PCM Industrial Applications

Amir Amini CEng FIMechEGroup Senior Research Specialist

The 31st HEXAG Meeting Northumbria University

20 May 2014

Contents

Phase Change Materials

Applications

Thermal Energy Storage

Future work

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

5

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

Typical PCM product

7

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

8

Sub-cooling

Temperature below melting point

9

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

11

Water Paraffin Wax

Water vs. Paraffin Wax

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)

13

• 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

16

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

18

TES

20

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

Thank You