Optimal Porosity of Fibrous Battings for Thermal Insulation

The porosity of fibrous porous materials is an important factor to the thermal insulating performance of the material. This paper considers both the optimal porosity of uniform fibrous battings and the optimal distribution of the porosity of non-uniform fibrous battings for thermal insulation. The former was determined by an approximate analytical solution and a numerical simulation by using Finite Volume Method, and the latter was studied by applying Simulated Annealing Method. The study showed that the optimal porosity of uniform fibrous porous materials is very much dependent on fiber emissivity, and fiber radius, but little influenced by the temperature difference of the boundaries. For non-uniform fibrous materials, there can be an optimal distribution of porosity, which can be predicted by applying the Simulated Annealing Method.