Nelium, a Refrigerant with High Potential for the Temperature Range between 27 and 70 K

In the search for the optimum process for the liquefaction of hydrogen, it was found that mixtures of helium and neon, called “Nelium”, allow processes with very high efficiency compared to pure helium or pure neon. This is demonstrated in the design of a 500 kW refrigerator between 40 and 60 K, whereby the composition is varied between pure helium and pure neon. It turns out that helium-rich mixtures have an advantage for the heat exchange, whereas the neon-rich mixtures are easier to compress in turbo compressors. In any case a process efficiency of over 44% is feasible.