Makine Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/263
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Article Citation Count: Totuk, Onat Halis; Selvi, Özgün; Akar, Samet (2023). "Fused filament fabrication in CAD education: A closed-loop approach", International Journal of Mechanical Engineering Education.Fused filament fabrication in CAD education: A closed-loop approach(2023) Totuk, Onat Halis; Selvi, Özgün; Akar, Samet; 315516Integrating low-cost fused filament fabrication 3D printing as a foundation for learning 3D modelling is explored. This method blends traditional computer aided design (CAD) instruction with additive manufacturing possibilities. Experimental results demonstrate increased comprehension speed and reduced learning time. This hands-on approach empowers students by enabling direct engagement with the modelling process. Analogous to reverse engineering, the strategy instructs engineering students from final product to model creation, closing the gap between theory and practice. Incorporating 3D printing bridges this divide, enhancing understanding, creativity and problem-solving. The study underscores technology's influence on learning strategies, aligning with the surge of 3D printing in education. Results link advanced design technology usage to improved student performance, with 3D-printed materials yielding 45% higher grades and 30% faster task completion. This study advocates curricular advancement for design-focused careers through enhanced technology integration and favourable 3D printing model reception.Article Citation Count: Çelebioğlu, Kutay...et al. "Exploring the potential of artificial intelligence tools in enhancing the performance of an inline pipe turbine", Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering.Exploring the potential of artificial intelligence tools in enhancing the performance of an inline pipe turbine(2024) Çelebioğlu, Kutay; Aylı, Ece; Çetintürk, Hüseyin; Taşçıoğlu, Yiğit; Aradağ, Selin; 265836In this study, investigations were conducted using computational fluid dynamics (CFD) to assess the applicability of a Francis-type water turbine within a pipe. The objective of the study is to determine the feasibility of implementing a turbine within a pipe and enhance its performance values within the operating range. The turbine within the pipe occupies significantly less space in hydroelectric power plants since a spiral casing is not used to distribute the flow to stationary vanes. Consequently, production and assembly costs can be reduced. Hence, there is a broad scope for application, particularly in small and medium-scale hydroelectric power plants. According to the results, the efficiency value increases on average by approximately 1.5% compared to conventional design, and it operates with higher efficiencies over a wider flow rate range. In the second part of the study, machine learning was employed for the efficiency prediction of an inline-type turbine. An appropriate Artificial Neural Network (ANN) architecture was initially obtained, with the Bayesian Regularization training algorithm proving to be the best approach for this type of problem. When the suitable ANN architecture was utilized, the prediction was found to be in good agreement with CFD, with an root mean squared error value of 0.194. An R2 value of 0.99631 was achieved with the appropriate ANN architecture.Article Citation Count: Özgirgin Yapıcı, Ekin; Aylı, Ece; Türkoğlu, Haşmet (2024). "Analysis of heat transfer enhancement of passive methods in tubes with machine learning", Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Vol. 238, No. 8, pp. 3613-3633.Analysis of heat transfer enhancement of passive methods in tubes with machine learning(2024) Özgirgin Yapıcı, Ekin; Aylı, Ece; Türkoğlu, Haşmet; 31329; 265836; 12941This study investigates the efficacy of machine learning techniques and correlation methods for predicting heat transfer