Verification of a T-history installation to measure enthalpy versus temperature curves of phase change materials

Abstract

Phase change materials (PCM) are able to store thermal energy in small temperature intervals very efficiently due to their high latent heat. Accurate knowledge of the enthalpy as a function of temperature, or the storage capacity at each temperature, is the key to design any application. Conventional methods for thermal analysis however often lack sufficient accuracy or sample size to be applied to PCM. The T-history method is a simple method to determine the storage capacity of PCM and allows the use of large sample sizes. The experimental setup and methods of data analysis have been significantly improved in recent years. In this paper, a proper methodology to verify the correct setup and data analysis method of a T-history installation using standard materials with known properties is described and tested. The implementation of the T-history method has been done at the ZAE-Bayern. Three standard materials, gallium, water and hexadecane, were measured, as well as two commercial PCM, RT27 and sodium acetate trihydrate graphite compound (SAT+G). The obtained results confirm that the T-history installation can be used to analyse different PCM.

Phase change materials and products for building applications: A state-of-the-art review and future research opportunities

“…This makes it difficult to assess the suitability for each individual application. Accurate knowledge of a PCM's enthalpy as a function of temperature or storage capacity at each temperature is important for design purposes (Lázaro et al [72]). …”

New method to evaluate the heat storage density in latent heat storage for arbitrary temperature ranges

“…Today, it is possible to determine the stored heat as a function of temperature with an accuracy better than 0.5 K in temperature and better than 5 % in the heat stored [6,7,8,9]. But even for PCM with a broad melting range, the measured data are often simplified: the melting enthalpy is completely attributed to a melting temperature.…”

Fire behaviour of a mortar with different mass fractions of phase change material for use in radiant floor systems

“…The enthalpy-temperature curve of the granulated material has been measured. Since the sample must be representative of the material that is being investigated, the volume of the sample should be of at least a few cubic centimetres or more if possible [28]. For this reason an installation of the T-history method was chosen.…”