Simulation of a hybridised solar gas turbine system
Date
2013-02-11
Authors
Quarta, Nicholas Joseph
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Abstract
This study involves the creation and analysis of a thermal-fluid network simulation
model using a specified commercial software package (Flownex), as part of a larger
solar power research programme at the Council for Scientific and Industrial Research
(CSIR). The model was needed for performance simulation of a Concentrating Solar
Power (CSP) system incorporating a Rover 1S/60 gas turbine engine with modified
recuperator, to be used in a hybridised operation mode with a solar receiver and
thermal storage unit. Full performance characteristics of the Rover 1S/60 gas turbine
engine were required prior to the final model being created. Fuel leaks in the
combustor resulted in unsustainable combustion, leaving the engine inoperable and
testing results from Prinsloo (2008) were used as a means to validate the simulation
results.
After the main components in the system had been characterised three simulation
models were created using Flownex software, a standard Rover model – excluding
recuperator, a modified Rover model – including recuperator and intake system, and a
solar Rover model – including the solar receiver tower and thermal storage unit.
Results of the models showed an increase in thermal efficiency, at the design
operating point of 46000 revolutions per minute, from 10.5 % for the standard model
to 12.8 % for the modified model and 14.1 % for the solar model. Furthermore the
fuel usage was seen to decrease rapidly with an increase in solar power into the
system. The thermal storage results were validated against testing results from Klein
(2011). These were found to correlate well and yielded similar charging and
discharging times. Further analysis showed that an increase in solar power input into
the system as well as a larger-scale thermal storage unit would greatly increase the
overall system performance and economic feasibility.
The model can be used to simulate other solar thermal systems of this type, with
instructions provided in an appendix on how to do this. The program offers the ability
to model combustion comprehensively with both reactants and products being
defined. It was recommended that Flownex is more than capable of modelling gas
turbine systems of this type.
Additionally the program does allow the user to construct an interface environment
which greatly simplifies the detailed network model into a manageable graphic
interface to easily monitor performance parameters of the system. From a solar
perspective while more advanced commercial software exists which allows for the
sensitive modelling of the solar tracking aspect of a solar power plant combined with
the power cycle, Flownex does allow the user to build custom defined power block
components for incorporating solar heat inputs into any model and is a powerful tool
for modelling thermal systems of this type.
The scientists of today think deeply instead of clearly. One must be sane to think
clearly, but one can think deeply and be quite insane.
Nikola Tsela