The Thermodynamic Properties Database
This introduction booklet demonstrates the use of the built-in thermodynamic properties database in the Chemical Reaction Engineering Module. The purpose of this database is to calculate thermodynamic and transport properties for pure solutions and mixtures of chemical compounds. Properties such as enthalpy of formation, heat capacity, thermal conductivity, density, and diffusivity can be computed using a range of models. These properties can be calculated for fluids consisting of a single gas phase or a single liquid phase and for liquid–liquid, gas–liquid, and gas–liquid–liquid systems. For multiphase systems, the equilibrium composition can also be calculated, for example, to calculate the phase envelope for a liquid mixture at equilibrium with its gas phase (flash calculations).
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The first example in this booklet shows the use of the thermodynamic properties database for the calculation of the heat of reaction, heat capacity, and thermal conductivity in the energy balance for a nonisothermal Hydrodealkylation in a Membrane Reactor. The thermal hydrodealkylation process is modeled using the built-in thermodynamic database and physical property evaluations. The transport and reaction problem is defined and solved with a thermodynamic system for a tubular reactor with and without membrane.
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The second example, namely Engine Coolant Properties, is a pure nonisothermal flow example where no reactions are involved. In this tutorial model, the properties of a liquid coolant for internal combustion engines are investigated. A mixture of ethylene glycol and water is studied, and the built-in thermodynamics functionality is used to show how the boiling point, density, viscosity, thermal conductivity, and heat capacity all depend on the composition of the coolant mixture and how changes in these properties affect the cooling process.
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The third example involves a Distillation Column and shows how flash calculations (gas–liquid equilibrium) can be carried out using the thermodynamic properties database. It treats a simple model of a binary distillation process, modeling the separation of a nonideal liquid mixture of ethanol and water. The distillation process is performed in a packed column. The model uses an equilibrium calculation function. The goal of the model is to find the optimal design of the column, in terms of the length of the stripping and rectifying sections, to meet a set of predefined distillate and bottoms compositions.
The thermodynamic properties database in the Chemical Reaction Engineering Module can be combined with models defined in any module that deals with transport in fluids — for example, the CFD Module, Mixer Module, Heat Transfer Module, Pipe Flow Module, and Subsurface Flow Module.