Preparation and characterization of lauric–myristic–palmitic acid ternary eutectic mixtures/expanded graphite composite phase change material for thermal energy storage

Abstract Based on the theoretically calculated mass ratio and the melting temperature of ternary eutectic mixtures, the ternary eutectic mixture of lauric acid (LA), myristic acid (MA) and palmitic acid (PA) was prepared firstly. The differential scanning calorimetry (DSC) results indicated that the eutectic mixture was composed by LA, MA and PA in the ratio of 55.24:29.74:15.02 (by mass). Then the LA–MA–PA was absorbed in expanded graphite (EG), which acts as a supporting material, to prepare six kinds of composite phase change material (PCM). The optimal mass ratio of LA–MA–PA to EG is found. The SEM, FT-IR and DSC comprehensive characterization results show that EG interacted with the capillary tubes and surface tension of LA–MA–PA via its porous structure, instead of any chemical action. At the maximum mass ratio of LA–MA–PA to EG of 18:1 (by mass), the phase change temperature and latent heat of LA–MA–PA ternary eutectic mixture were 31.41 °C and 145.8 J/g respectively; and the LA–MA–PA/EG composite PCM had a phase change temperature of 30.94 °C and a latent heat of 135.9 J/g, and the thermal conductivity of the LA–MA–PA/EG was measured as 1.67 W/m K, a sharp increase than that of LA–MA–PA. Thermal cycling test showed that the LA–MA–PA/EG composite had a good thermal reliability. Based on all results, it was concluded the prepared LA–MA–PA/EG composite PCM has a proper melting temperature and latent heat for low temperature thermal storage.

[1]  Lv Shilei,et al.  Eutectic mixtures of capric acid and lauric acid applied in building wallboards for heat energy storage , 2006 .

[2]  Yi Wang,et al.  Effect of preparation methods on the structure and thermal properties of stearic acid/activated montmorillonite phase change materials , 2012 .

[3]  Khamid Mahkamov,et al.  Solar energy storage using phase change materials , 2007 .

[4]  J. Su,et al.  Influence of temperature on the deformation behaviors of melamine–formaldehyde microcapsules containing phase change material , 2012 .

[5]  Zhongliang Liu,et al.  Experimental investigations on the characteristics of melting processes of stearic acid in an annulus and its thermal conductivity enhancement by fins , 2005 .

[6]  Yi Wang,et al.  Stearic acid/silica fume composite as form-stable phase change material for thermal energy storage , 2011 .

[7]  Sedat Keleş,et al.  Lauric and myristic acids eutectic mixture as phase change material for low‐temperature heating applications , 2005 .

[8]  D. Buddhi,et al.  Numerical heat transfer studies of the fatty acids for different heat exchanger materials on the performance of a latent heat storage system , 2005 .

[9]  Dong Zhang,et al.  Experimental study on the phase change behavior of phase change material confined in pores , 2007 .

[10]  Yuehong Su,et al.  Prediction of the melting temperature and the fusion heat of (quasi-) eutectic PCM , 1995 .

[11]  V. V. Tyagi,et al.  PCM thermal storage in buildings: A state of art , 2007 .

[12]  A. Sari,et al.  Thermal conductivity improvement of stearic acid using expanded graphite and carbon fiber for energy storage applications , 2007 .

[13]  A. Sayigh,et al.  Some fatty acids as phase-change thermal energy storage materials , 1994 .

[14]  A. Sari,et al.  Preparation, thermal properties and thermal reliability of palmitic acid/expanded graphite composite as form-stable PCM for thermal energy storage , 2009 .

[15]  A. Sharma,et al.  Review on thermal energy storage with phase change materials and applications , 2009 .

[16]  Peijun Ji,et al.  Improvement of the thermal conductivity of a phase change material by the functionalized carbon nanotubes , 2012 .

[17]  A. Sari,et al.  Thermal Energy Storage Characteristics of Myristic and Stearic Acids Eutectic Mixture for Low Temperature Heating Applications , 2006 .

[18]  Shi-bin Nie,et al.  Facile preparation and adjustable thermal property of stearic acid–graphene oxide composite as shape-stabilized phase change material , 2013 .

[19]  Jianguo Zhao,et al.  Microstructure and thermal properties of a paraffin/expanded graphite phase-change composite for thermal storage , 2011 .

[20]  Hui Li,et al.  Preparation and characterization of stearic acid/expanded graphite composites as thermal energy storage materials , 2010 .

[21]  Yu Yanping,et al.  Theoretic Prediction of Melting Temperature and Latent Heat for a Fatty Acid Eutectic Mixture , 2011 .

[22]  A. Sari,et al.  Preparation, thermal properties and thermal reliability of eutectic mixtures of fatty acids/expanded vermiculite as novel form-stable composites for energy storage , 2010 .

[23]  A. Sari,et al.  Preparation, characterization and thermal properties of lauric acid/expanded perlite as novel form-stable composite phase change material , 2009 .

[24]  Bogdan Diaconu,et al.  Experimental assessment of heat storage properties and heat transfer characteristics of a phase change material slurry for air conditioning applications , 2010 .

[25]  A. Sari,et al.  Thermal properties and thermal reliability of eutectic mixtures of some fatty acids as latent heat storage materials , 2004 .

[26]  R. Velraj,et al.  Heat transfer enhancement in a latent heat storage system , 1999 .

[27]  Hui Li,et al.  Preparation and properties of lauric acid/silicon dioxide composites as form-stable phase change materials for thermal energy storage , 2010 .

[28]  X. Py,et al.  Paraffin/porous-graphite-matrix composite as a high and constant power thermal storage material , 2001 .

[29]  C. Doetsch,et al.  Evaluation of paraffin/water emulsion as a phase change slurry for cooling applications , 2009 .