Temperature changes of hydrogen under reduced pressure
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Does the temperature of a hydrogen pipeline rise or fall after throttling to reduce pressure?
When hydrogen is depressurized through a throttle valve, it follows the Joule-Thomson effect. In fact, the temperature of most ideal gases decreases after throttling for pressure reduction. However, for hydrogen, when its pressure is reduced by throttling at normal temperatures (0–100 degrees Celsius) and normal pressure, its temperature actually rises, because the Joule-Thomson coefficient of hydrogen is negative within this temperature range. And when the temperature of hydrogen is below a certain point (known as the Joule-Thomson inversion temperature), reducing the pressure causes its temperature to drop. For hydrogen, this inversion temperature is around 193 K (-80 degrees Celsius). Therefore, the accurate answer depends on the specific hydrogen temperature and pressure reduction conditions. .
In other words, if the temperature drop is higher than -80 degrees, there will be no reversal, and it will remain positive (the temperature drops after gas throttling, rather than rising).
Yes, take a look at the Cryogenic Handbook; there are specific discussions on it.