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Papers by Hakan Bayraktar

Research paper thumbnail of An experimental study on the performance parameters of an experimental CI engine fueled with diesel–methanol–dodecanol blends

Fuel, 2008

The effects of using diesel-methanol-dodecanol blends including methanol of various proportions o... more The effects of using diesel-methanol-dodecanol blends including methanol of various proportions on a CI engine performance are experimentally investigated. The methanol concentration in the blend has been changed from 2.5% to 15% with the increments of 2.5%, and 1% dodecanol was added into each blend to solve the phase separation problem. Experimental study has been conducted on a single-cylinder, water-cooled CI engine. The engine has been operated at different compression ratios (19, 21, 23 and 25) and the engine speed was varied from 1000 to 1600 rpm at each compression ratio. The performance parameters such as torque, effective power, specific fuel consumption and effective efficiency for each blend at various conditions are calculated depending on the experimental data. It was concluded that among the different blends, the blend including 10% methanol (DM10) is the most suited one for CI engines from the engine performance point of view. Improvements obtained up to 7% in performance parameters with this blend without any modification to engine design and fuel system are very promising.

Research paper thumbnail of Experimental and theoretical investigation of using gasoline–ethanol blends in spark-ignition engines

Research paper thumbnail of Theoretical investigation of flame propagation process in an SI engine running on gasoline–ethanol blends

Renewable Energy, 2007

Turbulent flame propagation process in a spark-ignition (SI) engine is theoretically investigated... more Turbulent flame propagation process in a spark-ignition (SI) engine is theoretically investigated. Fueling with gasoline, ethanol and different gasoline-ethanol blends is considered. A quasidimensional SI engine cycle model previously developed by the author is used to predict the thermodynamic state of the cylinder charge during the cycle. The flame is assumed to be spherical in shape and centered at the spark plug. Computations are carried out for an automobile SI engine having a disc-shaped combustion chamber, for which the compression ratio and the nominal speed are 9.2 and 5800 rpm, respectively. Geometrical features (flame radius, flame front area and enflamed volume) of the flame, combustion characteristics (mass fraction burned and burn duration), and cylinder pressure and temperature are predicted as a function of the crank angle. Three different positions of the crank angle are studied: À101, TC and +101. It was concluded that ethanol addition to gasoline up to 25 vol% accelerated the flame propagation process. r

Research paper thumbnail of Investigating the effects of LPG on spark ignition engine combustion and performance

Energy Conversion and Management, 2005

A quasi-dimensional spark ignition (SI) engine cycle model is used to predict the cycle, performa... more A quasi-dimensional spark ignition (SI) engine cycle model is used to predict the cycle, performance and exhaust emissions of an automotive engine for the cases of using gasoline and LPG. Governing equations of the mathematical model mainly consist of first order ordinary differential equations derived for cylinder pressure and temperature. Combustion is simulated as a turbulent flame propagation process and during this process, two different thermodynamic regions consisting of unburned gases and burned gases that are separated by the flame front are considered. A computer code for the cycle model has been prepared to perform numerical calculations over a range of engine speeds and fuel-air equivalence ratios. In the computations performed at different engine speeds, the same fuel-air equivalence ratios are selected for each fuel to make realistic comparisons from the fuel economy and fuel consumption points of view. Comparisons show that if LPG fueled SI engines are operated at the same conditions with those of gasoline fueled SI engines, significant improvements in exhaust emissions can be achieved. However, variations in various engine performance parameters and the effects on the engine structural elements are not promising.

Research paper thumbnail of Development of an empirical correlation for combustion durations in spark ignition engines

Energy Conversion and Management, 2004

Development of an empirical correlation for combustion duration is presented. For this purpose, t... more Development of an empirical correlation for combustion duration is presented. For this purpose, the effects of variations in compression ratio engine speed, fuel/air equivalence ratio and spark advance on combustion duration have been determined by means of a quasi-dimensional SI engine cycle model previously developed by the authors. Burn durations at several engine operating conditions were calculated from the turbulent combustion model. Variations of combustion duration with each operating parameter obtained from the theoretical results were expressed by second degree polynomial functions. By using these functions, a general empirical correlation for the burn duration has been developed. In this correlation, the effects of engine operating parameters on combustion duration were taken into account. Combustion durations predicted by means of this correlation are in good agreement with those obtained from experimental studies and a detailed combustion model.

