Post on 15-Jan-2015
description
PCM Pellets for Thermal Energy Storage in Buildings
Ramin Abhari, P.E.July 22, 2013
Smart Building Construction Materials and Coatings
Honolulu, HI
Thermal Energy Storage (TES)
$$$?!
$!
Conventional Building System
Building System with PCM Thermal Storage
Day
Night
Air-Conditioning
Natural Ventilation Night
Night
DayPCM
Thermal Storage
The Prize for StorageL
oa
d,
arb
itra
ry s
ca
le
(me
ga
wa
tts)
1:0
0
2:0
0
4:0
0
3:0
0
5:0
0
6:0
0
7:0
0
8:0
0
9:0
0
Time of Day
10
:00
11
:00
13
:00
12
:00
14
:00
15
:00
16
:00
17
:00
18
:00
19
:00
20
:00
21
:00
22
:00
23
:00
0:0
0
Peak Load Power PlantsIntermediate Load
Power Plants
Base Load Power Plants
Typical summertime demand curve
Typical demand curve with TES
24
:00
200
300
400
500
600
700
800
900
1,000
-50 -40 -30 -20 -10 0 10 20 30 40 50 60
Enth
alpy (
J/g)
Temperature (deg C)
H-T Curves for Water and Octadecane Phase Change
Material (PCM)
Making PCM: Step 1. Paraffin Synthesis
O
O
O
O
O
OHC
+ 6 H2O + C3H8
+ 15 H2
3
(octadecane)
(veg oil)
H2C
H2C
NiMo cat
C16-C18 paraffin composition
Melt point = 21-23 ºC
Heat of fusion = 170-190 J/g
Making PCM: Step 2. Shape-Stable Pellets
70% paraffin, 30% HDPE
Twin-Screw Extruder
Under-water pelletizer
PVDC latex coating
Ethyl cellulose pre-coat
Wurster fluid-bed spray coater
Making PCM: Step 3. Coated Pellets
94%
95%
96%
97%
98%
99%
100%
101%
102%
0 1 2 3 4 5 6 7
Perc
ent o
f Ini
tial P
CM P
elle
t Mas
s Rem
aini
ng
Heat/Wash Cycle
Effect of PVDC Coating on Paraffin Seepage from PCM Pellets
5 kg scaleup coating lab coating uncoated
Coating eliminates paraffin seepage from PCM pellets
Alternate Pellet Coating
6% oil-absorbing calcium silicate powder in V-blender
SEM shows good two layer coverage
No paraffin seepage, but not solvent resistant
0
20
40
60
80
100
120
18 19 20 21 22 23 24 25 26 27 28
Ther
mal
Ene
rgy
Stor
ed (J
/g)
Temperature (ºC)
PCM pellet
brick
concrete
PCM Pellet Thermal Properties
Thermal mass in a flexible form
Compatible with sustainable architectural practices
Passive Storage: Building Envelopes
ORNL field test 2012
Add PCM to insulation
33% ↓ peak heat flux
13% ↓ net heat gain
-10
-5
0
5
10
15
20
25
30
35
40
0
1
2
3
4
5
6
7
8
9
10
8/29 8/30 8/31 9/1 9/2 9/3 9/4 9/5
Tem
pera
ture
(T),
'C
Heat
Flu
x (H
F), W
/m2
Heat Flux and Wall Cavity Temperatures: Aug 29 - Sept 4
HF cell
HF cell+PCM
HF cell/PCM/cell
T wall ext
42% reduction
Wall exterior temperature
Heat Flux across Cavities
Building Envelope Weekly Test Results
Heat Flux thru Cellulose Control
Heat Flux thru Cellulose+ PCM
PCM-Modified Insulation: Whole Building Model Addition of PCM
pellets to attic insulation
Up to 16% reduction annual electricity use
11-16 year payback
PCM-Modified Insulation: Flame Tests
PCM pellets added to cellulose attic insulation
Conformed to ASTM C739 flammability standard
Non-Passive Storage: Fixed-Bed Tubes
14” diam X 7.5’ PVC or PC pipe segment and a fan (cheap!)
Reduces heat gain of the inhabited space (1 ton-hr cooling capacity)
Warm a
ir
in (day)
Cool air out (day)
1
2
2
Cool air in (night)
Warm air out (night) 1
3
Air
flow
thro
ugh
bed
of P
CM
pel
lets
7.7 ft
14" ODPVC pipe
Air Out Air Out
Air In Air In
Outside
Wall
Inside Inside
10X higher heat transfer rate than passive storage
Replacing Daytime AC: Tube Wall
Visible energy conservation!
Summary
Demonstrated PCM production using commercial-scale equipment
PCM pellet performance validated in passive storage field test
Fire test passed on PCM-enhanced insulation system
Non-passive (PCM tube) application under development
Acknowledgements
U.S. Department of EnergySouthwest Research InstitutePolymer Center of ExcellenceAdvanced Fiber TechnologyThe Coating PlaceFraunhofer CSE