Understanding Potential for Phase Change Material ... · Understanding Potential for Phase Change Material Applications in Residential Buildings Jan Kosny Ph.D. Building Enclosure

© Fraunhofer USA 2009

Fraunhofer Center for Sustainable Energy Systems

Understanding Potential for Phase Change Material Applications in Residential Buildings

Jan Kosny Ph.D.

Building Enclosure Program Lead

Residential Energy Efficiency Meeting, sponsored by the U.S. Department of Energy's (DOE) Building America Program

Denver, COJuly 21, 2010


Massive Stone Cave - A First Home for Human Beings:

WHY…?

flat temperature profile year around uniform radiation temperature fields uniform humidity no drafts fresh air ???


Our Predecessors Knew How to Use Thermal Mass and Live in Hot Climates Without Air-Conditioning


Native Americans Preferred Massive Adobe Homes


Igloo is a First Known PCM House Developed for Heating Dominated Climates


Today, there is a serious reason why, we may utilize PCM thermal mass in building envelopes?Diminishing energy savings’ returns for conventional insulations

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00

6.54

2.80

1.56

0.99

0.69

0.50

0.38

0.30

0.25

0.20

0.17

0.15

0.13

Energy Savings kBtu/year per ft2 of Floor Area

R-va

lue

rang

e, h

.ft2 .

°F/B

tu

Living Room&

Open Kitchen Area Bedroom #3

Bedroom #2

Main Bedroom

Bathroom

Main Bath

Single story ranch house – floor area 130 m2 (1400 ft2)

9.5-

m (2

6-ft)

16-m (53-ft)

Attic insulation Atlanta

Energy Consumption Change GJ per year

R-v

alue

Cha

nge


-15

-10

-5

0

5

10

15

20

25

30

48 52 56 60 64 68 72 76 80 84 88 92 96

Time [hrs]

Btu

/(hr-

ft2)

~70%

~90%

Conventional asphalt shingle roof

Metal roof with cool-roof surface, PCM, and sub-venting

Metal roof with cool-roof surface, and sub-venting

-15

-10

-5

0

5

10

15

20

25

30

48 52 56 60 64 68 72 76 80 84 88 92 96

Time [hrs]

Btu

/(hr-

ft2)

~70%

~90%

Conventional asphalt shingle roof

Metal roof with cool-roof surface, PCM, and sub-venting

Metal roof with cool-roof surface, and sub-venting

PCMs are only one of many engineering means helping to enhance thermal performance of buildings


Other Enabling Technologies for New Generation of Dynamic Multifunctional Envelopes

Thermal Insulations Reflective Insulations Radiant Barriers Cool Coatings (cool roofing, cool walls) Conventional Thermal Mass Phase Change Materials Ventilated Cavities BIPVs and Solar-Thermal Systems Mechanical or Radiant Systems and Hydronic Heat

Exchangers


Whole Building HVAC Energy [GJ]

9698

100102104106108110

0 20 40 60 80 100

Attic R-value

Typical Roof Insulation Roof R-38 Insulation with 20% of PCM

75

Bakersfield, CA

Dynamic Attic R-value Equivalent

Whole Building HVAC Energy [GJ]

9698

100102104106108110

0 20 40 60 80 100

Attic R-value

Typical Roof Insulation Roof R-38 Insulation with 20% of PCM

75

Bakersfield, CA

Dynamic Attic R-value Equivalent

PCMs can be blended with conventional insulations

R-38 PCM-enhanced Attic Insulation in Bakersfield, CA works like R-75 conventional Insulation


Understanding of PCMs

Phase Change Process“Melting/Crystallization heat” Ice-Water: Δ H = 333 kJ/kg

at 0oC(32oF)

333 kJ/kg

Temperature Difference“Heat capacity”

Water: cp ≈ 4.2 kJ/kg · K

1oC 80oC (34oF 176oF)

332 kJ/kg


Engineering Functions of PCMs

Local Temperature Control Peak Load Time Control Dynamic Thermal Break Enhanced Heat Storage Thermal Comfort


Key Physical Characteristics and Other Important Parameters of PCMs

Total Enthalpy (heat storage capacity) Necessary Amount => Cost Phase Change

Temperatures• melting• freezing

Sub-Cooling Effect Purity Location within the Building

or Building Envelope


PCM Thermal Mass in Buildingscan be almost everywhere

Parts of the building structure• roofs and attics• exterior walls• interior walls• floors, and ceilings• fireplaces, stairs, etc...

