氦氢混合制冷工质的爆炸极限试验

EXPERIMENTAL STUDY ON THE SAFETY OF HELIUM AND HYDROGEN MIXTURE

在微型低温制冷机中 ,为了提高制冷机的热力学效率 ,越来越多地使用氢氦二元混合工质。由于氦气是惰性气体 ,具有阻燃作用 ,因此 ,在使用时容易产生麻痹思想而引发事故。为此对不同配比的氦氢混合气进行爆炸试验 ,分别得到了它们的爆炸极限。结果表明 :氦气对氢气虽然具有一定的阻燃作用 ,但当样气中氦的摩尔百分含量小于 5 0 %时 ,氦氢混合气的爆炸上、下限随氦的百分含量的增加而有所升高 ,但其爆炸区间的绝对值几乎与纯氢相近 ;只有当样气中氦的摩尔百分含量大于 5 0 %后 ,样气的爆炸下限随氢的百分含量的减少迅速递升 ;直至氦气和氢气摩尔比例大于 10时 ,样气与任何比例的空气混合都不会爆炸 ,且较氢氮混合气更安全。

In order to increase the thermodynamic performance of cryogenic refrigerators,the mixture of hydrogen and helium is becoming more and more popular in the cryogenic field.As helium is inert gas which can restrain the flammability of hydrogen,some carless application of the mixture may occur,which may cause some accidents.For this reason,the paper is focused on the study on the safety of helium hydrogen mixture,and the explosion limits of the mixtures with different proportion are presented through the explosion experiment.Some useful conclusions have been gained.Helium can restrain the flammability of hydrogen to some extent.When the mole fraction of helium is less than 50%,the upper and lower explosion limits both increase slightly with the increasing fraction of helium,and the explosion range of the mixture is close to that of pure hydrogen gas.Only when the mole fraction of helium is more than 50%,the lower explosion limit of the mixture climbs up quickly with the increasing mole fraction of hydrogen.Once the mole proportion of helium to hydrogen reaches 10,the gas mixture does not explode no matter what is the proportion of helium hydrogen mixture to air.Compared with nitrogen hydrogen mixture,the application of helium hydrogen mixture is much safe.