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    Guest editorial: The significance of clean and energy-efficient operations in sustainable aviation
    (Emerald, 2023) Karakoç, Tahir Hikmet; Colpan, Can Özgür; Yetik, Ozge; Dalkıran, Alper
    Air transportation should be done using clean energy resources and technologies, without causing environmental pollution, and in energy-efficient, economical, safe and fast ways. In short, it must be sustainable. Many developed countries have set net-zero emission targets for the near future. To achieve this goal, it is necessary to consider many factors. The first of these is to use efficient aircraft technology by using less energy and fuel. In this way, lower life cycle emissions can be produced. By using sustainable aviation fuel (SAF), CO2 emissions to the environment can also be reduced. Some typical feedstocks used are cooking oil, animal waste, solid waste from homes, forestry waste and energy crops. Improvement in operations and infrastructure is also another critical factor for sustainable aviation. It is possible to use less energy on the ground or to reduce the fuel consumed by choosing the optimum flight path. To make the airports sustainable, there are also issues such as reducing the maintenance costs of the devices, increasing the lifetime of the buildings and making the lighting, heating and cooling more economical. To ensure all this, researchers from around the world work together on materials and aircraft component development testing, wind tunnel testing, emissions and combustion testing, computational modeling and simulations.
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    Nanofluid-based cooling of prismatic lithium-ion battery packs: an integrated numerical and statistical approach
    (Springer, 2023) Morali, Ugur; Yetik, Ozge; Karakoc, Tahir Hikmet
    Recently, the need for thermal management of lithium-ion batteries in electrical transportation engineering has received increased attention. To get maximum performance from lithium-ion batteries, battery thermal management systems are required. This paper quantitatively presents the efects of several factors on both maximum battery temperature and tem perature gradient. These factors include ambient temperature (288 K, 293 K, 298 K, 303 K, 308 K), C-rate (1C, 2C, 3C, 4C, 5C), mixing ratio (1%, 2%, 3%, 4%, 5%), and inlet velocity (0.01 m s ?1, 0.02 m s ?1, 0.03 m s ?1, 0.04 m s ?1, 0.05 m s ?1). Five levels for each parameter were considered to develop the orthogonal array. The signifcance of the variables was orderly shown through the L25 experiment. Results indicated that for maximal battery temperature, C-rate and ambient temperature are the most signifcant factors while for temperature gradient, C-rate and inlet velocity play an important role. For maxi mum battery temperature ambient temperature, C-rate, mixing ratio, and inlet velocity of 288 K, 1C, 4%, and 0.05 m s ?1, respectively, were obtained at the optimal setting. An ambient temperature of 308 K, a C-rate of 1, a mixing ratio of 5%, and an inlet velocity of 0.05 m s ?1 was the optimal setting for the temperature gradient. The results showed that the confrmatory test validates the optimization process for maximum battery temperature and temperature gradient. This study may provide a pathway for manufacturers and researchers interested in minimizing battery temperature and improving temperature gradient in electric vehicle applications.
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    A numerical study of thermal management of lithium-ion battery with nanofluid
    (Elsevier, 2023) Yetik, Ozge; Morali, Ugur; Karakoc, Tahir Hikmet
    In this study, the NTGK model was used to evaluate the thermal and electrical analyzes of the battery model and Taguchi design was implemented to investigate the main effects of four control factors in the battery thermal management process, those are inlet velocity, mixing ratio, ambient temperature, and C-rate. The Taguchi’s L16 array was fabricated using varying control factors to obtain detailed battery temperature behaviors. As the discharge rate increased, the temperature value of the model increased, while the temperature value of the model decreased as the mixing ratio of the nanoparticle increased. As the inlet velocity of the refrigerant increases, the temperature value taken by the model decreases, while the higher the ambient temperature, the less the increase in the maximum temperature reached by the model. Also results showed that the most influential factor on both maximum battery temperature and temperature uniformity responses was the C-rate, while the least effective factor was the mixing ratio. It was found that an inlet velocity of 0.04 m/s, a mixing ratio of 5, a C-rate of 2, and an ambient temperature of 283 K will yield the lowest maximum battery temperature. The maximum battery temperature was 294 K under these conditions. On the other hand, to maximize the temperature uniformity, 0.04 m/s inlet velocity, 3 mixing ratio, 2 C-rate, and 313 K ambient temperature need to be set as processing parameters. The results showed that the C-rate has to be closely controlled during the discharge process and the influence of the mixing ratio is negligible. This study can be used as a robust guideline in the design of battery thermal management systems using nanofluids.
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    Promising fuels and green energy technologies for aviation
    (Taylor and Francis Ltd., 2022) Karakoc, T. Hikmet; Colpan, Can Ozgur; Ekici, Selcuk; Yetik, Ozge
    Promising fuels and green energy technologies for aviation
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    A study on lithium-ion battery thermal management system with Al2O3 nanofluids
    (John Wiley and Sons Ltd, 2022) Yetik, Ozge; Karakoc, Tahir Hikmet
    In this study, a comparison is made with regard to cooling of 15 prismatic batteries connected in series with air, alumina nanofluid. The concentration of the nanofluid was taken as 3% and 5%, the ambient temperature was taken 295 and 300 K, the inlet velocity of the refrigerant was taken 0.01, 0.02, 0.04 m/s, and the discharge rate was taken 1 to 5 C. When the discharge rate is less than or equal to 3, the battery module remained at a safe operating temperature. As the discharge rate increased, problems began to be encountered.
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    Thermal and electrical analysis of batteries in electric aircraft using nanofluids
    (Elsevier Ltd, 2022) Yetik, Ozge; Karakoc, Tahir Hikmet
    Batteries are the primary power supply for hybrid electric aircraft. The most important parameter affecting the performance, life, safety and cost of the batteries is the operating temperature. Therefore, thermal management of batteries is extremely important. The battery module (10 S, 3 P) consists of thirty prismatic lithium-ion batteries. The cooling of the battery is provided by nanofluid, which is a combination of nanoparticles and refrigerants in different mixing ratios (H2O + 3% Fe2O3, H2O + 4% Fe2O3, H2O + 6% Fe2O3), engine oil (EO + 3% Fe2O3, EO + 4% Fe2O3, EO + 6% Fe2O3). The temperatures of each of the batteries in the module are examined separately. The thermal and electrical studies of the battery model are also investigated with the volumetric ratio of the nanofluid, different input speeds and different discharge rates of the battery model. The busbar, which should not be ignored in the thermal management of the batteries, that is, the materials connecting the batteries to each other are included in the model. Air cooling, which is the traditional cooling method of the battery model, cannot bring the battery to the desired temperature range. For this reason, nanofluid cooling should be preferred. Considering the sensitivity to the volume fraction ratio, EO reacted more quickly than water. When the volume fraction ratio was increased from 3% to 6%, when the refrigerant was water, the temperature of the battery model changed by 0.05 K, and when the refrigerant was EO, there was a change of 1.15 K. Looking at all the results, they gave better results than the nanofluid EO added to the water. Considering the effect of the inlet velocity of the refrigerant on the maximum and minimum temperatures, there was a 1 K change at the maximum temperature, and a 0.2 K change at the minimum temperature (H20 + 6% Fe2O3).