An Explicit Finite Element Method for Thermal Simulations of Buildings with Phase Change Materials

Abstract

The thermal performance of building envelopes is essential for building thermal comfort and the reduction of building energy requirements. Phase change materials (PCMs) implemented in building envelopes can improve thermal performance. An explicit finite element method (ex-FEM) has been developed based on a previous study to investigate the heat transfer performance through building walls with installed PCMs. For verification, we introduce an electrical circuit analogy (ECA) method. For model validation, at first, COMSOL is used. For comparison, data were collected from experiments using a small hotbox, part of the sides are covered by PCMs with different configurations. This work shows how the ex-FEM model can predict the wall’s temperature profile with and without incorporated PCM. With the implementation of PCMs, the work problematizes unpredictable influences for modeling. In addition, the study introduces results from simulations of sequencing of PCM layers in wall construction.

Phase change materials influence on temperature variatio buildings

“…The extruded polystyrene XPS is purchased from Sundolitt AB, and the PCM is Climsel 28 purchased from Climator Sweden AB, with the phase transition temperature at 28 °C. The thermophysical properties of XPS and PCM can be found in [10] A fan is located inside of the hot-box to ensure a homogeneous air temperature. The inside temperature of the hot-box is regulated by a heating source, which is indicated in figure 1.…”

“…The inside temperature of the hot-box is regulated by a heating source, which is indicated in figure 1. More details of the set-up and wall materials can also be found in [10] Fig. 1.…”

“…The properties of XPS and PCM, which are used both in experiment and simulation can be found in the previous study [10].…”

“…The correlation for internal and external are 0.915 and 0.947 respectively. The Matlab model according to [10] gives a correlation factor of 0.987 and 0.88 for internal and external temperatures. Additionally, it shows that when a single PCM layer is used as the wall component, it undergoes a fast phase transition which is not noticeable from the internal surface in the experimental results.…”

“…Their results indicate that with the incorporation of PCM, the power consumption can be reduced up to 34.8%. Zhou et al [10] have developed an explicit finite element method for the study of PCM on the temperature distributions in building envelopes. The model was validated by the experimental data purchased from a simplified hot-box.…”