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Öğe A detailed investigation of the temperature-controlled fluidized bed solar dryer: A numerical, experimental, and modeling study(Elsevier, 2022) Gurel, Ali Etem; Agbulut, Umit; Ergun, Alper; Ceylan, Ilhan; Sozen, Adnan; Tuncer, Azim Dogus; Khanlari, AtaollahSolar thermal systems are generally utilized for providing sustainable and environmentally friendly thermal energy that can be used in different applications. In the present study, a temperature-controlled fluidized bed solar drying system along with flat plate and plate with zigzag fins has been designed, manufactured, and experimentally tested. In the first step, the thermal behavior of designed solar air collectors has been numerically modeled. In the next step, the drying system's performance has been experimentally investigated. The overall efficiency of the system was found to be 64%. The maximum exergy efficiency of flat and zigzag plate solar air collectors was calculated as 7.2% and 11.6%, respectively. Then moisture content (MC) and moisture ratio (MR) values were modelled by response surface methodology (RSM), and the predicted results were compared with four metrics. It was found that the drying parameters were highly fitted with the mathematical models. MC metric was predicted with accurate values for performance criteria of R-2, R-RMSE, and MBE as 0.9995, 1.94%, and -0.0096, respectively. The general outcomes of numerical, experimental and modeling analyses of this research exhibited successfulness of the developed the fluidized bed solar drying system.Öğe The effect of ejector on the performance of diffusion absorption refrigeration systems: An experimental study(Pergamon-Elsevier Science Ltd, 2012) Sozen, Adnan; Menlik, Tayfun; Ozbas, EnginIn this study, an experimental analysis on performance improvement of a diffusion absorption refrigeration system (DARS) was conducted. For the experiment, three DARS cycles were set up and investigated. (i) In the first cycle (DARS-1), representing the most commonly employed model in the industry, the condensate is sub-cooled prior to the evaporator entrance by the coupled evaporator/gas heat exchanger in a similar manner with the refrigeration systems manufactured by Electrolux Sweden [1]. (ii) In the second cycle (DARS-2), the condensate is not sub-cooled prior to the evaporator entrance and the gas heat exchanger is separated from the evaporator as proposed by Zohar et al. [2]. (iii) In the third cycle (DARS-1WE), the novel system being proposed in this study, differing from DARS-1 in certain aspects is used, in which an ejector was installed to the absorber inlet of OARS-I. The weak solution coming from the generator is separated into two parts with equal flows and then one of the parts is connected to the mixing tube of ejector and the other inlet is connected to the absorber. Experimental results show that the DARS-1WE cycle demonstrates a higher performance compared to DARS-1 and DARS-2 cycles. In addition, internal temperature of the cooling area in DARS-1WE decreased to 3.2 degrees C as well. In other words, the duration of attaining the predetermined cooling area temperature decreased even further in DARS-1WE. Consequently, the reduction of energy consumption for relatively low temperatures (6 degrees C) of the cooling area is in the order of 40%. The corresponding level of energy saving falls down to 20% for higher temperatures (10 degrees C). (C) 2011 Elsevier Ltd. All rights reserved.Öğe Experimental Investigation of an Al2O3/Distilled Water Nanofluid Used In the Heat Pipes of Heat Exchangers(Gazi Univ, 2018) Ozturk, Ahmet; Ozalp, Mehmet; Sozen, AdnanThis study investigates the thermal performance of a heat pipe heat recovery system in air-to-air heat recovery systems using a nanofluid of Al2O3 (aluminum oxide) particles and distilled water. The experimental setup used 15 wickless vacuumed copper pipes with a length of 1000 mm, a 10.5 mm inner diameter and a 12 mm outer diameter. The evaporator section consists of 450 mm of heat pipes, the condenser section is 400 mm, and the adiabatic section is 150 mm. In experimental studies, 33% of the evaporator volume of the heat pipes was filled with working fluids. Experiments were carried out at temperatures between 25 degrees C and 90 degrees C by using five different cooling air flows (40 g/s, 42 g/s, 45 g/s, 61 g/s and 84 g/s), and two different heating powers (3 kW and 6 kW) for the evaporation section, to determine the heat removed from the condensation section. Experiments were performed for distilled water and Al2O3 nanofluid, respectively, and the results were compared with each other. As a result of the experiments, it was observed that using a nanofluid as the working fluid increased the efficiency of the heat pipe. The highest efficiency (eta = 59%) was obtained in the experiments carried out using an Al2O3 nanofluid at a heating power of 3 kW and an air flow of 112 g/s.