An improvement for dynamic twin chamber method to measure VOC diffusion coefficient and partition coefficient

This paper provides an improvement on the dynamic twin chamber method to measure volatile organic compound (VOC) diffusion coefficient and partition coefficient by considering the convective mass transfer resistance on the both surfaces of the building material. A formula analyzing this improvement is obtained. It is found that the diffusion coefficient is underestimated by ignoring the convective mass transfer resistance in the traditional twin chamber method. The relative error is high to 46% when the convective mass transfer coefficient is 0.00262 mph (0.00117 m/s) according to the experimental data and simulation. However, the effect of this ignoring on the partition coefficient tends to be small. In addition, a dimensionless analysis is introduced to further consider the effect. The proposed method can improve the precision of diffusion coefficient obviously for the cases studied.