The most important parameter which affects the results of building energy analysis is the weather... more The most important parameter which affects the results of building energy analysis is the weather data and it can be obtained by different methods for the same location. Although lots of studies have been conducted for Türkiye, it was seen that the impact of different weather data for the same location has never been investigated. The aims of this study were to compare the heating and cooling demands of the buildings with respect to different weather files. Building loads were calculated using five different meteorological source data. Calculations are made for eight cities which represent heating and cooling dominated climates of Türkiye. Calculation procedure of internal heat gain was explained in detail. All simulations were performed using Energyplus v9.2. The findings of the comparison showed that although some results are similar to each other for some weather files, they could have great variances in the energy analysis also. A common missing meteorological data-filling alg...
TEZ10657Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2014.Kaynakça (s. 163-177) var.xiv, 180 s.... more TEZ10657Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2014.Kaynakça (s. 163-177) var.xiv, 180 s. : res. (bzs. rnk.), tablo ; 29 cm.Bu çalışmanın amacı çeşitli kanal geometrilerindeki akış karakteristiklerini belirlemek ve ısı transferinin iyileştirilmesine kanal geometrilerinin etkisini sayısal ve deneysel olarak araştırmaktır. Çalışmanın tamamı Reynolds 3000 ?Re?6000 aralığında yapılmıştır. İlk aşamada, oluk yüksekliğinin kanal yüksekliğine oranının, s/H ısı transferini iyileştirme ve akış yapısı üzerindeki etkisi incelenmiştir. Bu amaçla üç farklı yükseklik, s/H=0.1, 0.2, 0.3 oranlarında oluklu kanal geometrileri tasarlanarak sayısal çalışmalar gerçekleştirilmiştir. Yapılan çalışma sonucunda ısı transferinin en fazla iyileştirildiği oran belirlenmiştir. Daha sonra, hidrodinamik yapının incelenmesi ve sayısal çözüm bulgularının doğrulanması için deneysel çalışmalar Parçacık görüntülemeli hız ölçüm (PIV) yöntemi ile yapılmıştır. Çalışmalarda üç farklı faz, ?=180?, 90?, 0? açısı kul...
Makine Teknolojileri Elektronik Dergisi (elektronik), 2015
Bu çalışmada kanal içerisine yerleştirilen çeşitli engellerin ısı transferi ve basınç düşümü kara... more Bu çalışmada kanal içerisine yerleştirilen çeşitli engellerin ısı transferi ve basınç düşümü karakteristikleri üzerine etkisi, hidrodinamik olarak tam gelişmiş türbülanslı akış ve sabit ısı akısı sınır şartları varsayılarak sayısal olarak incelenmiştir. Çalışma 10000≤Re≤20000 aralığında yapılmıştır. Yapılan analizlerde sonlu hacimler yöntemi kullanarak çözüm yapan paket program kullanılmıştır. Sayısal hesaplamada standart k-ε metodu kullanılmıştır. Analizler sonucunda ortalama Nusselt sayısı Nu, sürtünme katsayısı f ve toplam ısı transferi iyileştirme faktörü η hesaplanmıştır. Elde edilen sonuçlar daha önce literatürde[14] yapılan çalışmayla mukayese edilmiş, sonuçların uyumlu olduğu gözlemlenmiştir. En etkili ısı transferi iyileştirme oranının düşük Reynolds sayılarında ve üçgen engelde olduğu belirlenmiştir.
Mühendislik bilimleri ve tasarım dergisi, Dec 20, 2021
Kavite akışı içerisinde dönen adyabatik bir silindir varlığının akış yapısı ve ısı transfer üzeri... more Kavite akışı içerisinde dönen adyabatik bir silindir varlığının akış yapısı ve ısı transfer üzerindeki etkisinin incelendiği sayısal bir çalışma gerçekleştirilmiştir. Çalışmada uzunluk ve derinlik oranı (D/L) 2 olan açık bir kavite içerisine 0.025m çapa sahip adyabatik bir silindir yerleştirilmiştir. Silindir kavite içerisinde 11 farklı konuma yerleştirilmiş ve bu konumlarda 6 farklı dönme hızı tanımlanmıştır. Silindir çapı ile tanımlanan Reynolds sayısı 10000 olarak belirlenmiştir. Isı transfer analizi için kavite duvarlarına 10000 W/m 2 değerinde sabit ısı akısı uygulanmış, sonlu hacimler yöntemi kullanılarak çözümlemeler yapılmıştır. Çalışmanın sonuçları kavite içerisinde silindirin kullanılmadığı boş kavite akışı olarak ifade edilmiş olan durum dikkate alınarak incelenmiştir. Boş kavite akışına nispeten silindire farklı konumlarda tanımlanan dönme hızları akış yapısını ve ısı transferini iyileştirici yönde etki sağladığı gözlemlenmiştir.
