NUMERICAL SIMULATION OF MULTIPLE BUBBLE INTERACTION DURING FLOW BOILING IN MICROCHANNELS

A numerical study has been performed to analyze the wall heat transfer mechanisms during growth of multiple vapor bubbles inside a microchannel. The microchannel is of 200 mu m square cross section and multiple vapor bubble begins to grow at once and after delay on the walls, with liquid coming in through the channel inlet. The complete Navier-Stokes equations along with continuity and energy equations are solved using the SIMPLER method. The liquid vapor interface is captured using the level set technique. It can be seen that the second bubble which is far from the inlet always got bigger than the first one. When the second bubble nucleates 0.0549 ms after the first one, both bubbles grow almost to the same size. The numerical results show that bubbles with the lowest contact angle resulted in the highest wall heat transfer. Finally, a comparative study was done between single bubble and two bubbles inside a microchannel. wall heat transfer is better when two bubbles do not merge together compared to the single bubble and when they do merge.