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Papers by Hikmet Ş . Aybar

Research paper thumbnail of An Experimental Study on the Effect of the Energy Storage Materials in Solar Still

Proceedings of the 20th National and 9th International ISHMT-ASME Heat and Mass Transfer Conference, 2010

Research paper thumbnail of The Impact of Renewable Energy Sources on the Sustainable Development of the Economy and Greenhouse Gas Emissions

Sustainability

Growing population and limited energy resources have impacted energy consumption. Limited fossil ... more Growing population and limited energy resources have impacted energy consumption. Limited fossil fuel resources and increased pollution threaten national and human societies. These elements emphasize energy sources. Renewable energy use affects growth. All new energy sources, including renewables, are crucial for global economic growth. Economic and environmental issues have led to new approaches in international environmental law, including the green economy. This study employs structural vector auto-regression (SVAR) to compare the effects and outcomes of increasing the use of renewable energy in the context of economic growth and greenhouse gas emissions in middle income countries (MICs) and high income countries (HICs). The results show that these indicators demonstrate that the production of energy from renewable sources has positive short-term and long-term economic effects with varying contributions. However, renewable energies have a greater impact on the green economy in se...

Research paper thumbnail of Investigating the Index of Sustainable Development and Reduction in Greenhouse Gases of Renewable Energies

Sustainability

Considering the limited resources of fossil energy and the problems caused by the emission of gre... more Considering the limited resources of fossil energy and the problems caused by the emission of greenhouse gases, it is necessary to pay more attention to renewable energies, because in this way, the goals of sustainable development can be achieved. The importance of renewable energies in sustainable development, reducing greenhouse gases and increasing energy security on the one hand, and the need for financial resources and large investments for renewable energy projects on the other hand, doubles the role and importance of financial development in the development of renewable energies. Considering the importance of this issue, the present study examines the impact of the development of modern facilities and renewable energy technology. In this study, dynamic interactions in the Sustainable-Energy-Energy Development Pattern of carbon dioxide are investigated using the Bayesian Vector Auto Regression (BVAR) method. One of the most important indicators for evaluating sustainable devel...

Research paper thumbnail of Performance Analysis of Solar Desalination Systems

Solar Desalination Technology, 2019

Rapidly growing population of the world increases the demand for clean and freshwater. Solar desa... more Rapidly growing population of the world increases the demand for clean and freshwater. Solar desalination is a simple and environment-friendly process adopted for the conversion of saline and brackish water into potable drinking water. The solar desalination process mainly depends on the system design, operational and climatic conditions and is improved by many methods such as incorporating energy storage material, wick materials, and reflectors. The simple and widely accepted solar desalination system is of solar still. The performance of solar still is highly influenced by various factors such as water depth, basin materials, transparent glass angle, water–glass temperature difference, and absorber area. Moreover, the productivity of freshwater varies according to system design features and technical competence of the system. The purpose of this chapter is to explore the basic theoretical method used for the evaluation of a simple solar desalination system performance. This chapter also presents a case study to investigate the effect of few design and operational parameters on the performance.

Research paper thumbnail of Renewable hydrogen driven CHCP device

International Journal of Hydrogen Energy, 2021

Research paper thumbnail of Experimental Study on Enhancing the Productivity of Solar Still Using Locally Available Material as a Storage Medium

Journal of The Institution of Engineers (India): Series C, 2016

This experimental study focuses on the effect of pebbles as an energy storage medium on the perfo... more This experimental study focuses on the effect of pebbles as an energy storage medium on the performance of a solar distillation system. Two single basin solar stills are fabricated with an effective area of 0.5 m2, the glass cover was tilted at 10° with respect to the horizontal. The experiments on the still were carried out under the same climatic conditions for two different modes of operations, (1) conventional still and (2) modified still (pebbles as storage medium). From the study, it could be concluded that (1) the productivity of solar still is increases 9.5 % when pebbles are used as storage medium (2) the maximum amount of heat losses occurs in the solar still is the combined effect of radiation and convection heat transfer from glass to ambient (3) pebbles have the potentiality to store the heat during high solar intensity period and to release the stored energy to water when the solar intensity is low.

