Microstructure and thermal conductivity of paraffin@burning garbage ash phase change energy storage materials embedded in hydraulic cementitious composites: Experiments and numerical simulation

Abstract

The incorporation of phase change materials into buildings such as concrete has a significant effect on tempering and energy saving. Paraffin@burning garbage ash Phase change energy storage Materials (PPMs) were manufactured through a mixed grinding-heating method, whose chemical-physical properties were observed using a series method. Then, PPMs were added to gypsum and cement paste to evaluate their mechanical properties and thermal conductivity. Finally, a thermal conductivity numerical model of cementitious materials was established using the lattice Boltzmann method and compared with the experimental results. The results demonstrate that the paraffin can be fully incorporated into the pores of burning garbage ash and the composited material can form a whole, and its chemical and thermal properties are stable. The compressive strength of the composited material hardly changes when the PPM dosage is less than 10% while the compressive strength declines by approximately 40% when the dosage reaches 30%. With the increasing PPMs, the thermal conductivity of hydraulic cementitious composites decreases significantly up to 61%. Therefore, the phase change composites have good latent heat of phase change and mechanical properties when the doping amount is between 10% and 20%. The effective thermal conductivity simulated corresponds well with the experimental results. This study provides a theoretical basis for the use of this composite phase change material for energy saving in concrete.