mass transport phenomenaj-t.o.oo7.jp/kougi/ee-tech/hirai-ppt.pdfunderstanding mass transport...
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化学反応、燃焼とCO2隔離Chemical Reaction ,Combustion and CO2 sequestration
Bill
ion
ton
(oil)
/ ye
ar
coal
oil
natural gas
atomic power
waterpower
New energy ?
Oil shock (2nd)
Oil shock (1st)
Increase of fossil-fuel consumption
Increase of CO2 concentration
futurepast
Global warming
Measures for CO2 mitigation
Oil :45 yearsNatural gas :65 yearsCoal :230 years
(1) promotion ofenergy saving
(2) renewable energy
(3) sequestration of CO2
Present talk
Promotion ofenergy saving
Polymer electrolyte fuel cells (PEFCs)
vehicle applications local on- site power generation system
Sequestration of CO2
CO2 ocean / underground Sequestration
Understanding mass transport phenomenaincluding reactionin PEFC and CO2 ocean sequestration is necessary for implementation
Phase diagram of H 2O- CO2 - hydrate
100
50
10
5
1
p[M
Pa]
275 280 285 290
T [K]
Hydrate|Liquid CO2|H2O
Liquid CO2|H2O
CO2 gas|H2O
Hydrate|CO2 gas|H2O
Intermediate and deep ocean
Liquid CO 2 H2O
CO2 hydrate
Large cage Small cage
CO2 molecule
mass transport phenomena in CO 2 ocean sequestration
2
Liquid CO 2 droplets
Direct dissolution of CO 2
CO2 dissolved seawater
Initial stage
Liquid CO2
H2O
Pipe wall
massivehydrate plugs liquid CO2 to discharge
liquid CO 2could be discharged if hydrate keeps thin film
Liquid CO2
H2O
What is the conditions to distinguish these two types?
P=400[kgf/cm2] , T=7.2[℃]
Polycarbonate wall
Stainless wall
Liquid CO 2
Hydrate film
H2O
Stainless wall Polycarbonate wall
massive hydrate formation
No massive hydrate formation
low-polar-surface free energy
high-polar-surface free energy
use of low-polar surface free energy material for pipe wall would prevent massive hydrate growth to plug liquid CO 2 discharge
direct dissolution typedirect dissolution type
CO2 droplet dissolution must finish before arriving seasurfaceCO2 droplet dissolution must finish before arriving seasurface
Control of released liquid CO2 droplet sizeControl of released liquid CO2 droplet size
Fundamental understanding of liquid CO2 injection behavior with hydrate
Fundamental understanding of liquid CO2 injection behavior with hydrate
Injection and Boiling of
Liquid CO2 with Hydrate
direct dissolution typedirect dissolution type
Control of released liquid CO2 droplet sizeControl of released liquid CO2 droplet size
Liquid CO2 injection behaviorwith hydrateLiquid CO2 injection behaviorwith hydrate
CO2 droplet dissolution must finish before arriving seasurfaceCO2 droplet dissolution must finish before arriving seasurface
500m
Boiling of liquid CO2 with hydrate due to decompressionBoiling of liquid CO2 with hydrate due to decompression
gas
liquidP
Experimental apparatus for injection behavior
Hydrate filmNozzle diameter 1.6(mm)
LiquidCO 2
3
Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature
0
5
10
15
20
25
30
35
0 1 2 3 4 5 6 7 8 9 10 11
Temperature [ ℃]
Inje
ctio
n ve
loci
ty [
cm/s
ec]
(a ) sphere -like droplet separation
(b) Slenderdropletformation
(c) Dropletformation fromthe hydratecolumn
Hydrateformation
Tension of hydrate LargeSmall
Propagation velocity of hydrateLarge Small
(1) Single droplet perfectly covered with the hydrate film
(3) Droplet formation from laminar flow
(2) Single droplet not perfectly covered with the hydrate film
Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature
0
5
10
15
20
25
30
35
0 1 2 3 4 5 6 7 8 9 10 11
Temperature [ ℃]
Inje
ctio
n ve
loci
ty [
cm/s
ec]
(1) Single droplet perfectly covered with the hydrate film
(2) Single dropletnot perfectlycovered with thehydrate film
(3) Droplet formation from laminar flow
(a ) sphere -like droplet separation
(b) Slenderdropletformation
(c) Dropletformation fromthe hydratecolumn
Hydrateformation
Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature
