Transforming heat-recovery system performance by exploiting multi component turbine flows

Living standards in the UK are at significant risk from the rising costs of energy and the increasing gap between demand and the UK's generating capacity. Plugging this gap requires technological innovations which are affordable and can be implemented over reasonably short time-scales. An important area where efficiency gains can be achieved quickly is improving the management of heat released from industrial processes. All industrial and power generation processes produce heat which is often released into the environment in the form of high temperature exhaust products. New technologies are being developed to recover this otherwise wasted energy for use elsewhere, such as electricity, heating or cooling. If applied across the UK manufacturing sector, these technologies could save the energy output of around 20 power stations. Heat-recovery technologies are also used for renewable power from biomass, geothermal, solar-thermal sources and in de-centralized power generation. The development of heat recovery technology is therefore important in terms of cutting our carbon footprint as well as increasing UK energy security.

Heat recovery systems work by transferring heat into a high-pressure working-fluid, using a heat exchanger. In order to produce electricity, the working fluid drives a turbine which is connected to an electrical generator. Heat recovery systems often use working fluids which are refrigerants or long-chain hydrocarbons. The properties of these working fluids differ greatly from those which have traditionally been used within turbines (such as air within aero-engines/gas-turbines or water vapour within steam turbines) and can be made up of several components including mixtures of gases and liquids. There is very little known about the behaviour of these unconventional working fluids within turbines largely due to a lack of experimental data with which to test current theories. This is important because turbine designers require accurate models in order to develop high performance machines, and uncertainties in the modelling can have a detrimental impact on both the development costs and the overall performance of a heat recovery system. There is also a potential to exploit the unusual behaviour of these working fluids, such as their ability to change from liquid to gas across the turbine, which can be exploited to increase system power to size ratios (power density) in ways not possible using normal working fluids like water.

The project will explore how the behaviour of multi-component fluids can be used to increase turbine performance. In order to achieve this, the work will involve developing methods to simulate multi-component fluids within turbines. The project will use experiments and computational techniques to model these flows and use the results from this work to improve current computational methods. The project involves a collaboration with GE who are global leader in the design, manufacture and supply of heat recovery systems. GE will incorporate the results of this work into their design systems. In doing so, the results from this project will accelerate the development of heat-recovery technologies which will be used world-wide.

Heat recovery systems are used in a wide range of low carbon technologies such as co-generation, biomass, solar, geothermal. Heat recovery systems can also be used to reduce energy demand in industrial processes; it is estimated that around 40TWh of energy can be recovered from UK industries through the implementation of heat recovery technologies. Given that the global market for low carbon technologies is estimated to increase to nearly £900bn by 2050, growth in research capabilities in these technologies is very important for maintaining UK competitiveness in the future.

The economic and societal benefits of developments in heat recovery technologies are large due to the rising pressures for increased sustainability of energy supply. According to Ofgem, spare electricity power production capacity could fall to 2% by 2015, which means that measures to reduce energy demand are urgently needed and technological solutions must be delivered rapidly. The implementation of heat recovery systems can help to alleviate these risks by improving how we manage heat released from many industries. This can have a transformative impact on UK energy use, particularly in the manufacturing industries which will be required to reduce emissions by up to 70% to meet the UK 2050 targets.

This project will help put the UK at the forefront of this emerging field and attract research investment from market leaders, such as GE, who are committed to providing financial support for this project. GE's support for this project provides a route to exploitation of this work and will ensure the results impact technological developments in the near term. This means that the results from the project will have a significant global impact as GE provide heat recovery systems internationally for a large number of applications including reciprocating engines, biomass boilers and micro-turbines, and industries including waste-treatment, oil and gas and agriculture. The results from the work will be published in a broad range of academic and public media, and will therefore be available to beneficiaries working in industry and academia. The dissemination of this work will be further facilitated through a number of events, such as workshops and public road-shows, and using several social and on-line media.

The importance of this work stems from its potential to increase UK competitiveness and energy sustainability and is further strengthened by its cross-disciplinary relevance to an extensive range of technologies and research areas. The focus of this work on transonic/highly-loaded turbines means that the results will have impact to many turbine applications where power-to-weight or specific cost is critical. As well as this, the focus of the work on multi-phase effects provides a strong link with oil and gas pumping and steam-turbines which also suffer from two-phase flows; these technologies are vital to current power generation. The study of multi-component fluids is also integral to understanding many chemical and biological processes, and so this project has the potential to lead to technological developments in several other turbomachinery applications and engineering disciplines.