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The growing interest in hydrogen (H 2) within the energy sector has necessitated the development of alternative storage systems for H 2. Depleted natural gas reservoirs, currently utilized for large-scale natural gas storage, are also seen as a feasible choice for storing H 2. This study presents the results of numerical simulations to assess the applicability of utilizing the Değirmenköy gas field for underground hydrogen storage. The Değirmenköy gas field is onshore and depleted in the Thrace region of Türkiye. Cyclic storage simulations were run in four distinct scenarios to assess the reservoir's injection and withdrawal capacities and the H 2 ratio of the withdrawn gas from the reservoir. If the injection and withdrawal flow rates are 1.5 million Sm3/day (250.0 thousand Sm3/day/well), a constant flow rate can be achieved on almost all days of the injection and withdrawal periods, and annual average H 2 injection and withdrawal capacities were estimated as 221.5 million Sm3 and 177.7 million Sm3, respectively. Besides, H 2 ratio of the withdrawn gas increased as storage cycles repeated and average H 2 ratio increased to 88% in the last cycle. On the other hand, in the simulations performed with constant bottom hole pressure (BHP), both injection and withdrawal flow rates are quite variable during injection and withdrawal periods and peak flow rates at the beginning of each period is higher during H 2 storage as compared to natural gas. Nevertheless, in both cases the flow rate gradually diminished and eventually ceased before the related period ended. Hence, it can be inferred that conducting storage operations with a steady flow rate, as opposed to a constant BHP, is deemed more suitable for the field under investigation due to the stability of flow rate. As a result, depleted natural gas reservoirs are considered a suitable option for H 2 storage in large-scale, especially for applications without the need to obtain pure H 2 , considering their storage, injection, and withdrawal capacities. • Underground hydrogen storage capability of the Değirmenköy gas field was studied. • Large-scale and seasonal hydrogen storage in a depleted gas field was examined. • A reservoir model was generated using MATLAB MRST based on real-field data. • Annual injection and withdrawal capacities of the recovered hydrogen were assessed. • Injection and withdrawal flow rates for hydrogen/natural gas storage were compared. [ABSTRACT FROM AUTHOR]

Copyright of Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım ve Teknoloji is the property of Gazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nanofluids have often been utilized lately for enhancing the thermal performance of heat transfer devices operating with a working fluid. In this study, using iron aluminate spinel nanoparticles, deionized water-based nanofluids at various mass concentrations (0.5%, 1.0%, and 2.0%) of nanoparticles were prepared and tested as the test fluid inside the heat pipes of the air-to-air heat exchanger operating between hot and cold air passages. The efficiency, as well as thermal resistance of the heat pipes, were investigated under varying Reynolds number combinations of hot and cold air passages. An increase up to 87.2% in efficiency and a decrease up to 71.6% in thermal resistance of the heat pipes were obtained with the utilization of magnetic nanofluid. Furthermore, the effect of nanoparticle concentration on performance was discussed. [ABSTRACT FROM AUTHOR]

In this research, wind energy potential of a specific region in Western Turkey has been analyzed by using WindPRO software. The analyzed site is located in Ayvacık district of Çanakkale province of Turkey. Two types of wind energy turbines with 3 MW power including Enercon E-101/3000 and Nordex N117/3000 have been selected for the analyses. Weibull distribution has been utilized in the wind energy potential assessment. Also, average wind speed values and prevailing wind directions have been calculated for the selected locations in the analyzed region. The prevailing wind direction was determined for Enercon E-101/3000 and Nordex N117/3000 turbines as NNW and SSE, respectively. Estimated electrical energy generation values for Enercon E-101/3000 and Nordex N117/3000 turbines were obtained between 10177-11925 MWh/year and 9283-10954 MWh/year, respectively. Moreover, shape and scale parameters for each wind directions and annual energy generation values of each location have been calculated within the scope of this work. [ABSTRACT FROM AUTHOR]

