Intercomparative tests on phase change materials characterisation with differential scanning calorimeter

Abstract

For the correct design of thermal storage systems using phase change materials (PCMs) in any application, as well as for their simulation, it is essential to characterise the materials from thermophysical and rheological standpoints (phase change enthalpy, thermal conductivity in solid and liquid phases, viscosity and density in function of temperature). Taking advantage of the different research groups facilities available in two international networks: within the IEA (International Energy Agency), the ECES Implementing Agreement (Energy Conservation through Energy Storage IA) and SHC Programme (Solar Heating and Cooling) Task 42/Annex 24 ‘‘Compact Thermal Energy Storage – Material Development for System Integration’’, and the COST Action TU0802 ‘‘Next generation cost effective phase change materials for increased energy efficiency in renewable energy systems in buildings (NeCoE-PCM)’’ a set of Round Robin Tests (RRTs) was proposed. The objective was to come to comparable results for PCMs using Differential Scanning Calorimetry (DSC) to determine their melting enthalpy as well as their melting and solidification behaviour. The first RRT was without defining the procedure, the second one with a predefined procedure for the measurements, but not for calibration and the third one with a predefined procedure for calibration, for the measurements and also for the data evaluation. This paper presents the conclusions after the three RRT. The main conclusion of the paper is that enthalpy in function of temperature determined using a dynamic method for DSC can be influenced by certain reasons and finally a methodology to avoid these influences have been proposed.

Authors would like to thank the manufacturers NETZSCH, Mettler Toledo, TA Instruments and Perkin Elmer as well as all the participants in the RRT and in the workshop. They would like to thank very specially to the Fraunhofer ISE for the organization of the Workshop. Authors would like to acknowledge the contribution of Dr. Macej Jaworski (Warsaw Institute of Technology, Poland), M. Dolores Romero (AIDICO, Spain), National Institute of Chemistry (Slovenia), Dr. A. Inés Fernández (University of Barcelona, Spain), TU Wildau, Polymer Institute of Slovak Academy of Science (Slovenia), Université de Pau (France), DLR (Germany). Furthermore, they would like to thank the Spanish government for partially funding this work, within the framework of research projects ENE2011-28269-C03-01 and ENE2011-22722 and the European Union (COST ACTION TU0802). The authors at the University of Lleida would like to thank the Catalan Government for the quality accreditation given to their research group (2009 SGR 534). Additionally we would thank the German Federal Ministry for Economics and Technology for funding Fraunhofer’s contribution to the IEA Task/Annex 42/24 within the project ‘‘PCM-Zentral’’ (Fkz 0327842A).