Yazarlar
- Akkurt, Nevzat(24)
- Kahraman, Gökhan(17)
- Sabanci, Serdal(11)
- Tuğan, Volkan(9)
- Işık, Erdem(8)
- Xu, Qian(8)
- Xiong, Yaxuan(7)
- Yucesan, Melih(7)
- Goksu, Ali(6)
- Demir, Yakup(5)
- Gul, Muhammet(5)
- Aghakhani, S.(4)
- Cevik, Mutlu(4)
- Icier, Filiz(4)
- Liu, Lin(4)
- Mahmoud, Mustafa Z.(4)
- Taşgın, Yahya(4)
- Yang, Gang(4)
- Yardımcı, Uğurcan(4)
- Younis, Obai(4)
- Yüzüak, E.(4)
- Yüzüak, G. Durak(4)
- Yüzüak, Gizem Durak(4)
- Çevik, Mutlu(4)
- Özdemir, Osman(4)
- Chen, Xingli(3)
- Ding, Yulong(3)
- Du, Yanping(3)
- Erdem, Necla Seval(3)
- Gunay, Mihriban(3)
- Göçmen, Elifcan(3)
- Hussein, Ahmed Kadhim(3)
- Karakaya, Hakan(3)
- Konurhan, Zekeriya(3)
- Qiang, Yujie(3)
- Sabancı, Serdal(3)
- Wang, Zhaoxiao(3)
- Yilmaz, Mehmet(3)
- Yüzüak, Ercüment(3)
- Zhang, Hui(3)
Yayınlar
- MakaleAçık Erişim2021Scopus SJRQ1Influences of sample shape, voltage gradient, and electrode surface form on the exergoeconomic performance characteristics of ohmic thawing of frozen minced beef
Çokgezme, Ömer Faruk; Döner, Deniz; Çevik, Mutlu; Kemahlıoğlu, Ali Varsın; İçier, Filiz
In the present study, it was aimed to investigate the exergoeconomic performance of ohmic thawing (OT) system during the thawing of frozen minced meat (lean beef). The effects of the sample shape (X: 13 × 4 × 3 cm, Y: 13 × 6 × 2 cm, Z: cylinder with a height of 13 cm and diameter of 3.91 cm), electrode surface form (titanium foil with smooth surface, titanium electrode with needle-type surface and titanium electrode with pyramid-type surface), and voltage gradients (10, 13, and 16 V/cm) were investigated. Lower exergoeconomic values were obtained for the cylindrical shape compared to the rectangular prism. The lowest exergy efficiency value (12.45 ± 0.42), is was obtained for the cylindrical shape at 10 V/cm voltage gradient with titanium foil electrode. The needle-type surface electrodes had higher performance values than other electrodes. The exergoeconomic performance increased as the voltage gradient increased. The lowest unit exergy cost (72.40 ± 2.8) was obtained for rectangular prism shape at 16 V/cm with needle-type electrode. The comprehensive exergoeconomic evaluation in this study exhibited the energy utilization effectiveness and unit exergy cost of OT.
AtıfScopus32WoS28OpenAlex30
İncele - MakaleYalnız künye2021Scopus SJRQ2Investigation of time effect on pectin production from citrus wastes with ohmic heating assisted extraction process
Sabanci, Serdal; Çevik, Mutlu; Göksu, Ali
Pectin is usually extracted by exposure to a high temperature and a specific pH value by conventional methods. However, due to reasons such as low energy efficiency of the process and damage to the pectin, alternative thermal and non-thermal methods are used in the pectin extraction process. In this study, the effect of different processing times (0, 5, 15, 30, 60, 120, 180 min) on pectin extraction was investigated for grapefruit, lemon, and orange samples at 80°C. Besides, it was determined that the electrical conductivity value ranged between 1.46–2.06 S/m during heating, the electrical conductivity value of the pH solution adjusted with sulfuric acid. Accordingly, it was figured out that the total amount of energy consumed increases as the process holding time increases. However, it was determined that there was a decrease in the average power value by turning on–off the system. Practical Application: Pectin is one of the additives used in many areas in the food industry. Pectin is now produced especially from agricultural waste peel. During this production, it is subjected to long processes at certain pH and certain temperatures. With the present study, determination of pectin yield over a wide period of time by using ohmic heating process and total ohmic heating energy was determined. In this way, it is thought that a serious contribution will be made to the literature and industry regarding different industrial agricultural waste peel (orange, grapefruit, lemon) during pectin production.
