Volume Gas L2 Chem

Created Mittwoch 21 Juni 2017

Basic model of a gas volume with dynamic energy and mass balances, taking convective heat transfer and pressure losses and chemical reactions into account.

1. Purpose of Model


The model is used as a basic model to form various components which handle gaseous media with chemical reactions.

2. Level of Detail, Physical Effects Considered and Physical Insight


2.1 Level of Detail


Referring to Brunnemann et al. [1], this model refers to the level of detail L2.

2.2 Physical Effects Considered


2.3 Level of Insight


Heat Transfer

Pressure Loss

Chemical reactions


Geometry

3. Limits of Validity


4. Interfaces


4.1 Physical Connectors


Basics:Interfaces:GasPortIn inlet
Basics:Interfaces:GasPortOut outlet
Basics:Interfaces:HeatPort a heat

4.2 Medium Models

5. Nomenclature


6. Governing Equations


6.1 System Description and General model approach


The model describes an ideally stirred volume element with heat transfer to the surrounding and chemical reactions.

6.2 Governing Model Equations


Conservation of Mass

Via parameter preset the user can determine whether the mass balance is calculated dynamic or static. The dynamic mass balance is calculated as follows:


and the static mass balance:

Conservation of Momentum

We use balance of stationary momentum to model the pressure losses on the control volume. The friciton pressure losses are calculated with the replaceable pressure loss models. In the model the pressure distribution is given by the influence of friction in the x direction, which is given with the direction of the flow. The friction pressure loss is lumped at the inlet to avoid direct coupling of two flow models.



Conservation of Energy

The energy balance considers ingoing and outgoing enthalpy flow rates as well as energy transport to the surrounding (). Please note the special structure of the energy balance with the differences of ingoing and outgoing enthalpies and the cell enthalpy and the additional term for the pressure derivative which is derived from the total derivative of the inner energy of the cell. The structure results from to the special choice of state variables as discussed in Basic Concepts of Modelling.

The model's density is taken as an explicit function of the states its total derivative should be used for completeness of the model given by:

while for stationary mass balance the following equation is used:

Conservation of Gas Components

The outlet composition of the gas is calculated inside the chemical reactions model.



Summary

A summary record is available which bundles important component values.


7. Remarks for Usage

This model is applied in a number of component models either via instantiation of inheritance.

8. References

[1] Johannes Brunnemann and Friedrich Gottelt, Kai Wellner, Ala Renz, André Thüring, Volker Röder, Christoph Hasenbein, Christian Schulze, Gerhard Schmitz, Jörg Eiden: "Status of ClaRaCCS: Modelling and Simulation of Coal-Fired Power Plants with CO2 capture", 9th Modelica Conference, Munich, Germany, 2012

9. Version History