The Chemical Thermodynamic Module Of The Expert System For Thermodynamics (“Test”) Web Application

Accessible from www.thermofluids.net, the TEST web portal is a freely accessible thermodynamics web-based software package for engineering education. It combines several modules – multi-media problems and examples, an online solution manual for educators, traditional thermodynamic charts and tables, fifteen chapters of animations to illustrate thermodynamic systems and fundamental concepts, and a suite of thermodynamic calculators called daemons for solving thermodynamic problems and pursuing what-if scenarios. Designed as ‘browsable’ Java applets, these daemons cover a wide range of topics property evaluation of working substances, energy, entropy, and exergy analysis of generic open and closed systems, IC engines, gas and vapor power cycles, refrigeration, HVAC, combustion, chemical equilibrium, and gas dynamics. In this paper, the chemistry module comprising of combustion and equilibrium analysis daemons for both open steady systems and unsteady processes is presented. The combustion daemons can be used for the analysis of both premixed and non-premixed reactants modeled with a perfect gas, ideal gas, or a solid/liquid model. Using the intuitive graphical user interface of the reaction panel, a user can quickly set up standard reactions such as theoretical reactions, reactions with a known amount of excess or deficient air, and reactions with known dry products analysis. The balanced equations are then used in the state panel and the states of fuel, oxidizer, and products are fully or partially calculated based on the known properties at the ports of a steady state reactor or at the beginning and final states of a process. Finally, in the device (or process) panel, known information about the device (or process) is supplied and the daemon updates the entire analysis to produce important combustion parameters such as the adiabatic flame temperature, heat transfer, and entropy generation in the device or the process. Once a solution is achieved, what-if studies can be performed by changing the fuel, the air fuel ratio, or any other controllable parameter by simply changing the parameter and calculating a single update button. The equilibrium daemons handle gas mixtures and condensed phases and builds upon the combustion daemons. Reactants are entered by selecting from a list of species and specifying their moles. From a list of plausible products, the user can select product species. In the state panel, known thermodynamic properties such as pressure and temperature are specified. The products composition is then calculated by minimizing the Gibbs function of the products mixture. These simple-to-use daemons, comparable in their accuracy to established codes such as NASA CEA and STANJAN, are used to determine equilibrium constant, equilibrium composition, and equilibrium temperature of methane combustion as a function of equivalent ratio.