The Interline Heat Transfer of Evaporating Thin Films Along a Micro Grooved Surface

Abstract

An analytical investigation of the heat transfer characteristics for evaporating thin liquid films in V-shaped microgrooves with nonuniform input heat flux was conducted. This investigation assumed that the capillary pressure difference caused by the receding of the meniscus is responsible for the axial liquid flow along the groove, and that the disjoining pressure difference along the groove side wall provided the driving force for the flow up the groove wall. The combined heat transfer mechanisms of both liquid conduction and interfacial vaporization were used to describe the local interracial mass flux in the interline region. Based on this approach, a local heat transfer coefficient was defined. The local and average heat transfer coefficients were both found to be sensitive to the characteristic thermal resistance ratio. In addition, when the film superheat was constant, the primary factor affecting the length of the evaporating interline region was found to be the heat flux supplied to the bottom plate, and for high heat flux conditions, the highest heat transfer coefficient did not necessarily exist at the axial dryout point. The expression developed for the evaporating film profile was shown to assume an exponential form if the heat flux distributed on the active interline region was assumed to be uniform.