I have noticed when I have done some combustion equilibrium that enthalpy is higher when doing a constant volume combustion than pressure constant combustion.
Why is it so ? What are the reasons explaining that ?
Is it because at constant pressure combustion the variation of enthalpy is equal to heat transfert $\Delta H = Q $ whereas at constant volume combustion the variation of enthalpy is $\Delta H = Q + V\Delta p$ ?
If so that suppose that heat transfer $Q$ is the same for both constant pressure and constant volume combustions. Is that so ?