Synthesis and thermal energy storage properties of xylitol pentastearate and xylitol pentapalmitate as novel solid–liquid PCMs

In this study, xylitol pentastearate and xylitol pentapalmitate were synthesized as novel solid–liquid PCMs by an esterification reaction in order to eliminate the unfavorable thermal properties of xylitol (such as high melting point) and stearic and palmitic acids (such as high melting point, low corrosivity, bad odor, and sublimating property). The synthesized ester compounds were characterized chemically by using Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy methods. By using the differential scanning calorimetry (DSC) method, the melting temperatures of xylitol pentastearate and xylitol pentapalmitate were measured as 32.35 °C and 18.75 °C, respectively, while their latent heats of melting were determined as 205.65 J g−1 and 170.05 J g−1 respectively. These results indicate that the synthesized PCMs have high latent heat values and suitable phase change temperatures for thermal energy storage applications. The thermal cycling test shows that the synthesized PCMs have good thermal reliability after 1000 thermal cycles. Thermogravimetric (TG) analysis results also reveal that the PCMs have good thermal stability over their working temperatures.

In this study, in order to eliminate the unfavorable thermal properties of xylitol, stearic acid and palmitic acid mentioned above, xylitol pentastearate and xylitol pentapalmitate were synthesized as novel solid–liquid PCMs via the esterification reaction of xylitol with stearic acid and palmitic acid. These esters were characterized chemically using FT-IR and 1H NMR spectroscopy methods. By using the DSC method, the melting temperatures of xylitol pentastearate and xylitol pentapalmitate were measured as 32.35 °C and 18.75 °C, respectively, while their latent heat values were determined as 205.65 J g−1 and 170.05 J g−1 respectively. The thermal cycling test showed that the synthesized PCMs had good thermal reliability after 1000 thermal melting–freezing cycles. Thermogravimetric (TG) analysis results also revealed that the PCMs have good thermal stability over their working temperatures.Figure optionsDownload as PowerPoint slideHighlights
► Xylitol pentastearate and xylitol pentapalmitate were synthesized as novel solid–liquid PCMs.
► These esters were characterized by FT-IR, 1H NMR, DSC and TGA techniques.
► The results indicated that the synthesized esters had suitable thermal energy storage properties.