Romanian Academy of Science Institute of Physical Chemistry “Ilie Murgulescu” Spl. Independentei 202, 060021 Bucharest,

M.Constantinescu

1

, L.Dumitrache

2

, S.Serban

2

, P.M.Pavel

1

, A.Stoica

1

, M.Ghiurea

2

, M.Ladaniuc

2

and M.Olteanu

1

.

1.ICF-AR “Ilie Murgulescu” 2. ICECHIM Bucuresti

Objectives and importance of energy storage in PCM

Energy storage aims to reduce the conventional energy consumtion with a direct impact on CO 2 emissions.

The advantages of phase change materials :

A constant temperature domain for the phase transformation, chosen for each application.

High storage density 70-100 kWh/m3

Directions of researches on heat storage in phase change materials :

Finding new materials with superior performances Elimination of existent material disadvantages.

Nanocomposites preparation

1)Glauber(Na 2 SO 4 10H 2 O)+5%Borax(Na 2 B 4 O7)+Ad -Temperature domain: 15-30C -Phase change temperature -31C.

-Microencapsulation in epoxi resin as a cross-linked structure -Geometric form of the material is application dependant 2) an epoxi mixture of polyethylene glycol of different molecular weights (1000, 1500, 2000) with Al powder).

3)-Eutectics of the binary and ternary systems : --Acetamide+ sodium acetate trihidrate

-

sodium tiosulfate(Na 2 S 2 O 3 .5H

2 O)+ sodium acetate trihidrate - Working temperature <60C

PCM +Ad melted and mixed with epoxi resin The PCM-epoxi nano-composite materials obtained as cross-linked three dimensional structures are attractive for space heating and cooling of buildings able to reduce the space and costs for containerization.

Properties of nanocomposites substantially improved:

 Mechanical properties : strength, modulus and dimensional stability i.e. by using a nanocomposite PCM-epoxi increases the strength by 100%  Thermal stability Thermal resistance, flame retardancy and reduced smoke emissions :Nanocomposites, with their superior thermal resistance, are also attractive for applications as housings for electronics  Chemical resistance The use of polymer-based nanocomposites are used as anticorrosion coatings on metals, and thin-film sensor.  Decreased permeability to gases, water and hydrocarbons Polymer-matrix nanocomposites can also be used to package films, due to their superior barrier properties and low permeability

Phase Change Materials

Glauber(Na 2 SO 4 10H 2 O)+5%Borax (Na 2 B 4 O 7 )+Al Nanocomposites PEG 1000 ,1500 +Al DSC for epoxi-PEG 1000 +Al Polyethylene Glycol- M2000 PCM Salt hydrates KF.4H

2 O CaCl 2 6 H 2 O Na 2 SO 4 .10H

2 O Na 2 HPO 4 .

12 H 2 O Zn(NO 3 ) 2 .

4 H 2 O Ca(NO 3 ) 2 . 4H 2 O LiClO 3 . 3 H 2 O Mn(NO 3 ) 2 . 6 H 2 O Melting temperature  C 18.5

29.7

32.4

35.0

36.4

47.0

46.5

58 Melting heat kJ/kg 231 171 254 281 PCM Organic materials Butilstearate 1-dodecanol Parafins 45/55capric/lauric acid Melting temperature  C 19 26 20-26 21 Melting heat kJ/kg 140 200 200 143 147 19 153 253 Propil palmitate Polyethylenglycole 1000-2000 1-tetradecanol 37-64 38 186 83.2

218.4

205 165.5

Material characterization and testing

Glauber+borax+amonium sulphate decahydrate +Al nano

Demands for Phase Change Material

Physico-chemical:

-Phase change temperature in the required domain -High latent heat of phase change and caloric capacity -High thermal conductivity -Low undercooling -Low volume changes -Reversible phase transition -Good physical and chemical stability

Hardening reaction of epoxi resin with PCM Kinetical :

-High nucleation and crystal grow velocity

Economical :

-low cost -Reciclability -Non-toxicity

Innovative applications

DSC for PEG 1500

CH 2 O CH CH 2 O CH 3 C CH 3

+

O CH 2 CH O CH 2

Phase change materials have been employed in: Thermal energy storage Conditioning of buildings Waste heat recovery Off peak power utilization Heat pump systems Space applications Laptop computer cooling Cool suits Telecom shelters

melted PCM in the epoxi matrix

SEM micrographs

for polyethylene glycol(PEG) 2000

SEM micrographs for Glauber –epoxi Al nano

CONCLUSIONS

Solar houses Kirally Passive and active cooling Rubiterm Blood motion Rubiterm 1.The nanocomposite materials for buildings were obtained by using melted (PCM +additives) 70 wt%, incorporated in an epoxidic resin 30 wt%. For all Epoxi-PCM materials was used Ropoxid 501 (Policolor), with a hardener threeethylentetramine (TETA) or I 3361 (Policolor). The composition of the inorganic PCM was: (Glauber salt)70wt %, additives (borax 10wt%, NH 4 HCO 3 , (NH 4 ) 2 SO 4 , or CaCO 3 20wt% and Al powder 0.1wt% for enhancing the thermal conductivity of the material, whereas the organic PCM ( polyethyleneglycoles 1000, 1500 and 2000) were also 70wt% and 0.1 wt%Al powder. The system hardened at the ambient temperature.

2.The materials present good mechanical, thermal and chemical properties suitable for building materials.

3.They can be used for different applications in active or pasive systems, depending on their melting temperature.The geometry used depends also on their melting temperature and on the chosen application.

4. Energy storage in building materials will reduce the conventional energy consumptions, will increase the living comfort, decreasing the CO 2 emissions.