Surface microstructures for boiling and evaporation enhancement in falling films of low-viscosity fluids

Development of Methods for Heat Transfer Enhancement During Nitrogen Boiling to Ensure Stabilization of HTS Devices

“…As the results of the authors in [115] show, the use of micro-structured capillary-porous coatings under these conditions would also be effective. As follows from analysis of experimental data [115][116][117][118][119], both these methods make it possible to significantly intensify the heat transfer during boiling in falling liquid films. In these works, results were obtained on the effect on heat transfer during boiling and evaporation in falling films of a mixture of R114/R21 freons and liquid nitrogen for various types of heat-release wall microstructures created by the deforming cutting method: micro-fins with semi-closed pores and micro-pin and needle structures.…”

Heat Transfer Enhancement on Multilayer Wire Mesh Coatings and Wire Mesh Coatings Combined with Other Surface Modifications—A Review

“…According to the authors, this enables implementation of a new enhancement mechanism based on the early evaporation of the microlayer. Shchelchkov et al [53] obtained CFH enhancement with the use of 3D microstructured surfaces with semi-closed pores having different parameters of pitch and height of basic microfinning, which were made by the promising method of deformational cutting (DCM, see the application of this method in [54]).…”

Falling film boiling of refrigerants over nanostructured and roughened tubes: Heat transfer, dryout and critical heat flux

“…No literature has been found for the use of surfaces that can be categorised as nanostructured in falling film-boiling conditions. Reduced dryout has been successfully achieved on 3D micro-enhanced and micro-porous tubes tested under falling film-boiling conditions with refrigerants, with plateau regions more insensitive to flow rate changes [16,17,24] and critical dryout at lower film flow rates [16,17,25,26] than for plain tubes. The improved wetting performance has been suggested to be through the ability of microstructured surfaces to better distribute the thin liquid films across the heat transfer surfaces [25] with interconnected internal pores distributing liquid [16] and nucleating bubbles further assisting by sucking liquid through the capillary pores to the nucleation sites [26].…”

“…Reduced dryout has been successfully achieved on 3D micro-enhanced and micro-porous tubes tested under falling film-boiling conditions with refrigerants, with plateau regions more insensitive to flow rate changes [16,17,24] and critical dryout at lower film flow rates [16,17,25,26] than for plain tubes. The improved wetting performance has been suggested to be through the ability of microstructured surfaces to better distribute the thin liquid films across the heat transfer surfaces [25] with interconnected internal pores distributing liquid [16] and nucleating bubbles further assisting by sucking liquid through the capillary pores to the nucleation sites [26]. Improved liquid distribution reduces falling film-boiling dryout as dry patches are thought to be formed by the evaporation of the thin liquid layers that appear between the larger waves that roll down the heat transfer surface during falling film boiling [25] or from the complete evaporation of the microlayer underneath nucleating bubbles [27].…”