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Clean Energy and Fuel (Hydrogen) Storage
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Clean Energy and Fuel (Hydrogen) Storage

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Energy Science and Technology".

Deadline for manuscript submissions: closed (31 December 2018) | Viewed by 96121

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Elias K. Stefanakos

E-Mail Website
Guest Editor
Clean Energy Research Center, College of Engineering, University of South Florida, Tampa, FL 33620, USA
Interests: solar energy conversion (photovoltaics, rectennas, etc.); fuel cells; hydrogen production and storage; energy systems; electric/hybrid vehicles—alternative fuels; thermal storage; photocatalysis; electrochromic, touch-chromic and thermochromic materials
Special Issues, Collections and Topics in MDPI journals
Dr. Sesha S. Srinivasan

E-Mail Website
Guest Editor
Assistant Professor of Physics, Florida Polytechnic University, 4700 Research Way, Lakeland, FL 33805, USA
Interests: hydrogen production; hydrogen storage; fuel cells; nanotechnology; multifunctional materials; photocatalysis; material synthesis and characterization

Special Issue Information

Dear Colleagues,

Clean energy and fuel storage is often required for both stationary and automotive applications. Some of these clean energy and fuel storage technologies, currently under extensive research and development, are hydrogen storage, direct electric storage, mechanical energy storage, solar-thermal energy storage, electrochemical (batteries), and thermochemical storage. The gravimetric and volumetric storage capacity, energy storage density, power output, operating temperature and pressure, cycle life, recyclability and cost of clean energy or fuel storage are some of the factors that govern efficient energy and fuel storage technologies for potential deployment in energy harvesting (solar and wind farms) stations and on-board vehicular transportation. This Special Issue, thus, serves the need to promote exploratory research and development on clean energy and fuel storage technologies while addressing their challenges to a practical and sustainable infrastructure. We invite contributions in topics that include but not limited to various state-of-the-art energy and alternative fuel storage technologies.

Prof. Dr. Elias K. Stefanakos
Dr. Sesha S. Srinivasan
Guest Editors

Manuscript Submission Information

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Keywords

  • Hydrogen Production and Storage

  • Thermal Energy Storage

  • Direct Electrical Energy Storage

  • Direct Mechanical Energy Storage

  • Electrochemical Energy Storage

  • Thermochemical Energy Storage

  • Other Clean Energy and Fuel Storage Options

Published Papers (17 papers)

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Editorial

Jump to: Research, Review

7 pages, 184 KiB  
Editorial
Clean Energy and Fuel Storage
by Sesha S. Srinivasan and Elias K. Stefanakos
Appl. Sci. 2019, 9(16), 3270; https://doi.org/10.3390/app9163270 - 09 Aug 2019
Cited by 8 | Viewed by 3021
Abstract
Clean energy and fuel storage is often required for both stationary and automotive applications. Some of the clean energy and fuel storage technologies currently under extensive research and development are hydrogen storage, direct electric storage, mechanical energy storage, solar-thermal energy storage, electrochemical (batteries [...] Read more.
Clean energy and fuel storage is often required for both stationary and automotive applications. Some of the clean energy and fuel storage technologies currently under extensive research and development are hydrogen storage, direct electric storage, mechanical energy storage, solar-thermal energy storage, electrochemical (batteries and supercapacitors), and thermochemical storage. The gravimetric and volumetric storage capacity, energy storage density, power output, operating temperature and pressure, cycle life, recyclability, and cost of clean energy or fuel storage are some of the factors that govern efficient energy and fuel storage technologies for potential deployment in energy harvesting (solar and wind farms) stations and on-board vehicular transportation. This Special Issue thus serves the need to promote exploratory research and development on clean energy and fuel storage technologies while addressing their challenges to a practical and sustainable infrastructure. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)

