- #1
RKT
- 18
- 0
Guys ,
Pl. help me out with this one. I got a vessel of vol. V and its filled with air to a pressure P. I want to know the energy contained in the compressed gas. The gas is going to be suddenly discharged via an orifice and I want to know how much work it can do.
I had imagined that the energy would be given by E = P x V however the number arrived by this calc. falls way short of another calc. done by a friend. I estimated the energy contained in a 490 cc vessel filled with air @ 200 bar as 9800 Joules. The friend puts it at abt 24,000 + Joules. He uses the formula for work done during adiabetic expansion.
Now I am wondering ... did I take only one 'type' of energy into account (pressure) while doing the calc. ? Should heat/thermal energy also be included ? Energy of molecules ? I did not take the heat energy as I figured that any heat generated was basically due to the applied pressure after all. So if I calculated energy using (P x V) it would automatically take that effect into account.
Dash it, this is really confusing. Someone pl. help ......
Pl. help me out with this one. I got a vessel of vol. V and its filled with air to a pressure P. I want to know the energy contained in the compressed gas. The gas is going to be suddenly discharged via an orifice and I want to know how much work it can do.
I had imagined that the energy would be given by E = P x V however the number arrived by this calc. falls way short of another calc. done by a friend. I estimated the energy contained in a 490 cc vessel filled with air @ 200 bar as 9800 Joules. The friend puts it at abt 24,000 + Joules. He uses the formula for work done during adiabetic expansion.
Now I am wondering ... did I take only one 'type' of energy into account (pressure) while doing the calc. ? Should heat/thermal energy also be included ? Energy of molecules ? I did not take the heat energy as I figured that any heat generated was basically due to the applied pressure after all. So if I calculated energy using (P x V) it would automatically take that effect into account.
Dash it, this is really confusing. Someone pl. help ......