This paper investigates and compares four commonly used flow transport equation-based cavitation ... more This paper investigates and compares four commonly used flow transport equation-based cavitation models and their applicability to predict the cavitation performance of an industrial centrifugal pump with a helical inducer. The main purpose of this study is to identify, for this specific application, the most appropriate cavitation model and the associated empirical constants. Each cavitation model is reviewed in detail and the uniqueness of each model is outlined. Each cavitation model is incorporated in a computational fluid dynamics code to study the vaporization and condensation transport rate of the fluid. Experimental tests are conducted on a pump system to determine the true cavitation performance in terms of net positive suction head (NPSH). Experimental results are compared to simulation results for different cavitation models to validate cavitation performance predictions, along with the empirical constants. Lastly, bubble formation, cavitation inception, and bubble growth...
Present study numerically investigates the flow field and heat transfer of water in two dimension... more Present study numerically investigates the flow field and heat transfer of water in two dimensional sinusoidal and rectangular corrugated wall channels. Simulations are performed for fully developed flow conditions at inlet sections of the channels that have 12 waves. The temperature of the input fluid is taken to be less than that temperature of wavy walls. The governing continuity, momentum and energy equations are numerically solved using finite volume method based on SIMPLE technique. The investigation covers Reynolds number in the rage of 100-1000. The effects of the distance between upper and lower corrugated walls are studied by varying Hmin/Hmax ratio from 0.3 to 0.5 for keeping wave length and wave amplitude values fixed for both geometries. The effects of the wall geometry, Reynolds number and the distance between walls on the flow characteristics, the local Nusselt number and heat transfer are studied. It is found that heat transfer enhancement increases by usage of corru...
The target of the heat exchangers’ design would be high efficient, low cost, lightweight, and sma... more The target of the heat exchangers’ design would be high efficient, low cost, lightweight, and small size by including studies of heat transfer enhancement. In order to achieve these goals, studies on nano fluids has been significantly increased to enhance heat transfer. It has always been claimed that if the nano sized particles are added into a fundamental fluid (i.e., water, ethylene, glycol, lubricating oil, etc.), obtained nano fluid would efficiently transfer the heat because of its high thermal conductivity. However, the heat transfer mechanism of nano fluids has not been clearly comprehended so far, and it would induce contradictory results. Therefore, in order to determine several thermo-physical properties of nano fluids such as density, viscosity, and thermal conductivity, both numerical and experimental studies have been summarized with considering one and two-phase flows in this study.
In this study, the TUBITAK’s budget that was distributed to universities in one year is analyzed.... more In this study, the TUBITAK’s budget that was distributed to universities in one year is analyzed. It has been observed that the amount of the support distributed to developed universities is higher than that of developing universities. However, emerging universities need more equipment, materials and personnel. In this respect, an approach has been presented for balancing the regional distribution of the TUBITAK budget on Turkey. The approach will accelerate their development in developing universities.
International Journal of Mechanical Sciences, 2019
In this paper, details of the flow characteristics in a duct with circular corrugated channel mou... more In this paper, details of the flow characteristics in a duct with circular corrugated channel mounted on walls were investigated both experimentally and numerically. In this research, in order to study the flow behaviors of corrugated ducts, the Particle Image Velocimetry (PIV) technique was used for obtaining extensive information. From this point of view, present experimental work, using the PIV method has been provided significant data about flow in corrugated channels. The aspect ratio of the investigated channel, a/R is selected as 1. The flow characteristics are studied as a function of four different Reynolds numbers, such as Re=2000, 3000, 4000 and 5000. Generally, the target of this comprehensive work is to investigate the flow characteristics and hydrodynamics in the circular corrugated channels in terms of instantaneous and time-averaged flow data such as velocity, streamline, turbulent kinetic energy, Reynolds shear stress and vorticity in the measurement plane. The find...
Energy need has been continuously increased with recent developments of the technology and by hig... more Energy need has been continuously increased with recent developments of the technology and by higher consumption rates of the energy. Decreasing the capacity of the energy resources gives rise to us to find out alternative and recovery systems. Approximately 25% of the used energy at the industrial facilities has been wasted away to the environment. If waste heat can be recovered at the facilities, it would benefit various ways such as both decreasing the cost and increasing the efficiency of the system. In this case study, the exhaust gas of an industrial boiler, 80 MW power-out operated by using natural gas, has been investigated to reveal the potential energy from the heat recovery, and thereby a system is designed for heat recovery purpose in order to benefit the heat from the exhaust of the boiler. In this system, it is aimed to pre-heat the combustion air of the boiler by using the recovery heat. Energy analyses have been conducted in order to determine the exhaust gas tempera...
