Modeling of phase change materials for applications in whole building simulation

The advanced buildings of tomorrow will need to take advantage of renewable, ambient and waste energy to approach ultra-low energy buildings. Such buildings will need to consider Thermal Energy Storage (TES) techniques customized for smaller loads.Recently, TES has attracted increasing attention due to the potential benefits it can deliver in energy efficiency, shift load from peak to off-peak, economics and environmental impact. Advanced design tools and technical improvements are required in TES technology and systems. Indeed the design of the building and the TES are often not coordinated. A building integrated with distributed thermal storage materials could shift most of peak load to off-peak time period.Even though various tools have been developed to model the behavior of applied phase change materials (PCM), unacceptable accuracy and/or high computational time are addressed as their major drawbacks. This implies that the development of a fast and reliable model is necessary in order to simulate the long-term behavior of these materials, especially for design and optimization.Therefore, a new and fast one-dimensional analytical model is proposed in this paper. The PCM behavior is modeled using a RC-circuit concept containing variable capacities for resistant and capacitor. In this approach, the length of mushy, solid, and liquid phases in each period of time signifies the RC capacity. In order to evaluate the performance of the proposed model, a computational fluid dynamics (CFD) model is then developed. The prediction of the newly developed model is compared with the prediction made by the CFD. There are good agreements between the predictions, and the results clearly show the high performance of the proposed model.