Research paper thumbnail of Effect of Honey Treatment on Some Quality Characteristics of Broiler Breast Meat

Journal of Applied Animal Research, 2005

Yücel, B., Önenç, A., Bayraktar, H., Açikgöz, Z. and Altan, Ö. 2005. Effect of honey treatment on... more Yücel, B., Önenç, A., Bayraktar, H., Açikgöz, Z. and Altan, Ö. 2005. Effect of honey treatment on some quality characteristics of broiler breast meat. J. Appl. Anim. Res., 28: 53–56.Breast meats of 12 broilers (Ross-308) were used to determine the effect of marination with honey water mixture (0, 20, 30% v/v) on their meat quality and bacterial activity. Treated meats were preserved at 4C for 7 days in vacuume. Drip loss, pH level and marinate uptake did not change significantly in breast meats marinated with different levels of honey and without honey. Marination with honey did not significantly affect the L*(brightness) and a*(redness) values of breast meats on 1st and 7th days of treatment. However, b* (yellowness) values were significantly affected by honey treatment. After 7th day, no significant differences were obtained for tenderness, flavor and acceptability between treatment and the control groups. Breast meats marinated with honey showed a slight decrease in bacterial number compared to control group after 4th day. It is indicated that honey marination might be considered as a means of limiting bacterial growth in broiler meat without any adverse effect on meat quality and sensory characteristics.

Research paper thumbnail of Karma Yeme Asit Yağ İlavesinin Etlik Piliç Performansi Üzerine Etkileri

Özet: Bu araştırmada, karma yemlere ilave edilen soya yağı (SY) veya asit yağın (AY) erkek etlik ... more Özet: Bu araştırmada, karma yemlere ilave edilen soya yağı (SY) veya asit yağın (AY) erkek etlik piliçlerde performans (canlı ağırlık, yem tüketimi ve yemden yararlanma) ve ham yağın sindirilebilirliği üzerindeki etkileri incelenmiştir. Toplam 621 adet Ross-308 genotipine ait günlük erkek civciv kullanılmıştır. Civcivler rasgele 3 tekerrürlü 3 deneme grubuna ayrılmıştır. Tüm gruplar ikinci haftanın sonuna kadar aynı başlatma yemiyle (3098 kcal ME / kg ve % 23.97 protein) beslenmişlerdir. Araştırmada, 3-4. haftalar arasında geliştirme, 5-6. haftalar arasında bitirme yemleri kullanılmıştır. Birinci, ikinci ve üçüncü gruplar sırasıyla % 6 SY, % 3 SY+ % 3 AY ve % 6 AY içeren eş enerjili ve eş proteinli geliştirme ve bitirme yemleriyle beslenmişlerdir. Dördüncü haftanın sonunda, ham yağın sindirilebilirliğini belirlemek için her gruptan 7 piliç seçilerek bireysel metabolizma kafeslerine taşınmıştır. Araştırmadan elde edilen bulgulara göre, geliştirme ve bitirme yemlerine % 3 SY ve % 3 AY karışımının ilavesi canlı ağırlığı artırmış ve yemden yararlanmayı iyileştirmiştir. Buna karşılık karma yeme % 6 düzeyinde AY ilavesi yem tüketimi ve canlı ağırlığı önemli düzeyde azaltmıştır. Ayrıca, karma yemlere AY ilave edilmesi ham yağın sindirilebilirliğini etkilememiştir.

Research paper thumbnail of Yüksek Sicaklikta Yumurta Tavuklarinin Su Tüketimi-Verim Performansi Arasindaki İlişki

Özet: Su, kanatlı hayvanlar için esensiyel besin maddelerinden birisidir. Vücut ağırlığının yakla... more Özet: Su, kanatlı hayvanlar için esensiyel besin maddelerinden birisidir. Vücut ağırlığının yaklaşık %70'ini, yumurta ağırlığının % 65' ini su oluşturur. Yumurta tavuklarında yumurta verimini ve kalitesini doğrudan etkiler. Su tüketim miktarı birçok faktöre bağlı olarak değişmektedir. Üretici yönünden bu faktörlerden yem ve çevre sıcaklığı çok daha önemlidir.

