Yasin Varol

• Professor
• Professor (Full) at Fırat University

This study provides a comprehensive evaluation of the integration of renewable energy sources, smart grid technologies, and the role of electric vehicles in energy systems. The environmental and economic benefits of renewable energy sources are discussed alongside the technical, economic, and social challenges encountered during their integration i...

This study provides a comprehensive research of thermal management systems (BTM) for electrochemical energy storage, focusing on batteries and supercapacitors. It discusses various cooling strategies, including air, liquid, PCM, and hybrid-based systems, emphasizing their advantages, limitations, and applications. Phase change materials (PCMs) are...

Alcohol fuels with different carbon numbers such as propanol (C3), butanol (C4) and pentanol (C5) have lately become popular in both conventionally and RCCI-operated diesel engines thanks to their high cetane number (CN) and oxygen content along with lower latent heat of evaporation, which are useful for reducing the high CO/HC emissions, whereas R...

The need for cooling technologies increases tremendously with raising demand on the powerful and compact electronics. There, it pushes the research and technology to the new investigations on varying heat transfer mechanisms and devices. While, one of these devices is vapor chamber (VC), an experimental study has been carried out to investigate the...

Yapılan çalışmada deney motoru, modifiye edilerek RCCI konseptine göre çalışır hale getirilmiş tek silindirli dizel motordur. HRF olarak dizel ve LRF olarak ta izooktan (%15, %30, %45 ve %60 karışım oranlarında) kullanılmıştır. Deneyler üç farklı yükte (%20, %40 ve %60) ve 2400 (d/d) sabit motor devrinde gerçekleştirilmiştir. %20 yükte basınç pik d...

This study investigates the changes in the combustion characteristics of a diesel engine modified to operate in reactivity controlled compression ignition mode using propanol as low reactivity fuel and BD35 as high reactivity fuel. In the study, BD35 fuel, a blend of 35% biodiesel and 65% petroleum-derived diesel, was sprayed directly into the cyli...

The utilization of alternative fuels in internal combustion engines has gained significant attention due to concerns about energy security and environmental sustainability. Waste tire pyrolysis oil (WTPO) is a potential alternative fuel that can be produced from waste vehicle tires through a pyrolysis process. In this study, the possible use of WTP...

https://authors.elsevier.com/c/1htsy1H~c~Ljpl

In this work, methanol dual-direct injection (DI2 mode) was compared with the port injection of methanol (RCCI mode) when biodiesel and diesel fuel were employed as HRFs (High Reactivity Fuels). This study presents an innovative dual-direct injection strategy as an alternative method to the commonly utilized port injection strategy in RCCI engines,...

Natural Gas (NG) with its high octane number and low C/H ratio is beneficial for reactivity controlled compression ignition (RCCI) engines in controlling the rate of pressure rise and lower the emissions, given that these engines still suffer from these two problems. Therefore, in this study, a detailed 3D combustion model was developed in ANSYS-Fo...

The injection strategies and charge temperature are two important factors that affect the mixture stratification and fuel reactivity, which have a great impact on the formation of pollutants in RCCI engines. Therefore, it is of great importance to study the effect of these variables in order to support the development of RCCI engines.

High carbon alcohol fuels such as heptanol (C7) and octanol (C8) have recently attracted attention among alternative fuels due to their high oxygen content, cetane number and energy density and their production using sustainable pathways in comparison to other common alcohols. Thus, their addition to reactivity controlled compression ignition (RCCI...

Reactivity Controlled Compression-Ignition (RCCI) concept presents a great potential to reduce both NOx and soot emissions from conventional diesel engines with improved thermal efficiency. Therefore, in this work, a single-cylinder diesel engine with CRDI was operated on RCCI mode. To investigate the effect of RCCI mode on engine performance and e...

The dual direct injection (DI²) strategy is expected to cover the advantages of conventional diesel (CDI) mode while avoiding deficiencies of reactivity controlled compression ignition (RCCI) strategy such as high amount of incomplete combustion emissions and extremely high rate of pressure rise. Therefore, the present study focused on the comparis...

