Research

My research focuses on designing and developing functional surfaces to enhance interfacial transport in energy and water systems. I use numerical and experimental approaches to investigate the interfacial transport in liquid/vapor phase change.

Evaporation:

Evaporation plays a crucial role in various fields due to its unique properties. In thermal management, it is used for cooling systems, leveraging the endothermic nature of the evaporation process to absorb heat, commonly seen in air conditioning and refrigeration. The food industry benefits greatly from evaporation, primarily in concentration and drying processes, which are essential for extending the shelf life of products and enhancing flavors. In biological applications, evaporation is pivotal in processes like perspiration in humans and transpiration in plants, aiding in temperature regulation and nutrient distribution. Furthermore, evaporation is central to water applications, particularly in water treatment and desalination processes, where it helps purify water by removing impurities and salts, thus making it suitable for consumption and various other uses. This versatility of evaporation underscores its importance across diverse sectors, contributing significantly to advancements in technology, health, and environmental sustainability.

-Sessile Droplet Evaporation on surfaces with mixed wettability
The interaction of evaporating adjacent drops has recently become a subject of great interest. This, however, has been mostly limited to spherical axisymmetric drops rather than elongated droplets, which could play essential roles in a wide range of applications. The dynamics of droplet evaporation dramatically change with droplet size, shape, and distance between adjacent droplets. While the evaporation rate of spherical droplets increases with distance from the center of the array, evaporation has a more complex behavior in cylindrical droplets regarding real-life application conditions.
Related publications:
https://doi.org/10.1115/ICNMM2020-1055
https://doi.org/10.1016/j.ceja.2022.100255

-Solar Driven Interfacial Evaporation

Solar-driven interfacial evaporation (SDIE) represents a cutting-edge advancement in efficiently utilizing renewable energy for water treatment and desalination. This technology harnesses sunlight, one of the most abundant and sustainable energy sources, to heat the water-air interface directly, significantly enhancing evaporation. Focusing energy at the interface minimizes heat loss and increases efficiency compared to traditional bulk heating methods. This approach is efficient in purifying water, as it can selectively evaporate water while leaving behind contaminants, making it ideal for desalination and wastewater treatment. This method’s scalability and low energy requirement make it a promising solution for providing clean water in remote or off-grid areas. We are exploring using novel materials, such as photothermal nanomaterials and advanced membranes, to optimize this process. SDIE exemplifies the innovative use of solar energy and offers a sustainable approach to addressing the global water scarcity challenge.
Related publications:
https://doi.org/10.1016/j.desal.2023.116707
https://doi.org/10.1016/j.clet.2022.100495

Boiling:

Boiling, a fundamental heat transfer process, has diverse applications across multiple industries. In air conditioning and HVAC systems, boiling is utilized in refrigeration cycles to facilitate the efficient transfer of heat, improving the cooling performance. Immersion cooling, an innovative technology often employed in data centers, leverages boiling to manage the high heat loads of electronic components, submerging them in a coolant that boils at a lower temperature to dissipate heat effectively. Beyond these, boiling finds applications in power generation, specifically in steam turbines where water is boiled to create steam that drives turbines, generating electricity. It is also crucial in the culinary world for cooking and sterilization processes. In the medical field, boiling sterilization is a common method to eliminate microbes from instruments. These applications highlight boiling’s versatility and effectiveness in managing heat transfer, essential for the functionality and efficiency of various systems and processes.

-Porous and rough bio-coatings for enhancing two-phase cooling system performance
With growing cooling demands due to global warming and the climate change crisis in the upcoming years, cooling systems should be utilized more efficiently. Boiling is an effective heat transfer mechanism critical in many cooling systems. Surface modification is considered the major approach for boiling heat transfer enhancement. For the first time, our group developed a microbial bio-coating surface modification technique for phase change cooling applications. Thermoacidophilic Sulfolobus solfataricus coating was implemented using a facile dip-coating method on metallic and non-metallic surfaces. Controlled by drying conditions, the coating exhibited rough and porous morphologies.
Related publications:
https://doi.org/10.1016/j.ijft.2022.100170
https://doi.org/10.1038/s41598-017-18192-2
https://doi.org/10.1016/j.energy.2021.119959

