scholarly journals Metal-Water mixtures for Propulsion and Energy-Conversion Applications: Recent Progress and Future Directions

2018 ◽  
Vol 20 (1) ◽  
pp. 53 ◽  
Author(s):  
Dilip Sundaram
Keyword(s):  
Particle Size ◽  
Energy Conversion ◽  
Experimental Studies ◽  
High Energy ◽  
High Energy Density ◽  
Full Potential ◽  
Predictive Tool ◽  
Practical Applications ◽  
Relative Safety ◽  
Metal Water

The metal-water system is attractive for propulsion and energy-conversion applications. Of all metals, aluminum is attractive due to its high energy density, relative safety, and low cost. Experimental studies provide new insight on the combustion and propulsive behaviors. The burning rate is found to be a strong function of both pressure and particle size. Furthermore, there is a wide scatter in the measured pressure exponents due to differences in particle size, pressure, pH, and equivalence ratio. A major problem with Al/H2O mixtures is incomplete combustion and poor impulses, thereby rendering Al/H2O mixtures unsuitable for practical applications. Efforts to improve the performance of Al/H2O mixtures have only met with moderate success. Although experiments have revealed these new trends, not much is offered in terms of the underlying physics and mechanisms. To explore the combustion mechanisms, theoretical models based on energy balance analysis have been developed. These models involve numerous assumptions and many complexities were either ignored or treated simplistically. The model also relies on empirical inputs, which makes it more a useful guide than a predictive tool. Future works must endeavor to conduct a more rigorous analysis of metal-water combustion. Empirical inputs should be avoided and complexities must be properly treated to capture the essential physics of the problem. The model should help us properly understand the experimental trends, offer realistic predictions for unexplored conditions, and suggest guidelines and solutions in order to realize the full potential of metal-water mixtures.

Thermal Model of a Thin Film Pulsed Pyroelectric Generator

2016 ◽  
Author(s):  
Nicholas R. Jankowski ◽  
Andrew N. Smith ◽  
Brendan M. Hanrahan
Keyword(s):  
Thin Film ◽  
Power Generation ◽  
Energy Conversion ◽  
High Speed ◽  
High Energy ◽  
High Energy Density ◽  
Working Fluid ◽  
Film Material ◽  
Thermodynamic Cycles ◽  
The Impact

Recent high energy density thin film material development has led to an increased interest in pyroelectric energy conversion. Using state-of-the-art lead-zirconate-titanate piezoelectric films capable of withstanding high electric fields we previously demonstrated single cycle energy conversion densities of 4.28 J/cm3. While material improvement is ongoing, an equally challenging task involves developing the thermal and thermodynamic process though which we can harness this thermal-to-electric energy conversion capability. By coupling high speed thermal transients from pulsed heating with rapid charge and discharge cycles, there is potential for achieving high energy conversion efficiency. We briefly present thermodynamic equivalent models for pyroelectric power generation based on the traditional Brayton and Ericsson cycles, where temperature-pressure states in a working fluid are replaced by temperature-field states in a solid pyroelectric material. Net electrical work is then determined by integrating the path taken along the temperature dependent polarization curves for the material. From the thermodynamic cycles we identify the necessary cyclical thermal conditions to realize net power generation, including a figure of merit, rEC, or the electrocaloric ratio, to aid in guiding generator design. Additionally, lumped transient analytical heat transfer models of the pyroelectric system with pulsed thermal input have been developed to evaluate the impact of reservoir temperatures, cycle frequency, and heating power on cycle output. These models are used to compare the two thermodynamic cycles. This comparison shows that as with traditional thermal cycles the Ericsson cycle provides the potential for higher cycle work while the Brayton cycle can produce a higher output power at higher thermal efficiency. Additionally, limitations to implementation of a high-speed Ericsson cycle were identified, primarily tied to conflicts between the available temperature margin and the requirement for isothermal electrical charging and discharging.

scholarly journals Synthesis of high-energy-density Pr2Fe14−x Co x B,x⩽3, magnets for practical applications

1995 ◽  
Vol 18 (8) ◽  
pp. 963-974 ◽  
Author(s):  
S Haldar ◽  
S Ram ◽  
P Ramachandrarao ◽  
H D Banerjee
Keyword(s):  
Energy Density ◽  
High Energy ◽  
High Energy Density ◽  
Practical Applications

The Critical Pressure at the Onset of Flame Instability of Syngas/Air/Diluent Outwardly Expanding Flame at Different Initial Temperatures and Pressures