Recently, reactivity controlled compression ignition (RCCI) has been proposed in order to achieve a higher thermal efficiency with lower emissions than conventional combustion. In RCCI mode, as the fuel types and their combinations affects the reactivity stratification inside cylinder, thus combustion control, in present study, iso-propanol was eva...

Yapılan çalışmada, Reaktivite kontrollü Sıkıştırma Ateşlemeli (RCCI) stratejiler altında çalışacak şekilde modifiye edilmiş tek silindirli bir dizel motorda biyodizel ve petrol bazlı dizel karışımı ve benzin kullanımının yanma ve egzoz emisyon özelliklerine etkisi deneysel olarak araştırılmıştır. Çalışmada dizel ve biyodizel karışımı yüksek reaktiv...

High-Efficiency Reactivity-Controlled Compression Ignition (RCCI) with ultra-low NOx and Soot emissions still needs to be investigated in terms of its operating conditions such as high load range and increasing CO and unburnt HC emissions, which are critical issues to be addressed before implementation for practical engines. Therefore, as the main...

The reactivity controlled compression ignition (RCCI) strategy using fuels with different reactivity’s has attracted attention due to its high thermal efficiency as well as very low NOx and PM emissions in comparison to conventional combustion. As previous studies have shown that the type and amount of low reactivity fuel have a significant contrib...

Bu çalışmada, RCCI modunda çalışacak şekilde modifiye edilmiş tek silindirli bir dizel motorda biyodizel ve petrol kökenli dizel karışımı ile benzin kullanımının yanma ve egzoz emisyon karakteristiklerine etkisi deneysel olarak incelenmiştir. Çalışmada hacimsel olarak %20 biyodizel ve %80 petrol kökenli dizel karışımından oluşan B20 karışım yakıtı...

Bu çalışmada, manyetik alan altındaki bir boruda Al2O3–su nano akışkanının akış karakteristikleri sayısal olarak incelenmiştir. Manyetik alan akış yönüne dik verilmiştir. Akışkan sıcaklığı boru sıcaklığından daha yüksek tutularak akışkanın soğuması sağlanmıştır (Ti > Tw). Re sayısı, Ha sayısı ve nano akışkan hacimsel oranı sırasıyla, Re = 10, 100,...

Mevcut çalışmada manyetik alan altındaki bir boruda Al2O3–su nano akışkanının ısı transferi olgusu sayısal olarak incelenmiştir. Dış manyetik alan akışkan yönüne dik olarak uygulanmıştır. Yönetici denklemler ANSYS Fluent ticari yazılım programı ile çözülmüştür. Akışkan sıcaklığı boru sıcaklığından daha yüksek tutularak akışkanın soğuması sağlanmışt...

In this study, the thermo-physics properties of jet streams at different temperatures within a confined channel were investigated experimentally and numerically. An experimental setup was constructed for the experimental part of the work and the numerical part was modeled using the Large Eddy Simulation (LES) turbulence model. Water was used as wor...

In this study, the behavior of Cu–water nano-fluid in a pipe has been investigated numerically. The pipe is under the external magnetic field, and the magnetic field is applied perpendicularly to the pipe. The temperature of pipe is higher than the temperature of fluid. The study was carried out for three different Reynolds numbers. The magnetic fi...

The heat transfer of mixed convection in a horizontal channel filled with a porous medium has been studied in this article, given that it plays an extensive role in various technical applications, such as flow of fluid in geothermal resources, formations in chemical industries, the storage of radioactive nuclear waste material, and cooling. Those e...

Thermal mixing phenomena of a coaxial jet with perforated obstacles are analyzed both experimentally and numerically. Perforated obstacles are used in front of a coaxial jet that has different temperatures of the fluid to control the thermal mixing behavior. An experimental setup was constructed to perform several cases and all cases are simulated...

