Experimental and numerical study on effective thermal conductivity of novel form-stable basalt fiber composite concrete with PCMs for thermal storage

• Novel form-stable basalt fiber composite concrete with PCMs was prepared.
• ETC of the composites with PCM was studied with experimental and numerical method.
• The numerical model was validated with experimental data.
• Contact thermal resistance between PCM with matrix affects ETC of the composites at solid state.

In this paper, the study on effective thermal conductivity (ETC) of a novel form-stable fiber composite concrete containing dispersed phase change materials (PCMs) is presented. Such composites are used in various thermal storage systems. The concrete matrix is prepared by mixing cement, fine sand, and gypsum with water. Paraffin is used as phase change material, and is dispersed in the matrix at liquid state. Basalt fibers are added in order to enhance the elastic modulus and strength. The distribution of fiber and paraffin particles is characterized through images taken from an electron microscope (EM). The ETC of the specimens are measured by steady-state method. A numerical model is developed to predict the effect of PCMs and fiber on the ETC of composite. The numerical model is validated with experimental data. The numerical results show that finite contact thermal resistance between PCM and matrix affects ETC of the composites at solid state, as the volume of PCM changes with temperature. The agreement between the numerical model and the experiments provides the opportunity to study form-stable fiber composite concrete with PCMs without performing repeated experiments.