Öğe Improving car radiator performance by using TiO2-water nanofluid(Elsevier - Division Reed Elsevier India Pvt Ltd, 2018) Ahmed, Siraj Ali; Ozkaymak, Mehmet; Sozen, Adnan; Menlik, Tayfun; Fahed, AbdulkarimThe most recent developments in nanotechnology have lead to improvements in original uses of nanofluids in car motor cooling. In the present study, enhancement of car engine radiator by TiO2-water nanofluid as a coolant of car engine radiator was investigated experimentally. In order to determine the effect of TiO2-water nanofluid on radiator's performance, experiments were performed with pure water and TiO2-water nanofluid separately and results were compared with other studies on vehicle engine system FIAT DOBLO 1.3 MJTD ENG. The main objective was to check the aspects of heat transfer of the TiO2-water nanofluid as a substitution to the customary coolant system. For this purpose, experiments were carried out using a TiO2 nanofluid with 0.1, 0.2 and 0.3% volume concentrations with flow rates of 0.097 and 0.68 m(3)/h in laminar floe region, where Reynolds number ranged from 560 to 1650. Our results show that the friction factor decreases when Reynolds number and the volume concentration are increased. Moreover, TiO2-water nanofluid with 0.2% concentration can enhance the effectiveness of car radiator by 47% as compared to 0.1 and 0.3% concentrations and pure water as a coolant. Finally, the average heat transfer coefficient was directly affected by the increase in Reynolds number and volume concentration fraction of the nanofluid. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.Öğe Modelling of Turkey?s net energy consumption using artificial neural network(Inderscience Enterprises Ltd, 2005) Sozen, Adnan; Arcaklioglu, Erol; Ozkaymak, MehmetThe main goal of this study is to develop the equations for forecasting net energy consumption (NEC) using artificial neural network (ANN) technique in order to determine the future level of the energy consumption in Turkey. Two different models were used in order to train the neural network: (i) Population, gross generation, installed capacity and years are used in input layer of network (Model 1). (ii) Energy sources are used in input layer of network (Model 2). The NEC is in output layer for two models. R-2 values for training data are equal to 0.99944 and 0.99913, for Model 1 and Model 2, respectively. Similarly, R-2 values for testing data are equal to 0.997386 and 0.999558 for Model 1 and Model 2, respectively. According to the results, the NEC prediction using ANN technique will be helpful in developing highly applicable and productive planning for energy policies.Öğe PERFORMANCE IMPROVEMENT OF THE HEAT RECOVERY UNIT WITH SEQUENTIAL TYPE HEAT PIPES USING TiO2 NANOFLUID(Vinca Inst Nuclear Sci, 2019) Ozturk, Ahmet; Ozalp, Mehmet; Sozen, Adnan; Guru, MetinThis paper deals with the improvement of thermal performance of the heat recovery system in air-to-air unit by using a nanofluid of TiO2 particles and distilled water. The experimental set-up equipped with 15 copper pipes of a 1000 mm length, 10.5 mm inner diameter; and 12 mm outer diameter was used. The evaporator section consists of 450 mm of heat pipes, the condenser section is 400 mm, and the adiabatic section is 150 mm. In experimental studies, 33% of the evaporator volumes of heat pipes were filled with working fluids. Experiments were carried out at temperatures between 25 degrees C and 90 degrees C by usingfive different cooling air-flows (40, 42, 45, 61, and 84 g/s), and two different heating powers (3 kW and 6 kW) for the evaporation section, to determine heat removed from the condensation section. Trials were performed for distilled water and nanofluid respectively, and the results were compared with each other. Results revealed that a 50% recovery in the thermal performance of the heat pipe heat recovery system was achieved in the design using TiO2 nanofluid as the working liquid, at a heating power of 3 kW, air velocity of 2.03 m/s and air-flow of 84 g/s.
