| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程學系 === 101 === Our aim is to find phase change material (PCM) mixtures which also have an increase in the heat capacity in solid or liquid state. Increasing heat capacity in liquid or solid state would enhance the part of heat storage which can be used in a wider temperature range, rather than just to absorb or release heat energy near the melting point or freezing point. We use low-temperature differential scanning calorimetry (LT-DSC) to determine the melting point and the equilibrium state, powder X-ray diffraction (PXRD) and small-angle X-ray scattering (SAXS) to determine the nano structures, temperature-history method to find the thermal properties in large-scale. 1: 1 molar ratios of palmitic acid/camphene mixture (PA1CA1) By using temperature-history method, thermal properties of anhydrous PA1CA1 are: Tm = 322.7+0.0 K, cpl = 2.04+0.04 kJ kg-1 K-1, cps = 2.17+0.06 kJ kg-1 K-1, ΔHls = 114.0+1.2 kJ kg-1, and ks = 0.21+0.00 W m-1 K-1 and the thermal properties of hydrated PA1CA1 are: Tm = 324.8+0.2 K, cpl = 2.29+0.04 kJ kg-1 K-1, cps = 2.61+0.01 kJ kg-1 K-1, ΔHls = 119.6+1.8 kJ kg-1, and ks = 0.21+0.01 W m-1 K-1. Overall, hydrated PA1CA1 is better than anhydrous PA1CA1 with increasing in both heat capacity in solid and liquid state. Partial amorphous phase formation (more disordered state) helps increase the heat capacity in solid state of anhydrous or hydrated PA1CA1. The mixture of palmitic acid and camphene in this research is not a eutectic mixture but rather palmitic acid particles nanometer-sized 222 nm ~431 nm are dispersed in partial amorphous camphene matrix to form a solid dispersion. Our systems can be used in passive storage in bio-climatic building/architecture and application in off-peak electricity for cooling and heating.
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