLUMNS:
P Ldryer150 air air_80C 1 p
2
gc p2
D22
p3
1.75 solid air2
1 p
gc p D2 p3
P 113.769 103
bar
DIFFUSIVE HEAT TRANSFER RATE CALCULATIONS
Diffusivity of Moisture into PET at 30.6C:Dv 25.03 10
8
cm2
s
Tneeded
D22
ln 8Hin
2
Hout
2
Dv
Tneeded 30.346 hr
