The present study is performed to numerically investigate temperature distribution at the channel walls during growth of a vapor bubble inside a microchannel. The microchannel is of 200 μm square cross section and a vapor bubble nucleates at one of the walls, with liquid flowing in through the channel inlet. Constant heat flux boundary condition is specified at the bottom wall of the microchannel. 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. The conjugate heat transfer problem is solved at the bottom and side walls. The bubble grows rapidly due to heat transfer from the walls and soon turns into a plug filling the entire channel cross section. The temperature distribution at the channel walls is studied for different values of wall heat flux. The bubble growth rate is found to increase with increase in wall heat flux. High temperatures are noted at the wall below the bubble base due to vapor contact causing axial temperature gradients. Areas of high heat transfer are also seen to exist in the thin layer of liquid between bubble and the channel sidewalls.

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