SDG 7 · Erişilebilir ve Temiz Enerji · SDG · Erzincan Binali Yıldırım Üniversitesi

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ArticleYalnız künye2022/r/ebyu/13770
Experimental investigation on the effect of anode functional layer on the performance of anode supported micro-tubular SOFCs
Timurkutluk, Cigdem; Bilgil, Keremhan; Celen, Ali; Onbilgin, Sezer; Altan, Tolga; Aydin, Ugur
In this study, anode supported micro-tubular solid oxide fuel cells (SOFCs) are fabricated by extrusion method and the effects of powder size, thickness and sintering temperature of the anode functional layer (AFL) on the electrochemical performance is experimentally investigated. For this purpose, four different commercial NiO powders are tested as initial powder for the fabrication of the anode functional layer. The thickness of AFL is also considered by varying the number of coatings. After deciding the optimum initial NiO powder size used in AFL and AFL thickness, the effect of pre-sintering temperature is examined. The performance tests are performed at an operating temperature of 800 °C under hydrogen and air. The microstructures of the samples are also investigated by a scanning electron microscope. The best peak power density is obtained as ∼0.5 W/cm2 from the cell having a single layer anode functional layer pre-sintered at 1250 °C prepared by NiO powders with 4 m2/g surface area.
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ArticleYalnız künye2022/r/ebyu/13730
Multi-objective optimization of a mini channeled cold plate for using thermal management of a Li-Ion battery
Kalkan, Orhan; Celen, Ali; Bakirci, Kadir
Mini channeled cold plates (MCCP) are an impressive choice for electric vehicles with a liquid-based thermal management system to keep the battery temperature within the desired range and to achieve a homogeneous temperature distribution. This paper came up with an optimum solution for maximum battery temperature (MBT), maximum temperature difference on the battery surface (MTD) and pressure drops in the channels (ΔP), which are vital parameters. Multi-objective optimization of geometric parameters and coolant flow rate of a designed MCCP which is experimentally investigated is carried out using the Desirability Function Approach. Firstly, the design of experiments (DoE) is generated using response surface method after determining the input variables and their levels. Then, each sample of DoE are modeled and analyzed numerically. Furthermore, the regression equations of the objective functions (MBT, MTD and ΔP) depending on the design parameters are developed and their variance analyzes are performed. Prediction accuracies of model equations developed for MBT, MTD and ΔP are 97.75%, 95.49% and 97.15%, respectively. As a result, optimum values of design variables, namely channel width (mm), distance between branches (mm), channel depth (mm), number of crossovers in branches and coolant flow rate (l/min) are 5, 5, 10, 13 and 0.7061, respectively.
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ArticleYalnız künye2022/r/ebyu/13717
A novel zero voltage transition boost converter and artificial neural network-based estimation of converter efficiency
Ting, Naim Suleyman; Aslay, Fulya; Sahin, Yakup
In this paper, a novel zero voltage transition (ZVT) boost converter is proposed, and the overall efficiency of the converter is predicted with an artificial neural network (ANN) model. In the proposed converter, the main switch is turned on by ZVT and turned off by zero voltage switching (ZVS). Also, the other semiconductor elements operate by soft switching (SS). Besides, the proposed snubber cell has the bidirectional direct power transfer feature. The theoretical analyzes of the converter are verified by an prototype having 50 VDC input voltage, 100 VDC output voltage, 250 W output power, and 100 kHz switching frequency. The overall efficiency of the converter in hard switching (HS) condition is increased from 87.2% to 95.4% thanks to proposed snubber cell. Moreover, the efficiency of converter at HS operation is estimated with ANN. For this estimation, 110 efficiency values are obtained based on the different switching frequency and the output power values. When the actual efficiency measurements and the estimation results obtained with the ANN model are compared, it is seen that the results overlap and is obtained very close result to the truth by ANN. Thus, owing to the ANN model, the semiconductor power elements will not need to be operated at high frequencies and overheating, and the damaging to the elements will be prevented. Finally, the efficiency curve measurement of the converter takes long time in the experimental study when it takes highly short time as a few minutes in the estimation with ANN.
