Schematic of the fluid handling system.
Cross section of the PTFE test chamber. The chamber inside diameter was 11.9 cm and the distance from the copper surface to the window was 8.1 cm.
Cross-sectional and isometric drawings of the copper substrate. The substrate was 2.5 cm thick and 12.7 cm in diameter.
Schlieren images of example experiment. Dichloromethane subject to 3.9 °C superheat. (a) Highly transient cells, 2.7 mm thick film, 300 s elapsed time. (b) Stable, regular cells, arrows indicate splitting cells, 1.9 mm thick, 950 s elapsed. (c) Transition to vermicular structures, 1.4 mm thick, 1350 s elapsed. (d) Fully vermicular structures, 1.1 mm thick, 1525 s elapsed. (e) Transition to non-disturbed film, 0.98 mm thick, 1575 s elapsed.
Measured thickness (top), evaporative heat flux (middle), and instability wavelength (bottom) time histories for example experiment. Dichloromethane film, superheat level 3.9 °C. The letters correspond to the images in Fig. 4.
Non-dimensional number time histories for the example experiment. Top: Nusselt number. Middle: Rayleigh number. Bottom: Marangoni number. The letters correspond to the images in Fig. 4.
Impact of buoyancy effects on heat transfer for the example experiment. The letters correspond to the images in Fig. 4.
Impact of buoyancy effects on normalized wavelength for the example experiment. The letters correspond to the images in Fig. 4.
Impact of buoyancy on heat flux for all working fluids.
Fixed surface, non-evaporating experimental results from Villarroel20 compared to the current experimental results.
Variation of heat flux versus Marangoni number for all dichloromethane tests. The solid markers indicate instability transitions. Note the significant variation in the critical Marangoni numbers.
Impact of buoyancy on instability wavelength for select working fluids. Top: each line represents an individual test. Bottom: averaged for each fluid.
Comparison of modeled wave number dependence on Rayleigh Number from Catton29 with current experimental results (averaged for each fluid).
Working fluid properties at 10 °C.
Measured transition Rayleigh and Nusselt number values for each working fluid.
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