Solve Gas Expansion Problem: CO2 Tank, Expansion Chamber & Ambient Heat

[mblackwolf]

Here is my problem i am working on a project in my free time and am stuck on figuring something out. I am going to be using a CO2 tank which is filled (contains both liquid and gas). I will then open a valve to fill an expansion chamber. This will allow for expansion of the liquid into gas and will help the liquid from getting pulled into the final location. Another valve will then pull this gaseous CO2 into a new chamber.

In the original expansion from teh tank into the expansion chamber the liquid CO2 boiling off will cause a reduction in the temperature. The ambient heat can then heat the chamber and tank combination to lead to the same pressure approx. 800psi at which no more liquid will turn to gas. My question is how do i go about finding the temperature decrease in the tank after the expansion and before ambient heat reheats the system. I need this info to calculate the amount of time ambient heat will take to reheat the system or to determine the new non reheated pressure. Thanks i will know the tank volume, liquid volume and expansion chamber volume. I just need to know how to use these to determine the temperature drop.

 

[coelho]

The first thing you need is some table of Thermodynamic Data for CO2. You will need the enthalpy of both liquid and gaseous CO2 at the temperature and pressure you intend to work. If you were able to find this data, the rest (calculations) is easy.

 

[mblackwolf]

If i could find the enthalpy of CO2 at the tanks original temperature and pressure how would i go about finding the new temperature and pressure after the expansion