Surface radiation interchange in an annular enclosure is numerically modeled together with evaporating meniscus-driven convection, for investigating the application of the concept for cooling in microelectronic devices. The geometry is axially discretised into ring elements, where the wall and fluid temperatures within each element are unknowns. The governing algebraic energy equations for convection and surface radiation for each element are formulated for steady-state operating conditions for heat generating cylinders. These equations are then solved simultaneously for all the elements, together with the integral form of the momentum equation, which equates the driving force due to the meniscus curvature to the weight of the coolant and the frictional resistance, and solely dictates the coolant rise length in the microchannel. The results reveal the coupling of fluid flow and heal transfer in the annular microchannel, and the relative importance of radiation. (C) 2000 Elsevier Science Ltd. All rights reserved.