Experimental and modeling investigation of non-equilibrium condensate vaporization in porous systems: Effective determination of mass transfer coefficient

Abstract Condensate vaporization in porous media occurs in several processes such as remediation, absorption/adsorption in packed beds, and gas recovery. Most of modeling/simulation investigations on condensate recovery processes assume local equilibrium to model mass transfer rate of components involved in the inter-phase mass transfer phenomenon. This assumption does not seem realistic, since high fluid velocity and limited contact area may result in an appreciable deviation from the equilibrium condition. In this study, vaporization of liquid condensate components into the flowing gas stream is explored through experimental and modeling approaches. We take into account the non-equilibrium inter-phase mass transfer. A key parameter in the non-equilibrium mass transfer is the mass transfer coefficient. Lack of adequate laboratory data concerning the vaporization of condensate components into the gas phase motivated us to conduct a systematic experimental work. Taguchi design of experiment (DOE) is implemented to optimize the experiments in terms of number of runs and process conditions. To accurately estimate the mass transfer coefficient, the diffusion/dispersion and convection mass transfer mechanisms are incorporated in the modeling of condensate vaporization in porous systems for the first time. The statistical tests are also employed to assess the relative importance of diffusion/dispersion and convection mechanisms in the condensate vaporization process. The optimum levels of design factors are found using signal to noise ratio (SNR) plots generated through using the Taguchi DOE. According to the statistical analysis, the diffusion term has no considerable impact on the magnitude of the mass transfer coefficient. The experimental results also reveal that the highest relative significance/contribution (about 36%) belongs to the gas flow rate. The second place is given to the liquid type with 28.83% contribution. The gas type and mean grain size hold the third and fourth ranks with 11.8% and 10.61% contributions, respectively. The experimental results confirm non-equilibrium mass transfer over condensate vaporization event, particularly at high-velocity conditions. Combining the theoretical concepts and experimental data, new empirical mass transfer correlations are suggested in this study that can be incorporated in commercial software packages for obtaining the mass transfer coefficient with a high precision.