Developing alternative and hybrid solution proposals for increasing Primary Resource Factor (PRF) values of the provinces in Turkey will lead to an increase in the use of renewable energy resources. In this study, each renewable energy sources should be evaluated with data envelopment analysis, and the obtained solution proposals for each province are the research subjects. Suggestions have been made that overlapping alternative solutions should be transformed into the hybrid structures in Turkey. In addition, a similar study was conducted using TOPSIS method, and an answer was sought to the question of what hybrid structures should be in terms of economics. Analysis results have been mapped for on-site solutions with renewable energy sources in the solution of district heating/cooling problems within the framework of increasing energy prices. Prominent alternative solutions are listed as solar, wind and hydraulic. [ABSTRACT FROM AUTHOR]

Heat pipes are one of the most preferred equipment because they have a variety of superior specifications. In this paper, the improvement of heat transfer properties of a thermosyphon heat pipe that was filled with bauxite nanofluid was experimentally investigated for different nanoparticle concentrations (1%, 2%, and 4%) and surfactant types (Triton X-100 and Sodium Dodecyl Benzene Sulfonate). Bauxite nanoparticles at different concentrations were utilized for the preparation of nanofluid suspensions. Different kinds of surfactants were also doped into the prepared nanofluid suspensions to show off how a surfactant affects the thermophysical properties of the nanofluid. The experiments were done under several heating powers and various mass flow rates of the cooling water circulating on the evaporator section. Temperature distributions both upon the evaporator and the condenser sections were recorded via 8 different K type thermocouples. Cooling water inlet and exit temperatures were also recorded and utilized for theoretical calculations. For doing an experimental comparison, thermal efficiency and resistance of the thermosyphon heat pipe were determined both for distilled water and prepared nanofluid suspensions. Moreover, contact angle-wettability analysis was carried out to determine how nanoparticles affect the surface tension. The encountered problems during the tests were addressed and discussed. The obtained experimental data illustrated that the thermosyphon heat pipe efficiency was increased by up to 20.9% with the usage of a 2% (mass) concentration of bauxite nanofluid and an anionic surfactant. The maximum enhancement in heat pipe's thermal resistance was found as 24.3%, through bauxite nanofluid usage. [ABSTRACT FROM AUTHOR]

Most recently, an ascending tendency in nanoparticles containing working fluid utilization has been observed in such thermal systems as double pipe heat exchangers and thermosiphons in so far as its advantages upon the performance of such systems. In order to investigate how the type of the base fluid affects the nanofluid's properties used for thermal applications, an experimental test rig was setup and two different nanofluid each of which involves different base fluid, but same nanoparticles and surface active agent were tested. During the nanofluid preparation process, bauxite nanoparticles as nanoparticle material and sodium dodecyl benzene sulfonate as surface active agents were used in volume fractions of 2% and 0.5%, respectively. As the base fluid type, ethylene glycol and deionized water were utilized. The tests were conducted under diverse working conditions and vacuum pressure. Distribution of temperature ahead the heat pipe wall, efficiency and heat pipe's thermal resistance was experimentally investigated. It was observed from the experiments that each nanofluid improved the heat pipe performance significantly; however, deionized water/bauxite nanofluid gave the best results in terms of heat pipe's thermal performance. For each nanofluid, the maximum increment in efficiency was observed under 200 W heating power and 10 g/s cooling water mass flow rate conditions, and improvement rates were 29.5% and 13.3% for ethylene glycol-based and deionized water-based nanofluids, respectively. At least 20% of decline in thermal resistance of the heat pipe was also recorded, when nanofluid was employed as working fluid. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In heat transfer applications, heat pipes are widely- preferred because of some characteristics such as low cost, being able to be produced in any size and low maintenance cost make them superior. Moreover, the working fluid to be employed substantially affects the heat transfer characteristics of a heat pipe. In this paper, effects of nanoparticle addition into the ethylene glycol on heat pipe’s thermal performance were analysed experimentally. Every test was done using two variant working fluids, ethylene glycol and dolomite nanoparticles-doped ethylene glycol, respectively. Dolomite nanoparticles (2% by weight) and Sodium Dodecyl Benzene Sulfonate (0.5% by weight) were doped into the ethylene glycol while preparing the dolomite/ethylene glycol nanofluid. After filling in the heat pipe, experiments were realized under changing working conditions. Using experimental data, efficiency and thermal resistance of the heat pipe were examined. Viscosity of the each working fluid was determined. The contact angle –wettability measurements were also performed to specify the effects of surface active agent addition. The obtained findings revealed that nanoparticle inclusion inside the base fluid, i.e. ethylene glycol, improved the thermal performance (efficiency) and decreased the heat pipe’s thermal resistance substantially. [ABSTRACT FROM AUTHOR]