Research

Jump to: Editorial, Review

13 pages, 3087 KiB  
Article
Slag as an Inventory Material for Heat Storage in a Concentrated Solar Tower Power Plant: Design Studies and Systematic Comparative Assessment
by Michael Krüger, Jürgen Haunstetter, Philipp Knödler and Stefan Zunft
Appl. Sci. 2019, 9(9), 1833; https://doi.org/10.3390/app9091833 - 03 May 2019
Cited by 10 | Viewed by 4374
Abstract
By using metallurgical slag from an electric arc furnace that is otherwise not recycled but deposited as an inventory material in thermal energy storage for concentrated solar power plants, it is possible to make a significant step forward in two transformation processes: energy [...] Read more.
By using metallurgical slag from an electric arc furnace that is otherwise not recycled but deposited as an inventory material in thermal energy storage for concentrated solar power plants, it is possible to make a significant step forward in two transformation processes: energy and raw materials. As this type of slag has not been considered as an inventory material for this purpose, it is important to clarify fundamental questions about this low-cost material and its storage design. In this paper, design studies of slag-based thermal energy storage are carried out. Different slag-specific design concepts are developed, calculated and evaluated by a method based on established management tools. Finally, concepts for further investigations are defined. The highest aptitude value and the lowest risk value are achieved by the vertical storage design with axial flow direction. Therefore, it is taken as the lead concept and will be considered in complete detail in further research. Also, a closer look, but not as detailed as the lead concept, is taken at the horizontal storage with axial flow and the vertical storage with radial flow direction. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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19 pages, 4905 KiB  
Article
Dynamics of a Partially Confined, Vertical Upward-Fluid-Conveying, Slender Cantilever Pipe with Reverse External Flow
by Xinbo Ge, Yinping Li, Xiangsheng Chen, Xilin Shi, Hongling Ma, Hongwu Yin, Nan Zhang and Chunhe Yang
Appl. Sci. 2019, 9(7), 1425; https://doi.org/10.3390/app9071425 - 04 Apr 2019
Cited by 13 | Viewed by 2961
Abstract
A linear theoretical model is established for the dynamics of a hanging vertical cantilevered pipe which is subjected concurrently to internal and reverse external axial flows. Such pipe systems may have instability by flutter (amplified oscillations) or static divergence (buckling). The pipe system [...] Read more.
A linear theoretical model is established for the dynamics of a hanging vertical cantilevered pipe which is subjected concurrently to internal and reverse external axial flows. Such pipe systems may have instability by flutter (amplified oscillations) or static divergence (buckling). The pipe system under consideration is a slender flexible cantilevered pipe hanging concentrically within an inflexible external pipe of larger diameter. From the clamped end to the free end, fluid is injected through the annular passage between the external pipe and the cantilevered pipe. When exiting the annular passage, the fluid discharges in the counter direction along the cantilevered pipe. The inflexible external pipe has a variable length and it can cover a portion of the length of the cantilevered pipe. This pipe system has been applied in the solution mining and in the salt cavern underground energy storage industry. The planar motion equation of the system is solved by means of a Galerkin method, and Euler–Bernoulli beam eigenfunctions are used as comparison functions. Calculations are conducted to quantify the effects of different confinement conditions (i.e., the radial confinement degree of the annular passage and the confined-flow length) on the cantilevered pipe stability, for a long leaching-tubing-like system. For a long system, an increase in the radial confinement degree of the annular passage and the confined-flow length gives rise to a series of flutter and divergence. Additionally, the effect of the cantilevered pipe length is studied. Increasing the cantilevered pipe length results in an increase of the critical flow velocity while a decrease of the associated critical frequency. For a long enough system, the critical frequency almost disappears. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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10 pages, 3358 KiB  
Article
Nucleation Triggering of Highly Undercooled Xylitol Using an Air Lift Reactor for Seasonal Thermal Energy Storage
by Marie Duquesne, Elena Palomo Del Barrio and Alexandre Godin
Appl. Sci. 2019, 9(2), 267; https://doi.org/10.3390/app9020267 - 14 Jan 2019
Cited by 22 | Viewed by 2926
Abstract
Bio-based glass-forming materials are now considered for thermal energy storage in building applications. Among them, Xylitol appears as a biosourced seasonal thermal energy storage material with high potential. It has a high energy density and a high and stable undercooling, thus allowing storing [...] Read more.