Research paper thumbnail of Exergy and environmental analysis of SOFC-based system including reformers and heat recovery approaches to establish hydrogen-rich streams with least exergy loss

International Journal of Hydrogen Energy

Research paper thumbnail of Parametric study on a convective flow in a thermal storage using IBM/ thermal lattice Boltzmann flux solver

One of the most popular topics in the field of engineering is natural convection due to its wide ... more One of the most popular topics in the field of engineering is natural convection due to its wide applications. Hence, the analysis of entropy production helps the researcher to design more efficient thermal systems. At this end, the present works tries to provide a comprehensive view on hydrodynamic, thermal and entropy production attitudes of free convection in a simplified thermal storage. The thermal storage is filled with alumina-water nanofluid. To solve the governing equations, the lattice Boltzmann method is employed and combined with Immersed Boundary Method. The immersed boundary method is applied to perform an accurate and effective numerical simulation of thermal flow in the curved boundaries. In the result section, the streamlines and temperature field are depicted. In addition, the contributions of entropy production are extracted graphically. The numerical results are gathered for various influential factors such as Rayleigh number (Ra in range of 10 3 to 10 6), alumina nanoparticle concentration 0≤wt%≤1 and aspect ratio of fins (AR in range of 0.200 to 0.588).

Research paper thumbnail of Thermal boundary condition analysis of cooling objects exposed to a free impinging jet using the heatline concept

Engineering Applications of Computational Fluid Mechanics, 2021

Heat and flow pattern of a vertical free jet impinging on a hot disk were numerically investigate... more Heat and flow pattern of a vertical free jet impinging on a hot disk were numerically investigated. A cylinder with various thicknesses and materials exposed simultaneously to uniform heat flux on one side and a free impinging jet on the other side is simulated by ANSYS Fluent 19.3. For simulations, the thermal boundary condition on the hot surface might differ due to the nature of the heat flow. The Volume of Fluid (VOF) approach is used to model the free jet heat transfer and fluid dynamics with the presence of air, while only the energy equation is solved in the cylinder. Heatline equation is solved to reveal the heat flow direction and effects of different geometry conditions. The maximum heat flux of 2.5 MW/m2 was obtained at the edge of stagnation region for hot target made of copper, while the value was 1.5 MW/m2 when the material was combined with stainless steel. However, the general thermal and hydrodynamic features of the jet flow were not influenced. It means that hot object condition may only affect the balance between heat flux and temperature, and the ideal uniform heat flux on the impinging wall may not be achieved in any experimental conditions.

Research paper thumbnail of Influence of artificial roughness parametric variation on thermal performance of solar thermal collector: An experimental study, response surface analysis and ANN modelling

Sustainable Energy Technologies and Assessments, Aug 1, 2022

Research paper thumbnail of Effect of using viscosity and thermal conductivity models onexperimental cavity flow natural convection of cuo-water nanofluids

Publication on cavity flow natural convection by using nanofluids has increased in recent years. ... more Publication on cavity flow natural convection by using nanofluids has increased in recent years. On the other hand, contrary results offered by different researchers, both in experimental and numerical works. In this research it is tried to indicate that the accuracy of the viscosity and the thermal conductivity of the nanofluids is the most important reason of the contrary results. Therefore, cavity flow natural convection of CuO-water nanofluids has considered experimentally for volume fractions 0.5% and 1% in this research. The results show that the natural convection of nanofluids are more sensitive on accuracy of the viscosity than the thermal conductivity as well as it recommends to measure the viscosity and thermal conductivity in experimental natural convection works. However, for the range of the volume fractions tested in this research, CuO-water nanofluids (30-50nm) have not shown heat transfer advantage. INTRODUCTION Nanofluids which are new heat transfer fluids have att...