AtıfScopus36WoS31OpenAlex36İncele - MakaleYalnız künye2021Scopus SJRQ2Effect of roof and ceiling configuration on energy performance of a metamaterial-based cool roof for low-rise office building in China
Tang, Saihong; Akkurt, Nevzat; Zhang, Kai; Chen, Lufang; Ma, Mingquan
Cool roofs with higher solar reflectance and emittance can effectively reduce building energy consumption. However, it is still limited to use at night on account of the development of roof materials during the past decades. The newly proposed metamaterial-based cool roof (MCR) greatly improves the possibility of the radiative cooling in the daytime. To study the influence of MCR on the energy consumption for the office building, a small single-floor office was adopted to analyse the cooling performance of MCR by using EnergyPlus. In this study, the optimization analysis was conducted based on the proposed dimensionless thermal resistance (θRTR) and roof pitch (Δ). Then the annual electricity saving potential of the office building with MCR was evaluated in details based on the selected cities from all five climate zones in China. The results show that more annual electricity saving can be achieved under the optimized values of θR7 = 1.53 and Δ = 20°. Furthermore, more than 15.7% of annual cooling electricity saving can be achieved while the optimized θRTR and Δ are applied.
AtıfScopus13WoS12OpenAlex15İncele - MakaleYalnız künye2021Scopus SJRQ3Comparison of heat transfer and condensation on the walls of buildings constructed with iron profiles versus other classic models
Kahraman, Gökhan
This study aims to present the evaluation of the thermal performance and the amount of condensation on the walls of a building with iron profiles under steady-state conditions. Elazig, situated in the east part of Turkey, was chosen for fieldwork. In this region, minimum average temperature is around 1°C during winter. Calculations are made in a real wall model and three different wall model scenarios. Estimated advantages and disadvantages of these have been investigated. Heat transfer and condensation amount are taken as variables. In four different building component models, the required amount of energy during the heating period is calculated month by month. Calculations reveal the resistance of the wall without application of insulation material with iron profile is higher than of the other three wall types. The wall built with betopen and iron profile saves 37.5% more energy than the wall with bricks. When the iron-profiled wall model is compared with the insulated brick wall, it is observed that energy savings are similar, but calculations show condensation begins on the iron profile wall. Iron profile buildings become popular increasingly in rural areas. As a result of this study, it is observed that iron profile buildings are advantageous in terms of energy saving compared to other building component models. However, condensation is inevitable in wall components of iron profile buildings and so the damage in the buildings is more than just a disadvantage, it is an irreversible result.
AtıfScopus2WoS3OpenAlex3İncele - MakaleYalnız künye2021Scopus SJRQ2Electrical conductivity and performance evaluation of verjuice concentration process using ohmic heating method
Cevik, Mutlu
The verjuice sample (14.5 ± 0.2% total soluble solid [TSS] content) was concentrated (at 102 ± 2°C evaporation temperature) until reach 50% TSS content by applying ohmic heating at 13, 15, 17, and 19 V/cm voltage gradients. The total process times up to 50% TSS content were determined as 2,100, 1,500, 1,200, and 1,020 s for 13, 15, 17, and 19 V/cm, respectively. The electrical conductivity values increased until reach 32% TSS content and then showed a decrease until the final TSS content. The total energy consumption values increased as the voltage gradient decreased. The total power and specific water removal ratio (SWRR) values decreased as the voltage gradient decreased. The efficiency of ohmic heating assisted concentration process increased with the applied voltage gradient and it ranged from 71.27 to 75.22%. By evaluating the effects of ohmic heating conditions applied in the present study on total process time, total energy consumption, and process efficiency, 19 V/cm voltage gradients could be recommended to be optimum evaporation conditions of verjuice concentration in case of decreasing process time and higher energy efficiency. Practical applications: Fruit juices are generally concentrated to extend their shelf life. Therefore, for concentration purposes, various techniques, such as thermal evaporation, freezing methods, and membrane techniques, are applied in the fruit juice industry. This technique has some disadvantages, such as high energy requirements, the formation of undesirable compounds, high initial investment cost, and high failure rate to reach the desired total soluble solid content. The ohmic heating method, which is among the alternative heating methods, has advantages such as high energy efficiency, shorter processing time, higher product quality, and not causing wastewater. As a result of this study, it is thought that the verjuice samples were successfully concentrated up to 50% TSS content by using the ohmic heating method and this method can be used as an alternative method instead of the traditional method due to higher process efficiency and shorter process time.