Çukurova Üniversitesi Mühendislik Fakültesi Dergisi, 2021
Yapılan bu çalışmada endüstriyel sistemlerde en çok kullanılan 2 farklı tesisat bağlantı parçasın... more Yapılan bu çalışmada endüstriyel sistemlerde en çok kullanılan 2 farklı tesisat bağlantı parçasının (L, T) içerisinden nanoakışkan geçirilip, bu bağlantı parçalarının basınç düşüşleri ve basınç kayıp katsayıları sayısal olarak incelenmiştir. Nanoakışkan, temel akışkan su alınarak içerisine farklı konsantrasyonlarda alüminyum, bakır ve titanyum esaslı nanoparçacıkların eklenmesiyle elde edilmiştir. Artan konsantrasyonun basınç kaybı ve akış yapısı üzerinde etkisini incelemek için farklı konsantrasyonlarda farklı nanoakışkanlar incelenmiştir ((A2O3, %0,3, %0.5, %1, %2, %3) ve CuO (%1, %2, %4). Nanoakışkanların termofiziksel özellikleri daha önce yapılmış olan çalışmalardan alınmıştır. Hesaplama sonuçları, literatürdeki sonuçlar ile doğrulanmıştır. Sayısal çözümlemelerde yaygın olarak tercih edilen standart kε ve standart kω türbülans modeli olmak üzere 2 farklı model kullanılmıştır. Elde edilen hesaplar sonucunda incelenen her akışkanda, konsantrasyon arttıkça viskozitenin artışı ile yerel kayıpların da arttığı ortaya konulmuştur. En uygun modelin her iki bağlantı parçası için de standart k-ε olduğu belirlenmiştir.
The region of the isolated bubble regime, in which the bubbling starts, is a very significant pro... more The region of the isolated bubble regime, in which the bubbling starts, is a very significant process for boiling heat transfer. In this study, Artificial Bee Colony algorithm (ABC), which is mainly based on the searching optimum foods sources for the bees, has been used for the optimization of the pool boiling heat transfer calculation. The ABC algorithm is very handy for numerical analysis. The ABC algorithm has been compared with a genetic algorithm as well as other well-known correlation models for pool boiling heat transfer calculation. The ABC algorithm is found to be useful for any boundary conditions. The boundary conditions have been changed in order to improve the results. Results show that the ABC algorithm works faster than the genetic algorithm for the given problem. The ABC algorithm also predicts less average absolute error when compared with other well-known correlations as well as the optimization using the genetic algorithm.
In the present research, heat and fluid flow between the parallel plates has been investigated in... more In the present research, heat and fluid flow between the parallel plates has been investigated in the presence of the forward triangular cross-section rods. The rods are located at different non-dimensional axial distances such as S/L h =1/3, 1/4, and 1/5. In addition, the rods are distributed at two rows having vertical non-dimensional gap spaces of G/H=0, 0.1, and 0.2. Computations have been performed numerically by means of the finite volume approach at various Reynolds numbers in the range from 400 to 1000 based on the channel mean velocity and its hydraulic diameter. Several quantitative and qualitative results are presented in the present study. It is found that all parameters under consideration such as S/L h , G/H, and Re have considerable effects on the flow behavior and heat transfer rate of the advanced channel. In other words, decreasing S/L h (or increasing the rods number) as well as increasing the Reynolds number upgrades the channel heat transfer performance, generally. However, the maximum heat transfer enhancements occur in the case of G/H=0.1 at each S/L h and Re. The maximum heat transfer enhancement of the advanced channel with respect to the conventional parallel plate is 2 obtained with 64.8% under Re=1000, G/H=0.1, and S/L h = 1/5. Moreover, values of the pressure drop penalty and goodness factor have been presented accordingly for all cases under consideration.
