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Automobile radiator which is one of the vital components used for engine cooling in vehicles is expected to provide higher thermal performance without changing the exterior dimensions of the radiator with the development of engine technology. This situation necessitates changes in both design and operating parameters in the currently used radiator. In the present study, all fundamental parameters affecting the thermal and hydraulic performance of an automobile radiator are evaluated and optimized with statistical methods. Optimization study is carried out using Taguchi and ANOVA methods for two specified objective functions (heat transfer and pressure drop). The order of importance and impact rates for each design and operating parameter, the best and worst working conditions in terms of both target functions are determined. Air velocity, air inlet temperature, coolant inlet temperature, and fin pitch are found to be the most effective parameters on the heat transfer with a contribution ratio of 88%. The best and worst working conditions are obtained for the heat transfer and under these working conditions, they are calculated as 43.68 kW and 1.63 kW, respectively. When the system is examined in terms of the pressure drop, the results show that the coolant flowrate and tube height have a great impact with a contribution ratio of 67.04% and 32.06%, respectively. Lastly, the maximum and minimum pressure drop within the studied operating condition range is determined as 20.68 kPa and 0.12 kPa, respectively.

In this study, the performance of organic Rankine cycle (ORC), which produces electrical energy, was examined by using a geothermal resource with a temperature of 145°C. The fluids used in the syst...

In this study, animal biomass energy potential of Turkey was presented in detail based on the countrywide livestock. Animal biomass resources were examined under three major groups: bovine, small ruminant, and poultry. Bovine animals were described in terms of three different cattle species, buffalo and other species (horse, donkey, camel, mule and pig). Sheep and goat were considered as two subspecies of small ruminant. Poultry consisted of two different chicken species, turkey, goose and duck. The status of animal biomass in Turkey and its exploitation by use of anaerobic digestion and consequent combustion of methane produced for energy production were presented. A detailed analysis was made to determine which animal species has high energy potential of biomass. The potential of energy, waste and the production depending on every single subspecies were indicated in the analyses. The waste coefficients for species were obtained from the biomass energy potential atlas of Turkey and the animal production data reported by the Turkish Statistical Institute. Additionally, energy potential changes in recent years for every single species were calculated. According to the results, bovine animals possess 67.1% of total energy potential, and among bovine animals, cattle has the highest energy potential with 61%. Results indicated that 1.36 million tons of oil equivalent would be exploited by the animal biomass potential of Turkey according to the 2016 data.

There are many factors affecting the Organic Rankine Cycle’s (ORC) performance, such as working fluid selection, evaporator and condenser temperatures, pinch point temperature differences (the minimum temperature difference between refrigerant and the waste heat source (PPTDevap) or cooling water (PPTDcon)), superheating temperature, heat exchanger effectiveness, and isentropic efficiencies of the turbine and pump. In this study, the parameters’ impact weights on the cycle’s efficiency are discussed and comparatively examined based on the statistical analyses. First, the system’s thermodynamic model was established, and variation of the cycle’s thermal efficiency was calculated for different parameters and their different ranges. Next, to obtain the contribution ratios and the order of importance of these parameters, the thermodynamic analysis results were evaluated using two statistical methods: Taguchi and ANOVA. In conclusion, the evaporator and condenser temperature and the turbine efficiency have a large effect on the thermal efficiency of the ORC, and the total impact ratio of these parameters is determined as approximately 70%. However, PPTDevap, PPTDcon and pump efficiency are found to be the least effective parameters. In addition, the best and the worst operating conditions are determined from the statistical analysis and in these operating conditions, the thermal efficiencies of the ORC are obtained as 18.1% and 9.6%, respectively.