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ArticleYalnız künye2022/r/ebyu/13703
Combustion and emission characteristics of premixed biogas mixtures: An experimental study
Sivri, Ilker; Yilmaz, Harun; Cam, Omer; Yilmaz, Ilker
In this study, effects of fuel composition, swirl number and hydrogen addition on combustion and emission characteristics of various biogas mixtures were experimentally investigated. To this end, a laboratory scale combustor and a swirl stabilized premixed burner were designed and manufactured. Later on, this combusting apparatus was equipped with flow, control, safety and measurement tools, hence entire test system was constituted. Combustion and emission characteristics of tested biogas mixtures were determined by measuring temperature and species (CO2, CO, O2 and NO) distributions throughout the combustion chamber. Additionally, flame structures of tested biogas mixtures were evaluated by examining flame luminosity, visible flame length and flame thickness from instantaneous flame images. Results of this study showed that both radial and axial temperature distribution variations of tested biogas mixtures differently alter with hydrogen addition based on the gas composition. Although flame temperature increases with swirl number at burner outlet, it presents a non-monotonous dependence on swirl number outside the flame region because of the modified flow characteristics. This is also the case for emissions of CO2.
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ArticleAçık Erişim2022/r/ebyu/13634
Variable determined for optimization of alternating energy on the load by the adaptive Taguchi method
Can, Erol
It is important to find the optimum point in terms of energy quality in the studies for electrical energy conversions with the converter and inverter circuits. In such studies, the authors tried to find the optimum operating point by using control systems such as PID and Fuzzy Logic in closed-loop controls. When a large number of variables are involved in finding the optimum point, closed-loop control methods such as these may be insufficient to find the optimum point. Therefore, in this study, the Adaptive Taguchi Method (ATM) with the maximum-minimum value is used for the estimation of variables providing the optimum point for energy quality by using it in a multilevel inverter with a double DC-DC converter. While in traditional Taguchi Methods, dependent variables predict the results by revealing their effects on independent variables, in ATM, besides the effects of the independent variables, the effects of different dependent variables on each other are also estimated. First, the system to which the ATM will be applied is introduced. Then, the principles of applying the ATM are explained. In the known Taguchi method, variable values to be found with 34 = 81 trials, variables are estimated with 27 trials, while the values of two different dependent variables in the system can be found with 54 trials instead of 2×34= 2×81 trials. The resulting values to be estimated with the proposed ATM method are estimated with 27 trials instead of 2×81 or 54 trials. Finally, the observation results to be used for estimation are analyzed and evaluated. By trying the prediction results, it is seen that the proposed system is quite effective because the estimated result value that is %3.71 in the experiments gives a lesser distortion value than the values used for prediction.
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ArticleYalnız künye2022/r/ebyu/13540
An experimental comparison of radiant wall and ceiling cooling system integrated with ground source heat pump and direct expansion fan coil system in a highly glazed office room
Dogan, Ahmet; Kayaci, Nurullah; Demir, Hakan; Kemal Sevindir, Mustafa
Hydronic radiant systems, which provide a thermal comfort environment, come to the fore in different building applications due to their energy saving potential and being integrated with renewable energy systems. The aim of this study is to present a full-scale experiment to compare the thermal comfort performances of radiant ceiling, wall and wall + ceiling systems coupled ground source heat pump and direct expansion fan coil system implemented in Yildiz Technical University Science and Technology Application and Research Center, Istanbul, Turkey. Air velocity, horizontal and vertical air temperature differences, mean radiant temperature and humidity values, which are four physical parameters that can affect the thermal satisfaction of office workers for 9 different experimental conditions, are measured for fan coil and all radiant systems. The results indicate that vertical temperature differences between ankle and head level vary from 0.9 °C to 1.4 °C for both fan coil system and all radiant system configurations in different location of the test room. Acceptable overall comfort in indoor environments Class A only showed stable performance with an average of 0.12 PMV and 5.3 % PPD when ceiling + wall radiant panels were actively cooled. The result shows that the difference between room air temperature and room operating temperature varies between 0.45 °C and 0.6 °C when cooling loads are met by radiant systems. This may not make it possible to use indoor air temperature instead of indoor operating temperature in the control of radiant systems. Moreover, the thermal environment of the radiant system are more uniform than fan coil system due to low air temperature stratification, air velocity and small differences between mean radiant temperature and indoor air temperature.