Research paper thumbnail of An experimental study on the performance parameters of an experimental CI engine fueled with diesel–methanol–dodecanol blends

Fuel, 2008

The effects of using diesel-methanol-dodecanol blends including methanol of various proportions o... more The effects of using diesel-methanol-dodecanol blends including methanol of various proportions on a CI engine performance are experimentally investigated. The methanol concentration in the blend has been changed from 2.5% to 15% with the increments of 2.5%, and 1% dodecanol was added into each blend to solve the phase separation problem. Experimental study has been conducted on a single-cylinder, water-cooled CI engine. The engine has been operated at different compression ratios (19, 21, 23 and 25) and the engine speed was varied from 1000 to 1600 rpm at each compression ratio. The performance parameters such as torque, effective power, specific fuel consumption and effective efficiency for each blend at various conditions are calculated depending on the experimental data. It was concluded that among the different blends, the blend including 10% methanol (DM10) is the most suited one for CI engines from the engine performance point of view. Improvements obtained up to 7% in performance parameters with this blend without any modification to engine design and fuel system are very promising.

Research paper thumbnail of Experimental and theoretical investigation of using gasoline–ethanol blends in spark-ignition engines

Research paper thumbnail of Theoretical investigation of flame propagation process in an SI engine running on gasoline–ethanol blends

Renewable Energy, 2007

Turbulent flame propagation process in a spark-ignition (SI) engine is theoretically investigated... more Turbulent flame propagation process in a spark-ignition (SI) engine is theoretically investigated. Fueling with gasoline, ethanol and different gasoline-ethanol blends is considered. A quasidimensional SI engine cycle model previously developed by the author is used to predict the thermodynamic state of the cylinder charge during the cycle. The flame is assumed to be spherical in shape and centered at the spark plug. Computations are carried out for an automobile SI engine having a disc-shaped combustion chamber, for which the compression ratio and the nominal speed are 9.2 and 5800 rpm, respectively. Geometrical features (flame radius, flame front area and enflamed volume) of the flame, combustion characteristics (mass fraction burned and burn duration), and cylinder pressure and temperature are predicted as a function of the crank angle. Three different positions of the crank angle are studied: À101, TC and +101. It was concluded that ethanol addition to gasoline up to 25 vol% accelerated the flame propagation process. r

Research paper thumbnail of Investigating the effects of LPG on spark ignition engine combustion and performance

Energy Conversion and Management, 2005

A quasi-dimensional spark ignition (SI) engine cycle model is used to predict the cycle, performa... more A quasi-dimensional spark ignition (SI) engine cycle model is used to predict the cycle, performance and exhaust emissions of an automotive engine for the cases of using gasoline and LPG. Governing equations of the mathematical model mainly consist of first order ordinary differential equations derived for cylinder pressure and temperature. Combustion is simulated as a turbulent flame propagation process and during this process, two different thermodynamic regions consisting of unburned gases and burned gases that are separated by the flame front are considered. A computer code for the cycle model has been prepared to perform numerical calculations over a range of engine speeds and fuel-air equivalence ratios. In the computations performed at different engine speeds, the same fuel-air equivalence ratios are selected for each fuel to make realistic comparisons from the fuel economy and fuel consumption points of view. Comparisons show that if LPG fueled SI engines are operated at the same conditions with those of gasoline fueled SI engines, significant improvements in exhaust emissions can be achieved. However, variations in various engine performance parameters and the effects on the engine structural elements are not promising.

Research paper thumbnail of Development of an empirical correlation for combustion durations in spark ignition engines

Energy Conversion and Management, 2004

Development of an empirical correlation for combustion duration is presented. For this purpose, t... more Development of an empirical correlation for combustion duration is presented. For this purpose, the effects of variations in compression ratio engine speed, fuel/air equivalence ratio and spark advance on combustion duration have been determined by means of a quasi-dimensional SI engine cycle model previously developed by the authors. Burn durations at several engine operating conditions were calculated from the turbulent combustion model. Variations of combustion duration with each operating parameter obtained from the theoretical results were expressed by second degree polynomial functions. By using these functions, a general empirical correlation for the burn duration has been developed. In this correlation, the effects of engine operating parameters on combustion duration were taken into account. Combustion durations predicted by means of this correlation are in good agreement with those obtained from experimental studies and a detailed combustion model.