performance in a dimpled tube under varying flow conditions, including the presence of nanoparticles. A comprehensive numerical analysis involving 120 cases was conducted to obtain Nusselt numbers and friction factors, considering different dimple depths and velocities for both pure water and water-Al2O3 nanofluid at 1%, 2%, and 3% volume concentrations. Utilizing the data acquired from the numerical simulations, a correlation equation, SVM ANN architectures were developed. The predictive capabilities of the statistical approach, ANN, and SVM models for Nusselt number distribution and friction factor were meticulously assessed through mean average percentage error (MAPE) and correlation coefficients (R2). The research findings reveal that machine learning techniques offer a highly effective approach for accurately predicting heat transfer performance in a dimpled tube, with results closely aligned with Computational Fluid Dynamics (CFD) simulations. Particularly noteworthy is the superior performance of the ANN model, demonstrating the most precise predictions with an error rate of 2.54% and an impressive R2 value of 0.9978 for Nusselt number prediction. In comparison, the regression model achieved an average error rate of 6.14% with an R2 value of 0.8623, and the SVM model yielded an RMSE value of 2.984% with an R2 value of 0.9154 for Nusselt number prediction. These outcomes underscore the ANN model’s ability to effectively capture complex patterns within the data, resulting in highly accurate predictions. In conclusion, this research showcases the promising potential of machine learning techniques in accurately forecasting heat transfer performance in dimpled tubes. The developed ANN model exhibits notable superiority in predicting Nusselt numbers, making it a valuable tool for enhancing thermal system analyses and engineering design optimization.Article Citation Count: Kaak, Abdul Rahman Sabra...et al. (2024). "A novel CFD-ANN approach for plunger valve optimization: Cost-effective performance enhancement", Flow Measurement and Instrumentation, Vol. 97.A novel CFD-ANN approach for plunger valve optimization: Cost-effective performance enhancement(2024) Kaak, Abdul Rahman Sabra; Çelebioğlu, Kutay; Bozkuş, Zafer; Ulucak, Oğuzhan; Aylı, Ece; 265836This paper introduces a novel computational fluid dynamics-artificial neural network (CFD-ANN) approach that has been devised to enhance the efficiency of plunger valves. The primary emphasis of this research is to achieve an optimal equilibrium between hydraulic flow and geometric configuration. This study is a novel contribution to the field as it explores the flow dynamics of plunger valves using Computational Fluid Dynamics (CFD) and proposes a unique methodology by incorporating Machine Learning (ML) for performance forecasting. An artificial neural network (ANN) architecture was developed using a thorough comprehension of flow physics and the impact of geometric parameters acquired through computational fluid dynamics (CFD). Using optimization, the primary aspects of the Artificial Neural Network (ANN), including the learning algorithm and the number of hidden layers, have been modified. This refinement has resulted in the development of an architecture exhibiting a remarkably high R2 value of 0.987. This architectural design was employed to optimize the plunger valve. By utilizing Artificial Neural Networks (ANN), a comprehensive analysis comprising 1000 distinct configurations was effectively performed, resulting in a significant reduction in time expenditure compared to relying on Computational Fluid Dynamics (CFD). The result was a refined arrangement that achieved maximum head loss, subsequently verified using computational fluid dynamics (CFD) simulations, resulting in a minimal discrepancy of 2.66%. The efficacy of artificial neural networks (ANN) becomes apparent due to their notable cost-efficiency, along with their