Bu calismada, Turkiye’deki iki farkli derece-gun (DG) bolgesinde yer alan illerin optimum yalitim kalinliklari gunes radyasyonu etkisi goz onune alinarak hesaplanmistir. Hesaplamalar isitma, sogutma ve yillik enerji ihtiyaclari dikkate alinarak yapilmistir. Faiz ve enflasyon oraninin disinda sistemin omrunun de hesaba katildigi bir maliyet analizi yapilmistir. Calismanin sonunda her iki il icin optimum yalitim kalinliklari, geri odeme sureleri, tasarruf oranlari, isitma-sogutma enerji yukleri elde edilmis ve farkli iklim kosullarina sahip bu iki ilin karsilastirilmasi yapilmistir. Sonuc olarak optimum yalitim kalinliklari isitma, sogutma ve yillik enerji ihtiyaclari dikkate alindiginda Bayburt’da daha fazla cikmistir. Yatirimin geri odeme suresinin de Bayburt ilinde daha kisa oldugu gorulmustur.

Bu çalışmada dikdörtgen kesitli odun malzemesinin zorlanmış taşınım ileısıtılması işlemi incelenmiştir. Öncelikle akış alanı için korunum denklemleri(Navier Stokes) bir sonlu eleman programı yardımıyla çözülmüştür. Daha sonrayüzeydeki ortalama ısı taşınım katsayısı, türbülans modellerinden Standart k-ɛtürbülans modeli kullanılarak hesaplanmıştır. Isı transferi denklemi zamanabağlı, yüzey sınır şartları kullanılarak iki farklı sonlu eleman programı ileçözülmüştür. Malzeme içerisindeki sıcaklık değerleri 3 farklı hız ile (1 - 1,5- 2 m/s) 200 saniye sonrası için elde edilmiştir. Aynı zamanda Ansys ve Comsolprogramlarında farklı hava sıcaklıkları (50°C -80°C -110°C -140°C) için deanalizler yapılmıştır. Denklemler için matematikselmodel, Fourier ısı iletim kanunu kullanılarak oluşturulmuştur. İki farklıprogram kullanılarak yapılan nümerik analizin sonuçları karşılaştırılmıştır.Ayrıca bu çalışmada elde edilen sonuç ile literatürde bulunan deneysel venümerik çalışmalardan elde edilen sonuçların karşılaştırılması yapılmış veuyumlu olduğu görülmüştür., In this study,convective heating process of wood material with rectangular shape wasexamined. First of all, Navier Stokes equations were solved by using a finiteelement programme for the flow field. After that average heat transfercoefficient on surface was calculated by using Standart k- ɛ Turbulence Model.Heat transfer equation were solved with two different finite element programmesusing boundary conditions at the surface dependent on time. Temperaturedistributions inside the solid were obtained for three different air velocity(1 - 1,5 - 2 m/s) for two hundred seconds. Furthermore, the analysis were madefor different air temperatures (50°C -80°C -110°C -140°C) using Ansys andComsol programmes. The mathematical model for equations was formed by usingfourier heat conduction law. The results of the numerical analysis which obtainfrom the two different programs were compared. Moreover, the results obtainedin this study were compared with the result obtained from a numerical andexperimental studies in the literature and the results were found to becompatible.

WOS:000543104900020 This paper investigates the factors affecting the optimum insulation thickness and its pay-back period, such as heating and cooling energy requirements of building, lifetime, present worth factor, costs of insulation material and installation, costs of energy sources for heating and cooling, heating and cooling system efficiencies, and solar radiation. For this purpose, by considering two cities characterizing the hot and cold climatic conditions, the optimum insulation thickness and its payback period have been calculated and a detailed parametric analysis has been carried out. To achieve practical results, the ranges of the parameters considered in the study include the values typically reported in the literature. The variations in the optimum insulation thickness and the pay-back period with all parameters are presented in graphical form. Finally, order of importance and contribution ratios of the examined parameters on the optimum insulation thickness are determined with the help of Taguchi method. It is found that heating degree-days is the most efficient parameter on the optimum insulation thickness with an impact ratio of 27.33% of the total effect while the least efficient parameter is the efficiency of heating system with an impact ratio of 3.21%.