Plate heat exchangers, a compact-type heat exchanger, are commonly used heat transfer devices because of their superior characteristics. Their thermal performances are strongly dependent to working fluid circulating inside the system. The influences of nanofluid utilization as the working fluid in a plate heat exchanger was experimentally and numerically analysed in this study. In order to show off the improvement rate in heat transfer, the experiments were performed by using deionized water and TiO2-deionized water nanofluid. The nanofluid was prepared at the rate of 1.5 % as weighted. A surface-active agent, Triton X-100, was also doped into the mixture at the rate of 0.2% of a final concentration to prevent the sedimentation and flocculation of the nanoparticles inside the solution. The experiments were performed in different temperatures as 40°C, 45°C, 50°C and varying cold fluid mass flow rates as 3,4, 5, 6 and 7 lpm. In addition, using the experimental data, a numerical simulation was realized by ANSYS Fluent software. The both results indicate that heat transfer rate in plate heat exchanger can be improved using nanofluid as the working fluid in place of deionized water. The maximum improvement rate in heat transfer was obtained as 11 % in experimental study. It is also seen that experimental and numerical results are in good agreement. [ABSTRACT FROM AUTHOR]

This study investigates how TiO2/deionized water nanofluids affect the thermal performance of a two-phase closed thermosiphon (TPCT) at various states of operation, according to the surfactant types. A straight copper tube with an inner diameter of 13 mm, outer diameter of 15 mm, and length of 1 m was used as the TPCT, i.e., heat pipe. The nanofluid utilizing in experiments was prepared by mixing the TiO2 nano-particles at the rate of 1.3% and a surfactant at the rate of 0.5% with deionized water. The surfactants used for lowering the surface tension give rise to prevent the flocculation in nanofluids. In order to see the influences of the surfactants on the nanofluid properties, two types surfactants, Triton X-100 and sodium dodecyl benzene sulfonate (SDBS), were selected as nonionic and ionic surfactants and used in this study. The nanofluid was charged with in the ratio of 33.3% (equals to 44.2 ml) of the volume of the TPCT. To be able to make experimental comparisons, three different working fluids prepared under the same conditions in the same heat pipe were tested at three different heating powers (200, 300, and 400W) and three different coolant water flow rates (5, 7.5, and 10 g/s). The experiments were conducted for both TiO2 and Triton X 100-deionized water nanofluid and TiO2 and SDBS-deionized water nanofluid. The findings obtained from the tests were also compared to each other for showing off to what extent a surfactant affects the nanofluid properties. The maximum improvement in the thermal resistance was achieved by 43.26% in the experiment realized at 200 W input power and 7.5 g/s cooling water mass flow rate, in which the working fluid is TiO2 and SDBS-deionized water nanofluid. [ABSTRACT FROM AUTHOR]

Copyright of Felsefe ve Sosyal Bilimler Dergisi (FLSF) is the property of Felsefe ve Sosyal Bilimler Dergisi (FLSF) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Beytulhikme: An International Journal of Philosophy is the property of Beytulhikme: An International Journal of Philosophy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)