Flow boiling has an advantage in higher heat flux application ideal for miniature applications. What are the limitations that govern the application of flow boiling heat transfer over sensible cooling with respect to size of the device? Are there correlative figures available for selection appropriate means of cooling method?
Different types of regimes are observed under flow boiling, based on heat input. Experimental correlations are developed for heat transfer and pressure drop based on the type of flow regime such as bubly, slug, dispersed, annular flow, etc. As long as you maintain the liquid flow at the entry till the formation of vapor phase at the exit, there should not be any limitation for transfer of energy. Since phase change takes place, the capability to absorb heat is many times higher than single-phase convection. When it concerns miniature tubes, it is to be ensured that flow takes place as the pressure drop can be high preventing the flow of fluid. You may refer the book "Boiling and two phase flow" by Tong and Tang for further information.
About the second question in " Bergles, A.E., 1998. Techniques to enhance heat tansfer, in : Rohsenow, W. M., Hartnett, J. P., Cho, Y. I. (Eds.), Hand Book of Heat Transfer, 3d ed., Mac Graw-Hill, New York, 11.1- 11.76" We can find figures and tables which deal with techniques used in intensifcation of heat exchange using boiling flow as heat transfert mode