Aykut Safa

Yıldız Technical University · Department of Naval Architecture and Marine Engineering

Machine learning methods can be utilized in artificial intelligence applications. The interest in machine learning has gradually increased from the beginning of artificial intelligence up to present. Today, it is...

The worldwide increasing energy demand, interest in alternative energy production and limited resources have made it inevitable to turn to recovering wastes, such as waste tires. Waste tires with annual increase of 2%, corresponding to significant reserves all over the world, brings a serious environmental pollution. In this study, energy recovery...

The use of pyrolytic oil (WTPO) obtained from waste vehicle tires in Turkey is evaluated and encouraged within the scope of YEKDEM (Turkey Renewable Energy Resources Support Mechanism). In order to benefit from this incentive, WTPO must be used as the main fuel in diesel engines. For this reason, in this study, unlike all other studies in the liter...

In recent years, diesel engine researchers have turned onto alternative fuel due to international emission legislations and depletion of fossil fuels. Natural gas and biofuels as an alternative fuel have gained popularity with simple and low-cost utilization in diesel engines. In the present study, effect of compressed natural gas (CNG) application...

The goal of this study is to investigate the use of compressed natural gas in a diesel engine compared to diesel fuel, according to exergetic and exergoe-conomic analyzes. For this purpose, compressed natural gas (CNG) injector has been mounted to intake manifold and small, single cylinder diesel engine was converted to dual mode. Experiments have...

Detailed performance analysis for a thermal system using a generalized irreversible solar-driven heat engine model is performed. The heat engine (HE) model is formed by the first and the second laws of thermodynamics and economical considerations. Also, the HE is optimized under the thermo-economic objective function (TEOF), power output, and overa...

Internal combustion engines (ICEs) have harmful effects on the environment in terms of emissions. According to present emission regulations, reducing NOX emissions came into prominence. One of the techniques of reducing NOX emissions is implementation of Miller Cycle to the engine. A comparative performance analysis and optimization based on the no...

Internal combustion engines (ICEs) have harmful effects on the environment in terms of emissions. According to present emission regulations, reducing NOX emissions came into prominence. One of the techniques of reducing NOX emissions is implementation of Miller Cycle to the engine. A comparative performance analysis and optimization based on the no...

Biodiesel fuels are among the leading renewable alternative fuels, available to implement on diesel engines simply. Testing biodiesel fuels on engines, results similar to nominal engine performance data are reported in the literature, since having chemical properties very close to diesel fuel. Methyl/Ethyl esters (Biodiesel fuels), of various oils...

Emissions, especially NOx, released from diesel engines used must be decreased because emissions have many bad effects on the environment. One of the known methods for reduction NOx emissions is to applying Miller Cycle to a diesel engine. In this study, Miller cycle is carried out by lowering the compression ratio according to the expansion ratio...

In this study, a two zone combustion model for second law analysis of a four stroke spark ignition engine has been developed and the cycle has been simulated with most common fuels including hydrogen and renewable fuels like ethanol, methanol and toluene. Results are presented for various cycle parameters and exergy destruction rate for each fuel h...

In this work, the effect of hydrophobicity has been studied experimentally on bow flare slamming and wet deck slamming by conducting water entry tests with a scaled ship section having bulbous bow and with a scaled catamaran section, respectively. The drop tests were performed from various heights with uncoated and hydrophobic coated models. The di...

Emissions, especially NOx, released from diesel engines must be decreased to limit values described by the regulations because emissions have many bad effects on the environment. One of the known methods for reduction NOx emissions is to apply Miller Cycle to a diesel engine. In this study, Miller cycle is carried out by lowering the compression ra...

Exhaust emissions have many detrimental effects on the human beings and the environment. Therefore, emissions released from diesel engines used in the present day land and sea vehicles are limited gradually. MARPOL (International Convention for the Prevention of Pollution from Ships) determines the limit values of ship sourced pollutants define lim...

This paper reports the thermodynamic optimization based on the maximum mean effective pressure, maximum power and maximum thermal efficiency criteria for an irreversible Otto heat engine model which includes internal irreversibility resulting from the adiabatic processes. The mean effective pressure, power output, and thermal efficiency are obtaine...

A theoretical performance analysis based on exergetic performance coefficient (EPC) criterion was carried out for a vapour compression refrigeration system for different refrigerants. The EPC criterion is defined as the ratio of exergy output to the total exergy destruction rate (or loss rate of availability). According to the results, the refriger...

In this study, exhaust system of the gas turbine of a ship with CODOG (Combined Diesel Or Gas-turbine) system is analyzed both analytically and numerically. The results obtained from these two different methods are then compared. The flow and heat transfer analysis of the exhaust system is done using a full scale two-dimensional (2-D) model and in...

A performance analysis based on an ecological performance criterion has been performed for an endoreversible regenerative Brayton heat-engine. In the model, the heat-transfer irreversibilities were considered and other irreversibilities were neglected. The ecologic objective-function, defined as the power output minus the loss rate of availability...