Browsing by Author "Şirin C."
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Item Effect of different heat transfer fluids on discharging performance of phase change material included cylindrical container during forced convection; [强制对流条件下不同传热流体对含相变材料柱形容器放热性能的影响](Central South University of Technology, 2021) Selimefendigil F.; Şirin C.; Öztop H.F.In the present work, effects of various heat transfer fluids on the discharging performance of a phase change material (PCM) included cylindrical container are numerically assessed during forced convection. The heat transfer fluid air, hydrogen, water and nanofluid with alumina particles are used and the the geometric variation of the PCM embedded region is also considered. The finite element method is used as the solver. Dynamic features of heat exchange with various phases are explored for different heat transfer fluid types, Reynolds number (between 100 and 300) and PCM embedded region geometric variation (hx between 0.01d1 and 0.65d1, hy between 0.1h1 and 0.4h1). It is observed that discharging time is significantly influenced by the heat transfer fluid type while full phase transition time for air is obtained as more than 10 times when hydrogen is utilized as heat transfer fluid. The best performance is achieved with nanofluid. When the PCM integrated region size is reduced, discharging time is generally reduced while due to the form of the geometry, vortex formation is established in the PCM region. This results in performance degeneration at the highest radius and height of the inner cylinder. Discharging time increases by about 12% when radius of the inner cylinder is increased from hx=0.35d1 to hx=0.45d1. Dynamic features of PCM temperature and liquid fraction are affected with Reynolds number while discharging time is reduced by about 48% when configurations with the lowest and highest Reynolds number are compared. © 2021, Central South University Press and Springer-Verlag GmbH Germany, part of Springer Nature.Item Thermal characterization of coolant maxwell type nanofluid flowing in parabolic trough solar collector (PTSC) used inside solar powered ship application(MDPI, 2021) Jamshed W.; Şirin C.; Selimefendigil F.; Shamshuddin M.D.; Altowairqi Y.; Eid M.R.Parabolic trough solar collectors (PTSCs) are generally utilized to reach high temperatures in solar-thermal applications. The current work investigates entropy production analysis and the influence of nano solid particles on a parabolic trough surface collector (PTSC) installed within a solar powered ship (SPS). For the current investigation, the non-Newtonian Maxwell type, as well as a porous medium and Darcy–Forchheimer effects, were used. The flow in PTSC was produced by a nonlinear stretching surface, and the Cattaneo–Christov approach was used to assess the thermal boundary layer’s heat flux. Similarity transformation approach has been employed to convert partial differential equations into solvable ordinary differential equations allied to boundary conditions. Partial differential and the boundary conditions have been reduced into a group of non-linear ordinary differential equations. A Keller-box scheme applied to solve approximate solutions of the ordinary differential equations. Single-walled carbon nanotubes-engine oil (SWCNT-EO) and Multiwalled carbon nanotubes/engine oil (MWCNT-EO) nanofluids have been utilized as working fluid. According to the findings, the magnetic parameter led to a reduction in the Nusselt number, as well as an increment in skin friction coefficient. Moreover, total entropy variance over the domain enhanced for flow rates through Reynolds number and viscosity fluctuations were monitored by using Brinkman number. Utilizing SWCNT-EO nanofluid increased the thermal efficiency between 1.6–14.9% in comparison to MWCNT-EO. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Item Improving the performance of an active greenhouse dryer by integrating a solar absorber north wall coated with graphene nanoplatelet-embedded black paint(Elsevier Ltd, 2022) Selimefendigil F.; Şirin C.; Öztop H.F.Greenhouse drying systems are sustainable and clean applications for preserving agricultural crops. In this work, a single-slope greenhouse drying system has been modified with solar absorber and thermally insulated north wall. Also, the designed and manufactured north wall has been coated with graphene nanoplatelet-embedded black paint. Greenhouse dryers with north wall and nano-embedded north wall modifications have been experimentally compared with a conventional greenhouse dryer. Main goal of this research is to upgrade the performance of a greenhouse drying system without using any auxiliary heating device and complex structural components. According to the experimental outcomes, drying time was reduced as 75 and 90 min by utilizing north wall and nano-enhanced north wall, respectively. Furthermore, exergy efficiencies of greenhouse dryers with north wall and nano-enhanced north wall were attained as 4.67% and 5.38%, respectively while this value for conventional greenhouse dryer obtained between 2.61 and 2.70%. Moreover, utilizing graphene nanoplatelets in black paint improved the specific moisture extraction rate as 40% in comparison to conventional greenhouse dryer. © 2021 International Solar Energy SocietyItem Energy and exergy analysis of a hybrid photovoltaic/thermal-air collector modified with nano-enhanced latent heat thermal energy storage unit(Elsevier Ltd, 2022) Selimefendigil F.; Şirin C.Electrical and thermal energy can be generated simultaneously by using photovoltaic-thermal (PVT) systems. Also, electrical efficiency can be enhanced by cooling the PV panel. In this study, three different PVT-air collectors have been designed, manufactured and experimentally analyzed including conventional (PVT), with paraffin-based thermal energy storage unit (PVT-TES) and with nano-enhanced paraffin-based thermal energy storage unit (PVT-NeTES). Copper oxide (CuO) nanoparticles (1 wt%) have been utilized to upgrade the thermal conductivity of the phase change material. Tests have been performed in two flow rates (0.007 and 0.014 kg/s). According to experimental results, overall exergy efficiencies for PVT, PVT-TES and PVT-NeTES were achieved between 10.52–13.59%, 11.08–14.36% and 12.52–15.44%, respectively. Moreover, sustainability index (SI) values were attained in the range of 1.12–1.16, 1.13–1.17 and 1.14–1.18, respectively. Obtained findings showed that utilizing nano-enhanced thermal energy storage system and increasing flow rate significantly upgraded both electrical and thermal performances of the PVT system. © 2021Item Exergy and environmental analysis of an active greenhouse dryer with Al2O3 nano-embedded latent heat thermal storage system: An experimental study(Elsevier Ltd, 2022) Selimefendigil F.; Şirin C.; Ghachem K.; Kolsi L.In this study, influences of integrating nanoparticles into paraffin-based latent heat thermal energy storage system on the thermal and drying behaviors of a greenhouse dryer have been analyzed. The major goal of this survey is improving the drying performance of a greenhouse dryer by employing nano-embedded latent heat storage unit. In this regard, two even-span greenhouse dryers have been produced and modified with paraffin-based and Al2O3 nano-embedded paraffin-based thermal energy storage units. Tests have been conducted at two flow rates that are 0.010 kg/s and 0.016 kg/s. According to the findings, average specific moisture extraction rates for the systems with and without nanoparticles were attained between 1.01 and 1.37 and 0.83–1.20 kg/kWh, respectively. Average exergy efficiency metrics were found as 3.45% and 2.74%, respectively in the test done at 0.016 kg/s flow rate for the greenhouse dryers with and without nanoparticles. These values were found as 3.01% and 2.40%, respectively in the test conducted at 0.010 kg/s. In addition, energy payback time, mean annual CO2 emission and net CO2 mitigation in lifetime values were obtained between 2.34 and 2.92 years, 33.04–34.28 kg/year and 8.45–9.08 tons, respectively. Results indicated the successful utilization of Al2O3 nanoparticle-embedded latent heat storage unit in a greenhouse dryer. © 2022 Elsevier LtdItem Experimental investigation of a parabolic greenhouse dryer improved with copper oxide nano-enhanced latent heat thermal energy storage unit(John Wiley and Sons Ltd, 2022) Selimefendigil F.; Şirin C.Solar dryers are clean and sustainable systems for preserving agricultural products. In this research, three different active greenhouse dryers, which are grouped in direct solar drying systems, have been designed, fabricated, and experimentally