FP7 project - SAM.SSA
Sugar Alcohol based Materials for Seasonal Storage Applications
Workshop and Onsite Demonstration– CiCenergigune
Miñano, Alava, Spain
Sugar alcohols properties and
performances
Presented by Alexandre GODIN
Participants:
•
CNRS-I2M: M. Duquesne,
A. Godin, R. Cadoret, E. Palomo
•
SOLVAY: J. Daranlot,
R.Tadmouri, B. Pavageau
•
TU/e: R.M.J van Wissen,
H. Zhang, S. V. Gaastraa-Nedea
• Screening and selection of
sugar alcohols (SA) and sugar
alcohol blends (SA-blend)
• Key thermodynamics and
physical properties of selected
SA and SA-blends
• Undercooling, probability of
spontaneous nucleation and
crystal growth rates
SCREENING
Starting point
DATA BASE
30 polyols
160
Mono-, Disaccharide
Linear, ramified, cyclic, mix
C-atoms: 3 – 12
120
AND SELECTION
Mono-Linear
Mono-Cyclic
Disaccharide
Including most widely used polyols
3
 hm (kWh/m )
140
Blends?
100
80
UPPER LIMIT
Defined by monosaccharide
polyols with linear chain
60
40
0
50
Tm < 100°C
But LOW LATENT HEAT
100
150
200
Melting point (°C)
250
300
HIGH LATENT HEAT
But Tm > 100°C
30 SA-based
binary systems
D-Mannitol
Dulcitol
Inositol
Glycerol
Xylitol
Adonitol
Sorbitol
Arabitol
Maltitol
have been
investigated
Looking for either
suitable eutectic
points or suitable
molecular alloys
High temperature - High energy density components
Erythritol
D-Mannitol
Dulcitol
Inositol
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
190
Phase diagram
determination
180
Temperature (°C)
170
Fast estimation by infrared
thermography (new method)
Fast method
Fast method
DSC
Model
160
150
Differential Scanning
Calorimeter (DSC)
140
130
Thermodynamic modeling
120
110
0
20
40
60
%wt B/(A+B)
80
100
Most of the systems show eutectic points
Those with melting point bellow 100°C have been considered
360
Pure SA
Eutectics
Er-Gly
Er-Man
340
Enthalpy by melting (J/g)
320
300
8 eutectics
with melting
point less
than 100°C
and latent
heat ranging
from 190 J/g
to 300 J/g
280
260
240
220
200
180
0
20
40
60
80
100
120
Melting point (°C)
140
160
180
200
Tm : 75°C - 120°C
Potential to achieved total energy
density by melting around
120 kWh/m3 – 200 kWh/m3
SELECTED PRODUCTS FOR
FURTHER ANALYSIS
360
340
Enthalpy by melting (J/g)
Erythritol
Xylitol
Adonitol
L-Arabitol
+
Four eutectics
Er/Xy (36/64)
Ar/Xy (44/56)
Ad/Er (70/30)
Ar/Er (60/40)
Pure SA
Eutectics
Molecular alloys
320
300
280
260
240
70
80
90
100
110
Melting point (°C)
120
130
FULL CHARACTERIZATION
Melting point
& Latent heat
LATENT HEAT as high as that of salt hydrates
BUT with no problems of separation, segregation and corrosion
Fit :  T   AT  B
Density and volume
expansion
Very high density values
compared to most organic PCMs
ρliq ~ 1250-1500 kg/m3
Moderate-to-Low volume
expansion for most of them
ΔV/V < 10%
Specific heat capacity
SA
Solid: 1 – 1.8 J/g/K
Liquid: 2.3 – 2.8 J/g/K
Fit : C p T   AT 2  BT  C
x 0.45 - 0.67
Water
4.19 J/g/K
x 0.43 - 0.71
SA-blends
Solid: 0.8 – 1.5 J/g/K
Liquid: 1.8 – 3.0 J/g/K
Thermal conductivity (solid phase)
SA
In the same
range than salt
hydrates
SA-blends
Most organic PCMs
< 0.2 W/m/K
Thermal conductivity
(liquid phase)
Less important than the
thermal conductivity in solid
0.36 – 0.46 W/m/K
Comparable to salt hydrates
No significant differences
between SA et SA-blends
No significant variation with
temperature
Rheology - Viscosity
Dynamical Mechanical Analysis
At low shear rates,
the SA and SAblends behave as
Newtonian fluids
Measurements at constant shear rate
Viscosity (Pa*s)
Erythritol
D-Mannitol
Arrhenius Model
Paraffin wax: 1.9 Pa.s
For the
other ones
Temperature (ºC)
The viscosity increases
rapidly when decreasing
temperature and becomes
very high in highly
undercooled melts
Atoms mobility
in the liquid
Nucleation rates
& crystal growth
kinetics
PROBABILITY
OF
SPONTANEOUS NUCLEATION
Within classical nucleation theory
For diffusion-limited crystallization
The nucleation rate under steady-state
conditions is governed by 2 exponential terms
activation energy
regarding the atomic
diffusion process
activation energy for
the formation of
critical nuclei
 G * (T ) 
 Ga (T ) 