Bio-based glass-forming materials are now considered for thermal energy storage in building applications. Among them, Xylitol appears as a biosourced seasonal thermal energy storage material with high potential. It has a high energy density and a high and stable undercooling, thus allowing storing solar energy at ambient temperature and reducing thermal losses and the risk of spontaneous nucleation (i.e., the risk of losing the stored energy). Generally when the energy is needed, the discharge triggering of the storage system is very difficult as well as reaching a sufficient power delivery. Both are indeed the main obstacles for the use of pure Xylitol in seasonal energy storage. Different techniques have been hence considered to crystallize highly undercooled Xylitol. Nucleation triggering of highly undercooled pure Xylitol by using an air lift reactor has been proven here. This method should allow reaching performances matching with building applications (i.e., at medium temperatures, below 100 °C). The advantages of this technique compared to other existing techniques to activate the crystallization are discussed. The mechanisms triggering the nucleation are investigated. The air bubble generation, transportation of nucleation sites and subsequent crystallization are discussed to improve the air injection operating conditions. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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19 pages, 1412 KiB  
Article
Hydrogeochemical Modeling to Identify Potential Risks of Underground Hydrogen Storage in Depleted Gas Fields
by Christina Hemme and Wolfgang Van Berk
Appl. Sci. 2018, 8(11), 2282; https://doi.org/10.3390/app8112282 - 19 Nov 2018
Cited by 148 | Viewed by 12653
Abstract
Underground hydrogen storage is a potential way to balance seasonal fluctuations in energy production from renewable energies. The risks of hydrogen storage in depleted gas fields include the conversion of hydrogen to CH4(g) and H2S(g) due to microbial activity, [...] Read more.
Underground hydrogen storage is a potential way to balance seasonal fluctuations in energy production from renewable energies. The risks of hydrogen storage in depleted gas fields include the conversion of hydrogen to CH4(g) and H2S(g) due to microbial activity, gas–water–rock interactions in the reservoir and cap rock, which are connected with porosity changes, and the loss of aqueous hydrogen by diffusion through the cap rock brine. These risks lead to loss of hydrogen and thus to a loss of energy. A hydrogeochemical modeling approach is developed to analyze these risks and to understand the basic hydrogeochemical mechanisms of hydrogen storage over storage times at the reservoir scale. The one-dimensional diffusive mass transport model is based on equilibrium reactions for gas–water–rock interactions and kinetic reactions for sulfate reduction and methanogenesis. The modeling code is PHREEQC (pH-REdox-EQuilibrium written in the C programming language). The parameters that influence the hydrogen loss are identified. Crucial parameters are the amount of available electron acceptors, the storage time, and the kinetic rate constants. Hydrogen storage causes a slight decrease in porosity of the reservoir rock. Loss of aqueous hydrogen by diffusion is minimal. A wide range of conditions for optimized hydrogen storage in depleted gas fields is identified. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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17 pages, 2165 KiB  
Article
Optimization of Battery Energy Storage System Capacity for Wind Farm with Considering Auxiliary Services Compensation
by Xin Jiang, Guoliang Nan, Hao Liu, Zhimin Guo, Qingshan Zeng and Yang Jin
Appl. Sci. 2018, 8(10), 1957; https://doi.org/10.3390/app8101957 - 17 Oct 2018
Cited by 23 | Viewed by 3844
Abstract
An optimal sizing model of the battery energy storage system (BESS) for large-scale wind farm adapting to the scheduling plan is proposed in this paper. Based on the analysis of the variability and uncertainty of wind output, the cost of auxiliary services of [...] Read more.
An optimal sizing model of the battery energy storage system (BESS) for large-scale wind farm adapting to the scheduling plan is proposed in this paper. Based on the analysis of the variability and uncertainty of wind output, the cost of auxiliary services of systems that are eased by BESS is quantized and the constraints of BESS accounting for the effect of wind power on system dispatching are proposed. Aiming to maximum the benefits of wind-storage union system, an optimal capacity model considering BESS investment costs, wind curtailment saving, and auxiliary services compensation is established. What’s more, the effect of irregular charge/discharge process on the life cycle of BESS is considered into the optimal model by introducing an equivalent loss of the cycle life. Finally, based on the typical data of a systems, results show that auxiliary services compensation can encourage wind farm configuration BESS effectively. Various sensitivity analyses are performed to assess the effect of the auxiliary services compensation, on-grid price of wind power, investment cost of BESS, cycle life of BESS, and wind uncertainty reserve level of BESS on this optimal capacity. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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17 pages, 15153 KiB  
Article
Numerical Investigation of Energy Saving Characteristic in Building Roof Coupled with PCM Using Lattice Boltzmann Method with Economic Analysis
by Bilin Shao, Xingxuan Du and Qinlong Ren
Appl. Sci. 2018, 8(10), 1739; https://doi.org/10.3390/app8101739 - 26 Sep 2018