In the literature, energetic and exergetic performance of Organic Rankine Cycle (ORC) were investigated by various researchers. The working parameters affecting the cycle's performance were determined but the impact weights and the order of importance of these parameters were not discussed with a statistical approach. In this context, nine fundamental process parameters such as working fluid type, pinch point temperature differences in the evaporator and condenser, superheating temperature, evaporation and condensation temperatures, heat exchanger effectiveness, turbine and pump efficiencies have been selected for the statistical evaluation. A comprehensive statistical analysis has been carried out to observe the effect of the parameters on the first and second law efficiencies of the ORC. The impact ratios and order of importance of these parameters on the system's performance indicators have been determined. While Taguchi method is performed to determine the optimum levels of each parameter, ANOVA method is used to obtain the impact weights of the parameters on objective functions. In addition to these methods, Grey Relational Analysis (GRA) method is used to optimize the multi-objective function. Evaporator temperature, turbine efficiency, effectiveness of heat exchanger, condenser temperature are obtained as main process parameters on the multiple performance characteristics of ORC and the impact ratios of these parameters are calculated as 31.37%, 19.53%, 16.64%, and 16.61%, respectively. The best condition for the multiple performance characteristics is determined as A(1)B(1)C(3)D(3)E(3)F(3)G(1)H(3)I(3) and under these operating conditions, the first and second law efficiencies of the system are found as 18.1% and 65.52%, respectively.

There are various factors having an impact on the energetic and exergetic performance (i.e., COP and eCOP) of an absorption refrigeration systems (ARS) such as the temperatures of the generator, condenser, evaporator and absorber, effectiveness of solution, refrigerant and solution-refrigerant heat exchangers and isentropic efficiency of the solution pump. Many studies have focused on these process parameters, but the importance order and contribution ratios of the parameters due to thermodynamic performance have not been determined by using statistical methods. Firstly, in this study, cycles’ thermodynamic model is established and the variation of the COP and eCOP are calculated for different working conditions with different parameters ranges. The effects of these parameters on the COP and eCOP are examined separately on a statistical basis. The importance order of the parameters are determined by using Taguchi and ANOVA methods and the results are compared. Optimum operating conditions are determined by means of statistical analysis for the COP and eCOP. Under these operating conditions, the COP and eCOP of the system are calculated as 0.697 and 0.2829, respectively. Furthermore, for the simultaneous maximization of these two performance indicators, Taguchi-Grey Relational Analysis (GRA) is used. By using this analysis, importance order of the examined parameters on multiple performance characteristics are determined. The absorber and evaporator temperatures are the most efficient parameters on multiple performance characteristics with a contribution ratio of 29.66% and 26.34% of the total effect while the least efficient parameters are the pump efficiency and effectiveness of solution-refrigerant heat exchanger with a contribution ratio of 0.48% and 2.41%, respectively. For the best condition considering the multiple performance characteristics, COP and eCOP of the system are found as 0.6255 and 0.2829, respectively.

In this study, the optimum insulation thickness to be applied to external walls was determined by using the heating degree days method for the different cost approaches. Calculations were made for a sample city in Turkey and extruded polystyrene (XPS) was used as an insulation material. By applying the simple payback method and life-cycle cost analysis, optimum insulation thickness, saving amount and payback period were calculated according to increased insulation thickness. As a result, the optimum insulation thickness was determined as 0.0689 m and 0.0558 m for simple payback method and life-cycle cost analysis, respectively. For the determined insulation thicknesses, the payback periods were varied between 7.09 and 9.23 years. Also, at the optimum insulation thickness, the saving amount was obtained between 20.35 USD/m2 and 35.58 USD/m2 depending on the cost analyses.

