Cycling stability of Poly(Ethylene Glycol) of six molecular weights: influence of thermal conditions for energy applications
Journal article, 2020

Utilizing energy storage technologies is beneficial for bridging the gap between supply and demand of energy, and for increasing the share of renewable energy in the energy system. Phase change materials (PCM) offer higher energy density and compact storage design compared to conventional sensible heat storage materials. Over the past years, polyethylene glycol (PEG) gained attention in the PCM field, and several new composites of PEGs are developed for thermal energy storage purposes. PCMs are investigated at a given heating/cooling rate to evaluate their phase change temperature and enthalpy. In the case of PEG, some molecular weights show a melting behavior that depends on the thermal history, such as the crystallization conditions. This study investigates the relationship between the molecular weight of PEGs (400 to 6000 g/mol), cooling/heating rates, and the behavior during phase transitions. To evaluate the performance of PEGs as a PCM under various thermal conditions. Experiments were performed using differential scanning calorimeter (DSC) and the transient plane source method (TPS). All PEG molecular weights were subjected to the same cooling and heating conditions, cooling and heating rate and number of cycles, to decouple the thermal effects from molecular weight effects. The behavior of phase transition for different thermal conditions was thoroughly analyzed and discussed. It was found that the melting temperature range of PEGs with different molecular weight was between 5.8 °C and 62 °C (at 5 °C/min). Each PEG showed unique responses to the cooling and heating rates. Generally, the behavior of the crystallization is changing most between the thermal cycles, while the melting peak is stable regardless of the molecular weight. Finally, it is recommended that the characterization of PEGs and their composites should be conducted at a heating and cooling rate close to the thermal conditions of the intended thermal energy storage application.

Poly(ethylene glycol) (PEG)

Molecular weight

Thermal Energy Storage (TES)

Crystallization

Cycling stability

Phase change material (PCM)

Melting

Thermal Analysis

Author

Robert Paberit

Chalmers, Architecture and Civil Engineering, Building Technology

Erik Rilby

Chalmers, Architecture and Civil Engineering, Building Technology

Johan Göhl

Chalmers, Architecture and Civil Engineering, Building Technology

Jan Swenson

Chalmers, Physics, Nano and Biophysics

Zakariaa Refaa

Chalmers, Architecture and Civil Engineering, Building Technology

Pär Johansson

Chalmers, Architecture and Civil Engineering, Building Technology

Helen Jansson

Chalmers, Architecture and Civil Engineering, Building Technology

ACS Applied Energy Materials

25740962 (eISSN)

Thermal Energy Storage (TES)

Chalmers, 2020-01-01 -- .

Driving Forces

Sustainable development

Subject Categories

Energy Engineering

Other Environmental Engineering

Energy Systems

Areas of Advance

Energy

DOI

10.1021/acsaem.0c01621

More information

Created

10/27/2020