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Solar power microturbines are required to produce steady power despite the fluctuating solar radiation, with concerns on the dispatchability of such plants where thermal energy storage may offer a solution to address the issue. This paper presents a mathematical model for performance prediction of a honeycomb sensible-heat thermal energy storage designed for application of concentrated solar power microturbine. The focus in the model is to consider the laminar developing boundary layers at the… Visualizza altro

Solar power microturbines are required to produce steady power despite the fluctuating solar radiation, with concerns on the dispatchability of such plants where thermal energy storage may offer a solution to address the issue. This paper presents a mathematical model for performance prediction of a honeycomb sensible-heat thermal energy storage designed for application of concentrated solar power microturbine. The focus in the model is to consider the laminar developing boundary layers at the entry of the flow channels, which could have a profound effect on the heat-transfer coefficient due to large velocity and temperature gradients, an effect which has not been considered in the modelling of such storage systems. Analysing the thermal and hydrodynamic boundary layer development, the Nusselt number and the friction factor were evaluated using a validated conjugate heat-transfer method. The simulations results were used to develop accurate regression functions for Nusselt number and friction factor. These formulations have been adopted within a one-dimensional model to evaluate the performance of the storage under different operating conditions. The model was in good agreement with conjugate heat transfer results with maximum relative error below 2%. Two case studies are presented to demonstrate the applicability of the proposed methodology Meno dettagli

Hybrid energy system consisting of a parabolic dish solar concentrator and a microturbine (MGT) has been considered as promising distributed generation technology, since it can be operated as a stand-alone system for power or combined heat and power (CHP) applications in remote areas with no connection to the grid. The main concern when it comes to distributed generation is the ability of maintaining high availability. Therefore, given the intermittency of the solar resource, the availability… Visualizza altro

Hybrid energy system consisting of a parabolic dish solar concentrator and a microturbine (MGT) has been considered as promising distributed generation technology, since it can be operated as a stand-alone system for power or combined heat and power (CHP) applications in remote areas with no connection to the grid. The main concern when it comes to distributed generation is the ability of maintaining high availability. Therefore, given the intermittency of the solar resource, the availability of consistent and computationally fast tools for modelling and monitoring of solar micro gas turbinesis essential for adequate and optimum operation.
This paper presents the application of artificial neural networks (ANNs) for performance prediction and monitoring of a hybrid solar MGT system. A validated inhouse tool, developed for evaluating the performance of solarhybrid MGT, was used to generate simulated data at various operational conditions by varying solar irradiation and ambient conditions. The obtained data was used to train the ANN model. The prediction accuracy of the ANN model was tested using another data set. The results showed that the ANN model can predict the solar hybrid MGT performance with high accuracy and could serve as a baseline model for monitoring applications.
Finally, the developed ANN model was integrated with an optimization algorithm. A case study was
conducted using the developed ANN model for multi-objective optimization of the hybrid solar MGT. By varying turbine inlet temperature and rotational speed, the system performance at part load operation were analysed resulting in a Pareto front for maximum electrical efficiency and minimal operational cost. Multi-objective genetic algorithm (GA) was applied to find the optimum solution. It is not clear whether the optimization algorithm was a part of the ANN model or a separate module. If separate, where did the optimization part come from and how and what data was these two modules. Meno dettagli

Solar powered micro-gas turbines (MGTs) are required to work over a wide range of operating conditions due to the fluctuations in the solar insulation. This means that the compressor has to perform efficiently over a wider range than in conventional MGTs.
To be able to extend the efficient operating range of a compressor at the design stage, both impeller blades and diffuser passage need to be optimised. Vaneless diffusers could offer more flexibility to extend the operating range than… Visualizza altro

Solar powered micro-gas turbines (MGTs) are required to work over a wide range of operating conditions due to the fluctuations in the solar insulation. This means that the compressor has to perform efficiently over a wider range than in conventional MGTs.
To be able to extend the efficient operating range of a compressor at the design stage, both impeller blades and diffuser passage need to be optimised. Vaneless diffusers could offer more flexibility to extend the operating range than typical diffuser vanes.
This paper presents a methodology for the design and optimisation of a centrifugal compressor for a 6 kW micro-gas turbine intended for operation using a Concentrated Solar Power (CSP) system using a parabolic dish concentrator. Preliminary design parameters were obtained from the overall system specifications and detailed cycle analysis combined with practical constraints. The compressor’s geometry optimisation has been performed using a fast and computationally efficient method, which involves the Latin hypercube Design of Experiment (DoE) technique coupled with the response surface method (RSM) in order to build a regression model through CFD simulations. Three different RSM techniques were compared with the aim to choose the most suitable technique for this specific application and then a genetic algorithm was applied. The CFD analysis for the optimised compressor showed that the high efficiency operating range has increased compared to the baseline design. Cycle analysis for the plant has been performed in order to evaluate the effect of the new compressor design on the system performance. The simulations demonstrated that the operating range of the plantwas increased by over 30%.
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: Solar power microturbines are required to produce steady power despite the fluctuating solar
radiation, with concerns on the dispatchability of such plants where thermal energy storage may offer
a solution to address the issue. This paper presents a mathematical model for performance prediction
of a honeycomb sensible-heat thermal energy storage designed for application of concentrated solar
power microturbine. The focus in the model is to consider the laminar developing boundary… Visualizza altro

