SDG 7 · Erişilebilir ve Temiz Enerji · SDG

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MakaleAçık Erişim2022/r/munzur/6485
Failure-based maintenance planning using bayesian networks: a case study hydraulic turbine
Yucesan, Melih; Kahraman, Gökhan
The assessment of existing infrastructures in the energy sector is of great economic importance for the world. The extension of the power generation life of hydroelectric power plants depends on logical decisions regarding the maintenance and renewal of the equipment. For this purpose, a Bayesian network (BN) has been applied to evaluate the failures in the hydraulic turbine to calculate the failure of the turbine. Forty-six nodes have been identified that will affect the operation of the system. Preventive measures have been established for failures with the highest posterior probability. By creating four different cases, failure probabilities and the change of the main fault have been calculated. How much savings could be made in each case is determined with the maintenance. This proposed framework will be guided in determining the maintenance strategies for hydroelectric power plant operators.
AtıfOpenAlex1
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MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2895
Heat and mass transfer mechanism and control strategy of clean low carbon combustion technology in the novel-type coke oven flue with MILD combustion
Xu, Qian; Shen, Meng; Xie, Kai; Zhang, Hui; Akkurt, Nevzat; Wang, Jiulong; Xiong, Yaxuan; Shi, Kejian; Chen, Xingli; Lv, Qian
In the field of emission reduction, considering the limitations of single clean combustion technology and joint control of carbon emission, the application of Technology of Mixed-Gas (TMG), Technology of Low-calorific Value Gas (TLVG) and Technology of Low Oxygen Combustion (TLOC) in the Novel-type Coke Oven Flue with MILD Combustion (MILD-NCOF) was realized. By adjusting the ratio of coke oven gas to blast furnace gas (α), the ratio of flue gas to gas (β) and the ratio of flue gas to air (γ), the heat and mass transfer mechanism of combustion process in MILD-NCOF was researched, the dual emission control system and the regulation strategy of pollutant and carbon emissions were established. The results showed that with the increase of α, β and γ, the fluidity of gas and the reaction rate of combustible components in the fire path were improved, the heat and mass transfer was enhanced, and the effect of dual emission reduction of pollutants and carbon emissions was improved. When the mixing ratio α was 0.6, Tave was reached at 1594.93 K. The NOx concentration at the outlet was 116.34 mg/m3, and the sum of the molar concentrations of CO and CO2 at the outlet was reduced to 1.440 × 10−1. When the mixing ratio β was 2.4, Tave was reached at 1518.73 K, the NOx concentration at the outlet was 128.42 mg/m3, and the sum of the molar concentrations of CO and CO2 at the outlet was 1.127 × 10−1. When the mixing ratio γ was 0.6, Tave was reached at 1627.28 K, the NOx concentration at the outlet was 142.73 mg/m3, and the sum of the molar concentrations of CO and CO2 was reduced to 1.128 × 10−1, which could meet the dual standards of clean production and low-carbon environmental protection of MILD-NCOF.
AtıfScopus30OpenAlex36
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MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2858
Heat transfer performance by forced convection of microencapsulated phase change material-latent functional thermal fluid flowing in a mini-channels heat sink
Xu, Qian; Zhu, Lidong; Yan, Xinyu; Yang, Jingbin; Wang, Zhaoxiao; Liu, DingHai; Yang, Gang; Chen, Xingli; Akkurt, Nevzat; Liu, Lin
Conventional single-phase coolants have not been able to meet the high cooling requirements of electronic devices. Microencapsulated phase change material-latent functional thermal fluid (MPCM-LFTF), a solid–liquid two-phase cooling medium, has the dual advantages of active liquid cooling and passive phase change material cooling. However, it also increases the power consumption in the mini-channels, and the cooling efficiency of MPCM-LFTF in practical applications needs to be further studied. A new MPCM-LFTF was prepared by paraffin melamine resin MPCM and base fluid (absolute ethanol and deionized water) in this work. The heat transfer performance and hydrodynamic properties were investigated using the dimensionless wall temperature and friction factor, respectively. The efficiency factor was introduced to evaluate the cooling efficiency of MPCM-LFTF in mini-channels. The experimental results showed that the addition of MPCM increased the viscosity of MPCM-LFTF, which increased the friction factor. MPCM-LFTF with a mass fraction of 15 % had the best effect of temperature control and reduced the dimensionless wall temperature by 40.5 %. However, considering the characteristics of flow resistance and improved heat transfer, MPCM-LFTF with a mass fraction of 10 % had the highest cooling efficiency and the efficiency factor was 57.0 % higher than that of the base fluid.