Cited by 6 | Viewed by 2925
Abstract
Due to their characteristics of high energy storage density and a nearly constant melting temperature, phase change materials (PCMs) could be inserted into the roof of green buildings in order to reduce the energy consumption and ameliorate the room thermal comfort. In this [...] Read more.
Due to their characteristics of high energy storage density and a nearly constant melting temperature, phase change materials (PCMs) could be inserted into the roof of green buildings in order to reduce the energy consumption and ameliorate the room thermal comfort. In this paper, an enthalpy based multiple-relaxation-time (MRT) lattice Boltzmann method (LBM) was developed to calculate the transient phase change conjugate heat transfer with solar radiation inside the green building’s PCM roof in the hot summer and cold winter areas of China. The effect of the PCM melting temperature on the variation of the roof internal temperature was investigated and the energy saving characteristic of the PCM roof under an intermittent energy utilization condition was also analyzed by comparing with the performance of the roof filled with sensible insulating materials (SIMs). Then, the life cycle incremental costs and incremental benefits of a PCM roof and SIM roof were studied by using the comprehensive incremental benefit model so that the green building roof could be economically evaluated. The results indicate that a temperature rise inside the roof during summer cooling time could be delayed due to the latent heat of the PCMs. It was also found that the melting temperature and the thickness of the PCM layer should be chosen appropriately for enhancing the energy saving amount of a PCM roof. Based on this, the PCM roof could have a better energy saving capability than the SIM roof. During the winter heating time, as the environment temperature and the room temperature are both below the PCM melting temperature, the PCM roof does not have a latent heat characteristic so that it performs like a SIM roof. Furthermore, due to the high price of PCMs, the incremental cost of green building is increased, which makes the PCM roof have a negative comprehensive incremental benefit. Under this circumstance, developing PCMs with a low price and stable chemical properties is a key scientific bottleneck for a wider application of PCM roofs in the architecture engineering field. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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15 pages, 5592 KiB  
Article
A State of Charge Estimator Based Extended Kalman Filter Using an Electrochemistry-Based Equivalent Circuit Model for Lithium-Ion Batteries
by Xin Lai, Chao Qin, Wenkai Gao, Yuejiu Zheng and Wei Yi
Appl. Sci. 2018, 8(9), 1592; https://doi.org/10.3390/app8091592 - 08 Sep 2018
Cited by 25 | Viewed by 4266
Abstract
In this paper, an improved equivalent circuit model (ECM) considering partial electrochemical properties is developed for accurate state-of-charge (SOC). In the proposed model, the solid-phase diffusion process is calculated by a simple equation about particle surface SOC, and the double layer is simulated [...] Read more.
In this paper, an improved equivalent circuit model (ECM) considering partial electrochemical properties is developed for accurate state-of-charge (SOC). In the proposed model, the solid-phase diffusion process is calculated by a simple equation about particle surface SOC, and the double layer is simulated by two resistance-capacitance (RC) networks. To improve the global accuracy of the model, a subarea parameter-identification method based on particle swarm optimization is proposed, in order to determine the optimal model parameters in the entire SOC area. Then, an SOC estimator is developed based on extended kalman filter. The comparative study shows that a model considering solid-phase diffusion with two RC networks is the best choice. Finally, experimental results show that the accuracy of the proposed model is one times higher than that of the traditional ECM in the low SOC area, and is able to estimate SOC with errors less than 1% in the entire SOC area. Furthermore, estimation results of two types of batteries under two working conditions indicate that the developed model and SOC estimator have satisfactory global accuracy and guaranteed robustness with low computational complexity, which can be applied in real-time situations. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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21 pages, 15012 KiB  
Article
Power to Fuels: Dynamic Modeling of a Slurry Bubble Column Reactor in Lab-Scale for Fischer Tropsch Synthesis under Variable Load of Synthesis Gas
by Siavash Seyednejadian, Reinhard Rauch, Samir Bensaid, Hermann Hofbauer, Gerald Weber and Guido Saracco
Appl. Sci. 2018, 8(4), 514; https://doi.org/10.3390/app8040514 - 28 Mar 2018
Cited by 15 | Viewed by 6136
Abstract
This research developed a comprehensive computer model for a lab-scale Slurry Bubble Column Reactor (SBCR) (0.1 m Dt and 2.5 m height) for Fischer–Tropsch (FT) synthesis under flexible operation of synthesis gas load flow rates. The variable loads of synthesis gas are [...] Read more.