surveyed. Different from other works, this research contains an experimental investigation on nano-embedded thermal storage-assisted greenhouse drying system. Major goal of this study is to analyze the impact of utilizing nano-enhanced thermal energy storage unit on the performance of a greenhouse dryer. In this context, tunnel-type parabolic greenhouse dryers with paraffin wax thermal storage unit (PGD-TES) and nano-enhanced paraffin wax thermal storage unit (PGD-NeTES) have been tested and compared with a conventional parabolic greenhouse dryer (PGD). Copper oxide (CuO) nanoparticles have been employed to upgrade the thermal effectiveness of the thermal storage unit. Tests have been done in two flow rates, which are 0.009 and 0.014 kg/s. Utilizing nano-enhanced modification decreased drying time approximately between 35% and 58% in comparison to the conventional dryer. According to the results, average specific energy consumption values were attained in the ranges of 2.10 to 2.48, 1.93 to 2.09, and 1.63 to 1.89 kWh/kg, respectively, for PGD, PGD-TES, and PGD-NeTES. Also, exergy efficiency was improved by 36% by utilizing the nano-enhanced thermal energy storage system. © 2021 John Wiley & Sons Ltd.Item Experimental Performance Analysis of a Solar Desalination System Modified with Natural Dolomite Powder Integrated Latent Heat Thermal Storage Unit(MDPI, 2022) Selimefendigil F.; Şirin C.; Öztop H.F.Solar desalination systems are effective and sustainable applications that are utilized to obtain potable water from saline or contaminated water. In this research, three solar desalination systems, including a conventional system, a phase change material (PCM)-based thermal energy storage unit (TESU), and a natural dolomite powder integrated PCM-based TESU, were structured and experimentally investigated. The developed solar desalination systems were analyzed simulta-neously and the findings were discussed in detail. According to the empirically obtained outcomes, utilizing PCM-based TESUs and dolomite-powder-embedded PCM-based TESUs increased daily cu-mulative productivity by 10.15% and 17.70%, respectively, in comparison to the conventional distiller. Employing dolomite powder increased the energy and exergy efficiencies of the conventional distiller from 15.91% to 18.28% and from 1.26% to 1.78%, respectively. Moreover, environmental metrics such as global warming potential and the sustainability index of the developed solar desalination systems were analyzed within the scope of this work. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Item Experimental analysis of combined utilization of CuO nanoparticles in latent heat storage unit and absorber coating in a single-slope solar desalination system(Elsevier Ltd, 2022) Selimefendigil F.; Şirin C.; Öztop H.F.In this survey, impact of combined utilization of copper oxide (CuO) nanoparticles both in thermal energy storage unit and absorber coating (matt black paint) on the performance of a single-slope solar still has been investigated experimentally. In this context, four different solar desalination systems including a conventional solar still, solar still with thermal energy storage unit, solar still with CuO nano-embedded latent heat storage unit and solar still with CuO nano-enhanced absorber coating and thermal energy storage unit have been developed, fabricated and empirically analyzed. Experimental results showed that combined employing nanoparticles upgraded accumulated productivity as 26.77% in comparison to conventional solar still. Also, energy and exergy efficiency values were enhanced from 15.96% to 19.90% and from 1.25% and 2.01%, respectively with the use of combined modification. © 2022Item Enhancing the performance of a greenhouse dryer with natural dolomite powder-embedded latent heat thermal energy storage unit and air-to-air heat recovery system(Elsevier Ltd, 2023) Selimefendigil F.; Şirin C.Greenhouse drying systems (GDSs) are grouped in direct-type solar dryers and are widely utilised because of their easy applicability, high product drying capacity and cost-effectiveness. In the present work, it is aimed to improve the drying performance of a GDS by using natural dolomite powder-embedded latent heat thermal energy storage unit (LHTESU) and air-to-air heat recovery system (HRS). In this context, three different types