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Ziyu Wang ◽  
Ziwei Bai ◽  
Guangying Yu ◽  
Sai Yelishala ◽  
Hameed Metghalchi
Keyword(s):  
High Speed ◽  
Critical Pressure ◽  
Hydrodynamic Instability ◽  
Experimental Studies ◽  
Initial Pressure ◽  
High Energy ◽  
Oxide Semiconductor ◽  
High Energy Density ◽  
Flame Instability ◽  
Wide Range

Syngas has gained attention recently due to its high energy density and environmentally friendly characteristics. Flame stability plays an important role in flame propagation in energy conversion devices. Experimental studies were performed in a cylindrical chamber to investigate flame instability of syngas/air/diluent mixture. A Z-shape Schlieren system coupled with a high-speed complementary metal–oxide–semiconductor camera was used to record flame pictures up to 40,000 frames per second. In this research, syngas is a mixture of hydrogen and carbon monoxide and diluent is a blend of 14% CO2 and 86% N2 with the same specific heat as the burned gases. Three main flame instabilities namely Rayleigh–Taylor (body force) instability, hydrodynamic instability, and thermal-diffusive instability have been studied. For the onset of flame instability, a power law correlation for the ratio of critical pressure to initial pressure of syngas/air/diluent flames over a wide range of initial temperatures (298–450 K), initial pressures (1.0–2.0 atm), equivalence ratios (0.6–3.0), diluent concentrations (0–10%), and hydrogen percentages (5–25%) in the fuel has been developed.

High-Performance Asymmetric Supercapacitors Based on the Ni1.5Co1.5S4@CNTs Nanocomposites

NANO ◽  
2020 ◽  
Vol 15 (10) ◽  
pp. 2050136
Author(s):  
Xuan Zheng ◽  
Xingxing He ◽  
Jinlong Jiang ◽  
Zhengfeng Jia ◽  
Yu Li ◽  
...  
Keyword(s):  
Energy Density ◽  
Power Density ◽  
High Performance ◽  
Specific Capacity ◽  
Negative Electrode ◽  
High Energy ◽  
Cycling Stability ◽  
Power Delivery ◽  
High Energy Density ◽  
Practical Applications

In this paper, the Ni[Formula: see text]Co[Formula: see text]S4@CNTs nanocomposites containing different carbon nanotubes (CNT) content were prepared by a one-step hydrothermal method. More hydroxyl and carboxyl groups were introduced on the surface of CNTs by acidizing treatment to increase the dispersion of CNTs. The acid-treated CNTs can more fully compound with Ni[Formula: see text]Co[Formula: see text]S4 nanoparticles to form heterostructure. When the CNTs content is 10[Formula: see text]wt.%, the Ni[Formula: see text]Co[Formula: see text]S4@CNTs-10 nanocomposite exhibits the highest specific capacity of 210[Formula: see text]mAh[Formula: see text]g[Formula: see text] in KOH aqueous electrolytes at current density of 1[Formula: see text]A[Formula: see text]g[Formula: see text]. The superior performances of the Ni[Formula: see text]Co[Formula: see text]S4@CNTs-10 nanocomposite are attributed to the effective synergic effects of the high specific capacity of Ni[Formula: see text]Co[Formula: see text]S4 and the excellent conductivity of CNTs. An asymmetric supercapacitor (ASC) was assembled based on Ni[Formula: see text]Co[Formula: see text]S4@CNTs-10 positive electrode and activated carbon (AC) negative electrode, which delivers a high energy density of 61.2[Formula: see text]Wh[Formula: see text]kg[Formula: see text] at a power density of 800[Formula: see text]W[Formula: see text]kg[Formula: see text], and maintains 34.8[Formula: see text]Wh[Formula: see text]kg[Formula: see text] at a power density of 16079[Formula: see text]W[Formula: see text]kg[Formula: see text]. Also, the ASC device shows an excellent cycling stability with 91.49% capacity retention and above 94% Columbic efficiency after 10 000 cycles at 10[Formula: see text]A[Formula: see text]g[Formula: see text]. This aqueous asymmetric Ni[Formula: see text]Co[Formula: see text]S4@CNTs//AC supercapacitor is promising for practical applications due to its advantages such as high energy density, power delivery and cycling stability.

scholarly journals Strongly Anchoring Polysulfides by Hierarchical Fe3O4/C3N4 Nanostructures for Advanced Lithium–Sulfur Batteries

