MadSci Network: Engineering

Re: What is the specific heat capacity of liquid hydrogen?

Date: Tue Jan 16 14:31:12 2001
Posted By: Allan Harvey, Staff,National Institute of Standards and Technology
Area of science: Engineering
ID: 978974554.Eg

At its atmospheric boiling point, the specific (constant-pressure) heat 
capacity of liquid hydrogen is about 10 J/(g K).  I got this from the 
database described at:

You should recognize that this property plays only a small role in how 
fast something will evaporate (unless the fluid starts much colder than 
its boiling point).  More important will be the heat of vaporization 
(around 440 J/g) and how fast heat can be transferred to the fluid (which 
will depend on many environmental factors).  For example, if you have a 
puddle of water, the rate of evaporation will be different if there is a 
strong wind blowing over it, and a wide shallow puddle will evaporate 
faster than a narrow deep one.

Since the normal boiling point of hydrogen is so far below normal 
temperatures, I'd expect the vaporization to be very fast under most 
circumstances.  I've seen liquid nitrogen poured on a lab floor (don't try 
this at home!) and it's gone in a second or so.  Hydrogen, being more 
volatile, would probably vaporize even faster.

Allan Harvey,
"Don't blame the government for what I say, or vice-versa."

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