Microencapsulated PCM slurries’ dynamic viscosity experimental investigation and temperature-dependent prediction model

Abstract

Microencapsulated PCM (mPCM) slurry is used both as a thermal storage medium and as a heat transfer fluid. The use of mPCM slurry as a working fluid in heat transfer systems requires knowledge of its rheological properties. In this study, experimental research results based on the mPCM product called Micronal® DS 5039 X were used. The research was carried out in the following range: a slurry temperature of 10–50 °C; a mass concentration of microcapsules in the slurry of up to 45%; two types of base liquid (water, an aqueous solution of propylene glycol); a shear rate of 3–130 s−1. This article presents a new temperature-dependent method of calculating the dynamic viscosity coefficient of microencapsulated PCM slurry. The average mean absolute percentage error (MAPE) for the investigated cases was MAPE = 14.19% and MAPE = 12.81% for the Micronal® DS 5039 X slurry in water and the aqueous solution of propylene glycol, respectively. Additionally, the validation of the model was based on the results of other authors’ research. Thus, it was found that 73.1% of the calculated viscosity results of mPCM slurry do not differ by more than 40% from other authors’ experimental results.