4 replies to this topic

[shahad]

Hi 

I am trying to calculate the energy released by a partial condenser which has many components including Methane, Ethane, Hydrogen and Nitrogen. 

My datum is liquid phase at 38oC

 

Is the latent heat of vaporization of these components just 0?

[latexman]

What is the pressure?

None of those components are liquid at 38 C and 1 atm pressure.

[shahad]

Pressure is around 2.6 bar.

My datum is in the liquid phase at 38oC, so I am calculating the latent heat of evaporation of these components at 38oC

 

@latexman

Edited by shahad, 15 April 2021 - 08:39 PM.

[MrShorty]

To delve into semantics and definitions, we don't usually talk about heats of vaporization for compounds above their critical points. For these compounds, I would expect to use terms like "heat of absorption or desorption", since I would expect to be thinking of these more like a "gas solubility in a solvent" scenario.

 

I recall once hearing it said that the difference between a chemist and a chemical engineer is one of practicality. The chemist in me would say that, "the heat of vaporization/absorption/desorption/condensation is never exactly 0." The engineer in me would reply, "maybe so, but these inert gases are so sparingly soluble in most solvent at these conditions that I wonder if I can assume the heat of vaporization/condensation/absorption/desorption is 0." The process of deciding if you can ignore the contribution of these gases to the overall heat of condensation probably involves determining how much total liquid you expect to get, the composition of that liquid, how rigorous is the calculation expected to be, and so on. Then judge whether these gases contribute to the heat of condensation significantly.

Edited by MrShorty, 16 April 2021 - 10:00 AM.

[shahad]

Thank you so much