reducing the energy consumption in buildings by...

Reducing the energy consumption in buildings by incorporating microencapsulated PCMs in rigid polyurethane foams

REDUCING THE ENERGY CONSUMPTION IN BUILDINGS BY INCORPORATING MICROENCAPSULATED PCMS

IN RIGID POLYURETHANE FOAMS

Manuel Salvador Carmona Franco

Ana María Borreguero Simón

Beatriz Talavera Almena

Ángel Serrano Casero

Ignacio Garrido Sáenz

Juan Francisco Rodríguez Romero

Institute of Chemical and Environmental Technology

Chemical Engineering Department

University of Castilla La Mancha

Ciudad Real, Spain


INTRODUCTION. THERMAL ENERGY STORAGE MATERIALS

A PCM is a substance with a high heat of fusion which, melting and solidifying, is able to absorb and store or release large amounts of energy.

ABSORB

STORE

RELEASE

Wide variety of PCMs can be used: Inorganics ( hydrated salts) Organics (alkanes, paraffin, waxes)

Development of new systems

for saving energy

Use of new renewable

energy sources

SOLAR ENERGY

IT NEEDS TO BE STORED!

Petroleum 50 years

Carbon 330 years

Uranium reactors 1000 years

Nuclear Fission 1 Million of years

Solar Energy 5000 millions of years

Energy sources

CLEAN UNIVERSAL RENEWABLE


INTRODUCTION. HOW DO PCMS WORK?

HOT OUTSIDE

BUILDING INSIDE

Heat Released

COLD

OUTSIDE

Heat Required

BUILDING INSIDE

External T > Melting T PCM becomes liquid

(Heat required)

External T < Freezing T PCM solidifies (Heat released)

Properties of PCMs for applications in buildings: • Melting temperature about 25ºC • High latent heat • Low cost • Good availability. • Non-toxic • Non-corrosive


INTRODUCTION. PCMs INCORPORATION IN BUILDINGS

• Building systems for PCMs incorporation

• Wallboards, ceilings and floors

• Shutter of windows

• Cooling and heating systems

• Ways of PCMs incorporation

• Direct incorporation

• PCMs microencapsulation

SHELL

CORE


Avoid loosing the PCM.

Avoid interactions between PCMs and the rest of building

materials.

Safe handling of PCMs.

Handling liquids as solid.

Increase the area of heat transfer.

INTRODUCTION. PCMs INCORPORATION IN BUILDINGS


INTRODUCTION. MICROENCAPSULATION OF PCMs

Spray drying technique

Suspension polymerization

Gas for solvent evaporation

Feed

Gas + solvent Product


INTRODUCTION. MICROENCAPSULATED PCMs PROPERTIES

Low Angle Laser Light Scattering (LALLS)

Scanning Electron Microscopy (SEM)

Differential

Scanning

Calorimetry

(DSC)

mSD-(LDPE-EVA-RT27)

-10 0 10 20 30 40-3

-2

-1

0

Hf=96,2 J/g

Hf=96,7 J/g

Inte

nsi

dad (

u.a

.)

Temperature (ºC)

Material

Original

After thermal treatment

Hf=85,81J/g

Hf=85,6J/g

-10 0 10 20 30 40-4

-3

-2

-1

0

HfJ/g

HfJ/g

Inte

nsi

ty (

u.a

.)

Temperatura (ºC)

Microcapsule

Pure paraffin

Hf=85,81J/

g Hf=200.2J/g


OBJETIVE. WHY USE PCMs IN BULDINGS?

EU directive 2010/31/UE: Directive on Energy Performance of Buildings

- Buildings are responsible for 40% of energy consumption and 36% of CO2 emissions in the

Europe Community.

- Energy performance of buildings is key to achieve the EU Climate and Energy objectives.

Money spent in energy

Reduction of

Environmental pollution

Energy consumption in heaters and air

conditioners

Development of buildings with a more efficient use of energy


EXTERNAL

SHEET

RESIN

CORE

(POLYURETHANE FOAM)

SANDWICH PANELS

EPOXI RESINS POLYURETHANE FOAMS

OBJETIVE. INCORPORATION OF PCMs IN BUILDINGS MATERIALS

The aim of this work is to develop sandwich panels exhibiting

high TES capacity


EXPERIMENTAL PROCEDURE. FOAM SYNTHESIS

n O=C=N-R–N=C=O + n HO-R’-OH

Polyisocyanate Polyol Polyurethane

[-CO-NH-R–NH-CO-O-R’-O-] n

Polyol

Additives (blowing agent,

surfactant and catalyst)