capacity to produce outcomes that are arduous and expensive to get through conventional optimization research utilizing computational fluid dynamics (CFD).Article Citation Count: Erşahin, Yasin; Türkoğlu, Haşmet. (2017). "Soğutma Yüküne Bağlı Olarak Set Sıcaklığı Değişen Hava Soğutmalı Soğutma Grubunun Performansının Deneysel İncelenmesi", Soğutma Dünyası, Vol.20, No.78, pp.60-72.Soğutma Yüküne Bağlı Olarak Set Sıcaklığı Değişen Hava Soğutmalı Soğutma Grubunun Performansının Deneysel İncelenmesi(2017) Erşahin, Yasin; Türkoğlu, Haşmet; 12941Alışılmış enerji kaynaklarının global enerji ihtiyacını karşılamadaki yetersizliği, her geçen gün enerji ihtiya- cının artması ve enerji üretiminden kaynaklanan çevre kirliliği gibi sebepler enerji verimliliğinin önemini artır- maktadır. Günümüzde bütün sektörlerde, enerjiyi ola- bildiğince verimli kullanabilecek teknikler geliştirilmeye çalışılmaktadır. Gelişmiş ülkeleri incelediğimizde, ısıt- ma ve soğutma alanındaki önceliklerde ilk sırayı enerji verimliliği almaktadır. Merkezi yaşam alanları için gerekli olan soğutma ih- tiyacı, gün veya sezon içerisinde sürekli değişiklik gös- termektedir. Mahaldeki insan sayısının ve hava hare- ketliliğinin değişmesiyle ihtiyaç olan soğutma yükü de değişmektedir. Mahale bağlı bulunan soğutma grubu- nun bu değişken soğutma yüküne göre kendini ayar- layıp, hızlı bir şekilde reaksiyon vermesi enerjinin daha verimli kullanılmasını sağlamaktadır. Bu çalışmada, standart soğutma grubu kontrol tekniği ve adaptif algoritmalı kontrol tekniği ile kontrol edilen bir soğutma grubunun performansı ve enerji tüketimi, deneysel olarak incelenmiş ve sonuçlar karşılaştırma- lı olarak sunulmuştur. Testlerde, her iki kontrol sistemi için değişken soğutma yükü sağlanması amacıyla ciha- zın evaporatör su giriş sıcaklığı 12-7°C arasında de- ğiştirilerek, soğutma grubu kompresörlerinin devreye girmesi ve devreden çıkması sağlanmıştır. Tam ve kıs- mi soğutma yükleri altında yapılan ölçümlerde, adap- tif kontrol sistemi ile kontrol edilen soğutma grubunun, standart kontrol sistemine göre ortalama %10,72 daha az enerji tükettiği ve toplam ekserji yıkımının ise orta- lama % 6,23 daha az olduğu görülmüştür.Article Citation Count: Aylı, Ece; Koçak, Eyup. (2022). "Prediction of the heat transfer performance of twisted tape inserts by using artificial neural networks", Journal of Mechanical Science and Technology, Vol.36, No.9, pp.4849-4858.Prediction of the heat transfer performance of twisted tape inserts by using artificial neural networks(2022) Aylı, Ece; Koçak, Eyup; 265836; 283455A numerical study is undertaken to investigate the effect of twisted tape inserts on heat transfer. Twisted tapes with various aspect ratios and single, double, and triple inserts are placed inside a tube for Reynolds numbers ranging from 8000 to 12000. Numerical results show that the tube with a twisted tape and different numbers of tape is more effective than the smooth tube in terms of thermo-hydraulic performance. The highest heat transfer is achieved with the triple insert, with the highest turning number and an increment of 15 %. Then, an artificial neural network (ANN) model with a three-layer feedforward neural network is adopted to obtain the Nusselt number on the basis of four inputs for a heated tube with a twisted insert. Several configurations of the neural network are examined to optimize the number of neurons and to identify the most appropriate training algorithm. Finally, the best model is determined with one hidden layer and thirteen neurons in the layer. Bayesian regulation is chosen as the training algorithm. With the optimized algorithm, excellent precision for measuring the output is provided, with R2 = 0.97043. In addition, the optimized ANN architecture is applied to similar studies in the literature to predict the heat transfer performance of twisted tapes. The developed ANN architecture can predict the heat transfer enhancement