Phenomenological modelling of phase transitions with hysteresis in solid/liquid PCM

Abstract

Technical-grade and mixed solid/liquid phase change materials (PCM) typically melt and solidify over a temperature range, sometimes exhibiting thermal hysteresis. Three phenomenological phase transition models are presented which are directly parametrized using data from complete melting and solidification experiments. They predict hysteresis phenomena and are used to calculate effective PCM properties. Two models have already been implemented in commercial building simulation and/or multiphysics software, but not the third novel model. Applications are presented for two commercial PCM: a paraffin, and a salt water mixture with additives. Numerical implementation aspects are discussed, and significant differences in the predicted absorbed and released heat are highlighted when simulating consecutive incomplete phase transitions. The models are linked with energy balance equations to predict recorded PCM temperatures of a thermal energy storage. The cross-validation with data from 26 partial load conditions clearly indicate a superior predictive performance of the novel hysteresis model.

The authors thank Birgo Nitsch, Vladimir Parfenov and Andreas Strehlow (AKG Verwaltungsgesellschaft mbH) for fruitful discussion and support in the modelling of the heat transfer in the compact plate fin heat exchanger. The authors would like to thank the Catalan Government for the quality accreditation given to their research group (GREiA 2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This project has received funding from the European Union’s Horizon 2020 research and innovation programme [grant number 768824] (HYBUILD) and from the Ministerio de Economía y Competitividad de España (ENE2015- 64117-C5-1-R (MINECO/FEDER)).