PCMs

Mix

Polyisocyanate

Different

microencapsulated

PCMs contents

• Microcapsules distribution

• Latent Heat

• Foam structure and cell size

• Density

• Mechanical resistance


1. Rotameter

2. Signal Transmitter

3. Computer for data recording

4. Peristaltic Pump

5. Thermostatic Bath

6. Termocouples

7. Isothermal Chamber

8. Insulating Structure

Experimental set up for thermal characterization

EXPERIMENTAL PROCEDURE. THERMAL ANALYSIS


Upper Tª

Middle Tª

Plate Tª

Upper Tª

Middle Tª

Plate Tª

Flow

Direction

Sensor Q out

Sensor Q in

Sensor

Q side

Sensor

Q side

Flow

Direction


THERMOCOUPLES DISTRIBUTION

HEAT FLUX SENSORS DISTRIBUTION

10 cm

3 c

m



Modulated Differential Scanning Calorimetry (MDSC)


EXPERIMENTAL PROCEDURE. MECHANICAL RESISTANCE

Mechanical characterization

Compression Experimental Set up

Uniaxial compression tests were performed according to ASTM D1621

(Standard Test Method for Compressive Properties of Rigid Cellular Plastics)


RESULTS AND DISCUSSION. SYNTHESIZED PU FOAMS

Microcapsules Content (%wt)

Foam system

viscosity

Rising

Rate

Final Foam

Height


RESULTS AND DISCUSSION. DENSITY

Density > 30kg/m3

(UNE 92120)

(prEN 14318-2)


Density

0% 10%

40% 50% 30%

15% 20%

0

50

100

150

200

250

300

350

0 10 20 30 40 50

De

nsi

ty (

kg/m

3 )

% PCM

Zone 1 Zone 2


RESULTS AND DISCUSSION. DSC ANALYSIS

-0,45

-0,4

-0,35

-0,3

-0,25

-0,2

-0,15

-0,1

-0,05

0

-10 0 10 20 30 40 50 60 70

Inte

nsi

ty (

u.a

)

Temperature (ºC)

0% Middle

10% Middle

20% Middle

30% Middle

40% Middle

50% Middle

% PCM QDOWN

(J/g)

QMIDDLE

(J/g)

QUP

(J/g)

QEXP

(J/g)

QTH

(J/g)

0 0 0 0 0 0

10 7,46 7,014 7,77 7,41 8,58

20 16,57 15,82 16,71 16,37 17,16

30 26,49 25,44 24,57 25,50 25,74

40 36,52 33,82 32,9 34,41 34,32

50 39,21 40,57 37,31 39,03 42,91

3

1

3

1exp

··

i

ii

ii

i

i

erimental

V

VQ

Q

Microcapsules were homogeneously

distributed into the whole foam

Microcapsules

Content (%wt)

Latent

Heat

)(gWeightFoam

(g)masslesmicrocapsu(J/g)Q(J/g)Q

lesmicrocápsu

ltheoretica

Hf=40.57 J/g

T=23.5ºC


RESULTS AND DISCUSSION. CELL STRUCTURE AND SIZE

SEM photographs of PU foams with different microcapsules content

RPU are formed with microcapsules into the strut and also the cell wall

0% 10% 20%

30% 40% 50%

0%


RESULTS AND DISCUSSION. COMPRESSION TESTS

S=0.2-8 MPa/g/cm3 y E=2-200MPa/g/cm3

No significant difference between the values of foams containing 0 to 20wt%

Sharp decrease in the mechanical resistance for contents higher than 20wt%

0

1

2

3

4

5

6

0 10 20 30 40 50

Spe

cifi

c C

om

pre

ssiv

e S

tre

ngt

h S

(M

pa/

(g/c

m3

))

% PCM

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Spe

cifi

c C

om

pre

ssiv

e M

od

ulu

s E

(Mp

a/(g

/cm

3))

% PCM

Uniaxial compression tests were performed according to ASTM D1621

Specific compression strength and modulus for excluding the density effect


3. PROCEDI-

MIENTO

EXPERIMENTAL

1. INTRO-

DUCCIÓN

2. OBJETIVOS

4. RESULTADOS

5. CONCLU-

SIONES

RESULTS AND DISCUSSION. THERMAL ANALYSIS

Experimental variation of temperatures at different points in a RPU foam without PCM

Influence of Temperature

15

20

25

30

35

40

0 2000 4000 6000 8000 10000 12000 14000

Tem

pe

ratu

re (

ºC)

t (s)

Tdown2

Tup2

Tbath

Tup1

Tenvironment

Tmiddle2

Tdown1

Tmiddle1

Tinsulation

Tbath change in step 18 to 40ºC

Tup1 =Tup2

Tmiddle1 =Tmiddle2

Tdown1 =Tdown2

One dimensional flow Termocouples opposite to the flow

with the same temperature profile



15

20

25

30

35

40

0 5000 10000 15000 20000

Tem

pe

ratu

re (

ºC)

t (s)