performance of similar problems with R2 values higher than 0.93.Article Citation Count: Koçak, Eyup; Aylı, Ece. (2022). "Performance Determination of Axial Wind Tunnel Fan with Reverse Engineering, Numerical and Experimental Methods", Journal of Computing and Information Science in Engineering, Vol.22, No.4.Performance Determination of Axial Wind Tunnel Fan with Reverse Engineering, Numerical and Experimental Methods(2022) Koçak, Eyup; Aylı, Ece; 283455; 265836In today's technology, in case of the need for rehabilitation, renovation, or damage, it is necessary to recover the problems quickly with a cost-effective approach. In the case of destructive failure, or misdesign of the devices, replacing the problematic part with the new design is crucial. In order to substitute the related part with the efficient one, reverse engineering (RE) methodology is utilized. In this paper, from the perspective of engineering implementation and based on the idea of reverse engineering, axial wind tunnel fan is rehabilitated using numerical and experimental methods. The current study is focused on an axial pressurization fan placed into Cankaya University Mechanical Engineering Laboratory wind tunnel that has firm guaranteed specifications of 5.55 m3/s airflow capacity. The measurements performed during experiments showed that the fan provides less than 60% airflow compared with firm guaranteed specifications. In order to determine the problems of the existing fan, a reverse engineering methodology is developed, and the noncontact data acquisition method is used to form a computer aided drawing (CAD) model. A computational fluid dynamics (CFD) methodology is developed to analyze existing geometry numerically, and results are compared with an experimental study to verify numerical methodology. According to the results, the prediction accuracy of the numerical method can attain 92.95% and 96.38% for flowrate and efficiency, respectively, at the maximum error points.Article Citation Count: Seyedzavvar, Mirsadegh;...et.al. (2022). "Numerical simulation and experimental investigation: Metal spinning process of stepped thin-walled cylindrical workpiece", Turkish Journal of Engineering, Vol.6, No.1, pp.67-80.Numerical simulation and experimental investigation: Metal spinning process of stepped thin-walled cylindrical workpiece(2022) Seyedzavvar, Mirsadegh; Seyedzavvar, Mirali; Akar, Samet; Abbasi, Hossein; 315516Many equipment and devices utilized in the aerospace industry are formed as symmetric parts through high plastic deformation of high strength sheet metal alloys with low thickness. Considering the inherent advantages of the spinning process of simple tooling and concentrated deformation loading, this process can be considered as one of the main options in producing these thin-sectioned lightweight parts. In this study, a Finite Element (FE) model has been developed to simulate the formation of a stepped thin-walled cylindrical workpiece of AISI 316 stainless steel alloy by spinning process. The FE simulation results were employed to investigate the effects of process parameters, including feed rate of the roller and rotational velocity of the mandrel on the distribution of stress and strain in the sheet metal, wrinkling failure, and thinning of the sheet metal during deformation. Experiments were carried out using selective input parameters based on the results of FE simulations. The comparison between FE simulations and experiments revealed that the developed model could predict the thinning of the sheet metals with over 93 % accuracy. Additionally, a good agreement between the experimentally deformed sheet configurations with those resulting from finite element simulations has been observed.Article Citation Count: Seyedzavvar, Mirsadegh;...et.al. (2021). "Molecular dynamic approach to predict thermo-mechanical properties of poly(butylene terephthalate)/CaCO3 nanocomposites", Materials