Research paper thumbnail of ANN usefulness in building enhanced with PCM: Efficacy of PCM installation location

Journal of Building Engineering

Research paper thumbnail of Reproduction of Nanofluid Synthesis, Thermal Properties and Experiments in Engineering: A Research Paradigm Shift

Energies

The suspension of different nanoparticles into various conventional thermal fluids to synthesize ... more The suspension of different nanoparticles into various conventional thermal fluids to synthesize nanofluids has been proven to possess superior thermal, optical, tribological, and convective properties, and the heat transfer performance over conventional thermal fluids. This task appears trivial but is complicated and significant to nanofluid synthesis and its subsequent utilization in diverse applications. The stability of mono and hybrid nanofluids is significantly related to stirring duration and speed; volume, density, and base fluid type; weight/volume concentration, density, nano-size, and type of mono or hybrid nanoparticles used; type and weight of surfactant used; and sonication time, frequency, mode, and amplitude. The effects of these parameters on stability consequently affect the thermal, optical, tribological, and convective properties, and the heat transfer performance of nanofluids in various applications, leading to divergent, inaccurate, and suspicious results. Dis...

Research paper thumbnail of Entropy generation of the laminar and mixed flow of alumina/water nanofluid flow in a two-dimensional rectangular enclosure affected by a magnetic field using the lattice Boltzmann method

Engineering Analysis with Boundary Elements

Research paper thumbnail of Investigation of the effect of twisted tape turbulators on thermal-hydraulic behavior of parabolic solar collector with polymer hybrid nanofluid and exergy analysis using numerical method and ANN

Engineering Analysis with Boundary Elements

Research paper thumbnail of Investigation of thermal entropy generation and nanofluid flow in a new heatsink with effect of nanoparticles shape

Case Studies in Thermal Engineering

Research paper thumbnail of Numerical simulation and optimization with artificial neural network of two-phase nanofluid flow in a circular heatsink with cylindrical pin-fins

Engineering Analysis with Boundary Elements

Research paper thumbnail of Numerical evaluation of the effect of air inlet and outlet cross-sections of a lithium-ion battery pack in an air-cooled thermal management system

Research paper thumbnail of Effect of different pitches on the 3D helically coiled shell and tube heat exchanger filled with a hybrid nanofluid: Numerical study and artificial neural network modeling

Engineering Analysis with Boundary Elements

Research paper thumbnail of Thermal analysis of building benefits from PCM and heat recovery- installing PCM to boost energy consumption reduction

Journal of Building Engineering

Research paper thumbnail of An Experimental Study on the Effect of the Energy Storage Materials in Solar Still

Proceedings of the 20th National and 9th International ISHMT-ASME Heat and Mass Transfer Conference, 2010

Research paper thumbnail of The Impact of Renewable Energy Sources on the Sustainable Development of the Economy and Greenhouse Gas Emissions

Sustainability

Growing population and limited energy resources have impacted energy consumption. Limited fossil ... more Growing population and limited energy resources have impacted energy consumption. Limited fossil fuel resources and increased pollution threaten national and human societies. These elements emphasize energy sources. Renewable energy use affects growth. All new energy sources, including renewables, are crucial for global economic growth. Economic and environmental issues have led to new approaches in international environmental law, including the green economy. This study employs structural vector auto-regression (SVAR) to compare the effects and outcomes of increasing the use of renewable energy in the context of economic growth and greenhouse gas emissions in middle income countries (MICs) and high income countries (HICs). The results show that these indicators demonstrate that the production of energy from renewable sources has positive short-term and long-term economic effects with varying contributions. However, renewable energies have a greater impact on the green economy in se...

Research paper thumbnail of Investigating the Index of Sustainable Development and Reduction in Greenhouse Gases of Renewable Energies

Sustainability

Considering the limited resources of fossil energy and the problems caused by the emission of gre... more Considering the limited resources of fossil energy and the problems caused by the emission of greenhouse gases, it is necessary to pay more attention to renewable energies, because in this way, the goals of sustainable development can be achieved. The importance of renewable energies in sustainable development, reducing greenhouse gases and increasing energy security on the one hand, and the need for financial resources and large investments for renewable energy projects on the other hand, doubles the role and importance of financial development in the development of renewable energies. Considering the importance of this issue, the present study examines the impact of the development of modern facilities and renewable energy technology. In this study, dynamic interactions in the Sustainable-Energy-Energy Development Pattern of carbon dioxide are investigated using the Bayesian Vector Auto Regression (BVAR) method. One of the most important indicators for evaluating sustainable devel...