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ArticleYalnız künye2022/r/ebyu/13465
Effect of climate change to solar energy potential: a case study in the Eastern Anatolia Region of Turkey
Bakirci, Kadir; Kirtiloglu, Yusuf
Architects, hydrologists, agriculturists, and solar engineers require the data of solar radiation for solar technologies such as solar drying, cooking, heating, and building illuminations. The aim of this study is to evaluate the effect of climate change on the potential of solar energy in the Eastern Anatolia Region (EAR) of Turkey. The global warming problem caused by greenhouse gases is increasing due to the increase in the use of fossil origin fuels in our world, and climate change is coming out. In this content, the values of monthly sunshine duration and global solar radiation are provided by the Meteorological Service in Turkish for the EAR of Turkey in the periods between 1987 and 2010. Thus, in a period of 24 years, it is investigated how much change took place in meteorological data. These changes are examined in the two different periods. In conclusion, it is observed that important changes occur in some meteorological data. The highest decrease in the variation amount of yearly average global solar radiation is seen in Erzurum, while the highest increase is seen in Erzincan. The highest increase in the variation amount of yearly average sunshine duration is seen in Erzincan, while the highest decrease is seen in Bitlis. In addition, the statistical analysis (t-test) is made to determine whether the difference between two periods is statistically significant for a considered region.
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ArticleYalnız künye2022/r/ebyu/12944
Investigation of hybrid nanofluids effects on heat transfer characteristics in VVER-1000 nuclear reactor
Uzun, Sinem; Genç, Yasin; Acır, Adem
In this study, the analysis of heat transfer characteristics of VVER-1000 nuclear reactor by using hybrid nanofluids as a coolants in subchannels in hot fuel assembly have been performed. Firstly, the criticality (keff) and fuel assembly power distributions of the VVER-1000 reactor by using Monte Carlo particle transport (MCNP) code to determine of the heat transfer characteristics with COBRA IV PC code have been examined. Secondly, the axial coolant temperature distributions and Departure from Nucleate Boiling Ratio (DNBR) values in hottest channel for Cu, CuO and TiO2 nanoparticles of the different volume fractions (0.05%, 0.01% and 0.1%) mixed with 0.1 vol % Al2O3 hybrid nanofluids have been analyzed. The obtained results by using hybrid nanofluids have been compared with the pure water results. The keff decreases with the increase of volumetric fractions of hybrid nanoparticles Cu, CuO and TiO2 mixed with 0.1% Al2O3 in the coolant. The maximum temperature has been reached by the püre water coolant at the end of the channel as 612.68 K whereas, the highest temperature change has been obtained in the case of 0.1% Al2O3 + 0.1% TiO2 as 617.35 K when evaluated among nanoparticle themselves. The results of analysis show that the heat transfer enhances with increasing hybrid nanoparticles volume fractions in the subchannel geometry. Also, the obtained minimum DNBR values using hybrid nanofluid haven't been exceed the safe operational limits; therefore the reactor operation would be safer.
