Thermal buffering performance evaluation of fatty acids blend/fatty alcohol based eutectic phase change material and simulation

Eutectic PCM was prepared by mixing a unique pracids blend, OM-21 and fatty alcohol, 1-dodecanol (DD) adopting blending-ultrasonication technique. The unique composition was found out based on thermal properties of series of samples made by mixing 0-100 wt. % of DD with 100-0 wt. % of OM-21 keeping overall wt. % fixed at 100. Despite the presence of two PCMs, only one crystallization peak at 0.68 degrees C (differential scanning calorimetry, DSC) was noted with 60:40 wt. % of OM-21: DD (denoted as OD-64) and the peak temperature was lower than either of the PCM, indicating eutectic behavior. FTIR-ATR spectra of OD-64 confirmed possibility of no chemical reaction in eutectic PCM. Enthalpies of phase transformation observed from DSC analysis were 140.6 kJ kg(-1) (melting) and 139.1 kJ kg(-1) (crystallization) while melting peaks were at 7.38 degrees C / 12.21 degrees C. Thermal stability was estimated from TGA (thermo gravimetric analysis) measurement. The duration of charging(-18 degrees C) and discharging(40 degrees C) for 180 g OD-64 in TCP box were estimated to be 65 min and 48 min respectively. 390 min of thermal buffering (between -17 degrees C - 25 degrees C) can be achieved for 240 g chocolate placed inside TCP box with ambient temperature of 27 degrees C. Additionally, a three dimensional TCP box model was made using COMSOL Multiphysics 5.5 and unsteady state energy balance equations along with its boundary conditions were used to define experimental conditions. The model equation was validated with experimental data obtained at two extreme ambient temperatures i.e. 27 degrees C and 40 degrees C. The validated model equation was found to be closely (<+/- 9.0%) matching with experiment performed at 30 degrees C ambient conditions. Thus, eutectic OD-64 with good enthalpy would be effective for low temperature thermal buffering applications.

Automated summary

Eutectic PCM OD-64 was prepared by blending a unique pracids blend OM-21 with a fatty alcohol 1-dodecanol. OD-64 exhibited a single crystallization peak at a lower temperature than either PCM component, indicating eutectic behavior with good enthalpy suitable for low temperature thermal buffering applications.