AtıfScopus23WoS19OpenAlex26İncele - MakaleYalnız künye2021Scopus SJRQ1A new type of two-supply, one-return, triple pipe-structured heat loss model based on a low temperature district heating system
Xu, Qian; Wang, Kang; Zou, Zhenwei; Zhong, Liqiong; Akkurt, Nevzat; Feng, Junxiao; Xiong, Yaxuan; Han, Jingxiao; Wang, Jiulong; Du, Yanping
Based on the design concept of a fourth-generation smart pipe network system, this paper innovatively proposes a new TOTS (Two-supply/One-return, triple pipe structure) arrangement method for district heating systems. Moreover, to accurately predict the heat loss due to the pipeline operation of the multi-pipe system, based on the multipole calculation method, a new heat loss theoretical analytical model for the TOTS was created; additionally, a corresponding three-dimensional numerical simulation model was established, which was analyzed and numerically solved. The results showed that in comparison with thermal loss data measured by Danfoss et al., the above analytical and numerical models have a high accuracy, and the deviation is within 2%. Additionally, through calculations, it was found that the distance between the heating pipes is an important factor that affects the total heat loss from the new multi-control heating system and the actual heat exchange between pipes.
AtıfScopus74OpenAlex75İncele - MakaleAçık Erişim2020Köprü Yapısından Piezoelektrik Tabanlı Enerji Hasadının Sayısal Modellemesi
Polat, Alper; Kouider, Bendine
Köprüler, dengesizlik ve titreşimlere neden olabilecek çeşitli harici yüklere maruz kalabilirler. İyi tarafından bakıldığında, bu tür titreşimler sınırsız bir enerji kaynağı olabilir ve köprüleri izlemek için kullanılan cihazlara güç sağlayabilirler. Mekanik titreşimler, genellikle piezoelektrik tabanlı enerji hasadı olarak bilinen bir işlem olan doğrudan piezoelektrik etkisinden yararlanılarak elektrik enerjisine dönüştürülür. Bu çalışmada bir köprüdeki piezoelektrik enerji kazanımı incelendi. Piezoelektrik enerji toplayıcıları yerleştirilen köprünün bir modeli ANSYS APDL kullanılarak oluşturuldu. Zaman ve frekans bölgelerinde farklı hareketli yüklere sahip çeşitli senaryolar incelendi. Ayrıca, toplayıcıların pozisyonlarının etkisi de araştırıldı. Elde edilen sonuçlar, köprü sistemlerinden titreşim enerjisinin toplanmasının umut verici bir enerji kaynağı olduğunu gösterdi. Ayrıca toplayıcıların maksimum mod şekil genliğine yakın yerleştirilmesi ve hareketli yüklerin doğal frekanslarının toplayıcıların doğal frekansına uyacak şekilde tasarlanması durumunda daha faydalı olabileceğini gösterdi.
