Yazar "Yildiz, Omer Faruk" seçeneğine göre listele

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    Effects of vortex tube on exhaust emissions during cold start of diesel engines
    (Elsevier, 2021) Celik, Adem; Yilmaz, Mehmet; Yildiz, Omer Faruk
    This study investigates the emissions of a 6-cylinder direct injection (DI) diesel engine with vortex tube for cold start conditions. Four ambient temperatures: 5 & DEG;C, - 3 & DEG;C, 0 & DEG;C and 4C were considered. The compressed air required to operate the vortex tube was supplied from compressed air cylinders from pneumatic brake system components located in heavy vehicles. The air from the compressed air tanks entered the vortex tube and the vortex emerged from the tube as hot and cold air. The hot air from the vortex tube was mixed with the intake air in the intake manifold to make the intake air hotter. Emissions analysis was conducted for carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO x ), and particulate matter (PM). Exhaust emission characteristics for the engine with vortex tube and without vortex tube were obtained and the results were compared with each other. The cold starting performance and fuel consumption of the diesel engine could be improved by using vortex tubes. The use of the vortex tube increased the intake air temperature, which decreased durations of engine starting-cranking, cranking-idling, and idling-stabling and reduced the fuel consumption. CO and PM emissions decreased, but HC and NO x emissions increased by using vortex tube.
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    Energy analysis of cold climate region airports: a case study for airport terminal in Erzurum, Turkey
    (Inderscience Enterprises Ltd, 2021) Yildiz, Omer Faruk; Yilmaz, Mehmet; Celik, Adem
    Airport terminals are among the major transportation facilities. They are among the facilities consuming a lot of energy. Energy demand depends on structural variables, operational variables related to the size of the airport, and climatic characteristics. The objective of this study is to analyse energy performance characteristics of Erzurum Airport terminal building, which is located in Turkey's coldest climate zone. Modelling of the Erzurum Airport terminal building was performed by using DesignBuilder software and simulation was performed by using EnergyPlus software. The actual energy consumption of the terminal building is compared with the consumption obtained by simulation. The difference between actual and simulated total final energy consumption is 11%. The total annual CO2 emission production of the terminal building is 1,855,590 kg as a result of consumption of natural gas and electricity. Some measures/practices to reduce energy consumption, reduce energy costs and improve energy efficiency within Erzurum Airport terminal building are proposed.
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    Improvement of diesel engine startability under low temperatures by vortex tubes
    (Elsevier, 2020) Celik, Adem; Yilmaz, Mehmet; Yildiz, Omer Faruk
    Cold start is one of the most problematic combustion phases for diesel engines. During this phase, a large proportion of pollutants are produced within the cylinder due to misfiring and incomplete combustion due to the low engine temperatures. Furthermore, exhaust after-treatment devices work inefficiently since their minimum operation temperatures cannot be reached. In addition to this, at temperatures below 0 degrees C the possibility of continuous misfiring could actually impede the engine start. Ambient temperature is one of the most important factors affecting the diesel engine cold startability. The aim of this study is to improve diesel engine startability under low temperatures by vortex tubes. A vortex tube was used to increase the intake air temperature in a six cylinders, four stroke and direct injection diesel engine of a truck. The hot air obtained from the hot outlet of the vortex tube was mixed with the air coming from the inlet of the intake manifold and the warmer air was sent to the cylinders. The compressed air required for the operation of the vortex tube was provided from the air tank of the compressed-air brake system of the truck. The effects of variation in ambient temperature on the engine cranking speed and in-cylinder pressure were analyzed and presented. Experiments were conducted for ambient air temperatures of -5, 0 and +4 degrees C. It was found that the reduction in ambient temperature resulted in prolonged cranking periods along with the longer time taken to reach idling speed as well as increased combustion instability for the engine without vortex tube. The use of the vortex tube increased the intake air temperature, which decreased durations of engine starting-cranking, cranking-idling, and idling-stabling. These results indicate that the cold starting performance of the diesel engine could be improved by using vortex tubes. (C) 2019 The Authors. Published by Elsevier Ltd.
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    Using solar photovoltaic energy in urban water supply systems: a case study in Kayseri, Turkey
    (Iwa Publishing, 2022) Sekmen, Ufuk; Yildiz, Omer Faruk; Yilmaz, Mehmet; Ozdemir, Ozgur
    Submersible pumps, widely used in deep wells drilled to meet the water needs of users in urban areas, add an additional load to the conventional electricity grid infrastructure and are responsible for increasing the concentration of greenhouse gas emissions in the atmosphere. The main objective of this study is to investigate the technical and economic feasibility of using solar photovoltaic (PV) energy to reduce the net power drawn from the grid by submersible pumps in urban water supply systems. The Germiralti catchment area (Kayseri, Turkey), which provides all of its energy needs from the city electricity grid, was chosen as the research area. Two different scenarios, 'hybrid-powered water pumping system' and 'grid-connected PV system', were analyzed and evaluated. A 1,620 kWp grid-connected PV system can inject 2,787.8 MWh/year of energy into the grid, which is more than the total annual energy need of the submersible pumps. The system operates with 85.7% performance ratio (PR), 19.6% capacity factor (CF) and 4.71 (h/d) final yield. The payback period of the system is calculated as 4.1 years. The results show that it is economically competitive to meet the energy needs of submersible pumps in urban water supply systems with solar PV energy.