AtıfScopus35OpenAlex36
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MakaleYalnız künye2022Scopus SJRQ2/r/munzur/2742
Ohmic heating: A futuristic method for cooking bulgur
Goksu, Ali; Omac, Basri; Sabancı, Serdal
Bulgur is a nutritious, healthy, and partially cooked food product with long shelf life and produced from wheat grains. In the present study, ohmic heating (OH) was used to cook bulgur as an alternative method to conventional cooking in case of bulgur pilaf due to its advantages including shorter heating time, uniform heat distribution in food, and higher energy efficiency. Bulgur was cooked in 0.1% salt solution to evaluate the effect of OH at various voltage gradients (10, 13, 16, and 19 V/cm) and conventional cooking processes on the textural properties of bulgur and energy consumption. The results showed that for the OH process, the total energy consumption for the cooking of bulgur reduced by approximately 80% compared to that for conventional cooking. In addition, the voltage gradients were significantly related to the cooking time, a crucial parameter for the water absorption of bulgur (p < 0.05). Novelty Impact Statement: Pre-cooked bulgur must be cooked in water by using electric or flame equipment before consumption. Nevertheless, in these systems, the cooking process consumes a pretty long time and causes a vast amount of waste energy. Therefore, alternative methods are needed to save time and energy. Thus, the ohmic heating was used as an alternative cooking process for bulgur prior to consumption.
AtıfScopus3WoS3OpenAlex9
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MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2663
Investigation of the effect of aspect ratio in an enclosure filled with phase change materials and its effect on thermal management of lithium-ion batteries: Applicable for storing solar energy
Akkurt, Nevzat
The numerical and transient behavior of a battery pack (BA-PK) consisting of three battery cells positioned within an air duct is investigated in this work. The BA-PK was connected to a solar system. The inside of the BA-PK is filled with phase change material. The air within the duct moved at a speed of 0.001–0.003 m/s around the BA-PK. The investigation was carried out by altering the dimensions of the BA-PK using COMSOL software. The finite element approach is used to solve the equations. The results of this research indicated that the battery temperature (Tbatt) drops gradually until the surrounding area is filled with molten PCM, but that once the PCM around the battery is entirely frozen, the Tbatt drops abruptly. The use of a larger BA-PK increases the temperature of the exhaust air out of the duct, but reduces the percentage of solid PCM. The Tbatt, as well as the maximum Tbatt and average TPCM within the compartment, are reduced by using a smaller BA-PK. In addition to increasing the quantity of solid PCM, increasing the speed lowers the temperatures of the batteries and PCM, as well as the temperature of the exhaust air.
AtıfScopus7WoS7OpenAlex7
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Derleme MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2626
Floating solar stills and floating solar-driven membranes: Recent advances and overview of designs, performance and modern combinations
Rashid, Farhan Lafta; Al-Obaidi, Mudhar A.; Hussein, Ahmed Kadhim; Akkurt, Nevzat; Ali, Bagh; Younis, Obai
For life to exist on earth, there must be water. Freshwater resources are in short supply due to industrialization and the world's rapid population expansion. Growing water shortage argues that using passive solar stills is the best and most practical solution in the world's arid and semi-arid regions. For applications in distant or rural coastal areas, floating solar stills are an appropriate technique. To provide accessibility to a wider population, the gadget should be constructed using inexpensive materials that are easily accessible nearby. However, the low-cost materials typically do not have the optimum physical characteristics, which reduces the overall performance of solar stills. This study intends to deliver a comprehensive review that summarizes recent research developments and gives a rundown of experimental, numerical, and experimental and numerical studies on floating solar stills and floating solar-driven membranes. This article also looks at a few more setups, researched parameters, and result-finding issues. Research on floating solar is currently ongoing, and recommendations for further research projects have been made in light of the study's findings.