0
5
10
15
20
25
30
35
0 1 2 3 4 5 6 7 8 9 10 11
Temperature [ ℃]
Inje
ctio
n ve
loci
ty [
cm/s
ec]
(1) Single droplet perfectly covered with the hydrate film
(2) Single dropletnot perfectlycovered with thehydrate film
(3) Droplet formation from laminar flow
(a ) sphere -like droplet separation
(b) Slenderdropletformation
(c) Dropletformation fromthe hydratecolumn
Hydrateformation
Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature
0
5
10
15
20
25
30
35
0 1 2 3 4 5 6 7 8 9 10 11
Temperature [ ℃]
Inje
ctio
n ve
loci
ty [
cm/s
ec]
(1) Single droplet perfectly covered with the hydrate film
(2) Single dropletnot perfectlycovered with thehydrate film
(3) Droplet formation from laminar flow
(a ) sphere -like droplet separation
dropletformation
(c) Dropletformation fromthe hydratecolumn
Hydrateformation
(b) Slender
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Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature
0
5
10
15
20
25
30
35
0 1 2 3 4 5 6 7 8 9 10 11
Temperature [ ℃]
Inje
ctio
n ve
loci
ty [
cm/s
ec]
(1) Single droplet perfectly covered with the hydrate film
(2) Single dropletnot perfectlycovered with thehydrate film
(3) Droplet formation from laminar flow
(a ) sphere -like droplet separation
(b) Slenderdropletformation
Hydrateformation
(c) Dropletformation fromthe hydratecolumn
Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature
0
5
10
15
20
25
30
35
0 1 2 3 4 5 6 7 8 9 10 11
Temperature [ ℃]
Inje
ctio
n ve
loci
ty [
cm/s
ec]
(1) Single droplet perfectly covered with the hydrate film
(2) Single dropletnot perfectlycovered with thehydrate film
(3) Droplet formation from laminar flow
(a ) sphere -like droplet separation
(b) Slenderdropletformation
(c) Dropletformation fromthe hydratecolumn
Hydrateformation
Injection Behavior with Lateral Flow(Typical case)
P
P
Hydrate film Nozzle diameter 1.6(mm)
Liquid CO2
5
Lateral water flowLiquid CO2 droplet with and without hydrate film
Buoyancy
Water flow
Boiling of Liquid CO2 by Decompression with Hydrate Film
Decrease of pressure Boiling
10
100
0 2 4 6 8 10 12 14 16Temprature(degree)
Pres
sure (
kgf/c
m2 )
with hydrate, dP/dt; ~0.1 (kgf/cm2/sec)with hydrate, dP/dt; 0.1~1.0 (kgf/cm2/sec)with hydrate, dP/dt; 1.0~ (kgf/cm2/sec)
without hydrate, dP/dt; 0.1~1.0 (kgf/cm2/sec)without hydrate, dP/dt; 1.0~ (kgf/cm2/sec)
50
40
30
20
60
70
8090
CO2(gas)CO2 (gas)+
hydrate
CO2(liq)CO2 (liquid)
+hydrate
Effect of decompression rate on boiling
Effect of hydrate film on boiling
Boiling starts as soon as pressure is lowered beyond the liquid-gas boundary in the case with hydrate.
Decompression rate
Time [sec]
Pres
sure
[kg
f/cm
2 ]
Small decompression rate(Same order of rising liquid CO2 droplet in ocean)
Large decompression rate
Liquid
Gas
Video Video (High speed camera)
Large decompression rate
Decompression rate (Small)Same order of rising liquid CO2 droplet in ocean
6
Liquid CO2 injection in CO2 saturated water
• Remarkable ruggedness was formed on the hydrate film
Temperature 281K
Pressure 39.2MPa(4000m depth)
Simulation of dissolution of liquid CO 2 droplet with hydrate film
( )oM k A C Ct ∞
∂ = − −∂
Hydrate film
Liquid CO 2
Surface concentration of hydrate
Dissolution of CO 2
with hydrate
20
30
40
50
60
70
80
90
5 10 15 20 25 30 35 40
T=13.0℃ (Without hydrate)T=8.0℃ (With hydrate)T=5.5℃ (With hydrate)T=3.0℃ (With hydrate)
C0 (
kg/m
3 )
P (MPa)
0.02
0.04
0.06
0.08
0.1
275 280 285 290
CO
2 co
ncce
ntra
tion
(-)
T (K )
C0 Surface concentration of hydrate
P = 30.4 MPaWith hydrate
Solubility (Aya et al., 1997)
Solubility (Dodds, 1956)
Liquid CO2
CO2 surface concentration of hydrate
Hydrate film
Large decomposition rate of hydrate (CO2-nH2O) to surface
Small mass transport rate of surface to water
Surface concentration of CO 2
= CO2solubility
深海底貯留Sequestration of CO2at sea floor
