Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2019Scopus SJRQ3/r/bayburt/13610
  Modeling of the impact of initial mold temperature, Al5Ti1B and Al10Sr additions on the critical fraction of solid in die casting of aluminum alloys using fuzzy expert system

  Teke, Ç.; Çolak, M.; Taş, M.; İpek, M.

  In the casting of liquid metal, the feeding stops when the mushy zone is clogged and does not allow the transfer of feeding liquid. The growing resistance of the solid dendrites against the fluidity of the feeding liquid is defined as the critical fraction of solid (CFS). CFS value varies depending on many factors such as alloy solidification range, initial mold temperature, and the grain size. Therefore, in many casting simulation applications, it is quite common to get inconsistent results due to insufficient information about the CFS. In this study, a fuzzy expert system (FES) model has been developed in order to determine the value of the CFS in the die casting process, based on the parameters of the alloy type, the initial mold temperature, Al5Ti1B addition and Al10Sr addition. In order to create the rule base for the FES model, 54 die casting experiments have been carried out. The CFS values obtained using the FES model has revealed that the developed model of the FES predicts the CFS value in a high performance.

  AtıfScopus4·WoS3·OpenAlex6

  İncele
• BildiriAçık Erişim2017Scopus SJRQ3/r/bayburt/13611
  Evaluation of marble dust for soil stabilization

  Yilmaz, F.; Yurdakul, M.

  Usage of marble dust was investigated for soil stabilization in the scope of utilization of waste material. Geotechnical properties, such as compaction, Atterberg limits, unconfined compressive strength of the mixtures and changes of these properties with the marble dust ratio were determined. From the test results it is seen that marble dust increases the mechanical properties of soil and application of dust wastes for soil stabilization will be an efficient practice in terms of solid waste management.

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  AtıfScopus20·WoS11·OpenAlex23

  İncele
• BildiriAçık Erişim2017Scopus SJRQ3/r/bayburt/12538
  Effect of copper addition to aluminium alloys on surface roughness in terms of turning operation

  Özen, F.; Fiçici, F.; Dündar, M.; Çolak, M.

  Aluminium alloys have found usage in numerous industries due to some superior properties, such as high strength-to-weight ratios and high oxidation resistance. Aluminum alloys can be strengthened by some techniques. One of them, the most practical one, is precipitation hardening in aluminum alloys. By adding Cu, aluminum gains strength and hardness. In this work the machinability of unalloyed aluminum and aluminum alloyed with 4% and 8% of Cu have been investigated. Machinability assessment was executed in terms of surface roughness during turning operation. Specimens were manufactured by sand casting method, which is a commonly utilized casting operation. In machinability experiments, three different cutting tool materials were employed. Three different cutting speeds and three different feed rates have been used. Effect of these feeds, speeds and cutting tool materials on surface roughness has been studied. In addition, effect of Cu addition to aluminum alloys on surface roughness has been examined.

  AtıfScopus9·WoS6·OpenAlex10

  İncele
• BildiriAçık Erişim2017Scopus SJRQ3/r/bayburt/12504
  Thermodynamic performance assessment of different fluids in a typical organic Rankine cycle for usage in municipal solid waste power plant

  Özahi, E.; Tozlu, A.; Abuşoǧlu, A.

  This paper presents the energy and exergy analyses of some different organic fluids which can be used in an organic Rankine cycle adapted to a municipal solid waste power plant in the frame of energy recovery. The novelty of the study is to adapt a well-known organic Rankine cycle system theoretically to the existing municipal solid waste power plant where the exhaust gas with a temperature of almost 560 °C is sent to atmosphere causing both energy loss and air pollution, and also violating the related legislation. The efficient organic fluid that can be used in such a plant is estimated by means of the thermodynamic analyses. It is known that, in a typical municipal solid waste power plant, a considerable amount of energy is sent up from a plant chimney to the atmosphere. This waste energy can be utilized by using an adapted organic Rankine cycle system with a proper organic fluid. In this frame, some different organic fluids were examined and compared thermodynamically in this study. The optimal operation conditions of some organic fluids, R141b, isobutane, R245fa, n-pentane and n-hexane have been evaluated by means of ASPEN and EES software programs. The effects of the outlet temperature of heat source on the energetic and exergetic efficiencies and the net power output at a given pinch point temperature difference were investigated. It can be deduced from the analyses that n-hexane has the highest energetic and exergetic efficiencies at all outlet temperatures of the heat source such as 8.92% and 34.47% at 82.08°C, respectively. It can also be stated that the maximum net power output is obtained by using the organic fluid n-hexane.