AtıfScopus63OpenAlex59
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MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2564
Evaluation of an ohmic assisted vacuum evaporation process for orange juice pulp
Sabanci, Serdal; Icier, Filiz
An ohmic assisted vacuum evaporation (OAVE) processes was used to concentrate orange juice from 11.4% total soluble solid content (TSSC) to 42% TSSC by applying 13 V/cm constant voltage gradient at different temperatures. The evaporation temperatures were adjusted to 100 °C, 85 °C, 75 °C and 65 °C by setting absolute system pressures of 101.32 kPa, 58 kPa, 39 kPa and 25 kPa, respectively. The total time for the processes, including heating and evaporation, was 34, 40, 48, and 54 min for 100, 85, 75, and 65 °C, respectively. As the evaporation temperature increased, the applied energy required for phase change decreased while maximum current values increased from 0.6 A at 65 °C to 2.52 A at 100 °C. During any given run, the current value increased as the orange juice pulp heated up, but then decreased after it began to boil, leading to a reduction in the rate of heat generation. Increasing evaporation temperature has a positive effect on evaporation rates, energy efficiency, specific water removal ratio (SWRR), exergy efficiency, and Improvement Potential (IP) (p < 0.05). The reduced energy requirement with higher temperature is partially due to reduced work from the vacuum pump at the higher absolute pressure.
AtıfScopus19WoS11OpenAlex16
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MakaleYalnız künye2022Scopus SJRQ2/r/munzur/2532
Investigation of electrical conductivity and bioactive quality during ohmic evaporation process of Apple juice
Karakavuk, Emrah; Goksu, Ali; Sabanci, Serdal
In this study, the evaporation of apple juice was completed with ohmic heating to eliminate some problems with conventional evaporation methods. Ohmic evaporation (OE) was performed at different voltage gradients (13–17 V/cm) for determining electrical conductivity (EC), Hydroxymethylfurfural (HMF), and the total phenolic content (TPC) changes. The voltage gradient affected the total consumed energy, average power, and specific water removal ratio (SWRR) values (p <.05). The shortest time was obtained at 17 V/cm, while the longest time was 13 V/cm during the OE process. The EC value varies between 0.19–0.85 S/m for the voltage gradients. EC and current values increase with temperature until boiling starts, then decrease, and the EC value tends to increase slightly. The TPC value ranged between 587.4–716,4 mg GAE/100 g and was higher at OE than in the conventional process. As a result, the OE process preserves the TPC value of apple juice better while shortening the processing time. Novelty impact statement: The ohmic evaporation process is an alternative method that can be preferred in concentrating fruit juices with consuming less energy and obtaining higher quality products. In addition, considering the phenolic distribution, it was determined in this study that the products were better preserved in the ohmic evaporation process. It is predicted that it will provide important data for both pilot and industrial designs for the establishment of any ohmic evaporation systems.
AtıfScopus6WoS5OpenAlex9
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Derleme MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2529
Inverted Solar Stills: A Comprehensive Review of Designs, Mathematical Models, Performance, and Modern Combinations
Hussein, Ahmed Kadhim; Rashid, Farhan Lafta; Abed, Azher M.; Al-Khaleel, Mohammad; Togun, Hussein; Ali, Bagh; Akkurt, Nevzat; Malekshah, Emad Hasani; Biswal, Uddhaba; Al-Obaidi, Mudhar A.
Fresh water is scarce, making it a worldwide issue. In order to address global freshwater demand, a filtration technique is needed. Solar distillation (SD) that purifies brackish and sub-terranean water has been proven to be a promising green technology. It produces distilled water which can be used as potable water for drinking and other purposes. The designs, operations, and configurations of several inverted solar stills are thoroughly examined in this article. All techniques for solar water distillation to separate saltwater from freshwater have the same fundamental idea. It has been demonstrated that for a specified mass of water in the top basin, the daily output of an inverted absorber double-basin solar still (IASS) grows with increasing water depth in the bottom basin. Nevertheless, as the water depth in the bottom basin rises from 1 cm to 5 cm, the output of an inverted absorber double-basin solar system falls by about 27%. At water depths of 4, 6, and 8 cm, the daily yields from inverted absorber solar stills paired with a refrigeration cycle (RIASS) were 6.4, 10.08, and 9.5 L/day, respectively. The results also showed a substantial rise in water temperature in the inverted absorber solar still as a result of lower bottom heat loss and larger absorptivity. In this study, the emphasis on energy, efficiency, and environmental concerns remains with the modified multi-wick basin-type inverted absorber solar panel. The performance of the inverted trickling solar still was assessed with a 60 ppm average salinity under various sun radiation, feed water flow rate, and existence conditions for natural convection. It was found that the still could produce 2.55 L/day m2 of fresh water, a 15% increase. Brackish water with a salinity of 6000 ppm was used to test the still in November at tilt angles of 47◦ and 32◦ . Condensate production at the specified angles was 2.8 and 2 L/d, respectively. A total output of 6.907, 5.681, and 4.650 kg/m2 /day was also generated using the modified multi-wick basin-type inverted absorber solar still (MMWBIASS) at water depths of 1, 2, and 3 cm, respectively. With black cotton wicks, the MMWBIASS had a total thermal efficiency of 34.04%, 28.17%, and 23.61%.