AtıfOpenAlex7TR Dizin1
İncele - MakaleAçık Erişim2020Application of Electrical Heating Method for Grape Juice; Ohmic Heating
Sabanci, Serdal
The application of current electrical heating processes is increasing with the developing technology. One of the current electrical heatingmethods as an alternative to the traditional heating process is Ohmic heating. Ohmic heating process is based on the heating principlethat depends on the heat generation in the product by passing alternating current from the solid / liquid substance. Ohmic heating isregarded as a particularly fast, homogeneous and efficient heating. In the present study, with the help of ohmic heating process (13 V /cm at constant voltage gradient), the grape juice is heated from 20 °C to 90 °C and kept at a constant temperature for 4 differentprocessing times (0, 20, 40 and 60 min.) It was aimed to examine some quality characteristics of grape juice. In addition, it was purposedto examine the electrical conductivity value, which is one of the important properties for ohmic heating during the process, and todetermine the total spent energy value for the waiting time at different constant temperature (90 °C). While the heating time of grapejuice from 20 °C to 90 °C was determined as 311 ± 5.01 s, it was stated that the temperature change due to time has a linear trend. Inaddition, it has been determined that as the temperature increases, the electrical conductivity value increases. It has been found that theelectrical conductivity value of grape juice during the heating process varies between 0.144-0.582 S / m. In addition, during the ohmicheating application, as the holding time increases, the total consumed energy value increases but the average power value decreases.The changes in some quality characteristics during the heating of grape juice and holding at constant temperature were investigated. Itwas determined that the amount of Total Phenolic Content (TFC), which is particularly sensitive to heat treatment, in grape juice duringthe heating and waiting periods was between 466-367 mg/L in terms of Galic acid equivalent. In addition, it was found that thehydroxymethylfurfural (HMF) content of grape juice was between 0.60-4.71 ppm depending on the process of holding at differentconstant temperature. As a result, it was concluted that it influences the TFC amount and HMF content, which are among the qualitycriteria, on the waiting time at 90 °C (p <0.05).
- Derleme MakaleAçık Erişim2020Phase change material applications on buildings using whole-building energy simulation tools
Erdem, Necla Seval; Orhon, Ahmet Vefa
In this paper, building energy simulation tools that analyze the applicability of phase change materials used in passive air conditioning applications in different building components and in different climatic conditions and studies using these tools will be discussed. Within the scope of the study, the concepts of phase change materials and energy simulation tools will be examined and selected examples based on the scanning model will be examined according to different environmental conditions and application details. The study is a review that emphasizes the need to match the experimental researches conducted in recent years with energy simulation tools.
AtıfOpenAlex1İncele - MakaleAçık Erişim2020Faults Caused by Cavitation in Hydraulic Power Plants and Solution Methods
Kahraman, Gökhan; Özdemir, Osman
Hydraulic energy is one of the richest and most useful renewable energy sources in the world. For this reason, hydraulic turbines must be operated at optimum efficiency levels against multiple transient situations such as starting and stopping that shorten their useful life and cause fatigue damages in order to generate energy continuously. Pressure variations occur due to flow irregularities in Francis turbines operating at non-optimal partial loads. If the sepressure variations coincide with the natural frequency of a hydraulic, mechanical or structural component, they create high vibrations due to resonance, causing the turbine to operate in an unbalanced (balanced) manner. In this study, the high vibrations of the Francis turbine were monitored with the help of a continuous (online) vibration monitoring system via the cavitation sensor mounted on the turbine adjustment blade and the cavitation vibration effects of the operation in the case of unbalance and the cavitation vibration effect after the imbalance was eliminated. Vibration caused by the cavitation phenomenon in different operating conditions of hydraulic turbines has been shown graphically. In the the graphic given in the last part of the article, it is seen that vibration magnitude is reduced from 2 mm s-1 to 0.5 mm s-1 after the bearing failure is eliminated. This is an important consequence for the hydraulic turbines to be operated in the safe cavitation zone to avoid high vibration levels.
AtıfOpenAlex1TR Dizin1İncele - MakaleYalnız künye2020Investigation of Phase Change Materials on the Use of Trombe Walls for Thermal Energy Storage Systems
Erdem, Necla Seval; Orhon, Ahmet Vefa
This study is conducted to determine the contribution of phase change materials (PCM) and trombe walls (TW) for energy efficiency and it is aimed to identify the criterias that is required during design process. In this study, after giving general definitions about PCM and TW, domestic and foreign literature is searched and application examples are analyzed and compared. It is observed that phase changing trombe wall (PCTW) application alleviated the heavy mass of the wall unlike the traditional methods and PCM increased the efficiency of heating and cooling applications by providing latent heat storage to the massive wall. Although TW has simple application schemes, there are some difficulties in achieving full efficiency. It can be confusing to predict how a PCTW, whose details are decided, will respond to environmental conditions throughout the whole year. Accordingly, considering the criteria that will affect the system before designing the PCTW, it will increase efficiency to see possible problems that the wall may face. In the PCTW system, which is planned to be designed in a specific climate zone, the most efficient result can be achieved by optimization of these criterias.
