CHARACTERISTICS OF MICROLAYER FORMATION AND HEAT TRANSFER IN MINI/MICROCHANNEL BOILING SYSTEMS: A REVIEW

This paper reviews recent research on microlayer fo rmed by confined vapor bubbles during boiling in mi ni/microchannels. Experimental measurements, simulations and theoretical studies a re described and compared. As a reference to clarif y the mechanism for the formation of a microlayer, Taylor flow (i.e. elongated bubble flow in mini/micro circular tubes under adiabatic condi tions and at Re << 1) and elongated bubble flow at high velocity, with consideration of the in fluence of inertia, are also reviewed. Compared to the steady adiabatic conditions, one of the distinct points for the boiling condition is that t he bubble grows exponentially due to rapid evaporat ion of the microlayer. A pattern of two regions (i.e., surface tension-viscosity controlled and bou ndary layer controlled regions) seems to be present ly acceptable to describe microlayer formation for a wide range of bubble growth velocity. In addi tion, the effect of microlayer evaporation on the b oiling heat transfer in mini/microchannel is