thermal energy storage for buildings with pcm pellets
DESCRIPTION
An introduction to a PCM pellets, and how they can be used for thermal energy storage.TRANSCRIPT
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