AtıfOpenAlex1İncele - MakaleYalnız künye2020Scopus SJRQ2Empirical modeling between degree days and optimum insulation thickness for external wall
Kallioğlu, Mehmet Ali; Ercan, Umut; Avcı, Ali Serkan; Fidan, Cihad; Karakaya, Hakan
Insulating is the most effective method that is used to save energy in buildings. Samples from cities from different climatic zones from TS 825 (Turkey) first. Optimum insulation thickness (xopt) analysis is based on two types of insulating and four different fuels (natural gas, coal, fuel oil and electric) of related cities. Cost accounts, payback period and CO2-SO2 emission calculations were performed based on these analyses. Second of all, the relationship between a number of degree day (NDD) and optimum insulation thickness (xopt) was developed by linear, quadratic and cubic correlations. Thirty different mathematical correlations based on different fuel types by using XPS and EPS insulating materials. Twenty-four of these models that were developed were generated peculiar to the fuel type; six of them were generated based on average insulation thickness. R2 values of related correlations are between 0.9989 most and 0.9952 at least as well as it is pretty close to (R ≤ 1) one value. The model among these models is the xopt xopt = a+b (NDD) + c(NDD)2+ d(NDD)3 cubic mathematical model that gives the best average value. a = 0.0036, b = 5E-05, c =–7E-09 and d = 6E-13 are the values for XPS material. Following values are for EPS material; a = 0.0028, b = 5E-13, c =–7E-09 and d = 4E-05. R2 determination coefficient of both two equations is pretty close to 0.9989 and 1; the models obtained are less-than-stellar. Optimum insulation thickness of the area can be known based on the type of material via the number of degree day without the need for long analyses. According to the R2 values, the use of all models is recommended for academic and industrial users.
AtıfScopus21WoS24OpenAlex22İncele - BildiriAçık Erişim2020Using Buck-Boost Rectifier with Single-Phase-Matrix Converter to Reduce Switch Count Operation
Boydak, Merve; Orhan, Ahmet; Caliskan, Abuzer
Recently, the development of advanced power semiconductor devices has made widespread use of power switching circuits and other power electronics applications in commercial and industrial environments. This paper focuses on Single Phase Matrix Converter (SPMC) as a AC-DC boost rectifier and AC-DC buck rectifier. The SPMC was operated in the desired mode using a single driver circuit. Insulated Gate Bipolar Transistors (IGBTs) are used in the power circuit as switching devices to implement SPMC topology. Switching signals are obtained by Sinusoidal Pulse Width Modulation (SPWM) technique. The simulation is carried out using MATLAB / Simulink.
AtıfScopus7WoS3OpenAlex5İncele - MakaleYalnız künye2020Scopus SJRQ2Synthesis and Characterization of Disodium Hydrogen Phosphate Dodecahydrate-Lauric-Palmitic Acid Used for Indoor Energy Storage Floor Units
Xu, Qian; Akkurt, Nevzat; Zou, Zhenwei; Liu, Yang; Feng, Junxiao; Yu, Chuqiao; Ding, Chong; Xiong, Yaxuan; Zhou, Jingzhi; Zang, Yong
Organic and inorganic phase change materials (PCMs) are considered potential materials for thermal energy storage (TES) with different phase change characteristics. In this study, a novel organic-inorganic composite phase change material (PCM) called disodium hydrogen phosphate dodecahydrate-lauric-palmitic acid (D-LA-PACM) was prepared. Expanded graphite (EG) was selected as the support material, and the novel organic-inorganic form-stable PCM called D-LA-PAPCM/EG was prepared using the vacuum adsorption method. Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, leakage testing, melting and solidification cycle testing, thermal conductivity testing, scanning electron microscopy observation of the micromorphology, and other characterization methods were used to study the micro structure and morphology, thermal physical parameters, thermal conductivity, stability of the PCMs, and the comprehensive material properties of D-LA-PAPCM under the composite action of EG. Results indicated that the melting and freezing temperatures and latent heats of D-LA-PAPCM/EG were measured to be 31.6°C and 34.3°C and 142.9 and 142.8 J/g, respectively. Although some of the lauric-palmitic acid (LA-PA) and disodium hydrogen phosphate dodecahydrate (DHPD) separated in the multiple porous structures of EG after 1000 cycles, they could still absorb and release latent heats independently, with D-LA-PAPCM/EG still exhibiting good thermal stability. The thermal conductivity of D-LA-PAPCM/EG was 1.361 W/(mK). Therefore, the material and thermal properties of the prepared D-LA-PAPCM/EG indicate that it could be well used as a feasible material for energy-saving phase change floor units in indoor TES systems.