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  AtıfScopus14·WoS12·OpenAlex13

  İncele
• BildiriAçık Erişim2017Scopus SJRQ3/r/bayburt/12448
  Thermoeconomic analysis and assessment of Gaziantep municipal solid waste power plant

  Tozlu, A.; Abuşoǧlu, A.; Özahi, E.

  This paper presents a thermoeconomic analysis and assessment of a municipal solid waste power plant system in Gaziantep. The operation of an existing municipal solid waste power plant is described in detail and a thermoeconomical methodology based on exergoeconomic relations and specific exergy costing (SPECO) method is provided to allocate cost flows through subcomponents of the plant. SPECO method is based on a step by step procedure which begins from identification of energy and exergy values of all states defined in the present system through fuel (F) and product (P) approach and ends at the point of establishing related exergy based cost balance equations together with auxiliary equations. The actual exergy efficiency of the solid waste power plant is determined to be 47.84% which shows that 52.16% of the total exergy input to the plant is destroyed. The net electrical power output of the Gaziantep municipal solid waste power plant is 5.655 MW. The total cost rate of the power plant is evaluated as 18.44$/h as a result of thermoeconomic analyses.

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  AtıfScopus12·WoS13·OpenAlex16

  İncele
• BildiriYayıncıda açık erişim2016Scopus SJRQ4/r/bayburt/13736
  Exergy analysis of a combined power and cooling cycle

  Karaali, R.

  Ammonia-water power cycles are important for efficient utilization of low temperature heat sources such as geothermal, solar, waste heat sources, etc. For some special conditions ammonia-water power cycle is an important and economical option. This paper presents an exergetic analysis of a combined power and cooling cycle that uses ammonia-water mixture as working fluid. Such cycles, use solar or geothermal energy or waste heat energy from a conventional power cycle. Ammonia-water power cycle can be used as independent cycles to provide power output and cooling. For a range (25-55 Bar) of boiler pressure the performance of the combined power and cooling cycle is investigated. The exergy of the boiler is very low compared to its energy. There is a boiling process and a heat transfer process at low temperature, both of which destruct the energy given to the boiler, so that the energy efficiency is low; however the exergy efficiency is higher than the energy efficiency. Increasing the turbine inlet pressure decreases the energy and exergy efficiencies.

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  AtıfScopus13·WoS12·OpenAlex75

  İncele
• BildiriAçık Erişim2016Scopus SJRQ4/r/bayburt/12322
  Thermodynamic analysis of a cascade refrigeration system

  Karaali, R.

  There is a need for cooling by using the waste heat energy in food industry. Absorption cycles can be driven by waste thermal, geothermal, solar or industrial processes energies. In this study, cascade refrigeration system is thermodynamically modeled, and analyzed by using first law of thermodynamics, and exergy method. Thermodynamic properties such as pressure, temperature, entropy, enthalpy, exergy, mass flow rate in each stream are calculated for 50, 75, 100?C and for 0.8, 1.0, and 1.5 MPa pump pressure. A computer program is used that was prepared in FORTRAN by the author for the analyses. It is found that the compression-absorption cascade cooling cycle is appropriate for most of the kind of waste heat applications. Increase of the generator inlet heat temperature increases the generator inlet heat, the absorber outlet heat and the condenser 2 outlet heat energies and decreases the coefficient of performance of the absorption and the overall cycles. The generator heat decreases with increase of the pump pressure. Also increase of the pump pressure decreases the coefficient of performance of the absorption and the overall cycles. Increase of the pump pressure and the generator temperature decreases the exergetic coefficient of performance. Increase of the generator temperature and pump pressure increases the generator inlet exergy. It is concluded that increase of the generator temperature and the pump pressure increases the total destructed exergy of the cycle.

