Thermal Entry Length and Heat Transfer Phenomena in Laminar Wavy Falling Films

Abstract

There are many techniques for the cooling of the parts of industrial apparatuses and electrical components. The use of liquid film flow is a possible technique, offering solutions for the problems associated with the microgravity applications and for the case of normal earth conditions. In this work the thermal entry length of laminar wavy falling films was determined experimentally under full gravity conditions by means of infrared thermography. The dependence of the entry length on the Reynolds, Prandtl and Kapitza number as well as the ratio Pr 0 /Pr W between the Prandtl numbers at inflow and wall temperatures, presented 2 year ago in the same journal, was modified for the case of a larger area of Reynolds numbers as well as for the case of a nonlinear dependence of viscosity from the temperature.

Heat Transfer Phenomena in Laminar Wavy Falling Films: Thermal Entry Length, Thermal-Capillary Metastable Structures, Thermal-Capillary Breakdown

“…Whereas for very low Reynolds numbers (Re 0 < 3) and heat fluxes the experimental data correlate satisfactorily with these dependencies, at larger Reynolds numbers and heat fluxes the experimental values lie under the ones obtained through correlations. [1] -experimental data by (Lel et al, 2007b); [2] -experimental data by (Lel et al, 2009).…”

“…This question stays unsettled and should be investigated in future. [1] -experimental data by (Lel et al, 2007b); [2] -experimental data by (Lel et al, 2009). …”