of GDSs have been designed and manufactured including a GDS with paraffin-based LHTESU, a GDS with natural dolomite powder-embedded LHTESU and a HRS-assisted GDS with natural dolomite powder-embedded LHTESU. Designed and manufactured GDSs have been experimentally analysed under the same environmental conditions. According to the experimentally achieved findings, combined utilisation of HRS and dolomite powder in the LHTESU reduced the drying time approximately as 36.36%. Moreover, highest instantaneous outlet air temperature was achieved as 51.4 °C in the system that used natural dolomite-embedded LHTESU and HRS. The exergetic efficiency of the GDS was upgraded as 46.21% by using the mentioned modifications in comparison to the base case (the system contains only paraffin-based LHTESU). In addition, specific moisture extraction rate for the analysed GDSs was attained between 0.96 and 1.52 kg.kWh−1. © 2023 International Solar Energy SocietyItem Performance Analysis and Identification of an Indirect Photovoltaic Thermal Dryer with Aluminum Oxide Nano-Embedded Thermal Energy Storage Modification(MDPI, 2023) Şirin C.; Selimefendigil F.; Öztop H.F.In the current paper, different thermal energy storage unit-integrated photovoltaic thermal (PVT) air collectors with and without nanoparticles have been designed, fabricated and tested. Aluminum oxide nanoparticles have been integrated into the thermal storage unit to increase the performance of the PVT collector. The developed collectors have been tested in a drying application at two different mass flow rates. The major goals of this work are upgrading the performance of the PVT air collector by employing a nano-embedded thermal energy storage unit and analyzing the impacts of using nanoparticles in the latent heat storage unit in the PVT collector on the drying performance of the system. The drying time was reduced by approximately 15–22% by employing nanoparticles in the thermal storage unit. Moreover, overall exergy efficiency values were obtained in ranges of 12.49–14.67% and 13.64–16.06%, respectively, for modified and unmodified PVT air collectors. It should be indicated that the overall energy and exergy efficiencies of the PVT air collectors were improved in the ranges of 6.91–6.97% and 9.20–9.47%, respectively, by using nanoparticles in the thermal energy storage unit. The combination of increasing the flow rate and integrating nanoparticles into the storage unit improved the overall exergetic efficiency of the PVT air collector by 28.58%. The mean exergetic efficiency of the drying room was between 48.33 and 54.26%. In addition to the experimental analysis, dynamic models for thermal and exergy efficiencies of developed collectors were constructed by employing the system identification method. © 2023 by the authors.Item EXPERIMENTAL ANALYSIS OF A SOLAR DESALINATION SYSTEM WITH GRAPHENE NANOPLATELET-EMBEDDED LATENT HEAT THERMAL ENERGY STORAGE UNIT(Begell House Inc., 2024) Şirin C.; Selimefendigil F.In the present work, it is aimed to improve the yield of a single-slope solar desalination system (SDS) using graphene nanoplatelet-embedded thermal energy storage unit (TSU). In the initial stage of this work, three SDSs with different slope angles of condensation surface including 40°, 50°, and 60° are considered. According to the result of the initial experiments, the SDS with 40° gave the superior performance. In the second part of the study, three different SDS configurations with 40° slope angle including a conventional SDS, an SDS with only paraffin-containing TSU, and an SDS with graphene nanoplatelet-embedded paraffin-containing TSU have been developed and tested under the same environmental conditions. According to the findings of the second experimental stage, utilizing only paraffin-containing and graphene nanoplatelet-embedded paraffin-containing TSUs in the conventional system with 40° slope angle improved the accumulated yield of the system as 11.85% and 26.96%, respectively. Also, energy and exergy efficiencies of the SDS with 40° slope angle were improved from 16.02% to 19.69% and from 1.36% to 2.13%, respectively, using the TSU with graphene nanoplatelets. The attained findings of this work clearly present the positive influence of employing graphene nanoplatelets in TSU of a single-slope SDS. © 2024 by Begell House, Inc.