Why does the temperature rise when high-pressure liquid ammonia is throttled to a low-pressure storage tank?
Thread Content
In the 15 MPa process, why does the temperature of liquid ammonia at -31 degrees, after being throttled and depressurized in a gas-liquid separator into a storage tank at 1.5 MPa, actually rise? Generally, liquid ammonia itself should have a cooling effect after being throttled, right?
It should be that liquid ammonia absorbs heat from the external environment and vaporizes after being depressurized; as a result, the ambient temperature drops while the temperature of the liquid ammonia itself rises.
As pressure decreases, the boiling point of liquid ammonia drops; liquid ammonia then evaporates easily, absorbing heat from the environment in the process and thus warming up.
I’ve learned it. What if it can’t absorb so much heat?
Back to floors 2 and 3; the reason probably isn’t this, right? Feel free to continue the discussion. Analyze whether it might be caused by the heating effect resulting from the throttling of entrained hydrogen?
When the liquid level in the ammonia separator is high, if you open the valve wider, you’ll notice that the temperature of the ammonia being discharged rises again. It should work the same way, right?
After the high-pressure liquid ammonia is decompressed, the H2 and N2 dissolved in it volatilize. What is observed is a rise in the temperature of liquid ammonia; this rise is caused by the evaporation of hydrogen and nitrogen gases dissolved in the liquid ammonia.
This post was last edited by 654262293 on 2010-12-7 at 11:26. It’s probably due to the desorption of hydrogen gas that was dissolved in liquid ammonia. The desorption of hydrogen gas under reduced pressure is exothermic, while the desorption of nitrogen gas under reduced pressure is endothermic; therefore, the temperature should decrease during the desorption of nitrogen gas!
Joule-Thomson effect: After throttling expansion of hydrogen gas, its temperature rises, causing the temperature of liquid ammonia to increase. Hydrogen is an exception. Nitrogen follows an inverted curve; under different conditions, it can either be heated or cooled.