Mehmet Akif Ezan

Dokuz Eylül University | DEÜ · Department of Mechanical Engineering

In this study, a transient heat transfer process of freezing water inside a two-dimensional square cavity has been investigated numerically. Water was used as a phase-change medium, and the numerical model has been created with control volume approach by using C++ programming language. To be able to accelerate the numerical calculations, CUT (Consi...

In this study, for a near-room-temperature magnetic cooling system, a decoupled multi-physics numerical approach (Magnetism, Fluid Flow, and Heat Transfer) is developed using a commercial CFD solver, ANSYS-FLUENT, as a design tool. User defined functions are incorporated into the software in order to take into account the magnetocaloric effect. Mag...

In this study, a three‐dimensional numerical model is developed to investigate the thermal and electrical characteristics of 18 650 lithium‐ion battery cells that are used in the solar racing car of Dokuz Eylül University, i.e., SOLARIS. The Newman, Tiedemann, Gu, and Kim (NTGK) battery model of ANSYS Fluent software is implemented to resolve the c...

Most past surveys and conclusions have clearly indicated that more than 55% of electronic device's failures are related to the inability to control high heat generated entirely. The conventional cooling methods typically consist of air-cooling processes, which involve various types of heat sinks in free and forced convection, becomes inadequate to...

Once upon a time, with my colleagues, we developed an FVM code in C++ to resolve the natural convection-driven melting inside a PV/PCM system. We summarised the significant findings in the paper below. I recently prepared a MATLAB script for this animation to enjoy the beauty of CFD. Ezan, M. A., Yüksel, C., Alptekin, E., & Yılancı, A. (2018). Imp...

Buildings contribute around 37% to global carbon emissions, prompting a growing interest in innovative carbon capture technologies. Among these, the integration of microalgae-based photosynthesis into building facades has emerged as a promising solution. This approach offers multiple benefits, including carbon sequestration, reduced energy consumpt...

Green buildings can provide a growth environment for microalgae growth on their façades, where a closed environment mimicks the organisms’ natural environment and functions as a window. This study investigates such a façade’s effect on energy saving by optimizing the performances of useful daylight illuminance (UDI) and energy use intensity (EUI) i...

Numerical investigations on the absorption of a metal hydride hydrogen storage tank based on various thermal management strategies

TÜBA-Energy Working Group, which was established under TÜBA (Turkish Academy of Sciences), joined the event on “Efficient Use of Natural Resources and Alternative Energy Solutions" with a specific workshop on “Alternative Energy Solutions where natural gas logistics are also considered through the presentations and panel discussion sessions. This p...

This research presents a simplified numerical investigation of pressure difference and vortices generation by a vertically oriented piezofan operating at different oscillating ratios and cooling effects in a vertical channel heated from side walls. The model was built by coupling the deformation overtime of a cantilever beam and the air surrounding...

In this study, a magnetic actuator is controlled to obtain a constant flow rate micropumping by a magnetic nanofluid flow inside a semicircular-shaped microchannel with a constant square cross-section. A closed-loop control strategy is developed to achieve adequate control by utilizing a model based on experimental data. A novel digital image proce...

Even though the performance of photovoltaic/thermal (PV/T) panels had been examined both computationally and experimentally for some time, the thermal models created in earlier research were mostly steady-state models for estimating the annual yields. In this study, the solar thermal collector and photovoltaic (PV) cells are combined to create the...

TÜBA bünyesinde oluşturulan “Enerji Çalışma Grubu” tarafından düzenlenen “TÜBA−Enerjide Yapay Zekânın Rolü Çalıştayı ve Paneli”nde akademisyenlerin yanı sıra çeşitli kamu ve özel kurum yöneticileri, enerji uzmanları ve dış paydaşların da dahil olduğu “Kamu Kurumlarında Çalışmalar”, “Yapay Zekânın Temelleri”, “Kamu ve Özel Sektör Uygulamaları”, “Aka...

In this work, inward solidification process of a spherical capsule subjected to a periodic boundary condition is numerically studied. The temperature transforming technique is utilized to solve the 1D phase change model and an in‐house model developed in C++. The interface position and the transient temperature profiles are evaluated with respect t...

Due to the increasing environmental awareness, the tendency to develop sustainable buildings has also increased interest in using renewable energy or energy-efficient technologies in recent years. Integrating a photobioreactor, an innovative building element on the façade, has received attention as an alternative approach to renewable energy system...

Due to the fossil-fuel-related climatic problems which got worse in recent decades, the worldwide share of renewable energy has significantly increased. Even though solar energy is one of the most accessible renewables, it has an intermittent nature throughout the day. Different energy storage techniques are implemented to resolve the intermittency...

