Work

Impact of triple contact lines and interface instabilities on heat-transfer in a vertical grooved plate falling film evaporator at subatmospheric pressure

Year: 2026

Type: article

Abstract: An experimental and numerical study on a grooved plate-type heat exchanger was carried out in order to estimate the impact of the triple contact line evaporation and the intensification factor due to heat-conduction following the formation of wavelets on thermal performances obtained. The evaporator thermal performance is experimentally studied at absolute pressures ranging from 13 mbar to 23 mbar, logarithmic mean temperature difference ranging from 1 to 14 K and Reynolds numbers from 80 to 460. The working fluid is distilled water. To estimate the impact of the triple contact line evaporation and the formation of wavelets on obtained thermal performances, three different simple models based on steady state thermal energy balance are introduced. First, a flat falling film with a flat interface curvature and a constant heat-transfer coefficient at the falling film side is considered. Then the effect of the fins and the liquid film interfaces curvature on the evaporator heat transfer performance is discussed. Finally, based on the architecture of waves experimentally observed with a CCI probe, heat-transfer resistance that could be representative to the development of these waves considering only heat-conduction through the film are implemented inside the 2D steady-state models previously described. It is shown that the intensification factor due to a decrease of the heat-transfer resistance through the film with the development of waves could reach 10 % at Re = 500 and that despite some overestimation at low Re number due to the probably bad knowledge of the free surface falling film curvature, models allow to predict relatively well obtained performances with a relative difference with experimental data standing at 8 % for Re around 388.

Source: Applied Thermal Engineering

DOI: 10.1016/j.applthermaleng.2026.130690

Authors: Florine Giraud, Justine Senechal, Benoît Stutz

Institutions: Centre National de la Recherche Scientifique, Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement, Université Savoie Mont Blanc

Language: English

Topic: Heat Transfer and Boiling Studies

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,660

Funders: Association Instituts Carnot, Institut Carnot Santé Animale