FlowPCM Concept as a Mobile Thermal Energy Storage System for Waste Heat Recovery and District Heating Integration

This study presents the FlowPCM concept, a mobile thermal energy storage (M-TES) system based on encapsulated phase change material (PCM) for waste heat recovery and potential integration with district heating and local heat supply systems. Unlike conventional M-TES solutions with stationary PCM beds, FlowPCM uses capsules containing ferromagnetic elements, enabling their magnetic handling and potential direct-contact charging in selected waste heat streams. The study combines a state-of-the-art comparison, capsule design and packing assessment, preliminary thermal calculations, and laboratory magnetic interaction tests. For the analysed industrial waste streams at 70–90 °C, the available thermal potential substantially exceeded the nominal storage capacity of a single FlowPCM unit (7.2 GJ), indicating that heat availability would not be the limiting factor in the considered application. Preliminary magnetic tests confirmed capsule attraction and lifting using permanent magnets. Depending on the magnet configuration, the first observable capsule interaction occurred at approximately 85–110 mm, while effective attraction suitable for practical handling occurred below approximately 50–60 mm. These results provide preliminary support for the technical feasibility of magnetically assisted capsule handling; however, direct-contact charging, long-term capsule durability, thermal performance, and magnetic recovery under representative industrial conditions still require experimental validation.