 exp  
I ss (T )  C exp  
k BT 
k BT 


At high undercooling,
this term controls the
nucleation
At small undercooling,
this term dominates
With increasing undercooling, the nucleation
rate first increases until a maximum value and
then it decreases
MOREOVER, with increasing
influence of the T-dependence of
the diffusion term, the maximum
value of the nucleation rate is shifted
to higher T and it is lower
Viscosity (Pa*s)
Erythritol
Xylitol
Adonitol
L-Arabitol
Er/Xy (36/64)
Ar/Xy (44/56)
Ad/Er (70/30)
Ar/Er (60/40)
Temperature (ºC)
For all the
products
(except Erythritol)
The energy barrier for atomic diffusion and
conformation changes is so high that the
nucleation rate is almost zero. The induction
time tends to infinity. The PROBABILITY OF
SPONTANEOUS NUCLEATION is negligible.
Nucleation cummulative distribution function
1
Test carried out at constant cooling
with droplets of different size deposited
on an Al-substrate
5.0 mg
6.8 mg
16.5 mg
0.9
0.8
0.7
Influence of the
droplet size
0.6
0.5
0.4
0.3
Test carried out at constant cooling
with droplets of 10 mg deposited on
different substrates
0.2
0.1
0
280
300
320
340
360
Temperature (K)
380
Erythritol
The probability of spontaneous
nucleation start to be higher than
1% at temperatures below 96°C
400
420
Influence of the
substrate
CRYSTAL GROWTH RATES
In situ experimental
analysis by microscopic
imaging techniques
OPTICAL MICROSCOPY
Isothermal conditions
MICROSCOPIC IR-THERMOGRAPHY
FACETED DENDRITIC
GROWTH
Xylitol
Erythritol
DENSE-BRANCHING
MORPHOLOGY
CRYSTAL GROWTH
KINETICS
•
•
•
Growth is controlled by
rearrangement processes
only at the liquid-solid
interface and is therefore
interface-controlled
The rearrangement process
involves a diffusive jump
(diffusion-limited kinetics )
as well as conformation
changes for some SA
The modern form of the
Wilson-Frenkel model
represents adequately
observed crystal growth
rates
fraction of interface
sites that are active
growth sites
activation energy
for atomic
rearrangements
chemical potential
difference between
the two phases
 Ga  
 Gls 
v  ao fv' exp  
 1  exp  

 RT  
 RT 
Wilson-Frenkel model
v
ao f
l2
3k BT
 S
exp   a
m
 R

 Gls 
 1  exp  


 RT 
Order of magnitude
for crystal growth
Erythritol
mm/s
Xylitol
Adonitol
L-Arabitol
Er/Xy (36/64)
Ar/Xy (44/56)
Ad/Er (70/30)
Ar/Er (60/40)
µm/s
Tm ~ 100°C
Conformational
changes in the
molecules are
required to go
from liquid to
solid
Viscosity (Pa*s)
The undercooled
melts are highly
viscous
µm/s
Temperature (ºC)
mm/s
FINAL SELECTION
Melting point
Latent heat
Availability in
the market
Cost
Enthalpy by melting (kWh/m3)
150
140
Pure SA
Eutectics
130
Er/Xy eu
Erythritol
120
Xylitol
110
100
90
80
70
0
50
100
Melting point (°C)
150
200
Very high undercooling with very
low probability of spontaneous
nucleation
Lower undercooling & higher
probability of spontaneous
nucleation
The activation of the
crystallization will be difficult
Lower crystal growth rates
Crystallization can be easily
activated
Higher crystal growth rates
COMPARED TO WATER
200
Xylitol
Erythritol
Xy/Er blend
Water Short-term
Water Long-term
180
Energy density (kWh/m3)
160
140
Sugar alcohols
120 – 190 kWh/m3
120
Water in a shortterm basis
60 – 100 kWh/m3
100
80
60
Water in a longterm basis
30 – 50 kWh/m3
40
20
0
30
40
50
60
70
80
90
Temperature (°C)
100
110
120
130
For seasonal storage applications, SA can provide total
energy density 4-6 times higher than that of water
Thank you for your attention