Thesis
Development of a high-temperature gas-phase solar receiver with optimum thermal performance
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2021
DOI:
https://doi.org/10.25918/thesis.202
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Abstract
In the process of a complete transition to renewable energies, concentrated solar thermal/power is considered a necessary part of a diverse energy portfolio according to IEA energy transition scenarios, due to its dispatchability. However, it needs to evolve to operate at higher temperatures (~1000 K) to enable advanced thermodynamic cycles. As the highest temperature point in the system, the receiver represents the key to this evolution. However, there is a classic trade-off between mean operation temperature and thermal efficiency of a solar receiver (due to radiation heat loss which is proportional to T4). In addition, conventional heat transfer fluids (e.g., oils and molten salt) are not stable at such high temperatures. To address these issues, this thesis proposed an innovative gas-phase receiver utilising transparent/absorbing spheres as a volumetric absorption medium. The motivation behind this design is to reduce the reradiation losses by maximising radiation penetration through the absorber in order to break the long-standing trade-off. Four stages of research activities were identified. For Stage I, an optical model and a 1-D heat transfer model were developed to preliminarily design a novel semi-transparent packed-bed receiver, and compared with the classic opaque ceramic packed-bed absorber. The designs showed a potential to obtain the elusive "volumetric effect" and demonstrated that the proposed design could potentially compete with the most successful gas-phase receivers developed. Next, the efficiency limits of the proposed design were extensively investigated by exploring a wide range of geometrical (e.g., ~0.01 to ~1.45 spheres per cm3) and operational parameters. The optimal holistic performance of the receiver was achieved with 18 rows of transparent spheres (i.e., ~0.3 spheres per cm3). While the thermal emission losses were addressed by this design, the reflection losses were identified as the most effective limiting factors. For Stage III, using the obtained optimal range of the parameters, the identified limiting factors were addressed by the 3-D pore-scale modifications using linked TracePro ray-tracing optical and ANSYS Fluent CFD models. The enhanced proposed designs showed a peak efficiency of ~90 % at a hot air outlet temperature above 1000 K. As the final stage (Stage IV), an experimental optical study was conducted to verify the concept by investigating the transmission versus absorption within a prototype semi-transparent absorber. Overall, this proposed receiver demonstrated a new pathway towards an inexpensive and efficient solar receiver providing an outlet temperature over 1000 K—a receiver which can enable advanced thermodynamic power cycles.
Details
- Title
- Development of a high-temperature gas-phase solar receiver with optimum thermal performance
- Creators
- Mohammadreza Sedighi
- Contributors
- Ricardo Vasquez Padilla (Supervisor) - Southern Cross UniversityMaree Lake (Supervisor) - Southern Cross UniversityAndrew Rose (Supervisor) - Southern Cross UniversityRobert A Taylor (Supervisor) - University of New South Wales
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- xxix, 411
- Identifiers
- 991013022834202368
- Copyright
- © Mohammadreza Sedighi 2021
- Academic Unit
- Faculty of Science and Engineering
- Resource Type
- Thesis