-Functional surfaces for boiling heat transfer

In our research, we investigate the intricacies of surface engineering to augment boiling heat transfer, focusing on micro, nano, and hierarchical texturing. Fundamental studies are conducted on diverse substrate materials to comprehend their impact on heat transfer characteristics and the applicability of the developed methods for different applications. These investigations are complemented by parametric studies, where we thoroughly vary surface properties such as roughness, texture, and wettability. This approach allows us to systematically assess each parameter’s effect on boiling phenomena. Alongside experimental studies, numerical analysis constitutes a significant portion of our work. Utilizing modified computational models, we simulate heat transfer processes to gain deeper insights into two-phase flow dynamics, such as bubble behavior and the overall boiling mechanism under varied conditions. Such numerical and experimental studies enhance our understanding of nucleation sites and bubble manipulation and improve the critical heat flux. This integrated approach, merging experimental investigation with computational analysis, is pivotal in advancing the field of thermal management and energy efficiency.
Related publications:
https://doi.org/10.1016/j.cartre.2022.100171
https://doi.org/10.3390/fluids5040239
https://doi.org/10.1016/j.ijthermalsci.2020.106420
https://doi.org/10.1016/j.ijheatmasstransfer.2019.118952
https://doi.org/10.1080/01457632.2018.1442305
https://doi.org/10.1016/j.ijheatmasstransfer.2019.01.139
https://doi.org/10.1016/j.applthermaleng.2018.05.013
https://doi.org/10.1021/acsomega.7b02040
https://doi.org/10.1016/j.applthermaleng.2017.08.018
https://doi.org/10.1115/1.4036651

Condensation:

Condensation, the process of a gas turning into a liquid, has a wide range of applications across different fields. In industrial and residential HVAC (Heating, Ventilation, and Air Conditioning) systems, condensation plays a vital role in cooling mechanisms, which helps transfer heat from inside to outside environments. In power generation systems, steam turbines utilize condensation to efficiently convert steam back into water, recycling it for continuous use, thereby maximizing energy efficiency.  Additionally, in distillation, used extensively in chemical processing and the production of spirits, condensation helps separate mixtures based on differing boiling points. This process is also integral to the desalination of seawater, where condensation is used to collect fresh water. In scientific research, condensation methods are employed in cloud chambers for particle detection. These diverse applications highlight condensation’s importance in natural and engineered systems, underlying its significance in environmental sustainability, energy production, and technological advancements.

– Flow condensation in mini- and micro-channels
Due to the high compactness needed for modern heat transfer systems, microtubes and microchannels are widely used in different areas of the industry, such as heat pumps, the chemical engineering industry, condensers and evaporators, heating ventilating, and air conditioning systems. With advancements in nanotechnology, surface modification methods have been proposed to increase the phase change efficiency in mini and microdomains. Altering surface energy and decreasing the channel dimension are two main approaches to enhancing flow condensation heat transfer.
Related publications:
https://doi.org/10.1021/acsanm.0c03181
https://doi.org/10.1016/j.applthermaleng.2021.117359
https://doi.org/10.1021/acs.langmuir.1c01844
https://doi.org/10.1016/j.ijheatmasstransfer.2021.121664

– Drop condensation

In water harvesting applications, surface wettability enhances condensation heat transfer efficiency. Surfaces engineered with specific wettability properties significantly influence the rate and pattern of water droplet formation and removal during condensation. (Super)Hydrophilic surfaces, with their high affinity for water, promote condensate spread, leading to a thin, uniform film that can easily be collected. On the other hand, (super)hydrophobic surfaces encourage the formation of discrete droplets that rapidly coalesce and roll off, minimizing thermal resistance and enhancing heat transfer. This behavior is particularly beneficial in water harvesting systems, where efficient condensation and collection of water from humid air are essential. We optimize the condensation process by tailoring the surface wettability, thereby improving water harvesting systems’ overall efficiency and effectiveness in various environmental conditions. This manipulation of surface properties demonstrates a fine synergy between material science and thermal engineering, offering innovative solutions to water challenges.
Related publications:
https://doi.org/10.1016/j.ijheatmasstransfer.2023.124929

 


In collaboration with

Prof. Ali Koşar – Sabanci University, TR.
Prof. Hyun Sun Park, Seoul National University, KR.
Prof. Khellil Sefiane, University of Edinburgh, UK.
Prof. Tansel Karabacak, University of Arkansas at Little Rock, USA.
Prof. Pinar Menguc, Ozyegin University, TR.
Prof. Luis Guillermo Villanueva, EPFL, CH.
Dr. Ghazaleh Gharib, University of Southern Denmark, DK.
Dr. Yiğit Akkuş, Ericsson AB, SE.
Dr. Osman Akdag, ASELSAN Inc., TR.
Dr. Murat Parlak, ASELSAN Inc., TR.