Abstract: A new design of direct contact membrane distillation (DCMD) with various hydrodynamic angles of inserting carbon-fiber spacers in flow channels was proposed to increase the pure water productivity in saline water desalination. Temperature polarization causes the reduction of effection temperature driving force for membrane distillation. Attempts to reduce the temperature polarization were made by implementing the spacer-filled channel to create wakes and eddy in the flow characteristic. Experimental study has demonstrated its feasibility, and sustainable performance enhancement was obtained for the experimental system. The purposes of this study are (1) to develop the heat-transfer coefficient correlation for the carbon fiber channel; (2) to develop a one-dimensional mathematical model and propose a general numerical method for predicting pure water productivity of DCMD systems; (3) to study the effects of various operation parameters including the inlet fluid temperatures, volumetric flow rate, spacer-filled channel on the pure water productivity improvement. A correlated equation for estimating heat-transfer coefficient for spacer-filled channels with different hydrodynamic angles was obtained, and the results show that the agreement between the experimental results and the theoretical predictions is fairly good. The new design of eddy promoter can effectively enhance the mass flux, among the operating conditions set in this study, up to 45%.