For accurate predictions of direct contact membrane distillation (DCMD), the model should be dynamic, in 2D, and consist of experimentally validated parameters. All of these conditions are not available in the existing literature on membrane distillation (MD) modeling. Therefore, in this study, a first-principle 2D Spatio-temporal model that consists of experimentally validated parameters is employed for accurate predictions of membrane system stability. Model parameters (k_(s,h), k_(s,c), _Heatloss, _Coil) were validated at different operating conditions using raw seawater and analytical grade NaCl; model accuracy was evaluated by comparing the model predictions before and after parameter estimation, and the calibrated model was compared with existing literature models to test model robustness. Flux decline predictions were in 95% agreement with the long-term experimental data. This study revealed that temperature polarization also occurs along the membrane surface (z-direction) and temperature polarization is prominent at the inlet of the feed channel.