Operation performance of thermosyphons employing titania and gold nanofluids

Experimental investigations with four large thermosyphons identical in construction operated with titanium dioxide and gold nanofluids and deionized-water as reference fluid are carried out. It is experimentally shown that the thermal resistance can be lowered by employing nanofluids only at small values of heat flow rates provided at the evaporator. The best results are achieved with a gold nanofluid at heat flow rates between 50 W and 150 W. The lowering of the thermal resistance is here about 20%. Accompanying distillation experiments clearly indicate that only some per mill of the nanoparticles originally suspended in the nanofluid are torn out of the working fluid and transported by the vapour phase. Beside descriptive explanations and diagrammatical representations of the experimental results three videos are provided. These videos allow for the first time in situ observations of the thermosyphons interior when operated with nanofluids in real time.