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・58,400,000tonが全て溶解するのに240年・It takes 240years for dissolution of 58,400,000ton of CO2
Hydrate film
地下帯水層へのCO2 隔離Underground disposal of CO2
• 帯水層への圧入
• Injection of CO2 into aquifer
p owe r plan t
CO2 se para tion
in je ction site
aquife rs
CO2 pipe -line
van derMeeret a l . , GHGT-6
T
T
P
P
MRI
test cell
high pressureregulator
pump
t hermostat ic bath
water injection system
air blowerair heater
CO2
P
CO2 injection system
pre ssure cont rolcylinder (100ml ,re sis ting pre ssure20MPa)
帯水層に圧入された超臨界 CO2 の可視化
Visualization of super-critical CO2 in aquifer
inlet exit(a) (b) (c) (d)
450 glass beads in a pixel
MR signal
1H(a)(b)(c)(d)
17.4
CO2圧入前Before CO2 injection
8
inlet temperature 49.1℃
inlet pressure 11 MPa exit pressure 9.87MPaexit temperature 36.4℃
inlet exit(a) (b) (c) (d)
0 1CO2saturation
packedbed ofglass beads
spongefilter
0 1CO2 saturation
2 minutes 10 minutes 14 minutes 19 minutes
超臨界CO2 の浮力による移動Super-critical CO2 behavior due to buoyancy
0 0.2 0.4 0.6 0.8 10
0.2
0.4
0.6
0.8
1
1.2
CO2 Saturation φ
Rel
ativ
e Pe
rmea
bilit
y
CO 2H2O
φ=0.32
縮流部をすぎるCO2と水Numerical simulation of CO2 - water through
contraction
φ=0.47
Promotion ofenergy saving
Polymer electrolyte fuel cells (PEFCs)
vehicle applications local on- site power generation system
Sequestration of CO2
CO2 ocean / underground Sequestration
Understanding mass transport phenomenaincluding reactionin PEFC and CO2 ocean sequestration is necessary for implementation
Polymer Electrolyte Fuel Cell (PEFC)
Vehicles and local on- site power generation system
High efficiency & high power density
Water management is very important because…
-. Solid Polymer Electrolyte (SPE) membrane shows high proton conductivity only in the wet (hydrated) state.
H2 O2
SPE membrane
H+
SPE membranePorous electrode (Cathode)(Anode)
H2
O2,N2
④H2OH+
e-
Load
H2O① Accompanied
water
③ Production of water
② inflow water vapor
⑤ Diffusion
Water transport in PEFC
We need to know water behaviors inside PEFC.Especially,-. Water diffusion-. Water distribution under PEFC operation.
But not easy to measure by conventional method.
To control hydration of the SPE membrane properly...
How about NMR/MRI?
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Magnetic Resonance Imaging (MRI) technique
・In- vivo and in- situ measurement・Visualization of molecules that include 1H inside the medium non- optically accessible,
e.g. porous media, polymer, complex flow system, etc...・3D Flow and temperature measurements・Chemical spices can be identified.・Self- diffusion coefficient can be measured.
Advantages and potential
Disadvantages
・nuclei limited (normally 1H, 13C, 19F…)・difficulties on gas phase・materials used in experimental apparatus ・temporal resolution
Exp. apps. (Diffusion measurement)
PEM
アクリル板
Magnet
Pre-amp.
Gradient power supplyNMR
console Work station
container
SPE membrane-. Nafion117-. Flemion
Acrylic plate
SPE membrane
Self-diffusion coefficient of water in the SPE membrane
JJ
JJJ
J
JJ
EE
EE
E
E
0
1
2
3
4
5
6
7
8
0 5 10 15 20 25
Dif
fusi
on c
oeff
icie
nt
cm2 /
s
water content n H2O/SO3H
J Nafion
E Flemion
×10-6
-. Self-diffusion coefficient decreases with decrease of water content in the membrane.-. In the most hydrated condition, self-diffusion coefficient is as 1/3 as that of pure water. -. Similar behaviors in both Nafion117(1100EW) and Flemion(1000EW)
H2, H2O
O2, H2O
A
e-
AH2, H2O
O2, H2O
Circuit: Open
Suddenly closed
Experimental condition for measurement of H2O
H2O & H+
H2O & H + & e- starts to move
How does the H2O in SPE membrane changes?
SPE membrane: Aciplex 340 µmSpatial resolution: 25 µm×780 µmSlice thickness: 10 mmAveraged image: 128Acquisition time: 40 min/image
Water distribution in the SPE membrane with various output current density
• MRI can probe water behaviors, especially water distribution, in the SPE membrane under the fuel cell operation.
