| Advanced solution inThermodynamics
| Thermodynamic Datenbase und Process Design

1.Constants and references are given in the file \AsTher\data\AsTher.ref
The value of the Gas Constant (R) can be changed, when another value is actual
Element names, symbol, atom weight can be reedited

| File \AsTher\data\AsTher.ref # AsTher version 7.25 [Constants] R=8.31446261 [Elements] # Add new Element # Symbol=Name; n:atom number; m: atomic mass # Add U{236} as new element U{236}=Uranium; n:92; m:236; # # Add new element, Delete # to take effect # T=Thritium; n:1; m:3.0160495 # # Rename an element # Delete # to take effect Lw to Lr # when Lr does not exists, an error message will be shown # Lw=Lawrencium; m:262; n:103; x:Lr [Reference] 1: JPCRD; JJ. Phys Chem. Ref. Data - JANAF Thermodynamical Tables \see also: https://www.nist.gov/srd/journal-physical-and-chemical-reference-data 2: NIST; https://webbook.nist.gov/chemistry/ 3: Perry; \R. H. Perry, C. H. Chilton: Chemical Engineers Handbook, 5th ed.(1973). \R. H. Perry, D. W. Green, J. O. Maloney: Perrys Chemical Engineers Handbook, 8th ed. (2007) 4: CRC; \David R. Lide: Handbook of Chemistry and Physics . . . . . . . . . 22: 22:noaa;https://cameochemicals.noaa.gov/chris/IPR.pdf n: add new reference n>22 |

2. Calculation of an equilibrium state
The initial state for calculating an equilibrium state is a hypothetical mixture consisting of the selected substances in all states of matter: gas, liquid, solid, and plasma.
The Lagrange coefficients of the elements in the equilibrium state are determined iteratively according to the phases, ensuring an elemental balance between the input composition and the calculated composition.
When the 'Calculation Option' 'Maximum Entropy' is selected
the calculation is terminated when,
the given pressure is reached in the gas phase,
or
when the sum of the activities of the substances in a phase corresponds to the system pressure
When the 'Calculation Option' 'Maximum Entropy' is not selected
Calculation is terminated when the sum of the frugalities and activities of the substances in a phase corresponds to the system pressure.
In several case, the sum of the activity or fugacity in a phase can not correspond to the system pressure,
In this case, the application may display a message, or the reason can be seen from the calculation results.

In both case of the calculation options, the following applies to each reaction: a A + b B = c C + d D

K=( [A]a . [B]b)/( [C]c . [D]d) = exp(-ΔG°/R T)
[A], [B], [C], [D]: Activity or fugacity of the substances in the equilibrium state

ΔG° = c G°C + d G°D - a G°A - b G°B
G°i:[J/mol]: The molar free energy of substance i at the temperature T and pressure P in the equilibrium state

3. Answer to the questions whether and how a process can be modelled or represented using thermodynamic calculations.

When we intend to create a thermodynamic model of a process, some of the circumstances to be considered are

3.1. Reactions are possible
Example, when an O2 molecule meets a CH4 molecule at 800 C, it reacts immediately, because the ignition temperature of CH4 is exceeded.
The extent of the reaction between O2 and CH4 is determined by natural laws and thermodynamics.
O2 also reacts immediately with C, CO, CH3OH, CH4 and several other substances at 800 C.

The cooling process of exhaust gases below 500 °C is difficult to calculate, even with an optimized reactor, since the ignition temperature of several substances, including CH4 and CO, is exceeded.
If a reaction cannot occur, thermodynamic calculations are only of limited use.

3.2. Flows, turbulence and geometry, sufficient mixing is ensured
It depends on how fast an O2 molecule hits z.B. a CH4 molecule.
An important factor is the turbulence (Re number) and the geometry of the reactor

3.3. The assumed temperature is approximately everywhere in the reactor.
In a reactor with an optimized flow and an approximately uniform local temperature, the product composition can be calculated thermodynamically with sufficient accuracy.

3.4. Liquid metal oxides are often unaffected by CO(g), CH4(g), or H2(g).
The reason why liquid metal oxides do not react with substances in the gaseous or solid state is often due, among other things, to the surface tension or the activity coefficient of MeOx(l) at the surface.
Based on measurements, the activity coefficients of MeOx(l) can be determined using thermodynamic calculations.

3.5 Carbon in the pure solid phase does not react directly with liquid metal oxides (FeO in a blast furnace).
Carbon only reacts with FeO(l) when carbon is dissolved in the liquid phase with the addition of CaO and SiO2.

3.6. Thermodynamic calculations are helpful in determining which product composition can be formed
when, for example, a given amount of O2 reacts with the input material.
By comparing the calculated and measured composition of the products, we determine which O2 fraction reacts in the reactor and what the proportion of leak air is.