This research developed a comprehensive computer model for a lab-scale Slurry Bubble Column Reactor (SBCR) (0.1 m Dt and 2.5 m height) for Fischer–Tropsch (FT) synthesis under flexible operation of synthesis gas load flow rates. The variable loads of synthesis gas are set at 3.5, 5, 7.5 m3/h based on laboratory adjustments at three different operating temperatures (483, 493 and 503 K). A set of Partial Differential Equations (PDEs) in the form of mass transfer and chemical reaction are successfully coupled to predict the behavior of all the FT components in two phases (gas and liquid) over the reactor bed. In the gas phase, a single-bubble-class-diameter (SBCD) is adopted and the reduction of superficial gas velocity through the reactor length is incorporated into the model by the overall mass balance. Anderson Schulz Flory distribution is employed for reaction kinetics. The modeling results are in good agreement with experimental data. The results of dynamic modeling show that the steady state condition is attained within 10 min from start-up. Furthermore, they show that step-wise syngas flow rate does not have a detrimental influence on FT product selectivity and the dynamic modeling of the slurry reactor responds quite well to the load change conditions. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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2959 KiB  
Article
The Effect of Magnetic Field on Thermal-Reaction Kinetics of a Paramagnetic Metal Hydride Storage Bed
by Shahin Shafiee, Mary Helen McCay and Sarada Kuravi
Appl. Sci. 2017, 7(10), 1006; https://doi.org/10.3390/app7101006 - 29 Sep 2017
Cited by 8 | Viewed by 4972
Abstract
A safe and efficient method for storing hydrogen is solid state storage through a chemical reaction in metal hydrides. A good amount of research has been conducted on hydrogenation properties of metal hydrides and possible methods to improve them. Background research shows that [...] Read more.
A safe and efficient method for storing hydrogen is solid state storage through a chemical reaction in metal hydrides. A good amount of research has been conducted on hydrogenation properties of metal hydrides and possible methods to improve them. Background research shows that heat transfer is one of the reaction rate controlling parameters in a metal hydride hydrogen storage system. Considering that some very well-known hydrides like lanthanum nickel (LaNi5) and magnesium hydride (MgH2) are paramagnetic materials, the effect of an external magnetic field on heat conduction and reaction kinetics in a metal hydride storage system with such materials needs to be studied. In the current paper, hydrogenation properties of lanthanum nickel under magnetism were studied. The properties which were under consideration include reaction kinetics, hydrogen absorption capacity, and hydrogenation time. Experimentation has proven the positive effect of applying magnetic fields on the heat conduction, reaction kinetics, and hydrogenation time of a lanthanum nickel bed. However, magnetism did not increase the hydrogenation capacity of lanthanum nickel, which is evidence to prove that elevated hydrogenation characteristics result from enhanced heat transfer in the bed. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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6465 KiB  
Article
Synthetic Rock Analogue for Permeability Studies of Rock Salt with Mudstone
by Hongwu Yin, Hongling Ma, Xiangsheng Chen, Xilin Shi, Chunhe Yang, Maurice B. Dusseault and Yuhao Zhang
Appl. Sci. 2017, 7(9), 946; https://doi.org/10.3390/app7090946 - 14 Sep 2017
Cited by 14 | Viewed by 5922
Abstract
Knowledge about the permeability of surrounding rock (salt rock and mudstone interlayer) is an important topic, which acts as a key parameter to characterize the tightness of gas storage. The goal of experiments that test the permeability of gas storage facilities in rock [...] Read more.
Knowledge about the permeability of surrounding rock (salt rock and mudstone interlayer) is an important topic, which acts as a key parameter to characterize the tightness of gas storage. The goal of experiments that test the permeability of gas storage facilities in rock salt is to develop a synthetic analogue to use as a permeability model. To address the permeability of a mudstone/salt layered and mixed rock mass in Jintan, Jiangsu Province, synthetic mixed and layered specimens using the mudstone and the salt were fabricated for permeability testing. Because of the gas “slippage effect”, test results are corrected by the Klinkenberg method, and the permeability of specimens is obtained by regression fitting. The results show that the permeability of synthetic pure rock salt is 6.9 × 10−20 m2, and its porosity is 3.8%. The permeability of synthetic mudstone rock is 2.97 × 10−18 m2, with a porosity 17.8%. These results are close to those obtained from intact natural specimens. We also find that with the same mudstone content, the permeability of mixed specimens is about 40% higher than for the layered specimens, and with an increase in the mudstone content, the Klinkenberg permeability increases for both types of specimens. The permeability and mudstone content have a strong exponential relationship. When the mudstone content is below 40%, the permeability increases only slightly with mudstone content, whereas above this threshold, the permeability increases rapidly with mudstone content. The results of the study are of use in the assessment of the tightness of natural gas storage facilities in mudstone-rich rock salt formations in China. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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3429 KiB  
