Thermal analysis and heat capacity study of even-numbered fatty alcohol (C12H25OH-C18H37OH) phase-change materials for thermal energy storage applications

Abstract

Fatty alcohols (FAs) have been widely studied as typical phase-change materials for their high latent heat, low undercooling, non-toxicity, and low cost in thermal energy storage applications. The thermal properties, especially the heat capacity, play a vital role in designing-related energy storage techniques. However, there are few studies on the thermal properties of FAs systematically investigated in a wide temperature region, which greatly limit their application in thermal energy storage field. In this study, the thermal properties of even-numbered FAs (C12H25OH-C18H37OH), such as thermal stability, thermal conductivity, phase transition temperature, and enthalpy have been systematically investigated using a combination of various thermal analysis and calorimetry methods. The corresponding thermodynamic functions such as the standard molar heat capacity, entropy, and enthalpy at 273.15 K and 0.1 MPa have been calculated based on the heat capacity curve fitting. Most importantly, the heat capacities of 1-tetradecanol and 1-hexadecanol are reported for the first time in the wide temperature range of 1.9–370 K. Furthermore, by fitting the heat capacities of FAs, a function of molar heat capacities (Cp) related to the number of carbon atoms (n) and temperature (T) has been established, which can express the heat capacity of FAs between C12H25OH and C22H45OH reasonably in the temperature region of 50–240 K. This work provides accurate and systematic thermodynamic data of FA samples for the future study on their thermodynamic property and related processing design of thermal energy storage application.