Lab-Scale Dynamic Thermal Testing of PCM-Enhanced Building Materials

摘要

Previous research studies have shown that incorporation of the phase-change material (PCM) in a building envelope material/component may bring significant reduction in the building energy consumption. A detailed knowledge of the key phase-transition (dynamic) properties, such as latent heat, sub-cooling, hysteresis during melting and freezing, etc., of the PCM-enhanced building materials is required to perform the whole building energy simulations and code work. In addition, the dynamic test data is critical in optimizing the distribution and location of the PCM within a building to maximize the energy savings. Until recently, the differential scanning calorimeter (DSC) has been the only available method to determine the dynamic properties of a PCM. Unfortunately, the DSC method is valid for small and homogeneous specimens, and is incapable of capturing the complexities observed in large-scale building components. Materials with nonuniform temperature distribution and non-homogeneity caused by the presence of additives, such as fire retardants, conduction inhibitors, and adhesives, cannot be analyzed by the DSC testing method. Dynamic heat-flow meter apparatus (DHFMA) is a recently developed method for dynamic property measurement of system-scale PCM and other building construction products. Although the DHFMA method is gaining acceptance among the scientific and research community, it is still under development. In this study, we focus on advancing the development, and conducting the validation of the DHFMA method. A detailed description of the DHFMA method is presented to highlight the difference with the conventional HFMA method. Next, a large-scale bio-based shape-stabilized PCM (ss-PCM) sample was tested using both DHFMA and DSC test methods. Specific heat as a function of temperature data measured by DHFMA method was found to be in very good agreement with slowest ramp and step data. This is the first direct verification of the HFMA method with the DSC method for PCMs.