City Research Online

Abstract

In recent years there has been an increasing interest in power generation using small-scale concentrated solar power units. Currently, photovoltaics are the main commercialised technology thanks to their low capital cost. However, their relatively low efficiency and power density has motivated research on the application of thermal engines. Dish-Stirling systems achieve reasonable efficiencies, but are relatively expensive and unreliable because of their technical complexity. The reliability of micro gas turbines and their potentially lower costs has motivated the current research, which is part of the EU funded OMSoP project, to study the thermo-economic performance of a micro gas turbine (MGT) engine coupled with dish concentrators in order to achieve suitable efficiency at low cost. To achieve this goal a system design, which takes into account the state of the art technology, is required to achieve an acceptable efficiency with minimised capital cost to promote dish-MGT systems in the market. An important issue to be addressed is to consider the effect of system design parameters on dish-MGT performance under the considerable variations of the solar irradiance.

A computational model for pure solar dish-MGT systems has been developed, which combines the cycle analysis of the MGT with component models to perform design point performance simulation, generate component performance maps and perform off-design performance simulation. The method has been proven to be quick and effective, particularly in terms of using minimal data and providing the component performance maps for off-design simulation. Different strategies which can be applied to pure solar dish-MGT systems are examined and novel concepts have been proposed to increase the generated electricity.

The computational model has been coupled with an up to date economic model which was specifically developed through the OMSoP project for dish-MGT systems. The integrated model is coupled to an optimisation platform to find system designs which lead to optimal thermo-economic performance for a 5kWe system. Then the optimisation has been extended over the rated power of 5-30kWe to find the power rating which results in the minimum cost of generated electricity by the dish-MGT systems.

The proposed concepts for the control and operation of the dish-MGT systems are shown to be advantageous for increasing electricity production and dealing with the variations of power demand. The results demonstrate the potential of pure solar dish-MGT systems to achieve economically competitive electricity when the economy of scale of these systems is taken into account.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TJ Mechanical engineering and machinery
Departments:	Doctoral Theses School of Science & Technology > Engineering School of Science & Technology > School of Science & Technology Doctoral Theses

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