Expanded Vermiculite/D-Mannitol as Shape-Stable Phase Change Material for Medium Temperature Heat Storage.

Area of Science:

• Materials Science
• Energy Storage
• Chemical Engineering

Background:

• D-mannitol is a promising phase change material (PCM) for thermal energy storage but suffers from low thermal storage efficiency and high supercooling.
• Developing shape-stable phase change materials (ss-PCMs) using affordable supporting materials is crucial for overcoming these limitations.

Purpose of the Study:

• To prepare a high-performance ss-PCM for medium-temperature heat storage by utilizing D-mannitol preserved in expanded vermiculite.
• To investigate the effectiveness of different vermiculite treatments (acid, calcination, microwave) in creating a suitable support material.

Main Methods:

• Expanded vermiculite was treated using dilute acid, calcination, and microwave heating.
• Calcined expanded vermiculite (CV) was selected as the optimal support material.
• D-mannitol was impregnated into the CV matrix via vacuum impregnation to create the ss-PCM.

Main Results:

• The CV/D-mannitol ss-PCM achieved a melting enthalpy of 205.1 J/g and a crystallization enthalpy of 174.1 J/g.
• Supercooling was significantly reduced to 45.6 °C.
• The ss-PCM demonstrated excellent reusability and long-term stability.

Conclusions:

• Calcined expanded vermiculite is a cost-effective and abundant supporting material for D-mannitol-based ss-PCMs.
• The developed CV/D-mannitol ss-PCM shows great potential for effective waste heat recovery and temperature regulation in medium-temperature applications.