Effect of Porous Coating on Heat Transfer in Minichannels with Intensive Localised Heating

The main objective of the work is to study the influence of the porous layer on the intensity of heat transfer during flow boiling in mini- and microchannels with localized heating from the wall side (heater size 3x3 mm2) with a channel width and length an order of magnitude larger. The following problems were solved to achieve these goals. A technology was created for forming various porous coatings on a heater based on Nickel powder with a characteristic grain size of about 60-100 mu m. As a result, three different thin (150 mu m scale) porous coatings were obtained: Nickel (100% Ni) and two bimetallic coatings containing copper or zinc powders (80% Ni + 20% Cu, 50% Ni + 50% Zn). Systematic studies of heat transfer during boiling with non-uniform heating in mini- and microchannels with a height of 0.55 to 2.0 mm with subcooling water were carried out. The experiments were carried out with intensive heating from the wall side, up to 1.6 kW/cm2. There are established facts that are important results. The values of heat transfer coefficients and critical heat flux on porous surfaces are significantly (up to 3 times) higher than for a smooth surface. The values of critical heat flux reached 1.2 kW/cm2, and the values of heat transfer coefficient reached 100 kW/(m2 K). The significance of the obtained results is that the features of localized heating are underestimated but are important in modern multi-chip electronic systems and promising power plants. This will allow achieving the required scale of heat exchange parameter values when developing highly efficient heat exchange systems for modern microelectronics and power engineering.