AtıfScopus43OpenAlex47
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MakaleYalnız künye2022Scopus SJRQ2/r/munzur/2509
Performance evaluation of pectin extraction from grapefruit peel powder by ohmic heating
Goksu, Ali; Duran, Gülseven; Çilingir, Seda; Çevik, Mutlu; Sabanci, Serdal
This study is to investigate the performance properties during the extraction of pectin from grapefruit peel powder using ohmic heating. Pectin extraction was carried out under different voltage gradients (7–11 V/cm), different solid: liquid ratios (1:20–1:60), and different holding times (0–180 min) at constant pH and temperature (80°C). The voltage gradient and solid: liquid ratio affected the time to reach the target temperature. The highest energy efficiency value for all voltage gradients and solid: liquid ratios were obtained in the 0 min holding time, and the efficiency value, which changed between 89.47% and 56.02%, was negatively affected by the increase in the holding time. The exergy efficiency was lower than the energy efficiency and decreased due to the increasing holding time and decreasing voltage gradient. Also, the exergy efficiency was found to be between 73.69% and 18.09%. Determining the performance characteristics of the system will make a significant contribution to pilot and industrial-scale system/process applications for the future. Practical application: In this study, pectin was successfully obtained from grapefruit powder using an ohmic heating system. The operating conditions for the obtained pectin include constant pH (pH:1) and temperature (80°C) but various voltage gradients, solid: liquid ratios, and extraction times. It has been observed that voltage gradient and extraction time were effective on energy efficiency. When looking at exergy efficiency, voltage gradient, solid: liquid ratio, and extraction time were effective. It has been observed that the improvement potential (IP) value calculated for the system decreases depending on the increasing voltage gradient. The results obtained in this study are thought to be an important data source for literature, pilot, and industrial-scale production systems. It has been realized that ohmic heating, which is increasingly used, is an alternative technique for pectin production.
AtıfScopus13WoS12OpenAlex16
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MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2503
Cooling of non-sloped, positively sloped, and negatively sloped arrangements of Li-ion batteries with a phase change material connected to a solar system
Akkurt, Nevzat; Aghakhani, S.; Mahmoud, Mustafa Z.; Abdelrahman, Anas
Three cylindrical Li-ion batteries are simulated using COMSOL Multiphysics in this study. A circular PCM layer is used to cover the batteries. A battery pack connected to a solar system is tested to store energy in a residential building. The PCM is 100% melted at the beginning, and the frozen PCM volume fraction (PVOF) is studied over time. In addition, the temperatures of individual batteries in three different configurations are analyzed at air velocities 1 and 3 mm/s. The three battery configurations included a positive slope, a negative slope, and no slope. The finite element method (FEM) is utilized to derive algebraic equations. The test results are given to the network as training data, and different neural network architectures are tested in terms of the number of layers and the number of neurons in each layer, and finally a structure that has a minimum mean squared error as a network. Battery behavior predictor is selected. Finally, this model is given to the optimization algorithm as an optimization function to investigate the point at which the maximum voltage is obtained. The results showed that the positively sloped battery configuration decreased the temperatures of the batteries, while the non-sloped configuration increased the temperatures. In addition, the positively sloped configuration resulted in more frozen PCM than non-sloped and negatively sloped configurations at a given time. The minimum frozen PCM was observed in the non-sloped configuration. A change in the air velocity from 1 to 3 mm/s increased the frozen PCM and improved the cooling of the batteries.