Effect of jet flow structures impinged on a heated cylinder has been investigated experimentally and numerically in this study. The FLUENT 6.3.26 was used to simulate this numerical problem. In the numerical section, the influence of some variables such as the distance between cylinder and jet on the fluid flow characteristics has been analyzed.

In this study, the thermal-mixing phenomenon of a coaxial jet with cylindrical obstacles is analyzed experimentally. Cylindrical obstacles are located in front of the coaxial jet to control the thermal-mixing behavior.A coaxial-jet nozzle designed and inserted into a rectangular cross section confined channel. The coaxial jet consists of two water...

Solar energy is one of the most important renewable energy sources but it is not available every time and every season. Thus, storing of solar energy is important. One of the popular methods of heat storage is using of phase change materials (PCMs) which have large thermal energy storage capacity. In this study, the heat storage tank in a domestic...

Thermal mixing and flow field due to two parallel jets which have different temperatures are investigated both experimentally and numerically. The perforated passive obstacles are used with different geometrical specifications. They are located in front of the jets to control flow field and mixing behavior of the jets. An experimental setup designe...

zet Bu çalışmada, sabit hava giriş hızı ve sıcaklığında alabalığın kurutma davranışı deneysel olarak incelenmiştir. Hava giriş hızı 1.5 m/s ve sıcaklığı 53 °C olarak seçilmiştir. Deneyler %28-42'lik bağıl nem aralığında gerçekleştirilmiştir. Balıklar tek parça, beş parça ve on parça olarak kurutulmuştur. Balığın nem içeriği, kuruma hızı ve iç sıcak...

In this study, natural convection heat transfer in a square cavity with an adiabatic fin mounted on a vertical wall was investigated numerically. Vertical boundaries were adiabatic and horizontal boundaries were isothermal at different constant temperature. Two-dimensional equations of conservation of mass, momentum and energy were solved using fin...

This study covers the drying behavior of rainbow trout (Oncorhynchus mykiss) in a square cross-sectioned dryer. For this, approximately 200 g fish was used to dry at different air inlet velocities like 0.5, 1.5, and 2.5 m/s for the constant air inlet temperature at 46 °C in ranges of 28–43 % of relative humidity. In the experiments, interior temper...

An experimental study on performance and exhaust emission of a spark-ignited engine fueled by gasoline-like fuel obtained from waste automobile tires using the prolysis process was performed in this study. Gasoline-like fuel has a higher octane number than unleaded gasoline; however, it has higher in viscosity in comparison to unleaded gasoline, wh...

Air pollution is becoming a serious problem in many urban cities of the world and it can have a serious effect on both health and the environment. Although experimental studies have shown that alcohol fuels burn cleaner than unleaded gasoline and produce lesser emission, there is limited information regarding the comparison among the alcohol fuels...

The present study numerically explores the melting process of a phase change materials in a rectangular geometry. More specifically, it investigates flow field, thermal phenomena, detailed phase and melting process by means of numerical simulation which is using as parameter; melting temperature, latent and specific heat capability, thermal conduct...

The issue of laminar natural convection and conduction in enclosures divided by a partition with different thicknesses is investigated numerically. The partition is accepted as conductive at different thermal conductivity ratio. The cavity is filled with air, and it is heated differentially from vertical walls while horizontal walls are adiabatic....

In this study, mixed convection heat transfer has been investigated in a horizontal plate filled with porous media. Mixed convection flow over a heated plate in a saturated porous medium is widely used due to a large number of technical applications, such as fluid flow in geothermal reservoirs, separation processes in chemical industries, storage o...

In this study, the effect of unleaded gasoline and unleaded gasoline blended with 5% and 10% of ethanol or methanol on the performance and exhaust emissions of a spark-ignition engine were experimentally investigated. The engine tests were performed by varying the engine peed between 1000 and 4000 rpm with 500 rpm period at threefourth hrottle open...

Purpose – The purpose of this numerical study is to investigate the effects of inclination angle and non-isothermal wall boundary conditions in a partially open cavity filled with a porous medium. Design/methodology/approach – In this study, the governing dimensionless equations were written using Brinkman-Forchheimer model. They are numerically so...