Today Communications, vol.28.Molecular dynamic approach to predict thermo-mechanical properties of poly(butylene terephthalate)/CaCO3 nanocomposites(2021) Seyedzavvar, Mirsadegh; Boğa, Cem; Akar, Samet; Pashmforoush, Farzad; 315516Thermo-mechanical properties of poly(butylene terephthalate) polymer reinforced with carbonate calcium nanoparticles have been investigated using molecular dynamics simulations. Detailed analyses have been conducted on the effects of nanofiller content, at concentration levels of 0–7 wt%, on the mechanical properties of PBT, i.e. Young's modulus, Poisson's ratio and shear modulus. Thermal properties, including thermal conductivity and glass transition temperature, have been determined using Perl scripts developed based on nonequilibrium molecular dynamics and a high temperature annealing procedure, respectively. Experiments have been performed to verify the accuracy of the results of MD simulations. The CaCO3/PBT nanocomposites were synthesized using melt blending and mold injection techniques. The uniaxial tensile test, thermal conductivity, differential scanning calorimetry and x-ray diffraction spectroscopy measurements were conducted to quantify the thermo-mechanical properties of such nanocomposites experimentally. The results showed significant improvements in the mechanical properties by addition of CaCO3 nanoparticles due to strong binding between rigid particles and PBT polymer and high nucleation effects of nanoparticles on the matrix. Thermal conductivity and glass transition temperature of nanocomposites represented a consistent increase with the ratio of CaCO3 nanoparticles up to 5 wt% with an enhancement of 38% and 36% with respect to that of pure PBT, respectively.Article Citation Count: Selvi, Özgün...et.al. (2021). "Strengthening Effect Of Flooding In 3d Printed Porous Soft Robotics Scaffolds", International Journal of 3D Printing Technologies and Digital Industry, Vol.5, No.2, pp.293-301.Strengthening Effect Of Flooding In 3d Printed Porous Soft Robotics Scaffolds(2021) Selvi, Özgün; Totuk, Onat Halis; Arslan, Ozan; Mıstıkoğlu, SelçukThis study aims to design and 3D print porous elements for soft robotic applications and test the stiffness changes when the cavities are filled with liquids. When an elastic element has porous scaffolds, the stiffness can be controlled by filling the cavities with a liquid. A gyroid structure is selected for the design and evaluation of the characteristics of elements. The stiffness of the element in both non-filled and liquid-filled modes is analyzed using FEM simulation Software in two modes where simple support with central loading and compressive uniform loading. A porous test structure is created and tested in these modes for observation of the stiffness change. Employing an FDM printer in this project enabled us to make our thoughts to reality. The results show that liquid-filling can be used as a stiffening method for porous scaffolds in soft robotic applications.Article Citation Count: Elibol, Emre Aşkın; Türkoğlu, H. (2017). " Gözenekli Düz Bir Yüzeye Çarpan Jetin Sayısal Olarak İncelenmesi", Karadeniz Fen Bilimleri Dergisi, Vol. 7, No.1, pp.1-9.Gözenekli Düz Bir Yüzeye Çarpan Jetin Sayısal Olarak İncelenmesi(2017) Elibol, Emre Aşkın; Türkoğlu, Haşmet; 12941Bu çalışmada, gözenekli malzeme ile kaplanmış sabit sıcaklıkta tutulan düz levha üzerine çarpan jetin akış ve ısı transferine etkileri nümerik olarak incelenmiştir. Birbirine paralel olarak duran, iki yatay levhadan biri olan alt levha, gözenekli bir tabaka ile kaplanmış ve üst levhanın ortasında bulunan lüleden çıkan hava jeti alt levhaya çarptırılmıştır. Gözenekli tabakanın katı matrisi ile akışkan arasında yerel ısıl denge olduğu kabul edilerek, laminar ve kararlı rejim için çözümler yapılmıştır. Gözeneklilik, gözenekli tabakanın kalınlığı ve jet Reynolds sayısının farklı değerlerinde simülasyonlar yapılarak, bu parametrelerin yerel Nusselt