This project is investigating heat loss from high-temperature solar thermal receivers and developing the next generation of improved receiver designs to reduce that loss.
This project focused on improving the efficiency of solar thermal receivers, with an emphasis on dish concentrators. The project has increased Australia’s capacity in designing, constructing and testing world-class solar thermal concentrators.
- Integrated modelling of receiver losses. Development of integrated CFD, ray-tracing, conductive and thermal emissions (radiosity) models as well as hydrodynamic flow model and wall heat transfer model, in order to obtain overall receiver performance. Development of approaches for iteratively converging the models when all of these mechanisms occur simultaneously.
- Importance of nonisothermal receivers. Variations in temperature on a receiver is something that must be actively used to enhance the receiver performance. Lower temperature regions should be placed where the receiver is more exposed to the environment, and higher temperature regions should be sheltered, preferably deep within a cavity, to reduce losses from those regions.
- Optimisation of receiver shapes. Developed approach to save on calculation time when assessing many (1000s) of receiver shapes, saving many millions of rays of computational cost.
- Performance of air curtains for receiver convective loss reduction. Performed numerical and experimental tests resulting in findings that a well-placed air jet with an optimised velocity can reduce cavity convective heat loss by 40-70%. These active airflow features can be incorporated in future receiver designs for greater efficiencies.
Developing the efficiency of open cavity receivers for commercial viability.
In this project, a new receiver was designed, built and tested on the 500 m² ‘SG4’ Big Dish at ANU. This open cavity receiver has a capacity of 450 kW, and converts focussed radiation into superheated steam with a theoretical efficiency of 98.7%. Close agreement between experimental and theoretical efficiencies were found during the testing program in Nov-Dec 2015. Apart from testing result, the project has resulted in a reusable set of design tools that ANU will adopt on several other current projects.
The ANU SG4 dish was built in 2009, but there had never been a receiver specifically designed for it. By undertaking a careful study to fine-tune a receiver to the excellent optics of SG4, a high efficiency design was demonstrated, and that advanced the development and relevance of Concentrating Solar Thermal Power (CSP) dish technology.
ANU are using similar experimental and computational approaches to develop other solar thermal system components. They’re publishing results regularly, and are contributing to several open-source software projects that other researchers and developers can use. These tools and others are being used across several ANU projects, and members of the team from this project are transferring to other projects and transferring their knowledge with them as they go.
Better performance leads to the reduction in cost of solar thermal energy which will increase the contribution that concentrated solar power can make to the renewable energy industry in Australia and globally, and hence to climate change mitigation.