International Journal of Energy Research
ISSN / EISSN : 0363-907X / 1099-114X
Published by: Wiley (10.1002)
Total articles ≅ 7,414
Latest articles in this journal
International Journal of Energy Research; doi:10.1002/er.7136
The work which has been done on cement-polymer composite based shielding materials was comprehensively described in the present article, the choice of the study presented here is based on the choice of the researches. The new Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane Plaster-concrete composites mixed with different percentage soft lead oxide and arsenic oxide is used to research gamma-ray shielding and thermal conductivity characteristics. The synthesis of new Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane copolymer was achieved by Atom Transfer Reaction and Condensation Polymerization methods. The characterization of Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane Plaster was made with the Nuclear Magnetic Resonance, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, Gel Permeation Chromatography, Thermogravimetric Analysis, Scanning Electron Microscope methods. The transmitted fluxes of gamma-rays that were emitted from source was detected by a High Purity Germanium (HPGe) detector system at Karadeniz Technical University-Department of Physics in Trabzon and analyzed by a GammaVision (Version:6.07-Ortec, Oak Ridge, TN) computer program. The composite phase change materials including 89, 87, 69, 67% Portland cement, 1% and 3% PU-Plaster, 10% and 30% weight percent lead oxide and arsenic oxide was irradiated in the various gamma ray photon energy region (121.78, 344.28, 778.90, 964.08, 1085.87, 1112.07, and 1408.01 keV) for 3600 seconds. Then, linear attenuation coefficients, mass attenuation coefficients, half-value layer, tenth value layer, mean free path, radiation protection efficiency, and gamma-rays absorption of concrete-the Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane copolymers specimens were experimentally investigated. Thermal properties and morphological analysis of the irradiated substances were explored handling differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscope methods of the nano lead oxide and arsenic oxide including composite phase change material via gamma irradiation were submitted. Moreover, the effect of the Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane amount on the radiation attenuation of the composite material was investigated. Gamma attenuation experiments have been performed to specify lead equivalent values for the improved composite material. The composite equivalent thickness values from 0.5 to 0.6 cm sample thickness and 0.665 cm radius were obtained. Via crosschecking the acquired data from concrete samples with and without lead and arsenic, it was observed that, if the powder of lead oxide and arsenic oxide to cement ratio of 10% and 30% by weight is added in the concrete mixture, the concrete-the Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane composite can be used as a suitable shield against gamma rays. Also, mass attenuation coefficients were calculated as theoretical with the National Institute of Standards and Technology(NIST)-XCOM database. The thermal conductivity coefficient and the heat capacity of the composites were determined.
International Journal of Energy Research; doi:10.1002/er.7104
Two-step pyrolysis (TSP) and one-step pyrolysis (OSP) of rice husk was conducted using a fixed-bed reactor, and the product distribution and physicochemical property were analyzed. TSP had two fast pyrolysis processes, which were, respectively, set at lower temperature (400°C) in the first step and high temperature (550°C) in the second step, while OSP was only set at high temperature (550°C). Compared with OSP, TSP increased the total yields of char and gas but decreased the total yield of bio-oil. The pyrolysis process of the first step facilitated the cross-linking and polycondensation reactions in the char of the first step, thus inhibiting the decomposition of the char from the first step and decreasing the yield of bio-oil in the second step. Due to the high pyrolysis temperature, there was no significant difference between the char from the second step and the char from OSP. The first step improved the selectivity of acids, furans and phenols with complex side chains in bio-oil. The bio-oil from the second step had lower acidity, and higher selectivity of phenols and hydrocarbons. Compared with the gas product of OSP, the H2 and CH4 contents of the gas product from the second step were improved by more than 70% and 35%. TSP could not only improve the selectivity of value-added chemicals but also achieve the higher quality of gas and bio-oil as fuel.
International Journal of Energy Research; doi:10.1002/er.7035
Photoelectrochemical (PEC) water splitting is widely regarded as an effective process for sustainable storage of solar energy as chemical energy in the form of H2. The efficiency of this process depends upon the light absorption, charge injection, and charge separation efficiency of the photoanode material used. In this work, doping hematite with 1% tin and loading with NiFe-layered double hydroxide (LDH) co-catalyst has been done to improve the charge transport properties. To enhance the PEC performance and study the effect of precursor concentration, NiFe-LDH at two different concentrations (low and high) was coated on Sn-doped hematite. A high photocurrent density ca. 2.9 mA/cm2 at 1.8 V vs reversible hydrogen electrode (RHE) and a 170 mV cathodic shift in onset potential compared to pristine hematite (0.22 mA/cm2 at 1.8 V vs RHE) was recorded for Sn-doped hematite coated with low precursor concentration. The enhanced PEC activity can be attributed to the synergistic effect of Sn doping and NiFe-LDH co-catalyst on hematite, which contributes to an efficient separation of the photogenerated charge carriers and reduces hole accumulation at the surface. However, for the high precursor concentration case, the formation of a thick film of NiFe-LDH results in a comparatively lower current density (0.85 mA/cm2 at 1.8 V vs RHE). The results obtained show that NiFe-LDH can be used as an effective co-catalyst to significantly enhance the charge transport properties of tin-doped hematite. A charge transfer mechanism of the developed photoanodes is also discussed in detail.