: Solar power microturbines are required to produce steady power despite the fluctuating solar
radiation, with concerns on the dispatchability of such plants where thermal energy storage may offer
a solution to address the issue. This paper presents a mathematical model for performance prediction
of a honeycomb sensible-heat thermal energy storage designed for application of concentrated solar
power microturbine. The focus in the model is to consider the laminar developing boundary layers at
the entry of the flow channels, which could have a profound effect on the heat-transfer coefficient due
to large velocity and temperature gradients, an effect which has not been considered in the modelling
of such storage systems. Analysing the thermal and hydrodynamic boundary layer development,
the Nusselt number and the friction factor were evaluated using a validated conjugate heat-transfer
method. The simulations results were used to develop accurate regression functions for Nusselt
number and friction factor. These formulations have been adopted within a one-dimensional model
to evaluate the performance of the storage under different operating conditions. The model was in
good agreement with conjugate heat transfer results with maximum relative error below 2. Meno dettagli

A multi-objective optimisation of a hybrid solar dish power plant aiming to minimise the levelised cost of energy while keeping emissions as low as possible is presented in this paper. The analysis was carried out for both regenerative Brayton-Joule regenerative cycle and inter-cooled and reheated regenerative cycle using an analysis tool developed during this research and validated against available experimental data.
The plant optimisation was performed using a fast and computationally… Visualizza altro

A multi-objective optimisation of a hybrid solar dish power plant aiming to minimise the levelised cost of energy while keeping emissions as low as possible is presented in this paper. The analysis was carried out for both regenerative Brayton-Joule regenerative cycle and inter-cooled and reheated regenerative cycle using an analysis tool developed during this research and validated against available experimental data.
The plant optimisation was performed using a fast and computationally efficient optimisation technique called “response surface optimisation”, which generates an approximated function (or response surface) that can be used to find a set of thermodynamic parameters that maximise the
plant efficiency while minimising emissions. A Design of Experiment (DOE) Latin hypercube technique was used to generate the training database and a one-dimensional model were used to evaluate the output variables for each point of the database. The DOE was then coupled to a Second Order
Polynomial regression technique to approximate the behaviour of the system in the design space. A genetic algorithm was then applied in order to find a high performance arrangement.
Results show a good trade-off between emissions and levelised cost of energy for both plant layouts.
The firstarrangment shows a minimum levelised cost of energy in the range between 38.5 and 38.8 €cts/kWh with an electrical power production of about 8kW. The second showed a LCOE in the range between 50.5 and 51 €cts/kWh and a net electrical power output of 16 kW.
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To enable renewable energy distributed power generation with minimum reliance on the grid, it is essential to develop systems that are able to operate in standalone mode. Advances in the development of parabolic dish systems powering a micro gas turbine coupled to thermal energy storage offer this possibility through being able to operate for many hours without the need for gird backup. Further backup can be provided through hybridisation with fossil fuels which could allow the system to… Visualizza altro

To enable renewable energy distributed power generation with minimum reliance on the grid, it is essential to develop systems that are able to operate in standalone mode. Advances in the development of parabolic dish systems powering a micro gas turbine coupled to thermal energy storage offer this possibility through being able to operate for many hours without the need for gird backup. Further backup can be provided through hybridisation with fossil fuels which could allow the system to operate completely in standalone mode (dispatchable). Although such systems are still in the development stage, they potentially offer a substantial advantage over photovoltaic cells that create significant grid instability if operated without local backup. The alternative is to provide battery storage which is very expensive or to provide diesel engines backup which has adverse environmental impact.
This Chapter describes recent developments in dispatchable parabolic dish solar concentrator systems powering a micro gas turbine operated by a single dish that tracks the sun on two axes. System arrangement and component design options are discussed. A bespoke micro gas turbine design is required with the aim to minimise the overall cost of the system which is dominated by the dish. The mechanical arrangement poses significant challenges compared to conventional micro gas turbines due to the potentially wide operating range and the interconnected thermal management requirements of the micro gas turbine, high speed alternator, recuperator and solar receiver. Solar receiver system design is of importance when the system is to be integrated with high temperature thermal energy storage depending on the storage technology used. Safe and efficient operation requires the development of suitable operation and control strategies that will also be discussed in this chapter.
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