Abstract
Phase diagram is a powerful tool to guide the exploitation of thermal energy materials. Heat storage technology of phase-change material (PCM) was widely used to solve major energy utilization problems on large energy consumption and low utilization efficiency. In this work, a novel solid-liquid phase diagram of the binary system octadecanoic acid (C18-acid) + octadecanol (C18-OH) was investigated using the differential scanning calorimeter (DSC). The phase-change temperature and phase-change enthalpies against the composition of C18-acid and C18-OH were determined experimentally, and then the binary phase diagram of T–X (X expresses the mass fraction of C18-OH in the two components of C18-acid and C18-OH) was established for the first time. The phase diagram belongs to a binary simple system with one eutectic point, and the content of C18-OH at eutectic point is 0.4 in mass fraction. Neither solid solution nor copolymer was formed. The thermal chemical properties on the phase-change latent heat (Q), phase-change temperature (Tp), and the thermal conductivity (λ) for the composition at the eutectic point of the binary system are 198.7 J·g−1, 44.2°C, and 0.2352 W·m−1·K−1, respectively. This result indicates that the material at eutectic point has a great potential to be used as energy storage material for supply of heat and scouring bath.
Highlights
As the rising demand for energy from the growing population, the fossil fuels have been largely consumed, which seriously caused the environmental pollution and emission of greenhouse gases into the atmosphere [1]
In order to avoid these limitations, the sustainable, reliable, and efficient energy storage systems have been developed as energy reserves. e occurrence of phase-change materials (PCMs) provides a suitable settlement for the problem of intermittent solar energy [5, 6]
E phase diagram belongs to a binary simple system with one eutectic point, and thermal performances of the eutectic point such as phase-change temperature, latent heat, and thermal conductivity were investigated systematically
Summary
As the rising demand for energy from the growing population, the fossil fuels have been largely consumed, which seriously caused the environmental pollution and emission of greenhouse gases into the atmosphere [1]. Phase-change materials (PCMs) have many attractive characteristics, such as high storage density in a small temperature region, compact energy storage systems under isothermal conditions, and high heat of fusion, which are considered to be the most effective methods actively pursued. Journal of Chemistry retardancy, high thermal conductivity, high heat of fusion, and large volume heat storage density (250–400 kg·dm−3) [15], due to the poorly cyclic stability of inorganic PCMs; the organic PCMs received tremendous attention nowadays for their advantages of high energy storage density, small corrosivity, no (or slight) supercooling, and no phase segregation on the application of thermal cycles [8]. Li et al [18] plotted a phase diagram for a sequence of binary and ternary eutectic fatty acids derived from four organic PCMs (stearic acid, palmitic acid, myristic acid, and lauric acid) and revealed their phase-change transition properties. E phase diagram belongs to a binary simple system with one eutectic point, and thermal performances of the eutectic point such as phase-change temperature, latent heat, and thermal conductivity were investigated systematically
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