sayısı’na (Nu) etkileri analiz edilmiştir. Sonuçlar, yatay (x) yönde; yerel Nu sayıları ve sıcak alt levhadan olan ısı akıları, gözenekli tabaka bulunmayan durum ile karşılaştırılarak yorumlanmıştır. Analizler için yazılım paketi olan ANSYS Fluent yazılımı kullanılmıştır. Sonuçlar, sıcak levha yüzeyinin gözenekli tabaka ile kaplandığı durumlarda, gözenekli malzemenin belirli gözeneklilik ve kalınlık değerleri aralığında olması halinde, ısı transferinin gözenekli tabaka kullanılmayan duruma göre daha etkin olduğunu göstermiştir.Conference Object Citation Count: Devrim, Yılser; Üregen, Nurhan; Özgirgin Yapıcı, Ekin. "Yüksek Sıcaklık Pem Yakıt Hücresi Mikro-Kojenerasyon Sistemi Tasarımı", 12. Ulusal Kimya Mühendisliği Kongresi, 2016.Yüksek Sıcaklık Pem Yakıt Hücresi Mikro-Kojenerasyon Sistemi Tasarımı(2016) Devrim, Yılser; Üregen, Nurhan; Özgirgin Yapıcı, Ekin; 31329Article Citation Count: Akyürek, Turgut. (2022). "Kinematic Analyses of Metallic Plate Perforation by Penetrators with Various Nose Geometries", Defence Science Journal, Vol.72, No.4, pp.334-342.Kinematic Analyses of Metallic Plate Perforation by Penetrators with Various Nose Geometries(2022) Akyürek, TurgutThis study analyses kinematics of a metallic plate perforation by a penetrator with truncated ogive nose geometry to find solutions also to blunt, conical, ogive, and hemi-spherical nosed penetrators. Plugging, ductile hole enlargement, dishing, and petal forming failure modes are used in the analyses. Acceleration throughout perforation is calculated by using the related failure mode, analytical model, and the target-penetrator interaction geometry. Depending on the failure model; back lip and front lip formation during ductile hole enlargement, plug formation during plugging, and deflection of target plate during dishing is also analysed. Analyses are based on projectile’s equation of motion, momentum and energy equations, and projectile-target plate interactions. The analyses results for selected cases, with the impact velocity range 215-863 m/s, are compared with the test data. The residual velocity estimation for a strike velocity is close to the related test data with an error of 0.3-2.2 %, eArticle Citation Count: Selvi, Özgün; Al-dulaimi, Hasan. (2015). "Kinematic Analysis Of A 5 Dof Overconstrained Manipulator For Rehabilitation Of Upper Extremite", Journal of Naval Sciences and Engineering, Vol.11, No.2, pp.52-69.Kinematic Analysis Of A 5 Dof Overconstrained Manipulator For Rehabilitation Of Upper Extremite(2015) Selvi, Özgün; Al-dulaimi, HasanThis study deals with one of the applications of parallel manipulator as a rehabilitation robot. This device is an over –constrained parallel manipulator 5 degree of freedom with 3 legs. This manipulator consists of a moving platform which is connected to a fixed base via three legs. Each leg is made of RRR(RR) (revolute) joints where the first three joint in all legs are parallel and the recent two joint are intersecting .Inverse kinematics of this device is solved by dividing manipulator into two sub-manipulators with the help of three imaginary joints placed at the intersection of platform joints with a direction parallel to base joints.Article Citation Count: Yılmaz, O.D.; Oliaei, S.D.B. (2020). "Kesici Takım Geometrisinin Ti-6Al-4V’nin İşlenmesi Sırasında Oluşan Tırtıklı Talaş Üzerindeki Etkisinin Sonlu Elemanlar Yöntemi ile Araştırılması"Dicle Üniversitesi Mühendislik Fakültesi Mühendislik Dergisi, Vol.11, No.3, pp.1131-1138.Kesici Takım Geometrisinin Ti-6Al-4V’nin İşlenmesi Sırasında Oluşan Tırtıklı Talaş Üzerindeki Etkisinin Sonlu Elemanlar Yöntemi ile Araştırılması(2020) Yılmaz, Okan Deniz; Oliaei, Samad Nadimi BavilTi-6Al-4V titanyum alaşımının işlenmesi sırasında tırtıklı talaş (serrated chip) oluşumunun modellenmesi oldukçazordur ve takım ömrünü, işlenmiş parçanın doğruluğunu ve yüzey kalitesini etkilediği için hayati öneme sahiptir.Kesici uç