In this study the effects of corrugated absorber plate and using aerosol-carbon black nanofluid o... more In this study the effects of corrugated absorber plate and using aerosol-carbon black nanofluid on heat transfer and turbulent flow in solar collectors with double application and air heating collectors, were numerically investigated. The two-dimensional continuity, momentum and energy equation were solved by finite volume and SIMPLE algorithm. In the present investigation all the simulations were done for two different angles of tilt of collector according to horizon, that these angles were the optimum ones for the period of six months setting. As a result the corrugated absorber plate was inspected in the case of triangle, rectangle and sinuous with the wave length of 1 mm and wave amplitude of 3 mm in turbulent flow regime and Reynolds number between 2500 to 4000. Choosing the proper geometry was carried out based on the best performance evaluation criteria (PEC), for collectors with dual usage and increasing the air temperature from collector inlet to outlet for air heating collector. The results revealed that using corrugated absorber plate has a considerable influence on flow field and heat transfer. For all times of the year the highest PEC was obtained for corrugated Sinusoidal model, however the highest temperature increase from inlet to outlet was obtained for rectangular corrugated model. Also it was understood that in the case of using air as a base fluid, whether for the case of temperature increment from inlet to outlet or the highest PEC, the optimum Reynolds is 2500. For each of the corrugated absorber plate with sinusoidal and rectangular models, the carbon black nanoparticles were added to air base fluid in volume fractions of 0.1% to1%. The results indicated that in sinusoidal model the nanoparticles volume fractions increase leads to heat performance coefficient increase and the best heat performance conditions were attained in volume fraction of 1% and Reynolds number of 4000 for both six months period. In rectangular corrugated model using nanofluid and Reynolds number increase do not worth and lead to outlet temperature decrease. Therefore for this model using air and Reynolds number of 2500 is recommended.
The study of quantitative visualization of flow hydrodynamics, turbulent flow characteristics and... more The study of quantitative visualization of flow hydrodynamics, turbulent flow characteristics and time-dependent development and disappearance of vortices in cavities of corrugated channel regarding enhancements of heat transfer is limited in the literature. For this reason, the aim of the work is to search the effects of two different phase shifts, φ (i.e. 90°, 0°) of corrugated channels on flow hydrodynamics and the rate of heat transfer for Reynolds numbers varying from 3x10 3 to 6x10 3. The technique of particle image velocimetry (PIV) which has the capability of observing turbulent unsteady flows and provide instantaneous velocity vectors covering defined flow fields were employed. An effective fluid mixture occurs between the core and the separated flow regions due to the occurrence of a rapid vortex shedding downstream of the entrance of cavities. Along the lower and upper sides of hollow spaces, these shedding vortices spin either counterclockwise or clockwise to stimulate entrainment. In addition, the effects of turbulent flow hydrodynamics on convective heat transfer were also investigated numerically. Numerical results of flow hydrodynamic were found to be consistent with the experimental results. Heat transfer augmentation was reported as a conclusion of different parameters including different phase shifts, φ, aspect ratios, s/H and Reynolds numbers, Re.
The aim of the study is to determine the flow characteristics of corrugated duct. The whole study... more The aim of the study is to determine the flow characteristics of corrugated duct. The whole study has been conducted for Reynolds numbers, Re=4000 and 6000. The corrugated duct geometry was designed for aspect ratios, s/H=0.3 and phase shift angle, φ=180. Variations in flow characteristics of corrugated duct were investigated using the Particle Image velocimetry (PIV) technique. Time-averaged velocity distributions, patterns of streamline and corresponding turbulent statistics were determined. Augmentation of the Reynolds number leads to an increase in velocity due to the sharp corner edges of cavity. Dimensionless turbulent kinetic energy, <TKE> contours indicate that the magnitude of turbulent kinetic energy, <TKE> increases as a result of sharp corner edges of the cavities. High rate of momentum transfer is expected due to an increase of turbulence intensity.
Öz Yapılan bu çalışmada endüstriyel sistemlerde en çok kullanılan iki farklı tesisat bağlantı ela... more Öz Yapılan bu çalışmada endüstriyel sistemlerde en çok kullanılan iki farklı tesisat bağlantı elamanının (ani daralma ve ani genişleme) içerisinden nanoakışkan geçirilerek bu bağlantı parçalarının basınç düşüşleri ve kayıp katsayıları sayısal olarak incelenmiştir. Nanoakışkan, temel akışkan su alınarak içerisine farklı konsantrasyonlarda alüminyum, bakır ve titanyum esaslı nanoparçacıkların eklenmesiyle elde edilmiştir. Artan konsantrasyonun basınç kaybı ve akış yapısı üzerinde etkisini incelemek için farklı konsantrasyonlarda farklı nanoakışkanlar incelenmiştir. Nanoakışkanların termofiziksel özellikleri daha önce yapılmış olan çalışmalardan alınmıştır. Hesaplama sonuçları, literatürdeki sonuçlar ile doğrulanmıştır. Sayısal çözümlemelerde yaygın olarak tercih edilen Standart k-ε ve Standart k-ω türbülans modeli olmak üzere 2 farklı türbülans modeli kullanılmıştır. Elde edilen hesaplar sonucunda incelenen her akışkanda, konsantrasyon arttıkça viskozitenin artışı ile yerel kayıpların da arttığı ortaya konulmuştur. En uygun türbülans modelinin bütün bağlantı parçaları için k-ε olduğu belirlenmiştir.