Research paper thumbnail of Performance Analysis of Solar Desalination Systems

Solar Desalination Technology, 2019

Rapidly growing population of the world increases the demand for clean and freshwater. Solar desa... more Rapidly growing population of the world increases the demand for clean and freshwater. Solar desalination is a simple and environment-friendly process adopted for the conversion of saline and brackish water into potable drinking water. The solar desalination process mainly depends on the system design, operational and climatic conditions and is improved by many methods such as incorporating energy storage material, wick materials, and reflectors. The simple and widely accepted solar desalination system is of solar still. The performance of solar still is highly influenced by various factors such as water depth, basin materials, transparent glass angle, water–glass temperature difference, and absorber area. Moreover, the productivity of freshwater varies according to system design features and technical competence of the system. The purpose of this chapter is to explore the basic theoretical method used for the evaluation of a simple solar desalination system performance. This chapter also presents a case study to investigate the effect of few design and operational parameters on the performance.

Research paper thumbnail of Renewable hydrogen driven CHCP device

International Journal of Hydrogen Energy, 2021

Research paper thumbnail of Experimental Study on Enhancing the Productivity of Solar Still Using Locally Available Material as a Storage Medium

Journal of The Institution of Engineers (India): Series C, 2016

This experimental study focuses on the effect of pebbles as an energy storage medium on the perfo... more This experimental study focuses on the effect of pebbles as an energy storage medium on the performance of a solar distillation system. Two single basin solar stills are fabricated with an effective area of 0.5 m2, the glass cover was tilted at 10° with respect to the horizontal. The experiments on the still were carried out under the same climatic conditions for two different modes of operations, (1) conventional still and (2) modified still (pebbles as storage medium). From the study, it could be concluded that (1) the productivity of solar still is increases 9.5 % when pebbles are used as storage medium (2) the maximum amount of heat losses occurs in the solar still is the combined effect of radiation and convection heat transfer from glass to ambient (3) pebbles have the potentiality to store the heat during high solar intensity period and to release the stored energy to water when the solar intensity is low.

Research paper thumbnail of Exergy and environmental analysis of SOFC-based system including reformers and heat recovery approaches to establish hydrogen-rich streams with least exergy loss

International Journal of Hydrogen Energy

Research paper thumbnail of Parametric study on a convective flow in a thermal storage using IBM/ thermal lattice Boltzmann flux solver

One of the most popular topics in the field of engineering is natural convection due to its wide ... more One of the most popular topics in the field of engineering is natural convection due to its wide applications. Hence, the analysis of entropy production helps the researcher to design more efficient thermal systems. At this end, the present works tries to provide a comprehensive view on hydrodynamic, thermal and entropy production attitudes of free convection in a simplified thermal storage. The thermal storage is filled with alumina-water nanofluid. To solve the governing equations, the lattice Boltzmann method is employed and combined with Immersed Boundary Method. The immersed boundary method is applied to perform an accurate and effective numerical simulation of thermal flow in the curved boundaries. In the result section, the streamlines and temperature field are depicted. In addition, the contributions of entropy production are extracted graphically. The numerical results are gathered for various influential factors such as Rayleigh number (Ra in range of 10 3 to 10 6), alumina nanoparticle concentration 0≤wt%≤1 and aspect ratio of fins (AR in range of 0.200 to 0.588).

Research paper thumbnail of Thermal boundary condition analysis of cooling objects exposed to a free impinging jet using the heatline concept

Engineering Applications of Computational Fluid Mechanics, 2021

Heat and flow pattern of a vertical free jet impinging on a hot disk were numerically investigate... more Heat and flow pattern of a vertical free jet impinging on a hot disk were numerically investigated. A cylinder with various thicknesses and materials exposed simultaneously to uniform heat flux on one side and a free impinging jet on the other side is simulated by ANSYS Fluent 19.3. For simulations, the thermal boundary condition on the hot surface might differ due to the nature of the heat flow. The Volume of Fluid (VOF) approach is used to model the free jet heat transfer and fluid dynamics with the presence of air, while only the energy equation is solved in the cylinder. Heatline equation is solved to reveal the heat flow direction and effects of different geometry conditions. The maximum heat flux of 2.5 MW/m2 was obtained at the edge of stagnation region for hot target made of copper, while the value was 1.5 MW/m2 when the material was combined with stainless steel. However, the general thermal and hydrodynamic features of the jet flow were not influenced. It means that hot object condition may only affect the balance between heat flux and temperature, and the ideal uniform heat flux on the impinging wall may not be achieved in any experimental conditions.

