Thermal performance of a closed advanced two-phase thermosyphon loop for cooling of radio base stations at different operating conditions

In this investigation an advanced thermosyphon loop with extended evaporator and condenser surfaces has been tested at high heat fluxes. The thermosyphon investigated is designed for the cooling of three parallel high heat flux electronic components. The tested evaporators were made from small blocks of copper in which five vertical channels with a diameter of 1.5 mm and length of 14.6 mm were drilled. The riser and downcomer connected the evaporators to the condenser, which is an air-cooled roll-bond type with a total surface area of 1.5 m2 on the airside. Tests were done with Isobutane (R600a) at heat loads in the range of 10–90 W/cm2 to each of the components with forced convection condenser cooling and with natural convection with heat loads of 10–70 W.