Anders Malmquist

Modeling and Simulation of an Externally Fired Micro-Gas Turbine for Standalone Polygeneration Application

Power generation using micro gas turbine (MGT) is gaining traction mainly due to high efficiency, decentralized operation and environmental benefits. It is expected that the market for MGT will grow steadily in the coming decades. MGTs are capable of providing multiple energy services. Produced electricity and heat from such systems can be used to fulfill instantaneous demand as well as can be stored for future use when operated in standalone mode. It can also be well fitted with the poly-generation concept when the produced heat is used in heat driven distillation process to produce purified water or in an absorption chiller to produce cooling effects.Most of the current MGTs are based on directly fired design; but the application of these power generators are limited by the more stringent fuel quality requirements. On the contrary, externally fired micro gas turbines (EFMGTs) are very flexible as well as can use a wide range of thermal power sources like combustors, furnaces, and solar concentrators and thus have higher potentials.The Poly-generation lab at KTH is equipped with a prototype of EFMGT that is owned by local industrial partner- Compower AB. A possible integration of this prototype with membrane distillation unit located in the same lab could unveil the possibility of using such poly-generation system in real life application.In order to investigate the applicability of EFMGTs in such poly-generation system, the modeling and simulation is necessary. The goal of this research work is to evaluate the performance of an EFMGT based standalone poly-generation system with the help of computational simulation studies. The main focus of this thesis is the development of a dynamic model for an EFMGT. The dynamic model is accomplished by merging a thermodynamic model with a mechanical model and a transfer function based control system model. The developed model is suitable for analyzing system performance particularly from thermodynamic and control point of view. Simple models for other components of the poly-generation systems: electrical and thermal loads, membrane distillation unit, electrical and thermal storage are also developed and integrated with the EFMGT model.The modeling of the entire poly-generation system is implemented and simulated in Matlab/Simulink environment. Available operating data from test run of both the laboratory setup are used in this work for further analysis and validation of the developed model.