Condenser Design for Thermosyphons Utilizing Segregated Hydrofluoroether Working Fluids

Tests were carried out to compare the performance of eight commercially available radiators suitable for use as condensers in compact thermosyphons in electronic systems. Examples of the practical application of the complete thermosyphon unit are described. One of the five condensers designed for 92mm fans produced a fluid-to-ambient resistance of 0.067degC/W at 1.1 m³/min air flow with a static pressure drop of 2.8 mm H₂O. Previously reported boiler data show that this enables sub 0.10degC/W sink-to-ambient operation for most modern microprocessors. One of the three condensers designed for 120mm fans produced a fluid-to-ambient resistance of 0.046degC/W at 1.23 m³/min air flow with a static pressure drop of 2.0 mm H₂O thus enabling sub 0.08degC/W sink-to-ambient operation with modest fan power. This performance level is competitive with more complex water cooling systems entering the mainstream market.