SOL-Art (Organic Trilateral Flash Cycle for Efficient Conversion of Solar Heat to Power) is a National research project funded by the Hellenic Foundation for Research and Innovation (H.F.R.I.) (Grant Agreement: HFRI-1087) in the context of the "1st Call for Research Projects to Support Faculty Members & Researchers and Procure High-Value Research Equipment". The total duration of the project is 42 months with the Department of Natural Resources Management & Agricultural Engineering of the Agricultural University of Athens (AUA) being the host institution.
The target of the project is the in-depth investigation of the two-phase expansion phenomenon, and, subsequently, the design, manufacturing, and performance evaluation of a small-scale (in the order of 2-3kWel) Trilateral Flash Cycle (TFC) engine for the exploitation of low-grade solar heat at low temperatures (in the order of 80-90oC). The strategic objective of the project is to prove in practice that a performance improvement of up to 30-35%, compared to the conventional Organic Rankine Cycle (ORC), is technically feasible by implementing the TFC power cycle architecture. This will be accomplished by the more efficient, inherent in the TFC configuration, exploitation of the heat source, provided that technological bottlenecks are overcome.
TFC concept
The TFC engine consists of the same components as the ORC one, i.e. pump, evaporator, expander, and condenser. The Working Fluid (WF) of the power cycle flows through the unit's evaporator, where heat is transferred to it by the heat source at elevated pressure until the saturated liquid state is reached. Then the WF flows through the two-phase expander, where it undergoes two-phase expansion and, as a result, power is generated. Subsequently, the WF rejects heat at the heat sink at the low condensing pressure of the cycle, and, finally, it is pumped again to the evaporator pressure.
From a thermodynamic point of view, the main advantage of the TFC is the omission of the WF vaporization at the system evaporator, a process that leads to increased exergy losses of the heat source. The temperatures of the heat source and the WF match optimally at the evaporator, and increased heat transfer rates between the fluid streams are achieved, leading to the maximization of power generation. The optimal utilization of the heat source's potential is especially important for solar energy harvesting, taking into account its intermittent availability and the high installation cost of solar collectors.
Science
A significant impact on science is anticipated, since a new research field, i.e. the TFC, will be initiated. The impact will not be limited to efficient solar heat harvesting, as the applicability of the TFC in the low-grade heat recovery field is much broader. Proving that TFC is technically feasible and more efficient in comparison to ORC will be one of the major achievements of the SOL-art project. This will establish the TFC expansion process as an attractive alternative to the classical ORC-type units. The project results will enhance the capacity of the research team, by involving and recruiting experienced and young researchers, who will be front-runners in this very promising new technological field and, in general, the development of waste heat recovery technologies.
Environment, Economy, and Society
The efficient utilization of solar energy will reduce the use of fossil fuels and the associated GHG emissions. Moreover, it will contribute to the reduction of the specific cost of solar energy, rendering, thus, solar thermal systems more competitive, in comparison to photovoltaics, in the energy market for electricity generation . The achievement of more competitive electricity costs will boost the expansion of solar thermal systems, leading, in the long term, to the generation of new jobs. Additionally, new job positions will be created during the project, aiming to be preserved, after the project has been completed, by establishing a spin-off company for exploiting the project results.
Although the integration of the TFC with solar thermal systems is challenging due to the intermittent availability of the heat source, the TFC can be a promising alternative technological solution to recover more efficiently heat from other sources as well, either renewables or waste. Accordingly, the TFC technology can be exploited in various energy systems, such as for waste heat recovery in the industry, in biogas power plants, and even onboard ships. In all these segments there is a large amount of waste heat, mainly from exhaust gases and cooling jacket water of engines, which can feed the TFC engine to generate electricity. When the project objectives are fulfilled, a novel heat-to-power technology, with superior performance and similar cost as the standard ORC units, will be established.
SOL-Art is elaborated with the cooperation of the Department of Natural Resources Management & Agricultural Engineering of AUA, and the Applied Thermodynamics and Heat Transfer research group of Ghent University (Ugent).
AUA team members
Dimitris Manolakos is the Principal Investigator of SOL-Art. He is an Associate professor at the Department of Natural Resources and Agricultural Engineering of AUA on the topic of Thermodynamics. His research focuses mainly on the field of heat-to-power conversion technologies, renewable energy systems, and heating and cooling applications for buildings, industry, and agriculture.
Anastasios Skiadopoulos is a Mechanical Engineer. His research is focused on two-phase expansion, low-grade heat recovery, renewable energy technology, CHP in domestic and industrial applications, integration of energy systems, and CFD.
Erika Ntavou is a Mechanical Engineer. Her main research area of interest includes the development of low-temperature, heat-to-power conversion systems, with a special focus on water desalination units and water treatment systems towards NZL.
Ugent team members
Michel De Paepe is is a Professor of Thermodynamics in the Faculty of Engineering and Architecture at Ugent. His research focuses on heat transfer, two-phase refrigerant flow, electrical drives, and thermal energy storage. He is also interested in energy efficiency in buildings and industry, fuel cells, ORCs and other small-scale energy conversion systems.
Steven Lecompte is an Assistant Professor on the topic of Thermal Machines in the Faculty of Engineering and Architecture at Ugent. His research focuses on thermal machines (heat pumps, ORCs, refrigeration cycles), including thermo-economic optimization, renewable energy integration, multi-phase processes, expanders, and compressors.
Peer-reviewed papers
A. Skiadopoulos, G. Kosmadakis, S. Lecompte, M. De Paepe, and D. Manolakos, Numerical modeling of flashing in TFC expanders for the efficient exploitation of low-grade heat, Therm. Sci. Eng. Prog., p. 102171, 2023, doi: https://doi.org/10.1016/j.tsep.2023.102171.
Conference papers
A. Skiadopoulos, X. van Heule, G. Kosmadakis, D. Manolakos, M. de Paepe, and S. Lecompte, Thermodynamic low-order model for the simulation of two-phase expansion within a TFC unit, Proceedings of the 6th International Seminar on ORC Power Systems, Technical University of Munich, 2021.
A. Skiadopoulos, X. van Heule, S. Lecompte, M. de Paepe, and D. Manolakos, Optimizing the performance of a hybrid Solar-Biomass micro-CHP system with a TFC engine as the prime mover for domestic applications, Proceedings of the 7th International Seminar on ORC Power Systems, Seville, 2023.
A. Skiadopoulos, and D. Manolakos, Comparison of the ORC and the PEORC for low-temperature industrial waste heat exploitation, Proceedings of the 9th World Congress on Momentum, Heat and Mass Transfer (MHMT 2024), London, 2024.
Powered by w3.css