Tdown average 0%

Tdown average 10%

Tdown average 20%

Tdown average 40%

Tdown average 50%

Tbath

0

20

40

60

80

100

120

140

0 5000 10000 15000 20000

Q (

W/m

2 )

t (s)

q in 0% (W/m2)

q in 10% (W/m2)

q in 20% (W/m2)

q in 30% (W/m2)

q in 40% (W/m2)

q in 50% (W/m2)

This behavior is more clear

with percentages higher than

20%

Hot Plate Temperature

Input Heat Flux

Down Temperature


Thermal

Damping

Slope of

the curves


Input

heat Flux

Maximum energy absorb

or lower insulating effect



-12

-10

-8

-6

-4

-2

0

0 5000 10000 15000 20000

Q (

W/m

2 )

t (s)

q out 0% (W/m2)

q out 10% (W/m2)

q out 20% (W/m2)

q out 30% (W/m2)

q out 40% (W/m2)

q out 50% (W/m2)

Similar temperatures at stationary condition, but

big difference in the transition step

15

20

25

30

35

40

0 5000 10000 15000 20000

Tem

pe

ratu

re (

ºC)

t (s)

Tup average 0%

Tup average 10%

Tup average 20%

Tup average 30%

Tup average 40%

Tup average 50%

Tbath

Hot Plate Temperature

3 cm in thickness

External Temperature

Output Heat Flux

Melting of PCM by energy

absorption


Output

heat Flux

Ability to

store energy


Influence of Heat Flows


Accumulation curves as a function of time and the percentage content of PCMs

THERMAL ENERGY STORAGE (TES)

-0,1

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

0 5000 10000 15000 20000

Q (

W)

t (s)

Accumulated (W) 0%

Accumulated (W) 10%

Accumulated (W) 20%

Accumulated (W) 30%

Accumulated (W) 40%

Accumulated (W) 50%

Microcapsules

Content (%wt)

Total energy absorbed during one

step temperature change 18ªC-40ªC


𝑐𝑝 =𝑞𝑎𝑐

𝑚𝑝𝑟𝑜𝑏𝑒𝑡𝑎 · 𝑇𝑓 − 𝑇𝑖

𝜅 =𝑄𝑖𝑛𝑙𝑒𝑡 ·Δx

ΔT

Determination of thermal conductivity and heat capacity


Thermal conductivity K

Heat Capacity Cp

Cp and K follow a straight line (0.05

and 0.0007 respectively)

Both are representative of those

reported in the literature

y = 0,0548x + 2,8559

y = 0,0007x + 0,0541

0,030

0,040

0,050

0,060

0,070

0,080

0,090

0,100

0

1

2

3

4

5

6

7

8

9

10

0 10 20 30 40 50

Th

erm

al C

on

du

cti

vit

y K

(J/m

·s)

Th

erm

al C

ap

ac

ity C

p (

J/g

·ºC

)

% PCM

Cp(J/g·°C)

K (J/m·s)


RESULTS AND DISCUSSION. THERMAL APPLICATIONS

Foam (% PCM) TES (kWh/m3) 0 0.53

10 0.77

20 1.38

30 1.75

40 3.06

50 5.38

1 m3 panels of RPU

(thickness of 3cm)

Standar Room 3x4x2.5 m3

Panels of RPU


As example…

RESULTS AND DISCUSSION. THERMAL APPLICATIONS

Consumption of a 60 Watt light bulb = 1.44kWh

Energy saved by a room

covered with panels

containing 50% of

microcapsules

Energy spent by

4 light bulbs

working

all the day

Centro Nacional

de la Energía (CNE)

CO2emitted = 0.35kg/KWh


Título presentación

REDUCING THE ENERGY CONSUMPTION IN BUILDINGS BY INCORPORATING MICROENCAPSULATED PCMS

IN RIGID POLYURETHANE FOAMS

THANK YOU FOR YOUR ATTENTION


CONCLUSIONS

- It is possible to incorporate up to a 50wt% of mSD-(LDPE-EVA-RT27) into the PU foams,

achieving a homogeneous distribution of the microcapsules and improving the TES capacity of

the foams.

- The higher the microcapsules content, the lower the final foam height. Moreover, the foam

density increases with this content.

- Microcapsules are mechanically stable and they can be found into the strut and also on the cell

wall.

- The higher amount of microcapsules inside the building materials, the higher is the TES

Capacity.

- Thermal capacity and the thermal conductivity follow a straight line, increasing of 0,055 and

0,0007 respectively.

- The incorporation of a 50 wt% of PCMs allows to save up to 5.38KWh/m3, equivalent to

1.44kWh equivalent to the spent energy by 4 light bulbs working all day.

- The incorporation of the mSD-(PEBD·EVA-RT27) into conventional housings will show a great

decrease in the energy consumption and thus in the CO2 emissions.

reducing the energy consumption in buildings by...

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