AtıfScopus18OpenAlex18İncele - MakaleYalnız künye2020Scopus SJRQ3Application of Local Hard Fillet Weld to Repair Damage Caused by Cavitation in Hydroelectric Power Plant
Kahraman, Gökhan; Taşgin, Yahya
Hydroelectric power plants come into prominence worldwide day by day due to their low operating and maintenance costs, environment friendly structure and their use as renewable energy sources. In order to obtain maximum energy from such an important energy source, it is necessary to reduce downtime due to failures. One of the most important failures of hydroelectric power plants is the damage caused to the turbine wheel by cavitation. In this study, a sample with the same material as the turbine wheels of the hydroelectric power plants is provided. The effects of the hard fillet weld on the turbine wheel, which we have applied locally to this material, have been investigated both metallographically and physically. As a result of the research, it is observed that the main material and hard fillet weld are mostly compatible. The damages of the turbine wheel of the hydroelectric power plant have been repaired by applying the same method to the turbine wheel damaged by the cavitation. After 10,000 h of operation, the turbine wheel is inspected again. As a result, it has been determined that the hard fillet weld applied to the turbine wheel surface is resistant to the harmful effects of cavitation.
AtıfScopus2WoS2OpenAlex2İncele - MakaleYalnız künye2020Scopus SJRQ2The effect of graphene oxide on structural, opto-electrical and thermal properties of manganese sillenite (Bi12MnO20) nano-powders
Aydin, C.; Taskin, M.; Aydin, H.
In this study, manganese sillenite nano-powders were produced by hydrothermal method by adding graphene oxide in different mass amounts. Structural, morphological, thermal, optical and electrical properties of the obtained undoped and graphene-oxide-doped samples were investigated. XRD results showed that the produced samples had nano-sizes and the crystal sizes changed with the addition of graphene oxide. SEM and TEM images showed that the microstructures of the samples were nano-sized and composed of randomly oriented particles without orientation relationship between them. From FT-IR spectra of the samples, chemical properties and bond structures were determined. With the help of thermal analysis measurements, reactions in the sample structures at increasing temperatures, reaction temperatures, reaction energies and total mass losses were determined. The forbidden energy ranges of the samples decreased at significant rates with the addition of graphene oxide. By checking the P–E hysteresis cycles, the samples are understood to show ferroelectric properties. Dielectric measurements and temperature-dependent electrical conductivity measurements of the produced nano-powders confirmed that the samples exhibited semiconductor behaviour. The obtained results showed that manganese sillenites can be synthesised by low-temperature hydrothermal method and physical, chemical and thermal properties can be controlled by adding different amounts of graphene oxide for use in electronic and energy applications.
AtıfScopus6WoS6OpenAlex6İncele - MakaleYalnız künye2020Scopus SJRQ1Study on model uncertainty of water source heat pump and impact on decision making
Zhang, Ying; Akkurt, Nevzat; Yuan, Jiaqi; Xiao, Ziwei; Wang, Qianjiang; Gang, Wenjie
Water source heat pump systems are widely used for cooling and heating due to high efficiency. The energy source can be surface water or underground water. Accurate modeling of water source heat pump systems is the basis for performance prediction, design and control optimization. However, various heat pump models are available to predict the system performance and results obtained can be very different under different models due to the model uncertainty. Without considering these uncertainties, the performance of water source heat pump systems would be overestimated or underestimated and the decision making would be affected. This paper attempts to quantify the model uncertainty of water source heat pump and its impact on the system performance. Thirteen commonly-used models are selected and validated using the manufacture data. By importing these models into the water source heat pump system, the impact of heat pump model uncertainty on the system performance is quantified. It shows that the model uncertainty can result in a deviation of up to 30% in the annual energy consumption. The energy saving potential of water source heat pump systems can vary from -18.43% to 14.78% compared with the chillers & boiler in the hot summer and cold winter area. The priority of water source heat pump systems is also controversial. The difference in the annual average coefficient of performance of the system can be up to 1.22. It demonstrates that the model uncertainty of water source heat pumps affects the system performance significantly and should be taken into account in building energy prediction and design optimization. The models considering the correction of part load ratio are recommended.
