TY - JOUR 
A1 - Egea Villarreal, Alberto
AU - García Pinar, Alberto
AU - Herrero Martín, Ruth
AU - Pérez García, José
T1 - Accelerated testing methods to analyse long term stability of a Phase Change Material under the combined effect of shear stress and thermal cycling
Y1 - 2022
SN - 2352-1538
UR - http://hdl.handle.net/10317/12168
AB - The long-term stability of a Phase Change Material (PCM) is a key point for its selection in energy storage devices. This work studies the suitability of a commercial paraffin wax in an active scraped surface heat exchanger for solar energy storage purposes. In these devices, the continuous scraping of inner walls during solidification removes PCM and increases the released heat. Hence, the PCM is affected by a high level of shear stress. In order to study a potential degradation of the paraffin, a novel accelerated procedure has been designed for obtaining samples with a different number of thermal and scraping cycles. The procedure allows to evaluate the effect of shear stresses, thermal cycles and their combined effects separately. Up to 3000 cycles have been generated, which accounts for around 8 years of continuous daily work in the heat exchanger. The measurements through Differential Scanning Calorimetry, rheometry and thermal conductivity analysis have shown that neither the thermal nor the scraping cycling have a significant impact on the paraffin thermo-physical properties. According to the findings reported in this work, paraffin wax RT44HC can be successfully used in scraped surface heat exchangers. It is expected that other commercial paraffins would be also suitable since most of them share the fact of being blends of alkanes and other hydrocarbons.
KW - Mecánica de Fluidos
KW - Phase change material
KW - Scraped surface heat exchanger
KW - Shear stress
KW - Accelerated thermal and scraping cycling
KW - Long-term stability
KW - 2204 Física de Fluidos
LA - eng
PB - ELSEVIER
ER -