Recently, the thermal emission issued from many components and devices in engineering fields has exceeded 10 MW/m^2. The common cooling methods have not met the requirement. Microbubble emission boiling (MEB) is expected for being employed to solve the problem due to its high heat transfer performance. A high-speed video camera (Fastcam SA5) was employed to study bubble dynamic behavior in MEB visually for improving the understanding of it. Experimental results showed that the bubble behavior of MEB differed from both nucleate boiling and film boiling. In the regime of MEB, a large irregular bubble would form on the heating surface and break up rapidly afterwards, but not departure from the heating surface. The period of bubble ebullition was shorter and the change rate of bubble radius was higher in MEB than those in other boiling modes. A dimensionless analysis showed that the wall superheat and heat flux had great impact on the variation of dimensionless bubble radius in MEB, while had slight influence on that in other boiling modes. The inertia effects increasingly dominated the condensation and collapse process with the increase in wall superheat and heat flux for MEB.
