高分子電解質による熱エネルギー貯蔵の促進(Boosting thermal energy storage with polyelectrolytes)

2023-11-16

添加剤混合物が相変化材料を安定化させ、ヒートポンプの可能性を解き放つ Additive mixture stabilizes phase change material, unlocks potential for heat pumps
1. 熱エネルギー貯蔵用途のための低コスト相変化材料の安定化 Stabilization of low-cost phase change materials for thermal energy storage applications

添加剤混合物が相変化材料を安定化させ、ヒートポンプの可能性を解き放つ Additive mixture stabilizes phase change material, unlocks potential for heat pumps

2023-11-15 オークリッジ国立研究所(ORNL)

◆オークリッジ国立研究所の研究者は、ポリマーと電解質からなる添加剤が、塩水和物相変化材料（PCM）の熱性能と安定性を向上させることを示しました。
◆この研究結果は、PCMの不安定性を解消し、安定性を150回のサイクルにわたり維持することが可能であることを示唆しています。これにより、低二酸化炭素排出のヒートポンプへのPCMの統合が進展し、建築物の熱蓄積材料の設計に有益な情報を提供する可能性があります。

＜関連情報＞

熱エネルギー貯蔵用途のための低コスト相変化材料の安定化 Stabilization of low-cost phase change materials for thermal energy storage applications

Damilola O. Akamo, Navin Kumar, Yuzhan Li, Collin Pekol, Kai Li, Monojoy Goswami, Jason Hirschey, Tim J. LaClair, David J. Keffer, Orlando Rios, Kyle R. Gluesenkamp
iScience Published: June 20, 2023
DOI:https://doi.org/10.1016/j.isci.2023.107175

Highlights

•Stabilization of sodium sulfate decahydrate (SSD) using polymeric additives
•Evaluation of structural, thermal, and rheological properties of PCM composites
•Improved thermal cycling stability up to 150 cycles using polyelectrolyte
•Polyelectrolyte-stabilized salt hydrate for long-term thermal stability of PCMs

Summary

Sodium sulfate decahydrate (Na₂SO₄^.10H₂O, SSD), a low-cost phase change material (PCM), can store thermal energy. However, phase separation and unstable energy storage capacity (ESC) limit its use. To address these concerns, eight polymer additives—sodium polyacrylate (SPA), carboxymethyl cellulose (CMC), Fumed silica (SiO₂), potassium polyacrylate (PPA), cellulose nanofiber (CNF), hydroxyethyl cellulose (HEC), dextran sulfate sodium (DSS), and poly(sodium 4-styrenesulfonate) (PSS)—were used to explore several stabilization mechanisms. The ESC of PCMs deteriorated when thickeners, SPA, PPA, and CNF, were added. DSS-modified PCMs exhibited greater stability up to 150 cycles. Rheology measurements indicated that DSS did not impact SSD viscosity significantly during stabilization. Dynamic light scattering showed that DSS reduces SSD particle size and electrostatically suspends salt particles in a stable homogeneous solution, avoiding phase separation. This study proposes a promising method to improve the thermal stability of salt hydrate PCMs by utilizing polyelectrolyte-salt hydrate mixture for thermal energy storage applications.