Araçlarda yapılan ani fren sonucundadisk balata sistemlerinde ısınma ortaya çıkmaktadır. Özellikle yükseksıcaklıklara ulaşıldığı zaman balata malzemesinde aşınma meydana gelebilir. Budurum fren performansını olumsuz etkilemektedir. Bu çalışmada, disk balatasistemi Comsol programında üç boyutlu olarak modellenmiş ve zamana bağlı nümeriksimülasyonlar yapılmıştır. Ani fren yapıldığı andaki disk balata ısınma süreci farklıaraç hızları için (80, 100 ve 120 km/h) incelenmiştir. Aynı zamanda farklı diskmalzemelerinin (dökme demir, paslanmaz çelik, karbon-karbon kompoziti) frenlemesürecindeki sıcaklık artışı belirlenmiştir. Bununla birlikte araç ağırlığının frensistemi üzerindeki etkisi olup olmadığı tespit edilmiştir. Son olarak disk vebalata arasındaki sürtünme katsayısının ısınma sürecine etkisi nümerik olarak incelenmiştir., As a result of the sudden brake in vehicles, heating isoccurred in the disc brake systems. Especially, when high temperatures arereached, corrosion may occur in the brake pad. This situation affects the brakeperformance negatively. In this study, disc brake system was built three-dimensionallyin Comsol program and time dependent numerical simulations were made. Discbrake heating when sudden braking is applied wasinvestigated for different vehicle velocities (80, 100 and 120 km/h). At thesame time, the temperature increase during the braking process was determined fordifferent disk materials (cast iron, stainless steel, carbon-carboncomposites). Also, it has been determined whether the vehicle weight is aneffect on the brake system. Finally, the effect of friction coefficient betweendisc and pad on the heating process was investigated numerically.

Son yıllarda dünyada enerji tasarrufu konusununartan nüfus ile birlikte ciddi derecede öneme sahip olduğu görülmektedir.Özellikle binalarda yalıtım ile önemli derecede enerji tasarrufu sağlanması bukonuya olan ilgiyi daha da artırmıştır. Bu sebepten ülkemizde uygulamayakonulan yalıtım yönetmeliği ile 2023 yılında en az 10 milyon konutta yalıtım veenerji verimliliği standardının yakalanması hedeflenmektedir. Yapılan çalışmadaTürkiye’deki bütün illere ait 65 yıllık sıcaklık ortalamaları alınarak her biril için optimum yalıtım kalınlıkları araştırılmıştır. Optimum yalıtımkalınlıklarının tespitinde çok konforlu durum şartı göz önündebulundurulmuştur. Sonuçların nümerik olarak elde edilmesi için kolon kirişyapısı Comsol programında 2 boyutlu modellenmiştir. Elde edilen sonuçlara göreTürkiye’nin yalıtım kalınlığı haritası oluşturulmuştur.

Muhendislik uygulamalarinin en onemli ve en cok karsilasilan islemlerinden biri farkli sicakliklardaki iki veya daha fazla akiskan arasindaki isi gecisinin isi esanjorleri ile saglanmasidir. Isi degistiricileri hacim isitilmasinda, iklimlendirme tesislerinde, termik santrallerde, atik isinin geri kazanilmasinda ve kimyasal islemlerde oldukca genis bir uygulama alani bulmaktadir. Bu calismada, ayni isil kapasite, ayni sicak - soguk giris ve cikis sicakliklari ile ayni sicak ve soguk su debileri icin (uc tip) sirasi ile plaka, govde boru ve minyatur boru tipi isi esanjorleri teknik ve ekonomik acidan karsilastirildi.

Strawberry drying was investigated experimentally and numerically in this study. In the experiments, samples of strawberry slices with 1 cm thicknesses were used to investigate the effect of the drying air velocity. 5-hour experiments were conducted for three different velocities (0.5, 1 and 2m/s) at 70°C air temperature. It was observed that increasing the drying air velocity up to 2 m/s decreased the drying duration by 17% on average. Moreover, the data obtained from the experimental study were compared to the numerical results. The results were found compatible with each other. Finally, the effect of air temperature and product thickness on drying was examined numerically., Bu çalışmada çilek kurutulması deneysel ve nümerik olarak incelenmiştir. Deneylerde kurutma hava hızının etkisini incelemek için 1 cm dilim kalınlığındaki çilek örnekleri kullanılmıştır. 70°C hava sıcaklığında üç farklı hız için (0,5-1 ve 2m/s) 5 saatlik deneyler gerçekleştirilmiştir. Kurutma hava hızının 2 m/s ye çıkarılmasının kurutma süresini ortalama %17 azalttığı görülmüştür. Ayrıca deneysel çalışmadan elde edilen veriler nümerik sonuç ile karşılaştırılmıştır. Elde edilen sonuçların birbiri ile uyumlu olduğu görülmüştür. Son olarak hava sıcaklığının ve ürün kalınlığının kurutma üzerine etkisi nümerik olarak incelenmiştir.