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ArticleYalnız künye2022/r/ebyu/12880
MnO2 nanosheets synthesized on nitrogen-doped vertically aligned carbon nanotubes as a supercapacitor electrode material
Yesilbag, Yasar Ozkan; Tuzluca Yesilbag, Fatma Nur; Huseyin, Ahmad; Salih, Ahmed Jalal Salih; Ertugrul, Mehmet
In the present study, nitrogen-doped vertically aligned carbon nanotubes (N-VACNTs) were synthesized on carbon cloth (CC) using the floating catalyst chemical vapor deposition (FCCVD) method, and MnO2 nanosheets were grown on them using the hydrothermal method to produce an N-VACNT@MnO2 nanocomposite structure. In this structure, a synergistic effect was obtained by combining N-VACNTs, which allow high electrical conductivity and fast ion transfer. In the galvanostatic charge-discharge (GCD) measurements performed separately in a three-electrode test cell using 1 M of Na2SO4 electrolyte, the specific capacitance of the N-VACNTs was found to be 53.7 F g−1 at a current density of 0.5 A g−1, and the specific capacitance of the N-VACNT@MnO2 electrode structure was found to be 497 F g−1. In addition, after 10,000 charge-discharge cycles at a current density of 10 A g−1, the N-VACNT electrode retained 99 % of its initial specific capacitance, while the N-VACNT@MnO2 electrode exhibited outstanding cyclic stability with 76 % of its initial specific capacitance. Moreover, in the as-fabricated asymmetric supercapacitor (ASC) using N-VACNTs and N-VACNTs@MnO2, the negative and positive electrodes achieved a stable voltage window of 0–1.7 V, with a specific capacitance of 59.4 F g−1 at a current density of 1 A g−1. Additionally, this ASC showed good cycling stability retaining 84 % of its specific capacitance at the end of 10,000 cycles. Therefore, this ASC structure with an energy density of 24.7 Wh kg−1 and a power density of 15.7 kW kg−1 are promising electrode materials for energy storage.
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ArticleAçık Erişim2021/r/ebyu/20867
Erzincan ili hayvansal atık kaynaklı biyogaz potansiyelinin değerlendirilmesine yönelik biyogaz tesisi senaryoları
Badem, Anıl; Kurnuç Seyhan, Aslıhan
Hayvan atıklarından biyogaz üretimi gibi atıkların enerji teknolojisine uygulanması, Türkiye de dâhil olmak üzeregelişmekte olan birçok ülkede sürdürülebilir enerji geliştirme hedeflerine ulaşmak için en iyi araçlardan biri olarak kabuledilmektedir. Türkiye, çok sayıda hayvan çiftliği ile önemli bir potansiyele sahip olsa da bugüne kadar biyogaz üretimiiçin potansiyel gerçekleşmemiştir. Bu makale, Türkiye'de alternatif bir enerji üretimi kaynağı olarak hayvan atıklarındanbiyogaz üretimi yoluyla atıkların enerji teknolojisine potansiyel uygulanmasının vurgulanmasını amaçlamaktadır. Hayvanatıkları gibi yenilenebilir hammaddelerin anaerobik sindirimi, biyogaz şeklinde temiz enerji üretimi için ileriye dönük birteknoloji olarak bilinmektedir. Bu çalışmada Erzincan ilinin hayvansal atık kaynaklı enerji potansiyeli hesaplanmıştır.Bulgular, Erzincan'daki hayvan atıklarından yaklaşık 15.5 milyon m3/yıl biyogaz potansiyelinin üretilebileceğinigöstermektedir. Bu doğrultuda, Erzincan ve ilçelerinin mesafeleri, atık kapasiteleri ve ekonomik verimliliği göz önünealındığında, 0.5 MW, 1.2 MW ve 2.4 MW kurulu güce sahip 3 farklı biyogaz santrali senaryosu hazırlanmıştır. Butesislerin yatırım maliyetleri ve her bir tesis için gerekli olan yatırımın geri ödeme süreleri hesaplanmıştır. Araştırmayadayanarak, Erzincan'da biyogaz üretimi ile hayvan atıklarının enerjiye dönüştürülmesi açısından birçok fırsataraştırılabilir. Bölgede, küçük boyutlarda olmak üzere, önerilen sayıdan daha fazla sayıda biyogaz tesisi kurmak damümkündür.