The most important parameter which affects the results of building energy analysis is the weather... more The most important parameter which affects the results of building energy analysis is the weather data and it can be obtained by different methods for the same location. Although lots of studies have been conducted for Türkiye, it was seen that the impact of different weather data for the same location has never been investigated. The aims of this study were to compare the heating and cooling demands of the buildings with respect to different weather files. Building loads were calculated using five different meteorological source data. Calculations are made for eight cities which represent heating and cooling dominated climates of Türkiye. Calculation procedure of internal heat gain was explained in detail. All simulations were performed using Energyplus v9.2. The findings of the comparison showed that although some results are similar to each other for some weather files, they could have great variances in the energy analysis also. A common missing meteorological data-filling alg...
TEZ10657Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2014.Kaynakça (s. 163-177) var.xiv, 180 s.... more TEZ10657Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2014.Kaynakça (s. 163-177) var.xiv, 180 s. : res. (bzs. rnk.), tablo ; 29 cm.Bu çalışmanın amacı çeşitli kanal geometrilerindeki akış karakteristiklerini belirlemek ve ısı transferinin iyileştirilmesine kanal geometrilerinin etkisini sayısal ve deneysel olarak araştırmaktır. Çalışmanın tamamı Reynolds 3000 ?Re?6000 aralığında yapılmıştır. İlk aşamada, oluk yüksekliğinin kanal yüksekliğine oranının, s/H ısı transferini iyileştirme ve akış yapısı üzerindeki etkisi incelenmiştir. Bu amaçla üç farklı yükseklik, s/H=0.1, 0.2, 0.3 oranlarında oluklu kanal geometrileri tasarlanarak sayısal çalışmalar gerçekleştirilmiştir. Yapılan çalışma sonucunda ısı transferinin en fazla iyileştirildiği oran belirlenmiştir. Daha sonra, hidrodinamik yapının incelenmesi ve sayısal çözüm bulgularının doğrulanması için deneysel çalışmalar Parçacık görüntülemeli hız ölçüm (PIV) yöntemi ile yapılmıştır. Çalışmalarda üç farklı faz, ?=180?, 90?, 0? açısı kul...
Makine Teknolojileri Elektronik Dergisi (elektronik), 2015
Bu çalışmada kanal içerisine yerleştirilen çeşitli engellerin ısı transferi ve basınç düşümü kara... more Bu çalışmada kanal içerisine yerleştirilen çeşitli engellerin ısı transferi ve basınç düşümü karakteristikleri üzerine etkisi, hidrodinamik olarak tam gelişmiş türbülanslı akış ve sabit ısı akısı sınır şartları varsayılarak sayısal olarak incelenmiştir. Çalışma 10000≤Re≤20000 aralığında yapılmıştır. Yapılan analizlerde sonlu hacimler yöntemi kullanarak çözüm yapan paket program kullanılmıştır. Sayısal hesaplamada standart k-ε metodu kullanılmıştır. Analizler sonucunda ortalama Nusselt sayısı Nu, sürtünme katsayısı f ve toplam ısı transferi iyileştirme faktörü η hesaplanmıştır. Elde edilen sonuçlar daha önce literatürde[14] yapılan çalışmayla mukayese edilmiş, sonuçların uyumlu olduğu gözlemlenmiştir. En etkili ısı transferi iyileştirme oranının düşük Reynolds sayılarında ve üçgen engelde olduğu belirlenmiştir.
Mühendislik bilimleri ve tasarım dergisi, Dec 20, 2021
Kavite akışı içerisinde dönen adyabatik bir silindir varlığının akış yapısı ve ısı transfer üzeri... more Kavite akışı içerisinde dönen adyabatik bir silindir varlığının akış yapısı ve ısı transfer üzerindeki etkisinin incelendiği sayısal bir çalışma gerçekleştirilmiştir. Çalışmada uzunluk ve derinlik oranı (D/L) 2 olan açık bir kavite içerisine 0.025m çapa sahip adyabatik bir silindir yerleştirilmiştir. Silindir kavite içerisinde 11 farklı konuma yerleştirilmiş ve bu konumlarda 6 farklı dönme hızı tanımlanmıştır. Silindir çapı ile tanımlanan Reynolds sayısı 10000 olarak belirlenmiştir. Isı transfer analizi için kavite duvarlarına 10000 W/m 2 değerinde sabit ısı akısı uygulanmış, sonlu hacimler yöntemi kullanılarak çözümlemeler yapılmıştır. Çalışmanın sonuçları kavite içerisinde silindirin kullanılmadığı boş kavite akışı olarak ifade edilmiş olan durum dikkate alınarak incelenmiştir. Boş kavite akışına nispeten silindire farklı konumlarda tanımlanan dönme hızları akış yapısını ve ısı transferini iyileştirici yönde etki sağladığı gözlemlenmiştir.
