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Submitted to: Solar Energy
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/10/2010 Publication Date: 5/31/2010 Citation: Kenar, J.A. 2010. Latent Heat Characteristics of Biobased Oleochemical Carbonates as Novel Phase Change Materials. Solar Energy Materials and Solar Cells. 94(10):1697-1703. Interpretive Summary: This research showed that novel biobased materials "oleochemical carbonates" can be used as thermal energy storage (TES) compounds to store and release heat to their surroundings. Roughly 39% of the total primary energy generated is consumed by residential and commercial buildings to provide lighting, heating, and cooling for these structures. The development of new materials derived from renewable resources to recover waste heat, store thermal energy, replace phase change materials (PCM) based on petroleum paraffin waxes currently dominating the thermal energy storage (TES) market, and improve energy conservation and efficiency within commercial and residential buildings is important. This work provides new fundamental information about the thermal properties of renewably derived biobased compounds "oleochemical carbonates", and showed that these compounds have high thermal energy storage capacities, appropriate phase transition temperatures, and good chemical stability for use as PCM. The basic knowledge gained from this research has clear importance for the potential utilization of novel biobased compounds as PCM for thermal heat storage applications. Technical Abstract: Oleochemical carbonates are biobased materials that were readily prepared through a carbonate interchange reaction between renewable C10-C18 fatty alcohols and dimethyl or diethyl carbonate in the presence of a catalyst. These carbonates have various commercial uses in cosmetic, fuel additive and lubricant applications. Oleochemical carbonates have not been examined for their applicability as phase change materials (PCM), and the latent heats of melting and freezing for a series of oleochemical carbonates were evaluated to develop a fundamental understanding of the solid-liquid transitions of these materials for utilization in thermal energy storage (TES) applications. The phase transitions and associated thermal properties were determined by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl carbonates had peak melting and freezing points of -2.2, 19.3, 33.7, 44.9, 51.6 and -6.3, 14.3, 28.7, 40.3, and 46.9 oC, respectively. These carbonates exhibited sharp phase transitions and good latent heat properties. The latent heats of melting and freezing for decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl carbonates were 144, 200, 227, 219, 223 J/g and 146, 199, 229, 215, and 215 J/g, respectively. These carbonates represent novel renewable-based PCM chemicals that compliment fatty acids, fatty alcohols and their fatty acid esters and provide potentially valuable biobased alternatives to paraffin wax and salt hydrate PCM currently dominating the PCM market. |