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ArticleAçık Erişim2021/r/ebyu/20794
Synthesis, Characterization and Photoelectrochemical Properties of $MoS_2$ decorated $TiO_2$ Nanotubes Electrodes
Çırak, Burcu Bozkurt; Eden, Çiğdem
In this research, $TiO_2$/$MoS_2$nanocomposite electrodes were synthesized to investigate the photoelectrochemical performances. Firstly, $TiO_2$ nanotubes were fabricated by anodic oxidation on Ti foil. Then, $MoS_2$ nanostructures were synthesis by hydrothermal method on $TiO_2$ nanotubes. The prepared nanocomposite films were characterized by using X-Ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The transient photocurrent response was analyzed to investigate photoelectrochemical activity of electrodes. The results show that TiO2 nanotube arrays coated with $MoS_2$ nanostructure homogeneously. Furthermore, $TiO_2$/$MoS_2$ nanocomposite electrode were shown better photoelectrochemical activity then bare $TiO_2$ electrode.
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Review ArticleAçık Erişim2021/r/ebyu/20733
The Investigation of Batteries and Thermal Management Systems Used in Electric Vehicles
Celen, Ali; Kaba, Muhammet Yasin; Kalkan, Orhan
Nowadays, electric vehicles come to the fore more than vehicles with internal combustion engines since electric vehicles are environmentally friendly and highly more efficient. Selection and thermal management of the battery, which is one of the most important equipment that constitutes electric vehicles, is important. In this study, the general view (history, classification, sales numbers, market shares) of electric vehicles, battery types that can be used in electric vehicles and battery thermal management systems were investigated. Different types of batteries commonly used in applications are compared according to their characteristics, and among these batteries, it has been observed that the type of battery that can be used in electric vehicles is lithium-ion batteries which have high specific energy (118-250 Wh/kg), high energy density (200-400 Wh/L), high specific power (200-430 W/kg), high cycle life (2000) and ideal operating temperature (-20oC-60oC). The thermal management systems, which can be used to obtain maximum performance from these batteries, are investigated and advantages and disadvantages of these methods are investigated. While it has been seen that air cooling is sufficient in vehicles with low thermal load (hybrid electric vehicles, etc.), it is observed that the use of liquid and hybrid cooling methods is appropriate in vehicles with high thermal load (full electric vehicles).
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ArticleYalnız künye2021/r/ebyu/18521
Numerical investigation on the usage of finned surface in lithium nickel manganese cobalt oxides batteries by using air cooling method
Celen, Ali; Kalkan, Orhan
In this study, a numerical thermal analysis of a lithium nickel manganese cobalt oxide prismatic battery having nominal voltage of 3.7 V and capacity of 26Ah was performed during air cooling conditions. The effects of discharge rate (in the range of 3C-5C) and air velocity (in the range of 1-3 m s(-1)) on average battery temperature, maximum battery temperature, and total heat transfer rate are investigated for both flat and finned cooling surfaces. The results showed that air cooling by means of flat cooling surface is only sufficient for low discharge rate and it is necessary to use finned surfaces in order to keep battery temperature in desired operation temperature range for high discharge rate conditions. Analysis results showed that average battery temperature is reduced up to 29%, 32%, and 30% by increasing air velocity for discharge rates of 3C, 4C, and 5C with the usage of flat surface, respectively. In addition, it was seen that the average and maximum battery temperatures are reduced up to 7.9 and 8.6 K with the usage of finned cooling surface instead of flat one. The heat removed from the battery is increased 8.7 W by using finned surface at the maximum air velocity of 3 ms(-1).
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ArticleAçık Erişim2021/r/ebyu/18520
Investigation of Neutronic and Thermal Performance Using UGD and MOX Fuel in VVER-1000 Nuclear Power Reactor
Uzun, Sinem; Genç, Yasin; Acir, Adem
When examining the safety and design features of nuclear power reactors, its thermal performance in addition to neutronic characteristics is important. In this study, the neutronic and thermal performances of VVER-1000 reactor with two different fuel assembly arrangements were examined. Those fuel assemblies named as YD1 and YD2 are composed of 3.7% enriched LEU and 3.6% enriched LEU with 4% Gd2O3 uranium-gadolinium (UGD) and 2%, 3%, 4.2% Pu and 3.6% enriched LEU with 4% Gd2O3 (MOXGD), respectively. The effects of using UGD and MOXGD fuel assembly arrangements on criticality and isotope transformations according to burnup rate were investigated by means of MCNP5 and MONTEBURNS2.0 nuclear code, correspondingly the temperature and enthalpy changes of the coolant along the hot channel were examined with the help of the COBRA-IV PC thermal analysis code. The results obtained from this study were compared with similar studies in the literature and it was observed that the obtained findings were in accordance with the literature.
