Systematic evaluation of mathematical methods and numerical schemes for modeling PCM-enhanced building enclosure

Latent heat storage using phase change material (PCM) has become one of the most viable solutions to mediate the climatic deficiency of light weight structures. Instead of expensive field tests, computational modeling can be utilized to evaluate its technical and economic feasibility. This study presents the calculation procedure for eight potential numerical models/schemes implemented in MATLAB/SIMULINK environment. A linearized enthalpy method with hybrid correction scheme is proposed as an improvement to the existing numerical schemes. The models have been validated and further verified against a well-known building simulation program “EnergyPlus”. The models have been analyzed for their computational efficiency and prediction accuracy. Some models are found sensitive to PCM's melting range, for example heat capacity method, but less sensitive to the latent heat. For all models, the time step should be small for accurate results. The iterative and the hybrid correction schemes are found computationally efficient and less sensitive to variations of PCM properties. In addition, a maximum time step of 15 min can be used without significant numerical error or changes in computational time. Hence, these two schemes can potentially be implemented into whole building simulation tools for modeling PCMs instead of existing slow and unstable numerical algorithms.