Coupling of flexible phase change materials and pipe for improving the stability of heating system

The extensive researches of flexible phase change materials (FPCMs) provide a new way for the coupling of heating system and latent heat storage technology to improve the limited thermal inertia of heating system. In this study, FPCMs were prepared with styrene ethylene butylene styrene (SEBS) as flexible supporting material, expanded graphite (EG) as thermal conductivity additive and paraffin as PCMs. The prepared materials with 8 wt% EG, enthalpy of 181.22 kJ kg−1 and thermal conductivity of 0.78 W m−1 K−1 was selected to couple with secondary heating pipe. The stability and indoor thermal comfort of heating system coupling with FPCMs and heating pipes were analyzed in detail by simulation. The results show that, for the object system, the addition of 53 mm FPCMs to heating pipe has the best economic applicability, which reduces the fluctuation of supply temperature by 20.99% (1.70 °C) and that of indoor temperature by 22.92% (0.11 °C). Besides, from the simulation results of 1–5 h non-heating condition, the secondary heating pipe using FPCMs can provide at least 3 h for the repair of heating equipment or boiler in primary pipe network. The results also provide technical support for the matching application of high proportion renewable energy, which is unstable and intermittent, and flexible latent heat storage in heating system.