Flat sheet direct contact membrane distillation desalination system using temperature-dependent correlations: thermal efficiency via a multi-parameter sensitivity analysis based on Monte Carlo method

In this paper, a 1D model of direct contact membrane distillation is presented in which all fluid properties are temperature-dependent. In addition, a Nusselt number (Nu) relationship for developing flow in ducts (accounting for both thermal and hydrodynamic effects) is used to obtain the convective heat transfer coefficient at each side of the membrane. Simulated mass flux shows very good agreement with experimental measurements at various feed temperature, flow rate and concentration. A comprehensive sensitivity analysis of all operational and geometrical parameters, as well as Nu estimation parameters on water mass flux across the membrane $$(J_{\text{m}} )$$ and thermal efficiency, is also done. To determine the relative importance of each parameter, a multi-parameter sensitivity analysis (MPSA) based on the Monte Carlo method is applied, and the sensitivity index of each parameter at the defined range is computed. Results show that $$J_{\text{m}}$$ is highly sensitive to bulk feed inlet temperature ( $$T_{{{\text{in}},{\text{f}}}}$$ ) while both $$J_{\text{m}}$$ and thermal efficiency are highly sensitive to membrane porosity. Results show that among all parameters, just membrane porosity is highly sensitive which affects both mass flux and thermal efficiency especially at low $$T_{{{\text{in}}.{\text{f}}}}$$ .