This paper investigates and compares four commonly used flow transport equation-based cavitation ... more This paper investigates and compares four commonly used flow transport equation-based cavitation models and their applicability to predict the cavitation performance of an industrial centrifugal pump with a helical inducer. The main purpose of this study is to identify, for this specific application, the most appropriate cavitation model and the associated empirical constants. Each cavitation model is reviewed in detail and the uniqueness of each model is outlined. Each cavitation model is incorporated in a computational fluid dynamics code to study the vaporization and condensation transport rate of the fluid. Experimental tests are conducted on a pump system to determine the true cavitation performance in terms of net positive suction head (NPSH). Experimental results are compared to simulation results for different cavitation models to validate cavitation performance predictions, along with the empirical constants. Lastly, bubble formation, cavitation inception, and bubble growth...
Present study numerically investigates the flow field and heat transfer of water in two dimension... more Present study numerically investigates the flow field and heat transfer of water in two dimensional sinusoidal and rectangular corrugated wall channels. Simulations are performed for fully developed flow conditions at inlet sections of the channels that have 12 waves. The temperature of the input fluid is taken to be less than that temperature of wavy walls. The governing continuity, momentum and energy equations are numerically solved using finite volume method based on SIMPLE technique. The investigation covers Reynolds number in the rage of 100-1000. The effects of the distance between upper and lower corrugated walls are studied by varying Hmin/Hmax ratio from 0.3 to 0.5 for keeping wave length and wave amplitude values fixed for both geometries. The effects of the wall geometry, Reynolds number and the distance between walls on the flow characteristics, the local Nusselt number and heat transfer are studied. It is found that heat transfer enhancement increases by usage of corru...
The target of the heat exchangers’ design would be high efficient, low cost, lightweight, and sma... more The target of the heat exchangers’ design would be high efficient, low cost, lightweight, and small size by including studies of heat transfer enhancement. In order to achieve these goals, studies on nano fluids has been significantly increased to enhance heat transfer. It has always been claimed that if the nano sized particles are added into a fundamental fluid (i.e., water, ethylene, glycol, lubricating oil, etc.), obtained nano fluid would efficiently transfer the heat because of its high thermal conductivity. However, the heat transfer mechanism of nano fluids has not been clearly comprehended so far, and it would induce contradictory results. Therefore, in order to determine several thermo-physical properties of nano fluids such as density, viscosity, and thermal conductivity, both numerical and experimental studies have been summarized with considering one and two-phase flows in this study.
In this study, the TUBITAK’s budget that was distributed to universities in one year is analyzed.... more In this study, the TUBITAK’s budget that was distributed to universities in one year is analyzed. It has been observed that the amount of the support distributed to developed universities is higher than that of developing universities. However, emerging universities need more equipment, materials and personnel. In this respect, an approach has been presented for balancing the regional distribution of the TUBITAK budget on Turkey. The approach will accelerate their development in developing universities.
International Journal of Mechanical Sciences, 2019
In this paper, details of the flow characteristics in a duct with circular corrugated channel mou... more In this paper, details of the flow characteristics in a duct with circular corrugated channel mounted on walls were investigated both experimentally and numerically. In this research, in order to study the flow behaviors of corrugated ducts, the Particle Image Velocimetry (PIV) technique was used for obtaining extensive information. From this point of view, present experimental work, using the PIV method has been provided significant data about flow in corrugated channels. The aspect ratio of the investigated channel, a/R is selected as 1. The flow characteristics are studied as a function of four different Reynolds numbers, such as Re=2000, 3000, 4000 and 5000. Generally, the target of this comprehensive work is to investigate the flow characteristics and hydrodynamics in the circular corrugated channels in terms of instantaneous and time-averaged flow data such as velocity, streamline, turbulent kinetic energy, Reynolds shear stress and vorticity in the measurement plane. The find...
Energy need has been continuously increased with recent developments of the technology and by hig... more Energy need has been continuously increased with recent developments of the technology and by higher consumption rates of the energy. Decreasing the capacity of the energy resources gives rise to us to find out alternative and recovery systems. Approximately 25% of the used energy at the industrial facilities has been wasted away to the environment. If waste heat can be recovered at the facilities, it would benefit various ways such as both decreasing the cost and increasing the efficiency of the system. In this case study, the exhaust gas of an industrial boiler, 80 MW power-out operated by using natural gas, has been investigated to reveal the potential energy from the heat recovery, and thereby a system is designed for heat recovery purpose in order to benefit the heat from the exhaust of the boiler. In this system, it is aimed to pre-heat the combustion air of the boiler by using the recovery heat. Energy analyses have been conducted in order to determine the exhaust gas tempera...
