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PCM Industrial Applications
Amir Amini CEng FIMechEGroup Senior Research Specialist
The 31st HEXAG Meeting Northumbria University
20 May 2014
Phase Change Material (PCM) products are:
• Organic, inorganic and Eutectic
• Engineered for Thermal Energy Storage (TES).
• Can store Energy as sensible and latent heat.
Organic, typically paraffin (alkanes) fatty acids, esters, alcohols
Inorganic, (salt hydrates)
Eutectic
Pros
· Low Cost(£85/kwh)
· Self nucleating
· Chemically inert and stable
· No phase segregation
· Recyclable· Available in large temperature
range
Phase change Temp.
2 to 167 (0C)
Moderate cost(£90/kwh)
High volumetric storage density(180-300 MJ/m³)
·Higher Thermal
Conductivity
(0.6W/m- K)· Non flammable· Low volume change
Phase change Temp.
7 to 117 (0C)
Sharp meltingpoint
· High volumetric
storage density
Phase change
Temp.0 to -114
(0C)
Cons Flammable· Low thermal conductivity
(0.2W/m-K)· Low volumetric storage density
(90-200MJ/m³)
Sub-cooling
· Phase
segregation
· Corrosion ofcontainmentmaterial
Limited availability
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Thermal properties • Phase change temperature in suitable operating range • High latent heat per unit mass • High specific heat
Physical properties• High density • Low density variation during phase change • Little or no super-cooling
Chemical stability •No chemical decomposition •Compatibility with container materials •Non-poisonous, non-flammable and non-explosive
• Available in large quantities • Inexpensive
Economic factors
*PCM selectionTo optimize storage performance and more cost effective TES
* Regin, A.F., Solanki, S.C. and Saini, J.S., Heat transfer characteristics of thermal energy storage system using PCM capsules: A review. Renewable and Sustainable Energy Reviews, 12 (2008), p. 2438–2458
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0
50
100
150
200
250
300
350
400
-75 -50 -25 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350
Late
nt
Hea
t (k
J/kg
)
Phase Change Temperature (⁰C)
Physical Properties of Various Manufacturers' Phase Change MaterialsACME PCP Australia PureTemp RGEES Rubitherm Salca Sasol Finoric Microtek Labs Climator Sweden AB PlusICE
>200 O C<200 O C
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SH Storage system vs. LH Storage system
Q = 𝑚 𝐶𝑝 DT= V cp ∆T ρ Q=m ( cp · ΔT + Δ hmelt )PCM
= V ρ ( cp · ΔT + Δ hmelt )PCM
Utilised heat capacity and change in Temp during charging and discharging
The smaller the working temperature difference, ΔT , the bigger the advantage of a latent heat storage unit versus a hot water storage unit.
10
0
50
100
150
200
250
300
350
400
450
0 20 40 60 80 100 120
Ene
rgy
Sto
red
(kJ
/kg)
ΔT ,K
Water
PCM
Comparison of PCM´s and water in storage systems
Applications / OpportunitiesWaste heat in the form of hot exhaust gases, cooling water (40-85 deg.C), and heat lost from hot equipment surfaces and heated products.
High: Temp>650ºC (Glass melting furnace)
Medium: 230ºC<Temp<650ºC (Steam boiler exhaust , Gas turbine exhaust,
Drying & baking ovens)
Low: Temp<230ºC (most industrial waste, condensate, Cooling water, Drying, baking,
and curing ovens, Heat pumps and ORC)
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• Automotive Direct / Indirect Passive Cooling
• Temperature Controlled Packaging & Shipping
• Military Backpack Battery Cooling
• Formula-1 Driver Comfort
• Datasafe Protection against Fire
• Integrated Domestic Solar Cooling & Heating
• Drink Can Passive Cooling
• Car Exhaust Heat Recovery Device for Domestic Hot
water Application
Typical small scale applications
Thermal Energy Storage with PCMBased on literature search, only a relatively small number of results have been reported on successful system studies with high capacity and high power rated storage units, especially for solar heating systems
Changzhou Sunhome Solar Water Heater Manufacture Co. 100ton high temperature molten salt storage tank.
• Thermal energy storage (TES) system Comprises:
• A suitable PCM for targeted application• Tank to contain PCM• Heat exchanger for transferring heat
from HTF to PCM
Thermal Energy Storage System
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Thermal Energy Storage System DesignTESHEX with embedding Heat pipe within PCM• Increasing heat transfer area with surface enhancement of the plate
will results faster PCM charging.• Increases heat transfer rate in TES heat exchanger system (melting
rate increases, improving discharging).• Maintaining small temperature difference between PCM and heat
transfer fluid• Compact design• Reduces volume in PCM space, and minimise TES capacity• Availability of the heat (Exergy) • High Efficient Heat pipe require to improve heat transfer
The defining characteristic of metal foams is a very high porosity: typically 75-95% of the volume consists of void spaces. The strength of foamed metal possesses a power law relationship to its density; i.e., a 20% dense material is more than twice as strong as a 10% dense material.
Metal Foam Enhanced Latent Thermal Energy Storage With Embedded Heat Pipes
*Heat transfer enhancement for thermal energy storage using metal foams embedded within phase change materials (PCMsC.Y. Zhao *, W. Lu, Y. TianSchool of Engineering, University of Warwick
*The metal foam can increase the overall heattransfer rate by 3–10 times
Metal foam wrapped Heat pipe PCM
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TES plate heat exchanger with Slurry PCM
PCM
Tank
Slurry
PUMP
Heat
Transfer
FluidTin
TPCM
Off
(charging)
On
(charging)
Tout
10% -20%
concentration
1-Plate2-Spacer3-Wide spacer
• Advantage• Increase heat capacity• Higher heat transfer
With Chemical EtchingPlates , Diffusion bonded
DisadvantageHTF influence by:• Fluid turbulence level• PCM concentration• Slurry breakup• Pumping
FUTURE WORK
Phase 1 –Identify an economical and efficient PCM with following properties:
• Compact and light • Thermally stable• High latent heat of fusion /unit mass• High specific heat• High thermal conductivity• High density• Operating temperature for application• Desire melting temperature range • Non-poisonous & non flammable• No chemical decomposition• Not corrosive
Phase 2Testing• Test and experiment with PCM• Analyse data and Identify properties• Develop small scale energy storage prototype with heat pipe for test
• Must be designed to withstand exposure to corrosive deposits.• Large unit required for heat Storage since storage capacity is a function
of PCM• This limits the economics of heat exchangers.
• Report
Phase 3Packaged design • Energy Storage Heat Exchanger utilising phase change materials (PCM)• Compact size • High Energy storage capacity, kWh• Test• Report