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ArticleAçık Erişim2021/r/ebyu/18515
Investigation of thermal performance of aluminum nanoparticle coolant in vver-1000 reactor
Uzun, Sinem; Genç, Yasin; Acir, Adem
Thermal analysis is of great importance when examining the safety and design features of nuclear power reactors. The aim of this study is to examine the effect of pure water and coolant containing Al2O3 nanoparticles on thermal performance of VVER-1000 nuclear reactor. In this study, the VVER-1000 reactor is in steady state and BOC (begining of cycle) condition, relative power density distributions for UO2 fuel with 3.7% enrichment were obtained with the MCNP code and then, thermal analysis were made with the COBRA code and DNBR value, which is very important for the safety criteria of the reactor, was examined. In addition, with the COBRA code, thermal values such as temperature, enthalpy, density, and temperature values of the fuel and clad regions, which are of great importance for the reactor, were calculated. As a result of the analysis, it was determined that the most efficient coolant is 0.1% Al2O3 fluid in the heat transfer of the reactor.
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ArticleAçık Erişim2021/r/ebyu/18215
Operation of DC Motor with Multi-Level Inverter in PWAM Method
Can, Erol
DC motor control with switching methods is an interesting devise with many practical applications. A DC-DC buck-boost converter is one of the methods used to operate the DC motor. Although the-DC buck-boost converter for dc motor applications has been widely studied, they have some handicaps. In this study, the multi-level inverter structure that is different from the methods of DC motor driving is used to drive the DC motor. There will be no passive elements in the proposed circuit although the dc-dc converters have passive elements. So, while the inadequacies for the loads needing high current will be eliminated, the handicaps of the switching can be avoided. Current, torque, and voltage on the load will also be created by Pulse Width Amplitude Method (PWAM). As a different from other Pulse width modulation methods (PWM); the torque, current, and voltage of the motor can be controlled with PWAM in the horizontal and vertical axes. In the design stage; inverter switch structure and operation are given after the method of produced PWMs introduced. The equations of the voltages that will occur in the loads are created according to the working structure of the switches. DC motor structure is also given. In the simulation stage; Continuous and discontinuous modes of the proposed circuit are performed. Then torque of dc motor, armature current and speed are tested according to switching at different frequencies and different modulation indices.
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ArticleYalnız künye2021/r/ebyu/14631
Experimental investigation of thermal performance of novel cold plate design used in a Li-ion pouch-type battery
Kalkan, Orhan; Celen, Ali; Bakirci, Kadir; Dalkilic, Ahmet Selim
The world's tendency towards electric vehicles has accelerated and the thermal management of them are critical part of the actual studies. Liquid-based cooling is known as the most common one among other cooling techniques. However, there is still need on the use of various heat transfer enhancement techniques to reduce the maximum temperature and maintain homogenous temperatures. This study experimentally investigated thermal performance of water-cooled cold plates used in thermal management of batteries by using conventional serpentine tube and a novel mini channel designs including a lithium-ion phosphate battery under certain discharge rates from 1C to 5C. Experiments are conducted for different water flow rates from 0.1 to 1.1 L/min as the coolant with inlet temperatures from 15 to 35 °C. Experimental results show that lower coolant inlet temperature causes the largest maximum temperature difference on battery surface. The use of mini channel cold plate resulted in 5.7 °C reduction in the maximum average battery surface temperature compared to serpentine one. Battery surface temperature homogeneity is improved up to 40% for operating conditions for mini channel cold plate usage. Thus, enhancement on thermal performance of proposed new mini channel cold plate is accomplished by temperature measurements.