Çukurova Üniversitesi Mühendislik Fakültesi Dergisi, 2021
Yapılan bu çalışmada endüstriyel sistemlerde en çok kullanılan 2 farklı tesisat bağlantı parçasın... more Yapılan bu çalışmada endüstriyel sistemlerde en çok kullanılan 2 farklı tesisat bağlantı parçasının (L, T) içerisinden nanoakışkan geçirilip, bu bağlantı parçalarının basınç düşüşleri ve basınç kayıp katsayıları sayısal olarak incelenmiştir. Nanoakışkan, temel akışkan su alınarak içerisine farklı konsantrasyonlarda alüminyum, bakır ve titanyum esaslı nanoparçacıkların eklenmesiyle elde edilmiştir. Artan konsantrasyonun basınç kaybı ve akış yapısı üzerinde etkisini incelemek için farklı konsantrasyonlarda farklı nanoakışkanlar incelenmiştir ((A2O3, %0,3, %0.5, %1, %2, %3) ve CuO (%1, %2, %4). Nanoakışkanların termofiziksel özellikleri daha önce yapılmış olan çalışmalardan alınmıştır. Hesaplama sonuçları, literatürdeki sonuçlar ile doğrulanmıştır. Sayısal çözümlemelerde yaygın olarak tercih edilen standart kε ve standart kω türbülans modeli olmak üzere 2 farklı model kullanılmıştır. Elde edilen hesaplar sonucunda incelenen her akışkanda, konsantrasyon arttıkça viskozitenin artışı ile yerel kayıpların da arttığı ortaya konulmuştur. En uygun modelin her iki bağlantı parçası için de standart k-ε olduğu belirlenmiştir.
The region of the isolated bubble regime, in which the bubbling starts, is a very significant pro... more The region of the isolated bubble regime, in which the bubbling starts, is a very significant process for boiling heat transfer. In this study, Artificial Bee Colony algorithm (ABC), which is mainly based on the searching optimum foods sources for the bees, has been used for the optimization of the pool boiling heat transfer calculation. The ABC algorithm is very handy for numerical analysis. The ABC algorithm has been compared with a genetic algorithm as well as other well-known correlation models for pool boiling heat transfer calculation. The ABC algorithm is found to be useful for any boundary conditions. The boundary conditions have been changed in order to improve the results. Results show that the ABC algorithm works faster than the genetic algorithm for the given problem. The ABC algorithm also predicts less average absolute error when compared with other well-known correlations as well as the optimization using the genetic algorithm.
In the present research, heat and fluid flow between the parallel plates has been investigated in... more In the present research, heat and fluid flow between the parallel plates has been investigated in the presence of the forward triangular cross-section rods. The rods are located at different non-dimensional axial distances such as S/L h =1/3, 1/4, and 1/5. In addition, the rods are distributed at two rows having vertical non-dimensional gap spaces of G/H=0, 0.1, and 0.2. Computations have been performed numerically by means of the finite volume approach at various Reynolds numbers in the range from 400 to 1000 based on the channel mean velocity and its hydraulic diameter. Several quantitative and qualitative results are presented in the present study. It is found that all parameters under consideration such as S/L h , G/H, and Re have considerable effects on the flow behavior and heat transfer rate of the advanced channel. In other words, decreasing S/L h (or increasing the rods number) as well as increasing the Reynolds number upgrades the channel heat transfer performance, generally. However, the maximum heat transfer enhancements occur in the case of G/H=0.1 at each S/L h and Re. The maximum heat transfer enhancement of the advanced channel with respect to the conventional parallel plate is 2 obtained with 64.8% under Re=1000, G/H=0.1, and S/L h = 1/5. Moreover, values of the pressure drop penalty and goodness factor have been presented accordingly for all cases under consideration.
