Thermodynamic Properties
The species’ heat capacity, Cp, the molar enthalpy, h, and the molar entropy, s, are computed using the polynomial format of Gordon and McBride (Ref. 1). This manual also refers to these expressions as NASA polynomials:
(5-8)
(5-9)
(5-10)
Here, Cp,i denotes the species’ heat capacity (SI unit: J/(mol·K)), T the temperature (SI unit: K), and Rg the ideal gas constant, 8.314 J/(mol·K). Further, hi is the species’ molar enthalpy (SI unit: J/mol), Δh is an additional enthalpy contribution (SI uint: V), F is Faraday’s constant (SI unit: C/mol), and si represents its molar entropy (SI unit: J/(mol·K)), at standard state.
The thermodynamic properties for a given reaction are computed from the enthalpy and entropy of the participating species. The enthalpy of reaction (SI unit: J/mol) is calculated using:
(5-11)
Similarly, the entropy of reaction (SI unit: J/(mol·K)) comes from the relationship
(5-12)
In these equations, hi and si are the species’ molar enthalpy (SI unit: J/mol) and entropy (SI unit: J/(mol·K)), respectively. The heat source of reaction (SI unit: J/(m3·s)) is given as:
The sum of Qj over all reactions is the total heat source due to chemical reaction:
This appears as an option in General source combobox in the Heat Source node in any of the Heat Transfer interfaces called Heat source for gas. This is how chemical reactions in a plasma heat the background gas.