In this work, a double-nozzle coaxial electrohydrodynamic atomization (CEHDA) system was designed as an instructive case toward large-scale production of core-shell microspheres. The effect of nozzle-to-nozzle distance was investigated to reveal that the interference between neighboring nozzles significantly affect the product quality in terms of morphology and core-shell structure. Optimal spacing indicated that similar to 3000 nozzle/m(2) packing density may be achieved with minimum interference of electric field from neighboring nozzle by adjusting the nozzle-to-nozzle distance greater than 0.018 m. The proposed multi-scale model also showed that the X-component of electric field strength (Ex) at the region near side nozzles increases with increasing nozzle number, and the bending of jets/sprays at the side may be reduced by using dummy nozzle at the edge side. The model could guide the design of multi-nozzle CEHDA system for production of core-shell microparticles in large-scale. (C) 2017 American Institute of Chemical Engineers