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ArticleYalnız künye2021/r/ebyu/14617
Flame and instability characteristics of high hydrogen content gas mixtures
Yilmaz, Harun; Yilmaz, Ilker
In this study, initially, 50%H2–25%CH4–25%CO2, 60%H2–20%CH4–20%CO2 and 70%H2–15%CH4–15%CO2 mixtures were combusted in a laboratory scale-swirl stabilized-premixed combustor so as to specify combustion and emission characteristics of respective gas mixtures. Later on, such mixture flames were exposed to acoustic perturbations at different frequencies between the values of 65–205 Hz and under these conditions, flame response was evaluated. The acoustic perturbations were intentionally created by loudspeakers located in side arms of the T-shaped combustor. Two openings on the combustor walls, and photodiodes and pressure sensors assembled in the experimental apparatus enabled interpreting flame response. During experiments, inlet parameters (such as thermal power – 4 kW, equivalence ratio – 0.5, mixture temperature, etc.) and geometric swirl number (1.2) were kept constant, and tested flames were acoustically forced for 30 s at each frequency step. Results showed that thermal Zeldovich mechanism doesn't dominate NOx formation for tested flames, and 50%H2–25%CH4–25%CO2 mixture emits nearly thirty times of magnitude of higher NO than 70%H2–15%CH4–15%CO2 mixture. Besides, the onset of flame instabilities depending on the forcing frequency isn't controlled by gas composition. However, flame and combustion chamber acoustics weakly couple, hence pressure and heat release rate oscillations weaken as hydrogen amount in gas mixture increases.
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ArticleYalnız künye2021/r/ebyu/14587
Experimental investigation of thermal energy storage efficiency using fin application with phase change material (pcm) under solar radiation
Acir, Adem; Canli, Mehmet Emin; Ata, Ismail; Uzun, Sinem; Tanürün, Himmet Erdi
In this paper, the energy storage behavior of the thermal energy storage unit (TESU) using phase change material (PCM) and copper fi ns under artifi cial solar radiation was analyzed experimentally. The experimental tests of the TESU were performed at three diff erent fi n numbers (n = 3, 5, and 7) and fi n thickness (t = 1, 1.5, and 2 mm) under variable solar radiations (q = 800, 900, and 1000 W/m2). The stored thermal energy of each TESU was calculated and compared with solar energy coming from a solar lamp. The highest thermal energy storage effi ciency was computed as 95.08% in Type-VIII (n = 7, t = 1 mm) TESU below 1000 W/m2 solar fl ux. The thermal energy storage effi ciency enhancement ratio (TESEER) was defi ned to understand the eff ects of n and t of the thermal energy storage effi ciency of TESUs. The highest TESEER was calculated as 1.68 in Type-VIII (n = 7, t = 1 mm) TESU below 1000 W/m2 solar radiation. In conclusion, the TESEER values were decreased with increasing fi n thickness, whereas its values were usually increased with the increase number of fi ns.
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ArticleYalnız künye2021/r/ebyu/14522
Experimental and numerical investigation of the LiFePO4 battery cooling by natural convection
Kalkan, Orhan; Celen, Ali; Bakirci, Kadir
In this study, the thermal performance of a LiFePO4 (LFP) pouch type battery in the range of 1C-5C discharge rate at 23 °C ambient temperature and natural convection conditions is experimentally and numerically investigated. Time-dependent temperature changes of the battery are imaged with a thermal camera for each discharge, and the maximum, minimum and average changes on the battery surface are examined. In addition, the heat transfer rate through the battery is calculated for each discharge rate under natural convection conditions of the battery, and the temperature and velocity distributions on the battery surface are investigated. For the experiment with the highest discharge rate (5C), the measured maximum and average battery temperatures are determined as 52.2 °C and 50.1 °C, respectively. The calculated maximum temperature difference on the battery surface is also 6.7 °C. Moreover, the homogeneity index defined for battery surface temperature is 0.147 at 5C discharge rate. It has been observed that natural convection cooling is not sufficient for the battery at high discharge rates Furthermore, a new correlation equation has been proposed for the estimation of the heat transfer rate from a 20 Ah LFP pouch type battery under natural convection conditions at 23 °C ambient temperature.
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