Heat transfer limitations of heat pipes for a cooling systems of electronic components

Heat pipes are highly effective heat transfer devices for electronic components cooling systems. In the present paper, calculation results of a maximum heat flux are shown for temperature value 60 °C. Calculation was made for heat pipes, which are used for LED cooling, with axially grooved and with metal fibred capillary structures. Main heat transfer limitation for grooved heat pipes is boiling limit for ammonia coolant and entrainment limit for R141b. As for heat pipes with metal fibred capillary structure, the main heat transfer limitation is the capillary limit for water, ethanol and R141b. Wherein, increasing of porosity higher than 60% leads to replacing of capillary limit by boiling limit for all researched coolants.