Thermal performance and ageing effects to model the life cycle assessment of heat-protective thermal insulation materials in pipe systems

Most power plants and district heating systems employ rock wool or ceramic fiberglass insulations to insulate their pipes. Over time, these materials lose some qualities. The present study tested two thermal insulation materials for applications in pipelines carrying hot steam in power plants or district heating (DH) systems: ceramic fiberglass (insulfrax) and flexible mineral wool. Thermal conductivity was measured at high temperatures (150 and 250 °C), simulating the effect of the passage of time. It was found that insulfrax had lower thermal conductivity in all cases 0.025–0.031 W/mK, compared to the mineral wool (0.038–0.422 W/mK). However, thermal conductivity of the mineral wool was continuously increasing (3 % and 9 %), and the thermal conductivity of the insulfrax jumped only after thermal annealing at 250 °C, but by about 24 %. Scanning electron microscopic imaging and differential scanning calorimetry experiments were used to reveal any possible changes in the structures of the materials after thermal annealing them at 150 and 250 °C for 1 day. The change in the specific heat was also calculated with differential scanning calorimetry, and crystallization processes were deduced. Finally, a comparative life cycle assessment was applied to select materials based on environmental performance, aligning with the Sustainable Development Goals requirements.