ABSTRACT
The term ‘critical heat flux’ (CHF) indicates an abrupt worsening of the heat transfer between a heating wall and a coolant fluid, generally with undesired consequences. This is typically due to the presence on the heated wall of a vapor layer, which strongly reduces the heat transfer rate from the heater to the coolant. Simply speaking, forced convective subcooled boiling involves a locally boiling liquid with a bulk temperature that is below the saturation value flowing over a surface exposed to a heat flux. Under such conditions, the critical heat flux is always of the DNB type, resulting in a significant increase in the wall temperature; the larger the temperature increase, the higher the heat flux. The magnitude and occurrence of the CHF are affected by many parameters, such as thermal-hydraulic, geometric, and external parameters. Among thermal-hydraulic parameters, have subcooling, mass flux, pressure, and binary component fluids, while important geometry parameters are channel diameter, heated length, channel orientation and material.
