Thermal Characterization of Medium-Temperature Phase Change Materials (PCMs) for Thermal Energy Storage Using the T-History Method

Abstract

To reduce energy consumption and increase energy efficiency in the building sector, thermal energy storage with phase change materials (PCMs) is used. The knowledge of the thermophysical properties and the characteristics of PCMs (like their enthalpy changes and the distribution of stored energy over a specified temperature range) is essential for proper selection of the PCM and optimal design of the latent thermal energy store (LHTES). This paper presents experimental tests of the thermophysical properties of three medium-temperature PCMs: OM65, OM55, RT55, which can be used in domestic hot water installations and heating systems. Self-made test chambers with temperature control using Peltier cells were used to perform measurements according to the T-history method. In this way the temperature range of the phase transition, latent heat, specific heat capacity, enthalpy and the distributions of stored energy of the three PCMs were determined. The paper also presents measurements of the thermal conductivity of these PCMs in liquid and solid state using a self-made pipe Poensgen apparatus. The presented experimental tests results are in good agreement with the manufacturers’ data and the results of other researchers obtained with the use of specialized instruments. The presented research results are intended to help designers in the selection of the right PCM for the future LHTES co-working with renewable energy systems, waste heat recovery systems and building heating systems.

Hybrid energy-temperature method (HETM): A low-cost apparatus and reliable method for estimating the thermal capacity of solid–liquid phase change material for heat storage system

“…The calorimetry method (differential scanning calorimetry) offers a versatile measurement with a shorter time at a limited sample quantity (less than 1 g). The restricted sample capacity can be solved using THM, which uses a larger sample capacity [11] , [12] , [13] . However, the measurement uses temperature as the main reference.…”

Performance analysis and PCM selection for adsorption chiller aided by energy storage supplied from the district heating system

“…Considering the PCM, knowledge of the specific heat for both the liquid and solid states is necessary as well as the phase transition temperature and specific heat of fusion. These parameters are often determined using the well-known differential scanning calorimetry (DSC) technique [45,46] or the T-history method [47]. Based on the known thermophysical properties, it is possible to estimate the thermal capacity of the storage but this only applies to the quasi steady-state conditions.…”

Experimental analysis of Shape-Stabilized PCM applied to a Direct-Absorption evacuated tube solar collector exploiting sodium acetate trihydrate and graphite

“…temperature history (T-history) method was adopted to obtain the C p,l , C p,s , and H F values of the SSPCMs with various components over 3 heating and cooling cycles using the temperature difference of the sample (i.e., SSPCM) with that of a reference material (i.e., water). The reason why T-history method was chosen over Differential Scanning Calorimetry (DSC) technique, was the fact that with the T-history method about 100 times more mass of the sample can be tested compared to the DSC analysis [32]. Thereby, 6 g of the SSPCM and 6 g of distilled water were placed inside two identical 3D-printed biodegradable plastic cylinders, and both cylinders were placed inside the insulation material.…”