International Journal of Energy Research; doi:10.1002/er.7098
A novel pH switch over of the electrolyte in all aqueous Redox Flow Battery (RFB) is studied to augment its voltage efficiency, capacity retention and volumetric capacity. By switching the pH of the anolyte from 2 to 5, the cell voltage stabilized at 0.44 V from 0.85 V vs SHE. pH switch over caused increase in the volumetric capacity from 64 mAh/l to 75 mAh/l. The device showed constant capacity of 40 mAh/l up to 200 cycles with 53% capacity retention. The device performed up to 200 cycles and 720 hours of operation, even in the presence of undesirable side reactions such as Hydrogen Evolution Reaction (HER). Thus by improving the design parameters, one can anticipate all aqueous RFB may be scaled up for practical applications.
International Journal of Energy Research; doi:10.1002/er.7114
This effort is founded on the modeling and simulation of the GaAsPN/GaP quantum dot (QD) solar cell. This quaternary alloy is one of the III-V semiconductors, which gained importance in the recent years for optoelectronic applications. This importance comes from the fact that the quaternary GaAsPN can be a well-grown lattice matched to GaP and Si substrates and to the bandgap that can be decreased drastically with the incorporation of nitrogen and arsenic into GaP, improving consequently the absorption and the wavelengths near the red part. These qualities make GaAsPN a good candidate for the growth on the Si substrate and low-cost solar cell fabrication. The optical properties of GaAsPN/GaP QDs, such as strain, critical thickness, bandgap energy, the external quantum efficiency, and absorption coefficient, have been reported. The heterostructures consist of GaAs0.18P0.814N0.006 QDs separated by GaP barrier layers. The width and thickness of QDs are about 5 and 5 nm, respectively. Our results have been shown that 20 GaAs0.18P0.814N0.006/GaP QD layers produce a short-circuit current of about 3.55 mA/cm2 and an efficiency of about 7.5%. In addition, we will be able to extend the absorption edge of a GaP solar cell from 0.48 μm to 0.5 μm for the same QD number layers inserted. The temperature effect on efficiency is considered.
International Journal of Energy Research; doi:10.1002/er.7008
The underground mine contains abundant geothermal energy resources. The casing-type mine heat recovery device with encapsulated phase change material (PCM) embedded in the backfill body is efficient technology for extraction of geothermal energy in mines. A heat transfer model of a casing-type mine heat recovery unit was established to study the influence of PCMs thermophysical property and phase transition process on the thermal performance of backfill body. The effects of phase transition temperature, thermal conductivity, specific heat capacity and phase transition latent heat of PCMs on the temperature variation in backfill body and the thermal performance of casing-type mine heat recovery device were studied in the heat storage/release mode. The result indicates that the phase transition temperature is expected to be lower in heat storage mode and higher in heat release mode, respectively. The heat transfer rate can be significantly enhanced by PCMs with larger thermal conductivity in both heat storage and heat release modes. Furthermore, PCMs with large specific heat capacity and latent heat should be used to improve the energy storage effect. After 10 hours of heat storage/release, when the specific heat capacity increases from 1000 to 3000 J/(kg ∙ K), the heat storage capacity and heat extraction capacity increased by 9.11% and 6.69%, respectively; when the phase transition latent heat increases from 100 to 200 kJ/Kg, the heat storage capacity and heat extraction capacity increased by 4.79% and 3.29%, respectively.
