In previous studies on DCMD process, it has been found that the microbubbles play a significant role in enhancing the heat and mass transfers in the liquid streams, leading to an improvement in the DCMD permeate flux. In this study, a novel swirling flow-type microbubble generator capable of supplying air is thus designed and fabricated for DCMD process. DCMD performance is evaluated for various operating conditions (i.e., air supply flow rate, feed temperature and flow rate) and geometrical (i.e., swirler length and nozzle tip size) conditions so as to demonstrate possibilities offered by the microbubbles. In order to analyze the microbubble characteristics generated by the microbubble generator, the probability distribution of microbubble diameter is inferred from these experimental measurements at assorted operation conditions. It is clearly evident that more microbubbles are generated at higher feed flow rates and lower feed temperatures, resulting in a higher DCMD permeate flux.