Research paper thumbnail of Influence of artificial roughness parametric variation on thermal performance of solar thermal collector: An experimental study, response surface analysis and ANN modelling

Sustainable Energy Technologies and Assessments, Aug 1, 2022

Research paper thumbnail of Effect of using viscosity and thermal conductivity models onexperimental cavity flow natural convection of cuo-water nanofluids

Publication on cavity flow natural convection by using nanofluids has increased in recent years. ... more Publication on cavity flow natural convection by using nanofluids has increased in recent years. On the other hand, contrary results offered by different researchers, both in experimental and numerical works. In this research it is tried to indicate that the accuracy of the viscosity and the thermal conductivity of the nanofluids is the most important reason of the contrary results. Therefore, cavity flow natural convection of CuO-water nanofluids has considered experimentally for volume fractions 0.5% and 1% in this research. The results show that the natural convection of nanofluids are more sensitive on accuracy of the viscosity than the thermal conductivity as well as it recommends to measure the viscosity and thermal conductivity in experimental natural convection works. However, for the range of the volume fractions tested in this research, CuO-water nanofluids (30-50nm) have not shown heat transfer advantage. INTRODUCTION Nanofluids which are new heat transfer fluids have att...

Research paper thumbnail of ANN usefulness in building enhanced with PCM: Efficacy of PCM installation location

Journal of Building Engineering

Research paper thumbnail of Reproduction of Nanofluid Synthesis, Thermal Properties and Experiments in Engineering: A Research Paradigm Shift

Energies

The suspension of different nanoparticles into various conventional thermal fluids to synthesize ... more The suspension of different nanoparticles into various conventional thermal fluids to synthesize nanofluids has been proven to possess superior thermal, optical, tribological, and convective properties, and the heat transfer performance over conventional thermal fluids. This task appears trivial but is complicated and significant to nanofluid synthesis and its subsequent utilization in diverse applications. The stability of mono and hybrid nanofluids is significantly related to stirring duration and speed; volume, density, and base fluid type; weight/volume concentration, density, nano-size, and type of mono or hybrid nanoparticles used; type and weight of surfactant used; and sonication time, frequency, mode, and amplitude. The effects of these parameters on stability consequently affect the thermal, optical, tribological, and convective properties, and the heat transfer performance of nanofluids in various applications, leading to divergent, inaccurate, and suspicious results. Dis...

Research paper thumbnail of Entropy generation of the laminar and mixed flow of alumina/water nanofluid flow in a two-dimensional rectangular enclosure affected by a magnetic field using the lattice Boltzmann method

Engineering Analysis with Boundary Elements

Research paper thumbnail of Investigation of the effect of twisted tape turbulators on thermal-hydraulic behavior of parabolic solar collector with polymer hybrid nanofluid and exergy analysis using numerical method and ANN

Engineering Analysis with Boundary Elements

Research paper thumbnail of Investigation of thermal entropy generation and nanofluid flow in a new heatsink with effect of nanoparticles shape

Case Studies in Thermal Engineering

Research paper thumbnail of Numerical simulation and optimization with artificial neural network of two-phase nanofluid flow in a circular heatsink with cylindrical pin-fins

Engineering Analysis with Boundary Elements

Research paper thumbnail of Numerical evaluation of the effect of air inlet and outlet cross-sections of a lithium-ion battery pack in an air-cooled thermal management system

Research paper thumbnail of Effect of different pitches on the 3D helically coiled shell and tube heat exchanger filled with a hybrid nanofluid: Numerical study and artificial neural network modeling

Engineering Analysis with Boundary Elements

Research paper thumbnail of Thermal analysis of building benefits from PCM and heat recovery- installing PCM to boost energy consumption reduction

Journal of Building Engineering