Article
Structure and Capacitance of Electrical Double Layers at the Graphene–Ionic Liquid Interface
by Pengfei Lu, Qiaobo Dai, Liangyu Wu and Xiangdong Liu
Appl. Sci. 2017, 7(9), 939; https://doi.org/10.3390/app7090939 - 12 Sep 2017
Cited by 18 | Viewed by 6896
Abstract
Molecular dynamics simulations are carried out to investigate the structure and capacitance of the electrical double layers (EDLs) at the interface of vertically oriented graphene and ionic liquids [EMIM]+/[BF4]−. The distribution and migration of the ions in [...] Read more.
Molecular dynamics simulations are carried out to investigate the structure and capacitance of the electrical double layers (EDLs) at the interface of vertically oriented graphene and ionic liquids [EMIM]+/[BF4]−. The distribution and migration of the ions in the EDL on the rough and non-rough electrode surfaces with different charge densities are compared and analyzed, and the effect of the electrode surface morphology on the capacitance of the EDL is clarified. The results suggest that alternate distributions of anions and cations in several consecutive layers are formed in the EDL on the electrode surface. When the electrode is charged, the layers of [BF4]− anions experience more significant migration than those of [EMIM]+ cations. These ion layers can be extended deeper into the bulk electrolyte solution by the stronger interaction of the rough electrode, compared to those on the non-rough electrode surface. The potential energy valley of ions on the neutral electrode surface establishes a potential energy difference to compensate the energy cost of the ion accumulation, and is capable of producing a potential drop across the EDL on the uncharged electrode surface. Due to the greater effective contact area between the ions and electrode, the rough electrode possesses a larger capacitance than the non-rough one. In addition, it is harder for the larger-sized [EMIM]+ cations to accumulate in the narrow grooves on the rough electrode, when compared with the smaller [BF4]−. Consequently, the double-hump-shaped C–V curve (which demonstrates the relationship between differential capacitance and potential drop across the EDL) for the rough electrode is asymmetric, where the capacitance increases more significantly when the electrode is positively charged. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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3943 KiB  
Article
Investigation of Catalytic Effects and Compositional Variations in Desorption Characteristics of LiNH2-nanoMgH2
by Sesha S. Srinivasan, Dervis Emre Demirocak, Yogi Goswami and Elias Stefanakos
Appl. Sci. 2017, 7(7), 701; https://doi.org/10.3390/app7070701 - 07 Jul 2017
Cited by 2 | Viewed by 3872
Abstract
LiNH2 and a pre-processed nanoMgH2 with 1:1 and 2:1 molar ratios were mechano-chemically milled in a high-energy planetary ball mill under inert atmosphere, and at room temperature and atmospheric pressure. Based on the thermogravimetric analysis (TGA) experiments, 2LiNH2-nanoMgH2 [...] Read more.
LiNH2 and a pre-processed nanoMgH2 with 1:1 and 2:1 molar ratios were mechano-chemically milled in a high-energy planetary ball mill under inert atmosphere, and at room temperature and atmospheric pressure. Based on the thermogravimetric analysis (TGA) experiments, 2LiNH2-nanoMgH2 demonstrated superior desorption characteristics when compared to the LiNH2-nanoMgH2. The TGA studies also revealed that doping 2LiNH2-nanoMgH2 base material with 2 wt. % nanoNi catalyst enhances the sorption kinetics at lower temperatures. Additional investigation of different catalysts showed improved reaction kinetics (weight percentage of H2 released per minute) of the order TiF3 > nanoNi > nanoTi > nanoCo > nanoFe > multiwall carbon nanotube (MWCNT), and reduction in the on-set decomposition temperatures of the order nanoCo > TiF3 > nanoTi > nanoFe > nanoNi > MWCNT for the base material 2LiNH2-nanoMgH2. Pristine and catalyst-doped 2LiNH2-nanoMgH2 samples were further probed by X-ray diffraction, Fourier transform infrared spectroscopy, transmission and scanning electron microscopies, thermal programmed desorption and pressure-composition-temperature measurements to better understand the improved performance of the catalyst-doped samples, and the results are discussed. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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3926 KiB  
Article
Experimental Study on the Physical Simulation of Water Invasion in Carbonate Gas Reservoirs
by Feifei Fang, Weijun Shen, Shusheng Gao, Huaxun Liu, Qingfu Wang and Yang Li
Appl. Sci. 2017, 7(7), 697; https://doi.org/10.3390/app7070697 - 07 Jul 2017
Cited by 12 | Viewed by 4805
Abstract
Water invasion in carbonate gas reservoirs often results in excessive water production, which limits the economic life of gas wells. This is influenced by reservoir properties and production parameters, such as aquifer, fracture, permeability and production rate. In this study, seven full diameter [...] Read more.
