Coupled EnergyPlus and CFD analysis of PCM for thermal management of buildings

Abstract

Building energy simulation (BES) tools are key instruments for sizing the PCM based system in the built environment and analyzing its effect on thermal comfort and energy demand. Due to complex solidification and melting phenomena of PCM, BES tools have limitations in predicting its performance with buildings. Computational fluid dynamics (CFD) tools are also used to model the PCM, but those models are not integrated with the building simulation models. This study aims to develop a co-simulation framework between BES tool (EnergyPlus) and CFD tool (Ansys Fluent) to model the PCM integrated built environment and compare its prediction accuracy with the most popular BES tool, i.e., EnergyPlus. Three experimental case scenarios 1) Active use of PCM, 2) Passive use of PCM during natural convection and 3) Passive use of PCM during forced convection have been modeled for prediction accuracy assessment. A common accuracy index (Root Mean Square Error) is used along with temporal temperature variation for the comparison. The results highlight that the proposed co-simulation has better prediction accuracy than the BES tool for active use of PCM and passive use of PCM under forced convection. For modeling the passive use of PCM during natural convection, BES tool is recommended. Since in the extreme climatic conditions, PCM with active use and forced convection are effective compared to the passive use of PCM, this study would be useful in modeling the built environment with PCM at early building design stages for extreme climatic conditions.