Space Conditioning Systems Furniture Finish materials Passive solar heat storage containers


Traditional Approach – Concentrated PCM - Thermal Storage

PCM charged bythe interiortemperature swings and solar gains through the glazing

Building HVAC system used todischarge PCM

Schematic of Distribution of Heating and Cooling Loads in Old PCM Applications

Energy Discharged Later by HVAC System

CavityInsulation

PCM-Thermal Storage

Exterior Finish

Exterior

Interior

Peak Loads

Energy Transferred INTO the Building

Energy Transferred Back to the Environment

Solar Gains


More Advanced PCM Applications

Use fluctuations in exterior temperature and solar irradiationfor charging and discharging of PCM

PCM material has to be able to fully charge and discharge energy during 24-hour dynamic cycle

Schematic of Distribution of Heating and Cooling Loads in PCM-Enhanced Building Envelopes with Thermally Active Core

Peak Hour Energy Transferred Back to the Environment

ThermallyActive Core

LOW HEATTRANSFERZONE

Gypsum BoardLow Delta T

Min. Heat Transfer

Exterior Finish

Exterior

Interior

Peak Loads


Large Selection of Inorganic and Organic PCMs is available today

PCM powder


Basic Differences in PCM Technologies

Inorganic Phase Change Materials Organic Phase Change Materials Different Encapsulation and Packaging

Methods;• Micro-encapsulation• Macro-encapsulation• Macro-packaging

Different PCM Applications:• Dispersed PCMs• Concentrated PCMs• PCM slurries


Thermal Characteristics of PCMs which have to be seriously considered

Enthalpy for commonly-used paraffinic PCM

-45

-30

-15

0

15

30

45

16 17 18 19 20 21 22 23 24 25 26

TEMPERATURE [C]

[J/g

]

melting freezing

Thermostat temperature control +/-2degF


Current Estimates for Expected Thermal Characteristics of PCMs to be used in residential buildings

Approximate PCM melting temperatures for Southern U.S. locations

Conditioned space

Approximate Range of Useful Temperature Fluctuations in Different Parts of the Building is Between 40oF and 180oF

Solar

HoursTe

mpe

ratu

re

150F

110F

80F

70F

65F


Some PCM Products are pretty COMPLEX and may require detailed simulations and advanced testing methods

1

2

3

z

12

34

56

78

9

x

12

34

56

78

9

y

X Y

ZFrame 001 08 Mar 2009 23-degF PCM HF apparatus SS test 3-D

4

5

6

y

107.063

89.4375

74.75

65.9375

X

Y

Z

T001107.063104.125101.18898.2595.312592.37589.437586.583.562580.62577.687574.7571.812568.87565.9375

Frame 001 08 Mar 2009 23-degF PCM HF apparatus SS test 3-D


PCM Technologies which have been Developed and already Field Tested in Collaboration with DOE’sBuilding Envelopes Program

21


New PCM-Enhanced Fiber Insulations - New Approach for Dispersed Thermal Mass

Blown Fiberglass Blown Cellulose


PCM-Enhanced Cellulose Insulation has been Field Tested in Two Locations


PCM-Enhanced Blown FiberglasAttic field testing in Oak Ridge, TN


PCM Test House in Oak Ridge, TN with R-30 PCM Walls and R-50 PCM Attic Insulation


Four generations of roofs with PCM heat sinkshave been field tested in Oak Ridge, TN


What to Avoid with PCM Technologies?

27


Price over $3.50 per lb for material of minimum heat storage density of 150 J/g

28


Final enthalpy of the PCM heat sink product lower from 120 J/g

29


Enthalpy for commonly-used paraffinic PCM

-45

-30

-15

0

15

30

45

16 17 18 19 20 21 22 23 24 25 26

TEMPERATURE [C]

[J/g

]

melting freezing

PCMs with significant sub-cooling effects

30

This temperature gap has to

be min.


Potentially Leaky PCM Packages with Corrosive PCMs

31


Let’s Work Together!

THANK YOU!

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Understanding Potential for Phase Change Material ... · Understanding Potential for Phase Change Material Applications in Residential Buildings Jan Kosny Ph.D. Building Enclosure