geometrisinin tırtıklı talaş oluşumu üzerindeki etkisi daha ileri araştırmalar gerektirirken, termalyumuşama, deformasyon yumuşaması ve hasara dayanan modeller olmak üzere bu sorunu çözmek için çeşitlimalzeme modelleri geliştirilmiştir. Bu çalışmada, teğet hiperbolik (TANH) fonksiyon kullanarak deformasyonyumuşama etkisini dikkate alan modifiye edilmiş bir Johnson-Cook temel malzeme modeli ele alınmıştır. Farklıgeometrilere (talaş açısı, boşluk açısı ve kenar yarıçapı) sahip olan kesici takımların tırtıklı talaş oluşumu üzerindeetkileri modellenmiş ve analiz edilmiştir. Kesme kuvveti, talaş morfolojisi ve tırtıklı talaşın derecesi talaşlı imalatverisi olarak kullanılmıştırConference Object Citation Count: Özbilgin, Onur; Türkoğlu, Haşmet. “Santrifüj Pompada Spiral Gövdenin Akışa Dik Kesit Alanının Pompa Performansına Etkisinin Sayısal Olarak İncelenmesi”, ULIBTK’17 21. Ulusal Isı Bilimi ve Tekniği Kongresi, 13-16 Eylül 2017, Çorum.Santrifüj Pompada Spiral Gövdenin Akışa Dik Kesit Alanının Pompa Performansına Etkisinin Sayısal Olarak İncelenmesi(2017) Özbilgin, Onur; Türkoğlu, HaşmetArticle Citation Count: Devrim, Yılser; Özgirgin Yapıcı, Ekin (2018). "YÜKSEK SICAKLIK PROTON DEĞİŞİM MEMBRAN YAKIT HÜCRESİ MİKROKOJENERASYON UYGULAMASININ DENEYSEL VE TEORİK İNCELENMESİ", Isı Bilimi ve Tekniği Dergisi, Vol. 38, No. 1, pp. 73-82.YÜKSEK SICAKLIK PROTON DEĞİŞİM MEMBRAN YAKIT HÜCRESİ MİKROKOJENERASYON UYGULAMASININ DENEYSEL VE TEORİK İNCELENMESİ(2018) Devrim, Yılser; Özgirgin Yapıcı, Ekin; 31329Bu çalışmada, yüksek verimlilikleri ve çevre dostu teknolojiler olmaları sebebiyle tercih edilen, güvenilir güç üretim tekniklerinden biri olan yüksek sıcaklık proton değişim membran (YSPEM) yakıt hücreleri kullanılarak bir evsel mikro-kojenerasyon (birlikte ısı-güç) sistemi tasarlanmıştır. Tasarlanan sistem, YSPEM yakıt hücresi tarafından üretilen elektrik gücü ve faydalı ısının kombine bir şekilde, kullanılmasını içermektedir. Hücrenin çalışması sırasında, yüksek performans ve kararlı güç üretimi sağlanabilmesi için hücre içerisinde üretilen ısının uzaklaştırılması ve hücre içi sıcaklığın sabit kalması gerekmektedir. Bu sebeple tasarlanan yenilikçi soğutma sisteminin atık ısısı, sıcak su ısıtmasında kullanılacak olan ısıl enerjinin teminini sağlamaktadır. Böylelikle toplam verim basit çevrimlere göre yaklaşık iki katına çıkabilmektedir. Çalışma kapsamında tasarlanan 225 W gücünde YSPEM yığını 160°C çalışma sıcaklığında hidrojen ve hava gazları ile test edilmiştir. Çalışması sırasında sıcaklığın hücre içerisinde homojen olarak dağılımı, hücrenin kısa sürede gerekli çalışma sıcaklığına ulaşabilmesi, yakıt hücresinde oluşan ısının hücreden sürekli olarak uzaklaştırılabilmesi için yakıt hücresi yığını soğutucu akışkan (Isı Transfer Yağı 32-Petrol Ofisi) kullanılarak soğutulmuştur. Hücre izolasyon malzemesi seçimi ve kalınlığı, doğal taşınım ve radyasyon yolu ile ısı kaybı hesabıyla belirlenmiştir. Maksimum verim çalışma koşulları için mikro-kojenerasyon sisteminin su giriş çıkış sıcaklıkları, su ve soğutucu akışkan debileri, uygun boru çapı hesabı ve pompa güç hesabı yapılarak nihai sistem tasarlanmıştır. Çalışmada tasarlanan kojenerasyon sisteminde, YSPEM yığınının soğutulması ile açığa çıkan atık ısı, 15-20C’lik şebeke suyunun ısıtılması için kullanılmıştır. Şebeke suyu sıcaklığı yalıtımlı hücre kullanılması durumunda ortalama 50C’ye kadar ısıtılmıştır. Elde edilen veriler yakıt hücresi mikro-kojenerasyon uygulamasının kullanılabilirliğini göstermektedir. Anahtar Kelimler: YSPEM, Yakıt hücresi, Polibenzimidazol membran, Mikro-kojenerasyonConference Object Citation Count: Phurimsak, Chayakom...et all. "Phaseguide assisted liquid lamination for magnetic bead-based assays", 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, 27-31 October 2013, Freiburg, Germany, pp. 1153-1155, 2013.Phaseguide assisted liquid lamination for magnetic bead-based assays(2013) Phurimsak, Chayakom; Yıldırım, Ender; Trietsch, Sebastiaan