AtıfScopus15OpenAlex13
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MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2496
Experimental study on heat transfer properties of gravity heat pipes in single/hybrid nanofluids and inclination angles
Wang, Zhaoxiao; Zhang, Hui; Yin, Lei; Yang, Di; Yang, Gang; Akkurt, Nevzat; Liu, Dinghai; Zhu, Lidong; Qiang, Yujie; Yu, Fan
In order to meet the working requirements of heat pipes under complex working conditions and high heat flux density, and propose corresponding thermal management solutions. In this paper, the single and hybrid nanofluids (TiO2-H2O, Al2O3-H2O, Al2O3+TiO2-H2O) with mass fraction of 5% under the gradient of gravity heat pipe at 50°, 60°, 70°, 80°, 90° are studied. The changes in thermal resistance, thermal efficiency and equivalent heat transfer coefficient of water were compared with deionized water. The results are as follows: The overall efficiency of gravity heat pipe ranges from 70% to 85%. Compared with deionized water, the nanofluid can effectively improve the heat transfer. At different inclination angles, the hybrid nanofluid with the same mass fraction shows the reverse trend compared with the single nanofluid by decreasing the thermal resistance of the heat pipe and increasing the heat transfer efficiency. At an inclination angle of 70°, the heat transfer efficiency of the nanofluid Al2O3+TiO2-H2O is 6.8% weaker compared to TiO2-H2O and 4.5% weaker compared to Al2O3-H2O. At a tilt angle of 60°, the heat transfer capacity of Al2O3+TiO2-H2O nanofluid increases by 7.3% compared to TiO2-H2O and by 5.6% compared to Al2O3-H2O.
AtıfScopus47OpenAlex45
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MakaleYalnız künye2022Scopus SJRQ2/r/munzur/2457
A mathematical programming model for facility location optimization of hydrogen production from renewable energy sources
Derse, Onur; Göçmen, Elifcan; Yılmaz, Ebru; Erol, Rızvan
Fossil fuels are the primary energy sources and meet the global energy demands. However, environmental and health problems related with these sources boosted the demand for renewable energy sources. Hydrogen, as an energy carrier has a growing potential for solving these problems. In this article, a mathematical programming model that integrates the production, storage and transportation, safety, location, and staff assignment decisions is presented considering minimization of costs. Although most of the studies focus on location, distribution, storage decisions of hydrogen energy networks, the article also includes production, safety and staff assignment decisions to make this problem more practical. Furthermore, we also investigate the set covering constraint will ensure that each region is covered by minimum number of the hydrogen facilities. The developed model ensures a balance between location, distribution, storage, production, safety and staff decisions by installing two production facilities by assigning total 9 warehouses, 22 tank trucks, 12100 km pipeline, 35 staffs under distance constraint 2000 km in regions 1 and 5. The computational results indicate that the proposed model produces effective solutions for the coverage to all region and minimum total cost for real-case situations.
AtıfScopus20WoS16OpenAlex29
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MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2452
Experimental study on synergistic enhancement of thermal performance of a closed two-phase thermosyphon by a TiO2nanofluid doped with Al2O3
Xu, Qian; Yang, Gang; Jia, Shuhui; Wang, Zhaoxiao; Akkurt, Nevzat; Zhang, Hui; Zhou, Qiang; Shen, Meng; Yang, Di; Zhu, Lidong
The heat transfer performance of two-phase closed thermosyphon solar collectors (TPCTs) can be improved by adding nanoparticles to the conventional working fluid, but it is necessary to ensure good rheological properties while improving the heat transfer performance. Therefore, spherical (TiO2) nanoparticles with good rheological properties and rod-shaped (Al2O3) nanoparticles with high thermal conductivity were mixed and applied to the TPCT. First, the effects of individual factors such as the concentration of nanoparticles and the operating parameters on the thermal performance of the TPCT were investigated and a regression analysis was performed. Then, the joint effect of inclination angle and filling ratio on the thermal performance of TPCT was further investigated by orthogonal experiment. The results show that doping TiO2 with Al2O3 can further improve the thermal performance of TPCT. For the volume concentration of 0.6% of nanoparticles, filling ratio of 50% and inclination angle of 80°, the best heat transfer performance of TPCT was achieved. Compared with the deionized water (DW), the thermal resistance of the single (TiO2-H2O) and hybrid (Al2O3+TiO2-H2O) nanofluid TPCT is reduced by 10.7% and 13.4%, the thermal efficiency is increased by 11.0% and 13.7%, and the equivalent heat transfer coefficient is increased by 16.2% and 18.7%, respectively.
