THE EFFECT OF GRAPHENE AND POROUS COATINGS ON FLOW BOILING IN FLAT MICROCHANNELS UNDER INTENSE LOCALIZED HEATING

Subcooled water flow boiling experiments were carried out in flat mini- and microchannels under intense uniform and nonuniform heating for different heater surface morphology, including two-dimensional (graphene) and three-dimensional (porous medium) coatings. Heat transfer coefficient and critical heat flux data were obtained on 3 × 3 and 10 × 10 mm heaters in channels with a height range from 0.55 to 2 mm. In experiments on flow boiling, it was found that with an increase in the channel height in the range of 0.55 to 2 mm, the critical heat flux increases significantly. For a given fluid flow rate and channel height, the critical heat flux on the 3 × 3 mm<sup>2</sup> heater exceeds the heat flux on the 10 × 10 mm<sup>2</sup> heater. It was found that in the studied range of parameters the behavior of boiling curves is similar, both with and without graphene coating. In turn, porous coatings (compared with a bare heater) provide significant enhancement of heat transfer and increase the critical heat flux.