J.; Hankemeier, Thomas; Tarn, Mark D.; Pamme, Nicole; Vulto, PaulWe demonstrate a simple, pump-free platform for performing rapid magnetic bead-based processes via their transfer through sequentially laminated liquid streams, made possible by the use of phaseguide technology. We have applied this strategy to two on-chip assays: (i) a streptavidin-biotin binding assay, and (ii) a sandwich immunoassay for the detection of C-reactive protein (CRP). Here, functionalized magnetic beads were pulled through alternating lanes of reagents and buffer solution, allowing multiple binding and washing processes to be reduced into a single step, significantly shortening procedural times compared to conventional multi-step bead-based assays.Article Citation Count: Budak, Y.; Özgirgin Yapıcı, E.; Devrim, Y. (2018). "Investigation Of Working Temperature Effect On Micro-Cogeneration Application Of Proton Exchange Membrane Fuel Cells", Hittite Journal of Science and Engineering, Vol.5, pp.25-32.Investigation Of Working Temperature Effect On Micro-Cogeneration Application Of Proton Exchange Membrane Fuel Cells(2018) Budak, Yağmur; Özgirgin Yapıcı, Ekin; Devrim, Yılser; 31329I n this study, micro-cogeneration application is used to increase the efficiency of Proton Exchange Membrane Fuel Cell (PEMFC) systems and effect of different operation temperatures on system performance is observed. For this reason, two different PEMFC systems were comparatively studied operating at 70o C and 160o C, respectively. Micro-cogeneration system design has done considering experimentally determined current density, power and temperature values. Since the amount of heat extracted from each PEMFC system is different related to the operating temperatures, different heat transfer fluids have been used for the cooling systems. These systems are designed for utilization of electricity and hot water for Atılım University Hydrogen Energy Laboratory. Heat loss calculation is made for the laboratory and thermal energy needed for heating the laboratory is calculated. Parallel to the design calculations, simple payback times for PEMFCs with micro-cogeneration applications were determined. LT-PEMFC and HT-PEMFC systems have 402 W and 456 W thermal powers respectively and 87.4 % and 92.8 % total cogeneration efficiencies were calculated for each system respectively. For each system maximum water temperatures and flow rates are calculated as a result of micro-cogeneration application. HT-PEMFC system has found to be capable of higher amount of heating. Even LT-PEMFC system has a lower thermal power and efficiency; it is determined to be more economical and has a lower pay pack time then HT-PEMFC system. For both systems, necessary number of stacks to be used for laboratory heating is calculated as four.Conference Object Citation Count: Yavuz, S.; Himmetoğlu, Selçuk. "Neck protection in autonomous car crashes", 24thInternational Scientific Conference on Transport Means 2020, Kaunas, Litvanya, 30 Eylül - 02 Ekim 2020, pp. 147-152.Neck protection in autonomous car crashes(2020) Yavuz, S.; Himmetoğlu, SelçukAll rights reserved.Autonomous cars which are expected to be on the market in the upcoming years, present new challenges to restraint system design since unconventional seating plans can put the occupants at more risk. For instance, an occupant sitting on a rear facing seat can experience higher risk of whiplash in a frontal impact considering the fact that statistically frontal impacts do happen at higher severities than rear impacts as seen in the crash test conditions of US NCAP. In this study, an improvement to car seat design is presented in which the seatback is automatically rotated into a more upright position prior to impact in order to increase the energy absorbing potential of the seatback. The study involves computer simulation of a seat-occupant system to demonstrate the benefits of the proposed system.