International Journal of Energy Research; doi:10.1002/er.7135
The LiMnPO4 material has the advantages of abundant raw materials, safety and environmental protection, low price, high theoretical capacity, high stable working voltage platform and so on, showing great potential in lithium-ion batteries. Dissimilar metal ion doping can essentially improve the electronic conductivity of LiMnPO4 and the material's charge and discharge performance, which is an ideal method to improve the electrochemical performance of LiMnPO4. In this paper, the optimal doping concentration of Mg-doped solid solution material was calculated by first principles. At the same time, the corresponding content of LiMn1−xMgxPO4/C cathode material was synthesized by hydrothermal method for experimental verification, so as to prepare the cathode material with excellent electrochemical performance. The results show that the doping of Mg cations does not change the phase of the main phase, but significantly changes the crystal structure parameters. The regulation of the band width directly affects the electronic conductivity of the material, which is directly proportional to the electrochemical performance. EIS and CV test results show that a proper amount of magnesium doping can effectively reduce the impedance of the material, and can effectively alleviate the polarization phenomenon of LiMnPO4 electrode material, accelerate the diffusion rate of Li+, and it is easier to obtain high capacity battery. LiMn23/24Mg1/24PO4/C showed the best electrochemical performance, with an initial capacity of 153.8 mAh/g at 0.05C ratio and a capacity retention rate of 97.5% after 100 cycles at 0.05C ratio. The theoretical calculation is in good agreement with the experimental results, which indicates that the theoretical calculation based on first principles can effectively provide a more reliable theoretical basis for experimental design and subsequent improvement.
International Journal of Energy Research; doi:10.1002/er.7130
Activated carbons (ACs) from biomass sources have attracted attention due to their superior properties including, easy preparation, abundant raw materials, ready availability, low cost, low mass density, high specific surface area and micropore volume, fast and reversible kinetics, structural diversity, and sustainable regeneration. Due to their tunable aspects, bio-derived ACs are among the most promising materials for the storage of hydrogen. In this contribution, the comparative evaluation of various carbon materials prepared from biomass sources for hydrogen storage applications is aimed. To carry out this goal, literature related to ACs having different chemical nature from a variety of precursors using various preparation methodology are compiled, and compared in terms of their characterization to correlate the surface characteristics with their hydrogen storage performances, focusing on the effects of the type of precursors/activating agents, and major affecting operational variables. An overview on the preparation, characterization, and analysis methods, hydrogen storage performances of biosorbents from different kinds of biomass, perspectives, and challenges are presented.
International Journal of Energy Research; doi:10.1002/er.7095
Melting rate enhancement inside an accumulator unit for a phase change material (PCM) has been numerically investigated in a shell-and-tube (S-T) arrangement that incorporates the circular type of fins, considering a fixed total volume of fins. The number of fins was chosen as the design parameter. The heat transfer fluid (HTF) was chosen as water that flows through the selected accumulator unit during the process of melting. The computational fluid dynamics (CFD) technique has been utilized for the simulation of the accumulator using ANSYS FLUENT software by considering a two-dimensional axisymmetric cylindrical accumulator in a vertical direction. During the melting process, two heat transfer mechanisms were considered, namely, conduction and convection. The HTF flow was 5 L/min with a flow temperature of 358 K for charging. The predicted complete melting time of the PCM decreased by 53.125%, 65.625%, 71.875%, and 71.875% for fins numbering 6, 18, 30, and 36, respectively, compared with the S-T without fins where it took approximately 480 minutes to melt completely. The optimal fin parameters are recommended in this study as follows: number of fins N = 30, thickness t/d = 0.01858, interval d/L = 0.03227, and aspect ratio t/h = 0.015. These recommended values maximize the thermal performance of the selected accumulator unit. The effects of changing the flow rate of the heat transfer fluid and its inlet temperature have been found to be significant on the PCM melting rate. The total melting time of the PCM is found to be reduced by about 57% when the inlet flow temperature is increased from 343 to 358 K. Moreover, the total melting time reduces by about 70.5% with an increase in the heat transfer fluid mass flow rate from 0.15 to 5 L/min. Furthermore, increasing the HTF flow rate from 0.15 to 5 L/min leads to a reduction of about 61.1% in the predicted total time that is required for solidification. The temperature differences for low flow rates are greater than those for high flow rates. The novelty of this study is in investigating the performance at a fixed total volume of fins.
International Journal of Energy Research; doi:10.1002/er.7121
Supercapacitors (SCs), or ultracapacitors, due to their attractive features, such as, high power density, long life cycle, etc., have received much attention from the transportation sector. SCs can be used as an additional energy storage system (ESS) in combination with lithium-ion batteries to enhance the performance of electric vehicles (EVs) in dynamic states, including acceleration and regenerative braking modes of operation. Online accurate estimation of SCs' state of health (SoH) and state of energy (SoE) is essential for an efficient energy management and real-time condition monitoring in EV applications. The accuracy of the estimation of the SoE and SoH is based on the model's efficiency, which ensures that in order to minimize the impact of aging, model parameters should be defined in real time. Nevertheless, because the SC model is obviously nonlinear and broad in scale, online identification of the parameters estimation is usually difficult. In this paper, a generalized SC model of high accuracy and good robustness is proposed. The classification of the estimation methodologies for SoH and SoE of SC will be very helpful in choosing the appropriate method for the development of reliable and secure ESS and an energy management strategy for EVs.