AtıfScopus38OpenAlex41
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MakaleYalnız künye2022Scopus SJRQ1/r/munzur/2422
The influence of battery distance on a hybrid air-cooled cylindrical lithium-ion battery phase change material thermal management system for storing solar energy
Akkurt, Nevzat; Aghakhani, S.; Mahmoud, Mustafa Z.; Tag El Din, ElSayed M.
The cooling of a lithium-ion battery pack made up of three cylindrical batteries in a channel is studied using the finite element technique in this research. The phase change material (PCM) is surrounded by a laminar flow of air. The solid PCM fraction values and the average temperature of each battery and battery pack at various periods were studied by varying the distance between the batteries from 7 to 10 mm and adjusting the speed from 0.1 to 0.3 cm/s. When compared to other batteries surrounding this battery, the left battery had the lowest temperature and the maximum quantity of solid PCM was generated at various periods, according to the findings of this article. At 0.1 cm/s, the distance 7 mm is the greatest and the distance 8 mm is the lowest in the left battery, the distance 10 mm is the largest in the center battery, the distance 8 mm is the lowest in the right battery, and the distance 8 mm generates the least amount of solid PCM in the battery pack. The second and third batteries, as well as the battery pack, have the lowest average temperature across various distances of the batteries due to a distance of 10 mm between them. Increasing the speed from 0.1 to 0.3 cm/s causes the temperature to decrease in a time-dependent manner.
AtıfScopus37OpenAlex38
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MakaleAçık Erişim2021/r/munzur/6683
Experimental Analysis of PV/T Collectors Assisted with PCM for Off-Grid Domestic Applications
Bayrak, Fatih; Oztop, Hakan; Bakır, Eda
An experimental study was carried out to examine the efficiency of solar energy in photovoltaic thermal collectors (PV/T) with energy storage. A photovoltaic thermal collector was used to generate both electrical energy and hot water. The effects of inclination angle of PV/T collectors on power, temperature, energy and exergy values were investigated. Also, effects of cellular shading are tested and discussed. PV/T was compared with the conventional PV/T collector by adding phase change material (PCM) for one of the collectors. In addition, the effect of different shading conditions (small, medium and large circle) on the power and hot water output of the PV/T collector at optimum slope angle were investigated. It is found that 7 ºC temperature differences are occurred in the hot water outlet between the PV/T collector and the PV/T-PCM collector. The highest energy efficiencies of PV/T-PCM collectors are obtained as 73.26%, 84.70% and 68.96% for slope angle 25º, 30º and 35º, respectively. The highest exergy efficiencies of shaded collectors are obtained as 11.92% for PV/T and 23.38% for PV/T-PCM.
AtıfOpenAlex4TR Dizin1
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MakaleYalnız künye2021/r/munzur/6623
Temiz enerji sektörü, teknoloji sektörü ve ham petrol arasındaki yayılım ilişkisi
Ekinci, Ramazan; Gençyürek, Ahmet Galip
Küresel ısınmanın sonucu olarak ortaya çıkan iklim değişikliği yenilenebilir enerjiye diğer bir ifadeyle temiz enerjiye olan ilgiyi artırmıştır. Gelişen teknolojiyle birlikte verimliliğin artması ve maliyetlerin azalması sonucunda da yenilenebilir enerji tüketimi hızlanmıştır. Petrol piyasasının yenilenebilir enerjinin ikamesi olması, teknolojinin de yenilenebilir enerjinin önemli bir girdisi olması nedeniyle teoride yenilenebilir enerjinin her iki değişkenden etkilendiği düşünülmektedir. Yapılan çalışma ile teoride ileri sürülen bu görüş hem ortalamada hem de varyansta nedensellik ilişkisinin tespitine olanak sağlayan Hong (2001) yöntemiyle incelenmek istenmektedir. Temiz enerji sektörü, teknoloji sektörü ve petrol piyasası sırasıyla Willderhill Endeksi (ECO), ArcaTech Endeksi ve WTI tarafından temsil edilmektedir. 2004-2019 döneminin analiz edildiği çalışma sonucunda ortalamada temiz enerji sektöründen petrol piyasasına doğru, varyansta ise; petrol piyasasından temiz enerji sektörüne doğru Granger nedenselliğin olduğu tespit edilmiştir. Kappa-1 yöntemiyle belirlenen varyans kırılma tarihlerinin dikkate alınması sonrasında nedensellik ilişkilerinin varlığında herhangi bir değişim gözlemlenmemiştir. Elde edilen sonuçların araştırmacılara, politika yapıcılara ve yatırımcılara önemli bilgiler sunacağı düşünülmektedir.