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  AtıfScopus10·WoS5·OpenAlex13

  İncele
• BildiriAçık Erişim2015Scopus SJRQ3/r/bayburt/12456
  Investigation of an alternative fuel for diesel engines

  Keven, A.; Karaali, R.

  Internal combustion engines use generally fossil fuel products. World resources of it is limited. Renewable alternative energy sources are getting important solution for energy demand. Hazelnut oil ethyl ester is obtained from raw hazelnut and mixed with diesel oil in certain proportions to use in a four-stroke direct injected single cylinder diesel engine. In this study the effects of the mixture of diesel oil with hazelnut oil ethyl ester on the engine performance and exhaust gas emissions are investigated for the first time in literature. The fuel injection system is regulated to use the mixture in the engine for the investigation. The results show that, the mixture with 25% ethyl ester extracted from hazelnut oil can be used as an alternative fuel without any change or regulation of the diesel engine.

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  AtıfScopus7·WoS3·OpenAlex7

  İncele
• BildiriAçık Erişim2015Scopus SJRQ3/r/bayburt/12319
  Thermoeconomic analyses of steam injected gas turbine cogeneration cycles

  Karaali, R.; Öztürk, I.T.

  In this study, three different gas turbine cogeneration systems that are preheating air, preheating air-fuel and simple cycles where steam injected in to combustion chamber are analyzed. The effects of steam injection on thermoeconomic performance are calculated and obtained. By using the first law of thermodynamics, the exergy analysis and economic methods, simulation programs written by the authors in FORTRAN code are obtained to use for the analyses. Thermoeconomic performance of these three different cycles for different stage and variable mass of injected steam are obtained and compared with literature. The effects of injection steam in to combustion chambers of those three cycles for variable compressing ratios, on power, efficiencies, product price and performances are obtained. Consequently, the advantages and the disadvantages of injection steam are evaluated. The results obtained in this study are compared with the results available in the literature. Injection steam into combustion chamber increases the electricity efficiency and electricity power but decreases the heat power of the cycles. Also the produced electricity price for per kWh is increasing.

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  AtıfScopus15·WoS12·OpenAlex18

  İncele
• BildiriAçık Erişim2015Scopus SJRQ3/r/bayburt/12307
  Soil stabilization with using waste materials against freezing thawing effect

  Yilmaz, F.; Kamiloʇlu, H.A.; Şadoʇlu, E.

  Freezing-thawing processes hapenning in seasonally cold climate cause deformation of soil in time of freezing and strength loss while thawing. Problems of ground frost heave and soil softening belong to the important factors, that could cause serious damage and financial loss. Bayburt tuff and tuffites known as Bayburt Stone mines, located around Bayburt, play important role on economy of the Bayburt city. As a result of researches in 2005 total of 2 535 700 tons proved reserve were determined several places in Bayburt. The goal of this study is proving, that deposits of Green Bayburt Stone wastes, created in the stone quarries during the stone processing, can be used as a stabilizing material. By recycling the waste material rejected stone was mixed with lime and used as a soil stabilizator against freezing-thawing effect. Prepared natural and stabilized soil samples were subjected to freezing-thawing cycles after curing for 28 days. After the freezing-thawing cycles, compressive strength of the samples was measured to investigate the influence of the additives on the freezing-thawing properties of soil samples. As a result of this study, it was determined that samples stabilized with Green Bayburt Stone mixtures have high freezing-thawing durability as compared to unstabilized samples. As a consequence, it was seen that those mixtures can be successfully used as an additive material to enhance the freezing-thawing effects of cohessive soils.

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  AtıfScopus25·WoS23·OpenAlex28

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