Experimental Investigation and Mathematical Modelling of Dynamic Equilibrium of Novel Thermo-fluids for Renewable Technology Applications

Asst. Prof. Hüseyin Utku Helvacı

 Dogus University, Faculty of Engineering,
Department of Mechanical Engineering, Istanbul, Turkey

Place: MS Teams
Date: 19 February 2021; Friday @14:00-15:00

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Abstract:

Environmental issues such as air and water pollutions and climate change can be linked to the fossil fuels being still the main source for human activities and therefore, its intensive consumption. As a result, there is a clear need to utilize alternative and clean energy sources to address these environmental problems. Solar thermal energy has a potential to diminish the dependency on fossil fuels and reduce CO2 emissions in which solar radiation is converted to heat via a thermal fluid for power and heat generation. Medium and high-temperature solar thermal systems where concentrated collectors are employed have been utilized for power generation, whereas low-temperature solar systems where non-concentrated collectors such as flat plate are employed have been used for heat generation. A review of the literature indicates that by using an appropriate thermal fluid, the generation of power and heat is possible via low-temperature solar thermal systems. It can also be revealed from the literature that when selecting a thermo-fluid to be used in such systems it is important to consider thermophysical, environmental and safety aspects all together.   This study focuses on the investigation of novel and environmentally friendly thermo-fluids that can be potentially utilized in low-temperature solar thermal systems for mechanical and heat energy generation. This is accomplished in three stages. Firstly, a low-temperature solar thermal system which consists of solar organic Rankine cycle and heat recovery units is designed, commissioned and tested experimentally. In the experiments, HFE 7000 refrigerant that has zero ozone depletion potential (ODP) and low global warming potential (GWP) is employed. The performance of the system is evaluated in terms of energy and exergy analyses. In the 2nd stage, the flat plate collector is mathematically modelled and simulated under various operating conditions. Then, the model is extended to the solar organic Rankine cycle to perform a simulation study where 24 organic compounds are examined according to their applicability in terms of the thermal performance of the cycle and environmental properties of the fluids such as flammability, toxicity and global warming potential. In the last stage, a numerical study of the laminar flow of HFE 7000 based nano-refrigerants at different Reynolds number and volume concentration ratio is conducted. The convective heat transfer coefficient, the pressure drop and the entropy generation of each flow are investigated.

Short Bio:

Huseyin Utku Helvaci is an Assistant Professor in the department of Mechanical Engineering at Dogus University. He received his PhD in Mechanical Engineering from Bournemouth University in 2017. After obtaining his PhD degree, Dr. Helvaci continued his work as a Postdoctoral Researcher at Bournemouth University for nine months. Then, he served as a Postdoctoral Research Fellow from 2018 to 2019 at Brunel University London. His research interests include thermodynamics, energy efficiency, heat to power conversion systems driven by renewable sources, thermal system design, heat and mass transfer and nanofluids. He has published his academic work in several journal articles, conference papers and book chapters.