Water invasion in carbonate gas reservoirs often results in excessive water production, which limits the economic life of gas wells. This is influenced by reservoir properties and production parameters, such as aquifer, fracture, permeability and production rate. In this study, seven full diameter core samples with dissolved pores and fractures were designed and an experimental system of water invasion in gas reservoirs with edge and bottom aquifers was established to simulate the process of water invasion. Then the effects of the related reservoir properties and production parameters were investigated. The results show that the edge and bottom aquifers supply the energy for gas reservoirs with dissolved pores, which delays the decline of bottom-hole pressure. The high water aquifer defers the decline of water invasion in the early stage while the big gas production rate accelerates water influx in gas reservoirs. The existence of fractures increases the discharge area of gas reservoirs and the small water influx can result in a substantial decline in recovery factor. With the increase of permeability, gas production rate has less influence on recovery factor. These results can provide insights into a better understanding of water invasion and the effects of reservoir properties and production parameters so as to optimize the production in carbonate gas reservoirs. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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10063 KiB  
Article
Simulation Investigation on Combustion Characteristics in a Four-Point Lean Direct Injection Combustor with Hydrogen/Air
by Jianzhong Li, Li Yuan and Hukam C. Mongia
Appl. Sci. 2017, 7(6), 619; https://doi.org/10.3390/app7060619 - 14 Jun 2017
Cited by 10 | Viewed by 7239
Abstract
To investigate the combustion characteristics in multi-point lean direct injection (LDI) combustors with hydrogen/air, two swirl–venturi 2 × 2 array four-point LDI combustors were designed. The four-point LDI combustor consists of injector assembly, swirl–venturi array and combustion chamber. The injector, swirler and venturi [...] Read more.
To investigate the combustion characteristics in multi-point lean direct injection (LDI) combustors with hydrogen/air, two swirl–venturi 2 × 2 array four-point LDI combustors were designed. The four-point LDI combustor consists of injector assembly, swirl–venturi array and combustion chamber. The injector, swirler and venturi together govern the rapid mixing of hydrogen and air to form the mixture for combustion. Using clockwise swirlers and anticlockwise swirlers, the co-swirling and count-swirling swirler arrays LDI combustors were achieved. Using Reynolds-Averaged Navier–Stokes (RANS) code for steady-state reacting flow computations, the four-point LDI combustors with hydrogen/air were simulated with an 11 species and 23 lumped reaction steps H2/Air reaction mechanism. The axial velocity, turbulence kinetic energy, total pressure drop coefficient, outlet temperature, mass fraction of OH and emission of pollutant NO of four-point LDI combustors, with different equivalence ratios, are here presented and discussed. As the equivalence ratios increased, the total pressure drop coefficient became higher because of increasing heat loss. Increasing equivalence ratios also corresponded with the rise in outlet temperature of the four-point LDI combustors, as well as an increase in the emission index of NO EINO in the four-point LDI combustors. Along the axial distance, the EINO always increased and was at maximum at the exit of the dump. Along the chamber, the EINO gradually increased, maximizing at the exit of chamber. The total temperature of four-point LDI combustors with different equivalence ratios was identical to the theoretical equilibrium temperature. The EINO was an exponential function of the equivalence ratio. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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2433 KiB  
Article
Dual Functionalized Freestanding TiO2 Nanotube Arrays Coated with Ag Nanoparticles and Carbon Materials for Dye-Sensitized Solar Cells
by Ho-Sub Kim, Myeung-Hwan Chun, Jung Sang Suh, Bong-Hyun Jun and Won-Yeop Rho
Appl. Sci. 2017, 7(6), 576; https://doi.org/10.3390/app7060576 - 02 Jun 2017
Cited by 16 | Viewed by 4407
Abstract
Highly ordered, freestanding TiO2 nanotube arrays (TiO2 NTAs) were prepared using an electrochemical method. The barrier layer was etched to open the bottom of each array, aptly named “open-ended TiO2 NTAs”. These arrays were coated with silver nanoparticles (Ag NPs) [...] Read more.
Highly ordered, freestanding TiO2 nanotube arrays (TiO2 NTAs) were prepared using an electrochemical method. The barrier layer was etched to open the bottom of each array, aptly named “open-ended TiO2 NTAs”. These arrays were coated with silver nanoparticles (Ag NPs) and/or carbon materials to enhance electron generation and transport. The energy conversion efficiency of the resulting dye-sensitized solar cells (DSSCs) with open-ended freestanding TiO2 NTAs, when coated with Ag NPs, increased from 5.32% to 6.14% (by 15%) due to plasmonic interactions. Meanwhile, coating the open-ended freestanding TiO2 NTAs with carbon materials increased the energy conversion efficiency from 5.32% to 6.07% (by 14%), due to π-π conjugation. When the Ag NPs and carbon materials were simultaneously applied to the open-ended freestanding TiO2 NTAs, the energy conversion efficiency increased from 5.32% to 6.91%—an enhancement of 30%, due to the additive effects of plasmonics and π-π conjugation. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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Review