Natural convection heat transfer in an inclined fin attached square enclosure is studied both experimentally and numerically. Bottom wall of enclosure has higher temperature than that of top wall while vertical walls are adiabatic. Inclined fin has also adiabatic boundary conditions. Numerical solutions have been done by writing a computer code in...

A numerical analysis of the process of jet drying of a moist cylinder was conducted. The drying jet was a laminar 2D jet stationed at three different distances (D/H = 0.22, 0.25, and 0.33) from the moist cylinder to investigate the jet effectiveness on heat and mass transfer. The diameter of the object and initial jet height were fixed in all cases...

A numerical investigation has been performed two-dimensional slot impingement onto two heated cylinders with different diameters turbulent flow conditions. Height of slot jet is taken as constant for all cases. The study is performed to see the effects of effective parameters on heat and fluid flow as jet Reynolds number (11,000 ≤ Re ≤ 20,000), dia...

This paper analyzes the detailed heat transfer and fluid flow within two entrapped porous trapezoidal cavities involving cold inclined walls and hot horizontal walls. Flow patterns and temperature distribution were obtained by solving numerically the governing equations, using Darcy's law. Results are presented for different values of the governing...

Effects of moving lid-direction on MHD mixed convection in a cavity with the bottom wall being linearly heated are analyzed using a numerical technique. Vertical walls of the enclosure are adiabatic and the sliding wall at the top has constant temperature. The lid moves in the negative and positive x-direction. Finite volume method has been used to...

The effects of buoyancy-aiding or buoyancy-opposing mechanisms on laminar mixed convection heat transfer in a porous enclosure partially cooled from the left vertical wall has been analysed numerically for two different forms of thermal boundary conditions in steady-state regime using the Darcy-Brinkman-Forchheimer equation model. In the first case...

An experimental study is performed to examine the heat transfer characteristics of impinging circular jet onto a heated circular disc. The disc is heated under constant heat flux and it has an inclination angle with impinging jet in the range of 90°≤φ≤150°. The air is supplied using a radial fan. The fluid flows through a designed tunnel. Experimen...

This paper examines the steady natural convection in a partially opened enclosure filled with porous media using the Brinkman–Forchheimer model. Whilst the part of the left vertical wall of the cavity is heated, the other walls are adiabatic or thermally insulated Based upon numerical predictions, the effects of pertinent parameters such as Grashof...

In this paper, the effects of volumetric heat sources on natural convection heat transfer and flow structures in a wavy-walled enclosure are studied numerically. The governing differential equations are solved by an accurate finite-volume method. The vertical walls of enclosure are assumed to be heated differentially whereas the two wavy walls (top...

A numerical work was performed to examine the heat transfer and fluid flow due to natural convection in a porous triangular enclosure with a centered conducting body. The center of the body was located onto the gravity center of the right-angle triangular cavity. The Darcy law model was used to write the governing equations and they were solved usi...

Natural convection in square-cross-sectional inclined enclosures bounded by two attached solid walls (composite wall) was simulated by a numerical technique in this study. Conduction heat transfer through each part of a composite wall was examined for different solid wall thicknesses and thermal conductivities. The opposite wall was accepted as thi...

The current study deals with mathematical study for natural convection flow resulting from the combined buoyancy effects of thermal and mass diffusion inside a triangular shaped solar collector. The solution is performed assuming the isothermal and isoconcentration boundary conditions of absorbers and covers of collector. The two-dimensional govern...

A numerical work has been performed to analyze the heat transfer and fluid flow in a pent-roof type combustion chamber. Dynamic mesh model was used to simulation piston intake stroke. Revolution of piston (1000 ≤ n ≤ 5000) is the main governing parameter on heat and fluid flow. k–ε turbulence model was used to predict the flow in the cylinder of a...

A numerical work was performed to determine the heat transfer and fluid flow due to buoyancy forces in divided trapezoidal enclosures filled with fluid saturated porous media. In the present investigation, bottom wall was non-uniformly heated while two vertical walls were insulated and the top wall was maintained at constant cold temperature. The d...