Research paper thumbnail of Effect of Honey Treatment on Some Quality Characteristics of Broiler Breast Meat

Journal of Applied Animal Research, 2005

Yücel, B., Önenç, A., Bayraktar, H., Açikgöz, Z. and Altan, Ö. 2005. Effect of honey treatment on... more Yücel, B., Önenç, A., Bayraktar, H., Açikgöz, Z. and Altan, Ö. 2005. Effect of honey treatment on some quality characteristics of broiler breast meat. J. Appl. Anim. Res., 28: 53–56.Breast meats of 12 broilers (Ross-308) were used to determine the effect of marination with honey water mixture (0, 20, 30% v/v) on their meat quality and bacterial activity. Treated meats were preserved at 4C for 7 days in vacuume. Drip loss, pH level and marinate uptake did not change significantly in breast meats marinated with different levels of honey and without honey. Marination with honey did not significantly affect the L*(brightness) and a*(redness) values of breast meats on 1st and 7th days of treatment. However, b* (yellowness) values were significantly affected by honey treatment. After 7th day, no significant differences were obtained for tenderness, flavor and acceptability between treatment and the control groups. Breast meats marinated with honey showed a slight decrease in bacterial number compared to control group after 4th day. It is indicated that honey marination might be considered as a means of limiting bacterial growth in broiler meat without any adverse effect on meat quality and sensory characteristics.

Research paper thumbnail of Karma Yeme Asit Yağ İlavesinin Etlik Piliç Performansi Üzerine Etkileri

Özet: Bu araştırmada, karma yemlere ilave edilen soya yağı (SY) veya asit yağın (AY) erkek etlik ... more Özet: Bu araştırmada, karma yemlere ilave edilen soya yağı (SY) veya asit yağın (AY) erkek etlik piliçlerde performans (canlı ağırlık, yem tüketimi ve yemden yararlanma) ve ham yağın sindirilebilirliği üzerindeki etkileri incelenmiştir. Toplam 621 adet Ross-308 genotipine ait günlük erkek civciv kullanılmıştır. Civcivler rasgele 3 tekerrürlü 3 deneme grubuna ayrılmıştır. Tüm gruplar ikinci haftanın sonuna kadar aynı başlatma yemiyle (3098 kcal ME / kg ve % 23.97 protein) beslenmişlerdir. Araştırmada, 3-4. haftalar arasında geliştirme, 5-6. haftalar arasında bitirme yemleri kullanılmıştır. Birinci, ikinci ve üçüncü gruplar sırasıyla % 6 SY, % 3 SY+ % 3 AY ve % 6 AY içeren eş enerjili ve eş proteinli geliştirme ve bitirme yemleriyle beslenmişlerdir. Dördüncü haftanın sonunda, ham yağın sindirilebilirliğini belirlemek için her gruptan 7 piliç seçilerek bireysel metabolizma kafeslerine taşınmıştır. Araştırmadan elde edilen bulgulara göre, geliştirme ve bitirme yemlerine % 3 SY ve % 3 AY karışımının ilavesi canlı ağırlığı artırmış ve yemden yararlanmayı iyileştirmiştir. Buna karşılık karma yeme % 6 düzeyinde AY ilavesi yem tüketimi ve canlı ağırlığı önemli düzeyde azaltmıştır. Ayrıca, karma yemlere AY ilave edilmesi ham yağın sindirilebilirliğini etkilememiştir.

Research paper thumbnail of Yüksek Sicaklikta Yumurta Tavuklarinin Su Tüketimi-Verim Performansi Arasindaki İlişki

Özet: Su, kanatlı hayvanlar için esensiyel besin maddelerinden birisidir. Vücut ağırlığının yakla... more Özet: Su, kanatlı hayvanlar için esensiyel besin maddelerinden birisidir. Vücut ağırlığının yaklaşık %70'ini, yumurta ağırlığının % 65' ini su oluşturur. Yumurta tavuklarında yumurta verimini ve kalitesini doğrudan etkiler. Su tüketim miktarı birçok faktöre bağlı olarak değişmektedir. Üretici yönünden bu faktörlerden yem ve çevre sıcaklığı çok daha önemlidir.