Water boiling at low pressure: dynamics of growth and bursting of bubbles in a plate-type evaporator

Patric Mantaropoulos (1) , Florine Giraud (1) , Brice Tremeac (1) , Pascal Tobaly (1)

1 Lafset - Laboratoire du froid et des systèmes énergétiques et thermiques

Water is a good candidate to be used as an eco-friendly refrigerant. However, its behaviour under subatmospheric pressure needs to be better understood to optimize the efficiency and sizing of compact evaporators. Previous studies conducted in a plate-type evaporator highlighted that after the bubbles burst, the formation and evaporation of a thin liquid film on the evaporator wall has a major contribution on heat transfer. This work thus aims to characterize the dynamics of vapour bubbles during nucleate boiling, and more specifically the projection height after the free surface breakup. Using previous high-speed visualizations, the bubbles' characteristics are computed thanks to an ad-hoc Python program. It is shown that the projection height is correlated with the growth velocity and the size of the bubble reached just before it bursts. The influence of relevant dimensionless numbers on the projection height is also studied to determine the underlying predominant forces.

Mots clés: Refrigeration; Plate-type evaporators; Water; Bubbles; Low pressure; R-718

Domaines: Sciences de l'ingénieur [physics]

Patric Mantaropoulos, Florine Giraud, Brice Tremeac, Pascal Tobaly. Water boiling at low pressure: dynamics of growth and bursting of bubbles in a plate-type evaporator. 14th IIR-Gustav Lorentzen Conference on Natural Refrigerants(GL2020), Dec 2020, Kyoto (on line), Japan. ⟨10.18462/iir.gl.2020.1059⟩. ⟨hal-03106574⟩