The performance of a solar collector system using sodium carbonate decahydrate (Na2CO3·10H2O) as Phase Change Material (PCM) was experimentally investigated during March and collector efficiency was compared with those of convectional system including no PCM. We also made a series of predictions by using three different soft computing techniques as...

A numerical study of the steady buoyancy-induced flow and heat transfer in a trapezoidal cavity filled with a porous medium saturated with cold water at a temperature around 4°C has been performed. The analysis has been done for a cavity with different aspect ratios ranging from 0.25 to 0.75 and Rayleigh numbers ranging from 100 to 1000 using a fin...

A numerical study on natural convection heat transfer of cold water near 4°C in a thick bottom walled cavity filled with a porous medium has been performed. It is assumed that the cavity is isothermally heated from the outside of the thick bottom wall and cooled from ceiling. The finite-difference method has been used to solve the governing partial...

Laminar natural convection in inclined enclosures filled with different fluids was studied by a numerical method. The enclosure was divided by a solid impermeable divider. One side of partition of enclosure was filled with air and the other side had water. The enclosure was heated from one vertical wall and cooled from the other while horizontal wa...

Numerical analyses of the flow and heat transfer due to buoyancy forces in a square enclosure divided by an impermeable partition between air and water filled chests were carried out using a finite difference technique. The enclosure was heated from left wall and cooled from right, isothermally. Horizontal walls were adiabatic. The partition divide...

Control of laminar, two-dimensional, steady forced convection heat transfer and fluid flow in an isothermally heated blocks located in a channel was analyzed numerically. The channel had three blocks attached on its bottom wall. The cooling air entered the channel with uniform velocity. A triangular cross-sectional bar was used as a control element...

The flow and heat transfer in a diagonally divided square cavity by an inclined plate and filled with a porous medium were numerically analyzed in this paper. Vertical walls are kept at isothermal conditions, while horizontal walls are insulated. A finite difference scheme was used to solve the dimensionless governing partial differential equations...

Purpose – The purpose of this paper is to study the conjugate heat transfer via natural convection and conduction in a triangular enclosure filled with a porous medium. Design/methodology/approach – Darcy flow model was used to write governing equations with Boussinesq approximation. The transformed governing equations are solved numerically using...

Analysis of natural convection in right-angle triangular enclosure filled with saturated cold water which has a density maximum around of 3.98 °C is performed numerically. The bottom and vertical wall of triangular enclosure is isothermal while inclined wall is adiabatic. But temperature of bottom wall is higher than that of vertical wall. Non-Bous...

Entropy generation due to buoyancy induced convection and conduction in a right angle trapezoidal enclosure filled with fluid saturated porous medium has been performed numerically. Left vertical solid wall of the trapezoidal enclosure has a finite thickness and conductivity. The outside temperature of the solid wall is higher than that of inclined...

Forecasting of entropy generation of laminar natural convection in a partially cooled square cross-sectional room has been performed using support vector machines (SVM). The two-dimensional room was modeled as floor heating story with a window. Values of temperature and velocities were obtained by solving governing equations of natural convection w...

Numerical simulation of magnetohydrodynamic (MHD) buoyancy-induced heat transfer and fluid flow has been analyzed in a non-isothermally heated square enclosure using finite volume method. The bottom wall of enclosure were heated and cooled with a sinusoidal function and top wall was cooled isothermally. Vertical walls of the enclosure were adiabati...

Natural convection has been performed in an insulated horizontally thin plate embedded in a triangular enclosure filled with fluid saturated porous medium, numerically. Bottom and inclined wall of triangular enclosure are isothermally heated and cooled, respectively. Vertical wall of enclosure is adiabatic. Steady, two-dimensional, laminar governin...

The phenomena of natural convection in an inclined square enclosure heated via corner heater have been studied numerically. Finite difference method is used for solving momentum and energy equations in the form of stream function–vorticity. One wall of the enclosure is isothermal but its temperature is colder than that of heaters while the remainin...

