The invention relates to a thermal syphon and a heat pipe having special working liquids which can be used in principle over the entire temperature range. However, in this case the range between -10 and +40@C is especially preferred, because so far no optimum working liquids have been available here. The heat-transporting capacity of the known working liquids of methanol and ethanol is not very high. The temperature range mentioned above is too low for water, which is overwise the ideal working liquid. The invention makes available a heat pipe having different working liquids based on azeotropic mixtures which not only cover a wide temperature range, but at the same time also have a very high heat-transporting capacity.