This edited book, which is a piece of artwork prepared TUBA-Energy Working Group, brings a holistic approach to energy and covers all aspects of it, ranging from its history and importance to fundamental thermodynamic concepts and from the dimensions of energy systems to the role of innovation in these systems. The topics covered in the book are ex...

In this work, the performance of a charging mode of a thermal energy storage system is investigated numerically, and results are assessed considering the first law and second law perspectives. The storage unit comprises parallel plates positioned vertically, and the heat transfer fluid flows within the spacing between the plates. The melting proces...

The convective heat transfer inside latent heat thermal energy storage systems governs the spatial and temporal variations and significantly depends on the tendency of density variation. For most fluids in nature, the density variation has a linear tendency, so the density reduces with increasing temperature. In contrast, water has a nonlinear beha...

All-air central HVAC systems are widely applied to provide fresh and conditioned air, which is very important for users to lead healthy and productive lives. Decentralized systems are another mechanical solution to ensure indoor air quality and thermal comfort with a heat recovery ventilation system integrated into the building wall. These commerci...

The biggest part of the energy consumption of buildings is for thermal comfort. Awareness on climate change and concerns about the depletion of natural resources made the necessity to use renewable energy sources in buildings evident. In this context, microalgae have high surface efficiency and consume inorganic carbon, thus enabling carbon-neutral...

Thermal energy storage (TES) methods stand out as a key technology that eliminates the supply-demand imbalance in cooling or heating systems. This paper focuses on investigating the charging performance of the solar-aided packed-bed latent heat TES system. An in-house 1D transient mathematical model is developed to simulate the latent heat TES syst...

Borehole heat exchangers are commonly used as ground source heat exchangers in ground source heat pump (GSHP) applications. Designing borehole heat exchangers is essential for GSHPs as the thermal performance of borehole heat exchangers affects the COP of GSHP systems. In this study, the thermal performance of a phase change material (PCM) integrat...

In this chapter, the thermodynamic performance assessment of a geothermal power plant based on the transcritical CO2-Rankine cycle (tCO2-RC) is presented. At first, the description of the system, its operating principles, its major differences from the subcritical cycle, and the significance of using CO2 as the working fluid are discussed in detail...

Today, the increase in energy needs combined with climate change issues has enabled more efficient use of energy resources and the accelerated adoption of renewable energy resources. In addition, CO2 emission is reducing, and air quality is improving with the integration of solar energy where PV panels play a key role for electricity generation. It...

Indoor air quality is an important issue for improving and maintaining the indoor environment because it is directly related to people's health and work performance. These days, in many settlements, the applicability of natural ventilation is limited in the face of the decreasing infiltration loads, increased atmospheric pollution, and the climatic...

Rapor, TÜBA-Enerji Çalışma Grubu tarafından düzenlenen “TÜBA−Jeotermal Enerji Teknolojileri ve Çalıştayı Paneli”nde sunulan bildiriler esas olmak üzere, güncel literatürden taranan bilimsel çalışmaların derlenmesiyle hazırlandı.

Here we show the hairpin vortices point the upstream direction of flow instead of downstream, and this characteristic is found intrinsic behavior for turbulent buoyancy-driven boundary layer. We uncover the coherent vortices straddle high-speed streak instead of low-speed streak; moreover, the quadrant of the tangential Reynolds shear stresses domi...

In this study, a numerical model of a reciprocating magnetocaloric regenerator using a Halbach magnet array is developed by using ANSYS Fluent. The model consists of three components, namely (i) the Halbach magnet array, (ii) the magnetocaloric material, and (iii) the heat transfer fluid. It is studied in a 2-D domain due to the axisymmetric geomet...

TÜBA-Enerji Çalışma Grubu tarafından “Enerji Depolama Teknolojileri” adlı, kamu ve özel sektör ile üniversite temsilcilerinden oluşan geniş kapsamlı bir çalıştay ve panel düzenlendi. Bu raporun hazırlanmasında çalıştay kapsamındasunulan bildiriler ve literatürde öne çıkan güncel bilimsel çalışmalar temel alındı. Raporun ilk bölümünde küresel ölçekt...

In this study, a novel rotating permanent magnetic actuator (PMA) system is proposed to manipulate magnetic nanofluids to pump of chemicals inside micro-sized channels with a circular path. The PMA consists of two permanent magnet pairs and a rotor-like structure. A semicircular-shaped microchannel with a square cross-section area is located at the...

This book provides high-quality research results and proposes future priorities for more sustainable development and energy security. It covers a broad range of topics on atmospheric changes, climate change impacts, climate change modeling and simulations, energy and environment policies, energy resources and conversion technologies, renewables, em...

Herein a magnetic actuation strategy is proposed to manipulate magnetic nanofluids in CPU thermal management applications. The proposed concept consists of a multi-circular microchannel unit and a rotating permanent magnet. A set of numerical simulations have been carried out to evaluate the influences of (i) magnet diameter, (ii) distance between...

