Performance comparison of three models for thermal property determination from experimental phase change data
SARChI, Department of Chemical Engineering, University of Pretoria, Lynnwood Road, Pretoria, South Africa
The characterization of thermal properties continues to be a challenge facing the development of composite phase change materials. To overcome the practical issues of current techniques a new experimental method was developed. The system is modelled using two fundamental models and a simplified analytical representation. Pure myristic acid is used for validation and a performance comparison based on time, accuracy and stability. All three approaches perform comparatively well in terms of accuracy with an average prediction error of less than one third of a degree and all thermal properties in line with expectations. The enthalpy model is susceptible to instability while the effective heat capacity method does not show any such behaviour. In addition, due to the choice of a smooth function for the transition from liquid to solid, this method delivers more realistic behaviour. The effective heat capacity method is faster than the enthalpy method by a factor of three, but the analytical approach is the fastest. However for a more robust and comprehensive representation the effective heat capacity method is preferred. © 2015 Elsevier B.V. All rights reserved.
Enthalpy; Hybrid materials; Specific heat; Thermodynamic properties; Analytical approach; Average prediction error; Composite phase change materials; Fundamental models; New experimental method; Performance comparison; Practical issues; Smooth functions; Phase change materials