AtıfOpenAlex2TR Dizin3
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MakaleAçık Erişim2021/r/munzur/6599
Application Of The Passive House Certification System In Existing Buildings: EnerPHit Certification System
Erdem, Necla Seval; Asikoglu, Ahunur; Altun, Müjde
In order to improve today's conditions and to ensure a healthy life for future generations, different solutions have been sought in different areas around the world and important steps have been taken in this direction. As the building sector is one of the leading sectors in terms of energy consumption, steps towards creating living conditions in comfortable and healthy spaces made by various regulations, directives, etc. started to be taken with studies, while reducing the energy use in buildings. According to the Energy Performance in Buildings Directive-recast published by the European Union in 2010, member states were asked to set and implement their own NZEB (nearly zero energy building) targets. During this period, there has been an increase in the use of existing certification systems whose criteria meet the country's NZEB objectives. In recent years, countries in different climatic zones have started to construct buildings that comply with the Passive House certification system and the EnerPHit certification system, the version used in existing buildings. In the study, specifications have been analyzed in detail and the results achieved over values through 34 different EnerPhit certified buildings in the world, including one in Turkey. With this study, it is aimed to contribute to the literature with the examination the analysis of EnerPHit certification system criteria, the application techniques, potential for Turkey. Reducing the dependence on foreign energy in Turkey with energy efficient improvement of the existing building stock in country, creation of healthy and comfortable and energy consumption costs will be provided.
AtıfOpenAlex2TR Dizin2
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MakaleAçık Erişim2021Scopus SJRQ2/r/munzur/3089
The usage of Ohmic heating in milk evaporation and evaluation of electrical conductivity and performance analysis
Ariç Sürme, Seda; Sabancı, Serdal
Ohmic heating is based on the principle of heating by passing an alternating current through the product between two electrodes and is an increasingly current electrical heating technique in food applications. The main purpose of the present study is to evaporate milk (cow's milk) from 7.85 kg-water/kg-dry matter (DM) content to approximately 3 kg-water/kg-DM content under atmospheric conditions in different voltage gradients and to examine the electrical conductivity (EC) value during the evaporation process. Also, performance evaluation was determined and compared with the traditional method. It was determined that the total process time in the Ohmic heating assisted evaporation (OHAE) process was 31–92.5 min, while in the traditional evaporation process, the total process time was 41.10 ± 2.1 min. The EC value was 0.43–1.89, 0.44–1.89, and 0.44–1.92 S/m for 7, 9, and 11 V/cm, respectively. In the OHAE process, it was determined that as the voltage gradient increased, the energy and exergy efficiency increased. The lowest energy and exergy efficiency values were obtained in the traditional method. In general, OHAE can be applied to milk, and it was a highly efficient process. Practical applications: Ohmic heating is one of the current electrical heating techniques studied in many areas by researchers. In this study, the change in electrical conductivity and performance values during the milk evaporation process was examined and compared with the traditional method. The OHAE process was more efficient than the traditional method in terms of both energy and exergy efficiency. It is thought that this evaluation will contribute as a data source for both industry and pilot-scale designs. Besides, it will contribute data to the literature with the exergy analysis that is limited in the Ohmic heating process. As a result, a concentrated milk sample with high yield and approximately 3 kg water/kg DM content was obtained.
AtıfScopus21WoS16OpenAlex20
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MakaleAçık Erişim2021Scopus SJRQ1/r/munzur/3046
Control of switched reluctance generator in wind power system application for variable speeds
Omaç, Zeki; Cevahir, Ceren
Switched reluctance generators (SRGs) come into prominence in other electrical machines with its simple structure, only stator winding, reliability, high fault tolerance and the possibility of working within wide speed range. These generators are used especially in wind power plants due to their ability to operate in variable speed range and applications of aviation and electric cars. In this study, the control of the SRG was performed. A simulation of SRG driver in Matlab/Simulink was performed and the real-time implementation control of SRG is carried out on DS1103 Ace kit digital signal processor to determine the performance of the SRG. The output voltage of the SRG is controlled by the proportional-integral (PI) voltage controller. As a result, the graphs of change in SRG phases currents and SRG output voltage were obtained according to different parameters. Simulation results compared with experimental results. Consequently, they overlap on experimental results.
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