AtıfScopus40WoS34OpenAlex45İncele - MakaleYalnız künye2020Scopus SJRQ1Techno-economic analyses of multi-functional liquid air energy storage for power generation, oxygen production and heating
Wang, Chen; Akkurt, Nevzat; Zhang, Xiaosong; Luo, Yimo; She, Xiaohui
Liquid air energy storage (LAES) is increasingly popular for decarbonizing the power network. At off-peak time, ambient air after purification is liquefied and stored; at peak time, the liquid air is discharged to generate power. One of the key challenges for the LAES system is the lower economic benefit as peak electricity is usually the only source of income, leading to a longer payback period of ~15 years. To address this issue, this paper, for the first time, proposes a multifunctional LAES system, which not only generates peak electricity but also provides pure oxygen and heating. The proposed system is composed of an air separation unit (ASU), a nitrogen liquefaction unit (NLU) and a power generation unit (PGU). Thermodynamic and economic analyses are carried out on the proposed system. Compared with the baseline LAES system (NLU + PGU), the multifunctional LAES system has a lower round trip efficiency of ~0.39 due to the extra electricity consumption by the ASU. However, it shows a much better economic performance with additional benefits from pure oxygen and heating. In a project life-span of 30 years, the multifunctional LAES system (10 MW/80 MWh) has a short payback period of ~5.7 years. Furthermore, it has a savings-to-investment ratio of 3.12, which is ~153% higher than that of the baseline LAES system. Investigation on the system operation strategy suggests that the ASU should operate at full time. The proposed system provides a feasible way to improve the economic benefits of the LAES system, thus promoting its wide applications.
AtıfScopus82OpenAlex86İncele - MakaleYalnız künye2020Scopus SJRQ1ENHANCEMENT OF THE PERFORMANCE OF SOUR CHERRY JUICE CONCENTRATION PROCESS IN VACUUM EVAPORATOR BY ASSISTING OHMIC HEATING SOURCE
Sabanci, Serdal; Icier, Filiz
Sour cherry juice was concentrated to 65% TSS content by using ohmic heating assisted vacuum evaporation (OVE) at voltage gradients (10, 12, 14 V/cm) and vacuum evaporation (VE). The change of performance efficiencies (energy/exergy) of OVE process depending on the voltage gradient applied and the increase in TSS content during the process were investigated by taking into account of both process and system boundaries, and compared with those of VE process. During this process, total energy consumption decreased as the voltage gradient increased, but it increased as TSS content increased. System boundary based efficiencies were lower than process based ones. Maximum efficiency was obtained for 14 V/cm. Improvement potential values increased as TSS content increased but the voltage gradient increased. The assistance of ohmic heating to VE increased the performance of the evaporation process in terms of energy and exergy efficiencies, and decreased the improvement requirements of the system.
AtıfScopus31WoS24OpenAlex31İncele - MakaleYalnız künye2020Scopus SJRQ3Increasing the Power Generation by Raising the Capacity of the Thrust Bearing Oil Cooling System in Hydroelectric Power Plants
Kahraman, Gökhan
Cooling capacity decreases due to faults appearing over time in the thrust bearing oil cooling systems of hydroelectric power plants and cooling process cannot proceed sufficiently. For this reason, while the turbine-generator unit generates energy, the thrust bearing heats up. This temperature problem prevents the unit from operating at full capacity and therefore decreases in energy production. Producing deficient energy in hydroelectric power plants, which is a renewable energy source, causes long-term economic losses for countries. In this study, the thrust bearing cooling system of a vertical Francis turbine, which produces 150 MW of energy per hour, is investigated. The reduction in the cooling capacity over time in turbine thrust bearing cooling system is solved by using exchanger system with additional plate and the power produced by the turbine-generator unit is increased 15 MW/h. This improvement has greatly contributed to the national economy. The method of increasing the cooling capacity applied to the hydroelectric power plant thrust bearings can be applied to all hydraulic turbines. This method will increase the energy production amount of the unit by approximately 10% and it costs approximately 80% cheaper than completely replacing the existing cooling system.
AtıfScopus5WoS2OpenAlex5İncele