The increasing trend of the energy consumption of humanity has brought forward the efficient use of current energy resources and seeking for the adaptation of renewable energy resources. Integration of renewable energy into transportation, on the other hand, has crucial importance as it reduces the emissions in the urban regions and increases the l...

The thermal system design strongly depends on material selection. Nanofluids offer design flexibility and fine-tuning of properties by incorporation of nanoparticles in base fluids. This flexibility is guided by particle-particle communication, which may be beneficial in creating ballistic routes in heat transfer but also detrimental due to affecti...

Due to the intermittent nature of the solar energy and the mismatch between the instantaneous demand and supply, solar energy could not be used effectively, or continuously, in solar-assisted applications such as heating of a building. As a common approach, it is possible to store the available solar energy when it is abundant and use it later to o...

A novel heat exchanger (HEX) with phase change material (PCM) is proposed to recover the waste heat from the flue gas of a combi‐boiler. The thermal energy that is recovered from the flue gas is stored within the PCM‐HEX when the combi‐boiler works in the central heating mode. The stored thermal energy is then released to pre‐heat the domestic wate...

We have extended our code to simulate the inward melting process inside the cylindrical annulus.

The current study presents a novel and straightforward approach for simulating photovoltaic/thermal (PV/T) systems using the commercial computational fluid dynamics (CFD) solver ANSYS‐FLUENT. Instead of resolving the natural convection within the air gap between the PV and the glass cover, the effective thermal conductivity approach is implemented....

In this study, the influences of inlet temperature and velocity of the heat transfer fluid and the capsule material on the performance of a latent heat thermal energy storage unit is numerically investigated. The enhanced thermal conductivity approach is implemented into the ANSYS‐FLUENT software to consider the natural‐convection‐dominated melting...

This chapter is presented to cover the basic aspects and key details of thermal energy storage (TES) methods at low to high temperatures. The chapter specifically covers some important TES techniques, including sensible, latent, and thermochemical methods. There are various examples and case studies presented to illustrate each of these significant...

This book covers emerging energy storage technologies and material characterization methods along with various systems and applications in building, power generation systems and thermal management. The authors present options available for reducing the net energy consumption for heating/cooling, improving the thermal properties of the phase change...

Nowadays, improving the energy efficiency of buildings without decreasing the comfort of its occupants is of great importance in the whole world. The most widespread passive energy control strategy is the utilization of insulation materials with low thermal transmittance. This chapter proposes an alternative control strategy that would help to crea...

The increasing trend of the energy consumption of humanity have brought forward the efficient use of current energy resources and seeking for adaptation of renewable energy resources. Intergration of renewable energy into transportation, on the other hand, has crucial importance as it reduces the emissions in the urban regions and increases the lif...

In this study, the utilisation of composite phase change materials (PCMs) slabs with fins in a thermal energy storage (TES) system is numerically analysed. The storage system consists of three PCM layers at different melting temperatures. First, the predicted results are verified against the analytical solution that is taken from literature. Afterw...

Bu çalışmada katı hal soğutma teknolojisinin önderliğini yapabilme potansiyeli olan manyetik soğutma sisteminin rejeneratörü sayısal olarak incelenmiştir. Sayısal inceleme bir ticari paket program aracılığı ile gerçekleştirilmiştir. Paralel plaka rejeneratörde görülen sıcaklık düşümü sunulmuştur. Sistemde plaka şeklinde Gadolinyum malzemeler kullan...

Personalized Share Link: https://authors.elsevier.com/a/1W4us4r6Kur~yZ Flat plate solar collectors (FPSCs) are commonly used devices to convert solar radiation into useful heat for a variety of thermal applications. Due to the lower thermal efficiencies of these systems, recently, nanofluids are suggested to be used in FPSCs as the working fluid to...

It is well known that the efficiency of a photovoltaic panel (PVP) dramatically decreases with an increase in the cell temperature. For a solar cell with no thermal control unit, the surface temperature can reach 80°C, which significantly reduces the efficiency of the PVP's power generation. In this chapter, a phase change material (PCM) reservoir...

In this study, the transient thermal behavior of a phase change material inside a spherical capsule is investigated under various working conditions. A two-dimensional axisymmetric model is considered using ANSYS-Fluent software. A definition of enhanced thermal conductivity is used to incorporate the effect of natural convection in the mathematica...

Thermal management of photovoltaic panels (PVPs) with phase change materials (PCMs) is prevalent since PCMs keep the PVP temperature within a certain temperature range while undergoing reversible charging/discharging cycles throughout a day. Even though there is a vast number of numerical works that deal with the modelling of PVP/PCM under various...