In this study the effects of corrugated absorber plate and using aerosol-carbon black nanofluid o... more In this study the effects of corrugated absorber plate and using aerosol-carbon black nanofluid on heat transfer and turbulent flow in solar collectors with double application and air heating collectors, were numerically investigated. The two-dimensional continuity, momentum and energy equation were solved by finite volume and SIMPLE algorithm. In the present investigation all the simulations were done for two different angles of tilt of collector according to horizon, that these angles were the optimum ones for the period of six months setting. As a result the corrugated absorber plate was inspected in the case of triangle, rectangle and sinuous with the wave length of 1 mm and wave amplitude of 3 mm in turbulent flow regime and Reynolds number between 2500 to 4000. Choosing the proper geometry was carried out based on the best performance evaluation criteria (PEC), for collectors with dual usage and increasing the air temperature from collector inlet to outlet for air heating collector. The results revealed that using corrugated absorber plate has a considerable influence on flow field and heat transfer. For all times of the year the highest PEC was obtained for corrugated Sinusoidal model, however the highest temperature increase from inlet to outlet was obtained for rectangular corrugated model. Also it was understood that in the case of using air as a base fluid, whether for the case of temperature increment from inlet to outlet or the highest PEC, the optimum Reynolds is 2500. For each of the corrugated absorber plate with sinusoidal and rectangular models, the carbon black nanoparticles were added to air base fluid in volume fractions of 0.1% to1%. The results indicated that in sinusoidal model the nanoparticles volume fractions increase leads to heat performance coefficient increase and the best heat performance conditions were attained in volume fraction of 1% and Reynolds number of 4000 for both six months period. In rectangular corrugated model using nanofluid and Reynolds number increase do not worth and lead to outlet temperature decrease. Therefore for this model using air and Reynolds number of 2500 is recommended.
The study of quantitative visualization of flow hydrodynamics, turbulent flow characteristics and... more The study of quantitative visualization of flow hydrodynamics, turbulent flow characteristics and time-dependent development and disappearance of vortices in cavities of corrugated channel regarding enhancements of heat transfer is limited in the literature. For this reason, the aim of the work is to search the effects of two different phase shifts, φ (i.e. 90°, 0°) of corrugated channels on flow hydrodynamics and the rate of heat transfer for Reynolds numbers varying from 3x10 3 to 6x10 3. The technique of particle image velocimetry (PIV) which has the capability of observing turbulent unsteady flows and provide instantaneous velocity vectors covering defined flow fields were employed. An effective fluid mixture occurs between the core and the separated flow regions due to the occurrence of a rapid vortex shedding downstream of the entrance of cavities. Along the lower and upper sides of hollow spaces, these shedding vortices spin either counterclockwise or clockwise to stimulate entrainment. In addition, the effects of turbulent flow hydrodynamics on convective heat transfer were also investigated numerically. Numerical results of flow hydrodynamic were found to be consistent with the experimental results. Heat transfer augmentation was reported as a conclusion of different parameters including different phase shifts, φ, aspect ratios, s/H and Reynolds numbers, Re.
The aim of the study is to determine the flow characteristics of corrugated duct. The whole study... more The aim of the study is to determine the flow characteristics of corrugated duct. The whole study has been conducted for Reynolds numbers, Re=4000 and 6000. The corrugated duct geometry was designed for aspect ratios, s/H=0.3 and phase shift angle, φ=180. Variations in flow characteristics of corrugated duct were investigated using the Particle Image velocimetry (PIV) technique. Time-averaged velocity distributions, patterns of streamline and corresponding turbulent statistics were determined. Augmentation of the Reynolds number leads to an increase in velocity due to the sharp corner edges of cavity. Dimensionless turbulent kinetic energy, <TKE> contours indicate that the magnitude of turbulent kinetic energy, <TKE> increases as a result of sharp corner edges of the cavities. High rate of momentum transfer is expected due to an increase of turbulence intensity.
Öz Yapılan bu çalışmada endüstriyel sistemlerde en çok kullanılan iki farklı tesisat bağlantı ela... more Öz Yapılan bu çalışmada endüstriyel sistemlerde en çok kullanılan iki farklı tesisat bağlantı elamanının (ani daralma ve ani genişleme) içerisinden nanoakışkan geçirilerek bu bağlantı parçalarının basınç düşüşleri ve kayıp katsayıları sayısal olarak incelenmiştir. Nanoakışkan, temel akışkan su alınarak içerisine farklı konsantrasyonlarda alüminyum, bakır ve titanyum esaslı nanoparçacıkların eklenmesiyle elde edilmiştir. Artan konsantrasyonun basınç kaybı ve akış yapısı üzerinde etkisini incelemek için farklı konsantrasyonlarda farklı nanoakışkanlar incelenmiştir. Nanoakışkanların termofiziksel özellikleri daha önce yapılmış olan çalışmalardan alınmıştır. Hesaplama sonuçları, literatürdeki sonuçlar ile doğrulanmıştır. Sayısal çözümlemelerde yaygın olarak tercih edilen Standart k-ε ve Standart k-ω türbülans modeli olmak üzere 2 farklı türbülans modeli kullanılmıştır. Elde edilen hesaplar sonucunda incelenen her akışkanda, konsantrasyon arttıkça viskozitenin artışı ile yerel kayıpların da arttığı ortaya konulmuştur. En uygun türbülans modelinin bütün bağlantı parçaları için k-ε olduğu belirlenmiştir.
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