Direct numerical simulation of bubble dynamics and heat transfer during nucleate boiling on the micro-pin-finned surfaces

Abstract

The pool boiling on the micro-pin-finned surfaces was numerically investigated using the curvilinear coupled Volume of Fluid and level set method (VOSET) with phase change. The information interaction problem on the boundary of a complex domain was solved by the partition identification function and unstructured storage. The experiment and simulation of single bubble growth on the micro-pin-finned surface were conducted, whose results agree with each other and validate the accuracy of the numerical method. The bubble characteristics such as bubble shape, temperature distribution, pressure field and micro flow were analyzed and compared with that on the smooth surface, which demonstrates that the vortex near the three-phase contact line plays a significant role in the bubble growth and boiling heat transfer. The effects of wall superheat, gravity level, contact angle and the height of micro-pin-fins were investigated. With the increase of superheat, the average heat flux and bubble diameter increase while the departure time decreases. Under microgravity, the bubble diameter and departure time are larger compared with terrestrial gravity, which deteriorates the heat transfer performance. The fin height basically has no effect on the initial bubble growth. However, there exists a critical fin height leading to the smallest departure diameter and time. Besides, the double bubble coalescence on the micro-pin-finned surface was also investigated. The bubble growth rate reduces after the coalescence. During the coalescence, the surface energy converts into kinetic energy causing the violent deformation of the bubble shape, which promotes the liquid supply and increases the wall heat flux.