• The SPE membrane gradually gets dried after the cell starts.
J
J
J
J
J
J
00.10.20.30.40.50.60.70.80.9
0 50 100 150 200 250
Vol
tage
V
Output current density mA/cm2
A
BC
DE
814[mV], 0[mA]
481[mV], 122[mA]
693[mV] ,47.0[mA]
395[mV] ,147[mA]
570[mV] ,92.0[mA]
23[mV] ,142[mA]
A B C
D E
SPE membrane
High H2O content
Low H2O content
化学反応・燃焼と環境問題(chemical reaction, combustion and environmental problems)
化学反応chemical reaction
エネルギーの抽出extraction of energy
物質の生成formation of substance
電気エネルギーelectric energy
熱エネルギー(燃焼反応)thermal energy(combustion)
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H2
H2
O2
H2O
H2O
化学反応Chemical reaction(燃料電池)Fuel cell
電気エネルギーElectric energy
H2
H2
O2
H2O
H2O燃焼combustion
熱エネルギーThermal energy
サイクルcycle
電気エネルギー・仕事Electric energy ・work
2 2 21
H O H O2
+ →
熱エネルギーThermal energy
電気エネルギーElectric energy 2228.6kJ/molH
2241.8kJ/molH反応熱(heat of reaction)
rH∆ =
G∆ =
25℃,0.1013MPa(1気圧)で安定な物質Substance stable at 25℃,1atm
標準物質(reference substance)
H2, O2, N2, C, S
標準生成エンタルピー(standard enthalpy of formation)f H∆ o
標準物質からある物質を生成するときのエンタルピーEnthalpy to form a substance from reference substance
標準生
成エ
ンタ
ルピ
ー(kJ/m
ol)
0 C N2S O2
CO2
SO 2
H 2O
COCH 4
NO2C 2H 4
NO
C2H2
100
200
-200
-100
-300
-400
H2
stan
dard
ent
halp
y of
for
mat
ion
エン
タル
ピー
基準
生成物
反応物
反応熱
r eactfH
Hr
pr odfH
enth
alpy heat of
reaction
reactant
product
11
O2H2
H2O
2
oH O
241.826kJ/molfH = -
生成物
2
oO
0kJ/molfH∆
2
oH
0kJ/molfH∆
標準
生成
エン
タル
ピー
0
-200
-100
-300
H2 O2H2 O2
反応物
標準物質
=
=
reactantreference substance
product
stan
dard
ent
halp
y of
for
mat
ion
エン
タル
ピー
基準
生成物
反応物
反応熱
r eactfH
Hr
pr odfH
enth
alpy heat of
reaction
reactant
product
=0 kJ/molH2
= -241.8 kJ/molH2
= -241.8 kJ/molH2
25℃,0.1013MPa(1気圧)で安定な物質Substance stable at 25℃,1atm
標準物質(reference substance)
H2, O2, N2, C, S
標準生成ギブス自由エネルギー(standard Gibbs free energy of formation)
標準物質からある物質を生成するときのギブス自由エネルギーGibbs free energy to form a substance from reference substance
f G∆ o
標準
生成
自由
エネ
ルギ
ー(k
J/mol
)
0 C N2S O2
CO2
H2O
CO
CH4
O
NO
H
100
200
-200
-100
-300
-400
H2OH
stan
dard
Gib
bs f
ree
ener
gy o
f fo
rmat
ion
生成物H2O
反応物H2+1/202
仕事電気エネルギー
0
-100
-200
-300
reactant
product
WorkElectric energy = -228.6 kJ/molH2
H2
H2
O2
H2O
H2O燃焼combustion
熱エネルギー Thermal energy
サイクル cycle
電気エネルギー・仕事 Electric energy ・work
= -241.8 kJ/molH2 (2000 K)
= -161.5 kJ/molH2
燃料電池Fuel cell
電気エネルギー・仕事 Electric energy ・work = -228.6 kJ/molH2
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水素からエネルギーを抽出する場合について,燃焼させるよりも燃料電池を用いる方が効率がいいことを示しているが,これは理論値を示しているだけで,実際のエネルギーの有効利用を考えるには,各種損失やエネルギーの輸送まで含めた全体のシステムとして評価することが重要となる.Energy extraction from H2 shows that efficiency using fuel cell is higher than combustion. It is noted that it just demonstrates a theoretical value. Efficient utilization of energy must evaluate whole system including loss, energy transportation.
Compare two CO2 mitigation strategies; CO2 sequestration and application of fuel cell to automobiles. How much would be the CO2 mitigation for these two in case of Japan. Consider the case for various parameters, for example, how many automobiles are changed from internal combustion engines to fuel cell.