In this study, the utilisation of composite phase change materials (PCMs) slabs with fins in a thermal energy storage (TES) system is numerically analysed. The storage system consists of three PCM layers at different melting temperatures. First, the predicted results are verified against the analytical solution that is taken from literature. Afterw...

In this chapter we deal with the analysis and modeling of thermal energy storage systems and applications and present the step-by-step illustrative examples for sensible and latent heat storage systems in particular from both energetic and exergetic points of view. In addition, this chapter covers the fundamentals of heat transfer analysis of laten...

In this particular chapter, we deal with a wide range of thermal energy storage (TES) applications from residential sector to power generation plants. Some practical applications of sensible heat and latent heat TES systems into heating and cooling systems are presented. The chapter also includes a brief discussion on the phase change materials (PC...

In this chapter, we present an important topic, so-called: optimization, for various TES systems and applications. The basic details and concepts of optimization, along with objective functions and constraints, are discussed, and the necessary details are provided for the researchers and engineers.

In this chapter, we deal with two important subjects for TES systems and applications, namely system characterization and case studies. In the system characterization, we focus on storage materials and their roles in specific applications while the focus is placed on various selected applications, under case studies, from numerous sectors at variou...

This chapter specifically dwells on energy storage methods and hence provides the basic aspects of the chemical, electrochemical, electrical, mechanical, and thermal energy storage techniques. Various illustrative examples are presented to highlight the importance of these methods and their deployment in various applications.

The current chapter presents a comprehensive introductory material to provide the readers with the fundamental and basic concepts and details of thermodynamics and heat transfer. The balance equations for energy, mass, entropy, and exergy are developed for various types of closed and open systems. The key modes of conductive, convective and radiati...

THERMODYNAMIC ANALYSIS OF A TRIGENERATION SYSTEM IN HOSPITAL APPLICATION Abstract: In this study, a thermodynamic analysis of a trigeneration system, which can supply all of the electrical needs of a hospital in Ankara, and also some of the heating or cooling loads. The thermal efficiency of the system is calculated together with the heat recovery...

Determination Thermodynamic Properties of Magnetocaloric Materials via Mean Field Theory

A numerical study of conjugated heat transfer in ceiling-slot refrigerated containers is carried out to analyze the temperature distribution effectiveness and to determine the ventilation characteristics. The effect of slot size on thermal characteristics is studied by considering half-span and full-span injection. The container walls are defined a...

Phase change materials (PCMs) are widely used in heating and cooling applications to reduce the mismatch between the energy production and the demand. PCMs can also be incorporated into the thermal systems to maintain a constant temperature and conduce to increase the thermal comfort. Unlike any human-made thermal system, the thermal comfort of the...

This study numerically investigates the influence of integration of a phase change material (PCM) slab inside a vertical beverage cooler (VBC) on the energy consumption, the thermal stability and flow characteristics of air inside the cooler. The PCM, water, slab is placed on the rear side of the flat plate roll bond evaporator with five different...

In this study, transient heat transfer process inside a two-dimensional cavity has been numerically investigated. The numerical model has been created with control volume approach by using C++ programming language. In order to determine the accuracy of the numerical code, comparisons are made with the results of the numerical analysis and experimen...

In this study, performance of a near room temperature magnetic cooling system was investigated experimentally in terms of temperature span. The current setup has a permanent magnet pairs (0.7 Tesla), a magnetocaloric material (Gadolinium) and a heat transfer fluid (water, ethylene glycol and 10% ethanol-water mixing) furthermore solar energy was us...

In this study, airflow and heat transfer in a rectangular cavity that simulates a double skin facade and includes natural convection were examined numerically and experimentally. This cavity separates the exterior space and the thermally controlled interior space. The temperatures of the surfaces that interact with these spaces were determined expe...

Energy efficiency of a cement production process is quite small due to large amounts of heat loss from the systems. Rotary kilns have been widely used in the cement industry to produce clinker. The surface temperature of the rotary kiln reaches up to 300°C. Considering the higher temperature difference and higher surface area of the kiln (Diameter:...

The increasing demand on high performance designs forces companies to develop products consuming low energy. In this regard, this study numerically investigates different cases to improve the energy performance of a vertical type beverage cooler. Flow and thermal characteristics of the empty cooler were obtained by commercial CFD software ANSYS-FLU...

Recently, thermally and electrically conductive polymer nanocomposites have attracted considerable attention because of their potential applications in advanced technologies, for example, in light emitting devices, batteries, electromagnetic shielding, anti-static, corrosion resistant coatings, and other functional applications. The introduction of...

In this study, a series of binary mixtures of Adipic acid (AA) and Sebacic acid (SA) at various mass fractions were prepared. A binary mixture of AA and SA in the ratio of 48.0:52.0 wt% was shown to be an eutectic mixture with melting temperature of 116 °C, melting latent heat of 206.0 J g−1. In order to improve thermal properties of AA-SA eutectic...