Design of a portable water purification system using sweeping gas membrane distillation (sgmd) & high accuracy numerical simulation (hans) of a direct contact membrane distillation (dcmd) module part i: design of an sgmd module in this part, an sgmd desalination system was conceptualized. the design shows great prospects as a successful endeavour to create a portable membrane distillation water purifier. the membrane distillation module assembly (the eighteen units) takes up a volume of only 898.4 cm3 while for obtaining the same membrane area through conventional designs, we need a volume 25200 cm3. this is a substantial improvement. when the feed was distilled water, a permeate output of ~1.4 l/h was obtained. varying the feed and stripping-gas flow rates can provide significant control over the output, obviously at the expense of characteristics like system thermal efficiency. we could have added more module sub-assemblies (sets of six individual units) but then the feed reservoir would have to be accordingly larger, which could endanger the portability of our design. due to its portability, convenient handling, and low-energy consumption, the design shows immense potential for commercialization. the innovators hope that a day comes when everyone, regardless of economic class, can afford a hand-held water purifier that can be carried on the go. the current design is the first step towards the ambition. dcmd hans simulation: in this study, a 2d cfd simulation model was created in comsol multiphysics 5.4 for the purpose of explaining the momentum, heat and mass transfer phenomena in a dcmd module. the results were validated against the empirical work carried out by hwang et al. (2011) and were found to be in excellent agreement with the empirical data. the work also tries to overcome the isothermal shortcoming of the dusty gas model by using a fully non-isothermal nature of the temperature field and using variable, temperature and concentration-dependent fluid properties and diffusivities. the realism of the current modelling procedure is established by the results generally being within 0.8 % of those presented in existing experimental studies. if the units of temperature are changed to k (kelvin), the errors further drop to values less than 0.09 % (since temperature-based denominator increases). as of now, to the best of the authors’ knowledge, such accuracy has not been achieved in any of the modelling studies conducted on dcmd. the use of adaptive mesh refining has ensured that the solutions obtained from the model satisfy the mesh-independency tests. the use of fundamental physical equations in this study is helpful for modelling other membrane distillation configurations like agmd, sgmd, vmd, pgmd. with the hans method for md analysis, researchers can predict the heat and mass transfer characteristics of a membrane distillation system with sufficient levels of accuracy, exhaustiveness and robustness. ref: h.j. hwang, k. he, s. gray, j. zhang, i.s. moon, direct contact membrane distillation (dcmd): experimental study on the commercial ptfe membrane and modeling, j. memb. sci. 371 (2011) 90–98. https://doi.org/10.1016/j.memsci.2011.01.020.