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8265 KiB  
Review
A Review on Nanocomposite Materials for Rechargeable Li-ion Batteries
by Dervis Emre Demirocak, Sesha S. Srinivasan and Elias K. Stefanakos
Appl. Sci. 2017, 7(7), 731; https://doi.org/10.3390/app7070731 - 17 Jul 2017
Cited by 56 | Viewed by 13730
Abstract
Li-ion batteries are the key enabling technology in portable electronics applications, and such batteries are also getting a foothold in mobile platforms and stationary energy storage technologies recently. To accelerate the penetration of Li-ion batteries in these markets, safety, cost, cycle life, energy [...] Read more.
Li-ion batteries are the key enabling technology in portable electronics applications, and such batteries are also getting a foothold in mobile platforms and stationary energy storage technologies recently. To accelerate the penetration of Li-ion batteries in these markets, safety, cost, cycle life, energy density and rate capability of the Li-ion batteries should be improved. The Li-ion batteries in use today take advantage of the composite materials already. For instance, cathode, anode and separator are all composite materials. However, there is still plenty of room for advancing the Li-ion batteries by utilizing nanocomposite materials. By manipulating the Li-ion battery materials at the nanoscale, it is possible to achieve unprecedented improvement in the material properties. After presenting the current status and the operating principles of the Li-ion batteries briefly, this review discusses the recent developments in nanocomposite materials for cathode, anode, binder and separator components of the Li-ion batteries. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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