The TRANSEO code is an original tool for the transient and dynamic simulations of energy systems. The tool is specifically designed for managing microturbine-based cycles, but, in principle, any cycle layout and size could be modeled.
TRANSEO is based on the MATLAB-Simulink environment, but it merely exploits the visual interface and time machine, retaining the management of several fundamental calculations outside, in original dynamic-link libraries.
In late 2000, the TPG decided to develop TRANSEO, using MATLAB and the Simulink visual environment, both to collect the work already done in the transient and dynamic fields and to extend the field of application to microturbine cycles. For this purpose, two characteristics were necessary: modularity and flexibility. The modular structure allows any type of system to be built and run, while the flexibility means that the same models can be used for different applications: from a stationary microturbine to a complete hybrid fuel cell system. Now, TRANSEO is available and working, providing the user with more than 30 modules.
The focus of the analysis is on the transient behavior of the system, which is mainly related to the mass and energy balances; momentum balance related effects, such as pressure-wave propagation, are normally neglected. Nevertheless, TRANSEO is already provided with dynamic models of a few components (i.e.: pipe and ejector components), which can be employed for the full dynamic analysis of their behavior. Most cycles can be effectively simulated on a transient basis, which already provides sufficient accuracy, as demonstrated by the validation results.
The figure below presents a conceptual sketch of the TRANSEO position within MATLAB-Simulink, together with its own objects. At the MATLAB level a complete set of thermo-physical functions was developed to equip the tool with the properties required by the component models: the functions are available as C MEX functions and are derived from the TEMP code.
At the Simulink level, each component model, all of which are grouped in the TPG library, interacts with the C MEX function to get the necessary thermo-physical properties. The components can be arranged in any manner, thanks to the standardized interconnecting protocol (see related paragraph).
All gases are considered to be semi-ideal: they are supposed to follow the ideal gas law and to have cp variable with temperature. Water/steam has a different treatment since its properties are calculated according to steam tables. Humid air can be treated as a non-ideal gas, introducing the so-called enhancement factor, usually greater than 1, which accounts for the additional steam in the air under saturated conditions, when compared to the ideal gas law.
All component models are collected in the so-called “TPG library”. Each component is provided with more than one model, which can be flexibly chosen and changed by the user. The main models available are:
1. on-design model (static response)
2. off-design model (static response)
3. lumped-volume model
4. dynamic model
Depending on the component, just one or multiple models are available.
Recently, real-time deployment of TRANSEO models has been enabled. Original TRANSEO C-based models have been translated into embedded Matlab functions for direct use within Matlab-Simulink. The resulting models have then been used to auto-generate C-code with the Real-Time Workshop. The C-code has then been compiled to produce application specific executables, to be run in real-time targets.