Thermal Performance and Structural Optimization of Electric Heating Module Based on KAl(SO₄)₂·12H₂O/Expanded Graphite Composite Phase-Change Material

Under the background of vigorously promoting clean heating, the introduction of phase-change energy storage technology into heating systems has become a new hot issue. In this study, a novel KAl(SO₄)₂·12H₂O/expanded graphite (EG) shape-stabilized composite phase-change material (PCM), with a melting temperature of 91.6 °C, latent heat of 245.7 kJ kg⁻¹, and high heat conductivity of 2.07 W m⁻¹ K⁻¹, is prepared to manufacture a PCM-based module for space heating. This phase-change electric heating module is developed, and its heat storage and release characteristics are investigated through experimental and numerical studies. The numerical model is validated by experimental results. In view of the numerical simulation, the structure of the module is optimized and its thermal performance is studied. Based on the optimized module, a peak-valley time-of-use (TOU) electric heating module is finally proposed. It is revealed that the module exhibits good thermal performance and is capable of satisfying the indoor heating demand. The effective heat storage and release duration is 8.12 and 15.34 h, which can perfectly realize the operating mode under the “peak-valley TOU electricity” mechanism. In this study, it is demonstrated that peak–valley electric energy storage heating devices have broad prospects in building space heating and provides reference for future application.