Entropy generation due to natural convection in isosceles triangular enclosures with inclination angles (φ) filled with a fluid-saturated porous medium has been studied numerically. The enclosure has different inclination angles and it is non-uniformly heated from one side. The finite difference technique was adopted to solve the governing equation...

A numerical study is conducted to investigate the steady free convection flow in a two-dimensional right-angle trapezoidal enclosure filled with a fluid-saturated porous medium. The left vertical wall of the cavity is heated; the inclined wall is partially cooled; and the remaining walls are insulated (adiabatic). Three different cases are consider...

Numerical analysis has been performed to examine the conduction-natural convection in a partitioned triangular enclosure filled with a fluid-saturated porous medium. The enclosure is heated from the vertical wall and cooled from the inclined wall, while the bottom wall is adiabatic. In addition, the enclosure has a solid partition with finite therm...

A numerical study has been carried out on partially heated triangular enclosures with eave. The eave and inclined wall has a cold temperature. The laminar, two-dimensional, steady governing equations of natural convection are solved in the streamfunction-vorticity form using a finite difference technique. Streamline, isotherm and Nusselt number are...

Adaptive-network-based Fuzzy Inference System (ANFIS) was used to predict temperature and flow field due to buoyancy-induced heat transfer in a partially heated right-angle triangular enclosure. Results are obtained for two-dimensional, steady and laminar flow. Data were generated from earlier studies which were obtained from a CFD-based computer c...

Support vector machines (SVM), a soft programming technique, has been used to estimate the temperature distribution and flow fields in a square porous enclosure heated discretely by three isothermal heaters from the left vertical wall. Right vertical wall of the cavity was isothermal but it has colder temperature than the heaters while remaining wa...

Natural convection heat transfer in a porous media filled and non-isothermally heated from the bottom wall of triangular enclosure is analyzed using finite difference technique. Darcy law was used to write equations of porous media. Dimensionless heatfunction was used to visualize the heat transport due to buoyancy forces. Three different boundary...

Conjugate natural convection in a two-dimensional triangular enclosure filled with a porous medium is examined in this article. It is assumed that the solid vertical wall is of finite conductivity and that the temperature of the inclined wall is lower than that of the vertical wall, while the horizontal wall is adiabatic. A finite difference method...

A theoretical study of buoyancy-driven flow and heat transfer in an inclined trapezoidal enclosure filled with a fluid-saturated porous medium heated and cooled from inclined walls has been performed in this paper. The governing non-dimensional equations were solved numerically using a finite-difference method. The effective governing parameters ar...

The present study deals with the numerical analysis of natural convection heat transfer inside the inclined solar collectors. Two collectors are compared. In the first case, the collector has wavy absorber and in the second case, it has flat absorber. The solution was performed assuming the isothermal boundary conditions of absorbers and covers of...

The flow and heat transfer in a triangular enclosure filled with a fluid-saturated porous medium with a conducting thin fin on the hot vertical wall has been numerically analysed. The Darcy law model was used to write the governing equations and they were solved using a finite-difference method. Computations were carried out to analyse the effects...

A numerical analysis of the entropy production has been performed due to natural convection heat transfer and fluid flow in isosceles triangular enclosures with partially heated from below and symmetrically cooled from sloping walls. Governing equations are solved by finite difference method. Governing parameters on flow and temperature fields are...

A numerical was performed analysis on laminar natural convection heat transfer and fluid flow in both protruding heaters (PHs) and flush-mounted heaters (FMHs) located in a triangular enclosure using finite-difference technique. The heaters were isothermal and the temperature of the inclined wall was lower than that of the heaters while the remaini...

Entropy generation due to conjugate natural convection heat transfer and fluid flow has been studied inside an enclosure with bounded by two solid massive walls from vertical sides at different thicknesses. Enclosure is differentially heated from vertical walls and horizontal walls are adiabatic. Governing equations which are written in streamfunct...