TRANSEO is an original tool for the transient and dynamic simulation of energy systems. The tool was specifically designed by TPG for the analysis of microturbine-based cycles in the late 2000s. However, it can be used to model many different cycle layouts of any size. TRANSEO is based on the Matlab®‑Simulink® environment, but it merely exploits its visual interface and time machine. Several fundamental calculations are executed outside Matlab®-Simulink®, by original dynamically‑linked functions developed in C and Fortran. The communication between Matlab®-Simulink® and the external functions is performed by C MEX Functions and S-Functions.
TRANSEO has two key features that make it possible to model quickly various layouts: modularity and flexibility. The modular structure allows any type of system to be modeled and simulated, while the flexibility allows all the model components to be used for different applications, from a simple stationary microturbine to a complex fuel cell hybrid system. The model components are collected and organized in a library, which has been constantly expanded over the years and has today more than 30 modules.
Concept and approach
The focus of TRANSEO is the transient analysis of energy systems, which is mainly related to mass and energy balances. Momentum balance-related effects, such as pressure-wave propagation, can be generally neglected. Nevertheless, TRANSEO provides a few components (i.e.: pipe and ejector), which can be set up to simulate their full dynamics. The accuracy of a transient analysis is sufficient for most cycles, as demonstrated by the validation performed on the TRANSEO components and presented in various studies.
Each component in the library is provided with more than one model. The model to be used can be easily selected by the user in a drop-down menu. The main types of models are:
- on-design model (static response)
- off-design model (static response)
- lumped-volume model
- dynamic model
For transient analysis, the most used models are those based on the lumped-volume approach. A lumped‑volume model is made up of two elements: an actuator disk, simulating the off-design performance of the component, and a duct, characterized by equivalent length and cross-section area to take into account the fluid dynamic delay. The actuator disk reacts to the component inlet and duct conditions, the duct delays its output on the basis of its geometrical properties. Thanks to this approach it is possible to simulate accurately all the main transient phenomena of the component, without making the simulation too cumbersome.
All gases are considered to be semi-ideal in TRANSEO: they follow the ideal gas law and have cp variable with temperature. Water steam is simulated differently, and its properties are calculated according to steam tables. Humid air can be treated as a non-ideal gas introducing the so-called enhancement factor, which is usually greater than 1. This factor is used to consider the different behavior of humid air caused by the presence of water steam when compared to an ideal gas.
More recently, a real-time version of TRANSEO models was developed. Original TRANSEO C-based functions have been translated into Matlab® programming language and embedded for direct use within Matlab®‑ Simulink®. The real-time TRANSEO also introduces a set of simplifying assumptions in the models, which make it possible to execute the simulations in real time and open up possibilities of cyber-physical and digital-twin applications. Moreover, being completely coded within Matlab®‑ Simulink®, these models can be used to auto-generate C-code with the Real-Time Workshop tool and then compiled to produce executable files.
Fields of Application
The extended library of components allow the user to evaluate the off-design and dynamic performance of several different system, from microGT, to heat pumps, to fuel cells.
Publications
TRANSEO code for the dynamic performance simulation of micro gas turbine cycles.
Traverso A.
Turbo Expo: Power for Land, Sea, and Air. Vol. 47284. 2005.
Externally fired micro-gas turbine: modelling and experimental performance.
Traverso, Massardo, Scarpellini
Applied Thermal Engineering 26.16 (2006): 1935-1941.
Influence of the anodic recirculation transient behaviour on the SOFC hybrid system performance.
Ferrari, M. L., et al
Journal of power sources 149 (2005): 22-32.
Ejector model for high temperature fuel cell hybrid systems: experimental validation at steady-state and dynamic conditions.
Ferrari, M. L., Pascenti M., and Massardo A.F.
Journal of fuel cell science and technology 5.4 (2008).
Dynamics and control of a turbocharged solid oxide fuel cell system.
Mantelli, L., M. L. Ferrari, and A. Traverso
Applied Thermal Engineering 191 (2021): 116862.
Surge Prevention Techniques for a Turbocharged Solid Oxide Fuel Cell Hybrid System.
Mantelli, L., M. L. Ferrari, and A. Traverso
Journal of Engineering for Gas Turbines and Power 143.12 (2021).
A prototype recuperated supercritical co2 cycle: Part-load and dynamic assessment.
Gini L., Maccarini S., Traverso A., Barberis S., Guedez R., Pesatori E., Bisio V.
Applied Thermal Engineering, Volume 225, 5 May 2023, 120152