Bubble Coalescence Characteristics in Micro-Scale Nucleate Boiling

Micro-scale bubble growth, coalescence and heat transfer characteristics are numerically investigated. Bubble interface is tracked with VOF（Volume of Fluid） method in CFD（Computational Fluid Dynamics） software. A 3 mm×2 mm×2 mm 3-D micro-channel is set up and 5 heating elements are arranged at the bottom surface. These elements can measure the local heat flux as well as provide the power for the bubble nucleation. Bubble growth and coalescence characteristics and heat flux distributions under bubbles are analyzed and compared with the experimental observations. The heat transfer mechanisms in nucleate boiling are better interpreted by developing the correlations of bubble dynamics and heat flux variations at different positions.