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Soochan Kim ◽  
Simindokht Shirvani-Arani ◽  
Sungsik Choi ◽  
Misuk Cho ◽  
Youngkwan Lee
Keyword(s):  
High Surface ◽  
Specific Capacity ◽  
High Surface Area ◽  
High Energy ◽  
High Energy Density ◽  
Energy Storage Devices ◽  
Shuttle Effect ◽  
Practical Applications ◽  
Storage Devices ◽  
Lithium Sulfur Batteries

AbstractLi–S batteries have attracted considerable interest as next-generation energy storage devices owing to high energy density and the natural abundance of sulfur. However, the practical applications of Li–S batteries are hampered by the shuttle effect of soluble lithium polysulfides (LPS), which results in low cycle stability. Herein, a functional interlayer has been developed to efficiently regulate the LPS and enhance the sulfur utilization using hierarchical nanostructure of C3N4 (t-C3N4) embedded with Fe3O4 nanospheres. t-C3N4 exhibits high surface area and strong anchoring of LPS, and the Fe3O4/t-C3N4 accelerates the anchoring of LPS and improves the electronic pathways. The combination of these materials leads to remarkable battery performance with 400% improvement in a specific capacity and a low capacity decay per cycle of 0.02% at 2 C over 1000 cycles, and stable cycling at 6.4 mg cm−2 for high-sulfur-loading cathode.

Aerosol technology and Si nano-composite electrode assembly for Li-ion batteries

2011 ◽  
Vol 1313 ◽  
Author(s):  
David Munao ◽  
Mario Valvo ◽  
Jan van Erven ◽  
Esteban Garcia-Tamayo ◽  
Erik Kelder
Keyword(s):  
Particle Size ◽  
Hybrid Electric Vehicle ◽  
Chemical Vapor ◽  
Good Control ◽  
High Energy ◽  
Thin Layers ◽  
Nano Particles ◽  
High Energy Density ◽  
Clear Understanding ◽  
Silicon Based

ABSTRACTIn this work novel approaches to fabricate silicon-based electrodes are shown. Starting from silicon nano-particles it is possible to create nano-structured porous thin films. Both the synthesis of the Si nano-particles and the electrode assembly are performed via aerosol routes. This guarantees a very good control on the particle size and the particle size distribution, on the purity of the product and on the morphology and texture of the deposited layers. Particles are produced via Laser assisted Chemical Vapor Pyrolysis whereas electrode thin layers are deposited via Electro Spray method. The range of particle sizes can be tailored according to the selected application. Here, particles of a mean size of about 10 nm have been synthesized. Since Si is well known to forms highly lithiated intermetallic compounds [1], it is regarded as one of the most promising material for energy storage [2], especially looking at high energy density applications, such as hybrid/electric vehicle traction. In this work its promising performance are presented. The role of the additives in the composite formulation is also taken into account for a more clear understanding of the capacity fading mechanism of such electrodes.

scholarly journals Production of sub-gigabar pressures by a hyper-velocity impact in the collider using laser-induced cavity pressure acceleration

2017 ◽  
Vol 35 (4) ◽  
pp. 619-630
Author(s):  
J. Badziak ◽  
M. Kucharik ◽  
R. Liska
Keyword(s):  
Energy Conversion ◽  
Conversion Efficiency ◽  
Inertial Confinement Fusion ◽  
High Pressures ◽  
Strong Shock ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
High Energy Density ◽  
Cavity Pressure ◽  
Shock Energy

AbstractProduction of high dynamic pressure using a strong shock wave is a topic of high relevance for high-energy-density physics, inertial confinement fusion, and materials science. Although the pressures in the multi-Mbar range can be produced by the shocks generated with a large variety of methods, the higher pressures, in the sub-Gbar or Gbar range, are achievable only with nuclear explosions or laser-driven shocks. However, the laser-to-shock energy conversion efficiency in the laser-based methods currently applied is low and, as a result, multi-kJ multi-beam lasers have to be used to produce such extremely high pressures. In this paper, the generation of high-pressure shocks in the newly proposed collider in which the projectile impacting a solid target is driven by the laser-induced cavity pressure acceleration (LICPA) mechanism is investigated using two-dimensional hydrodynamic simulations. A special attention is paid to the dependence of shock parameters and the laser-to-shock energy conversion efficiency on the impacted target material and the laser driver energy. It has been found that both in case of low-density and high-density solid targets, the shock pressures in the sub-Gbar range can be produced in the LICPA-based collider with the laser energy of only a few hundreds of joules, and the laser-to-shock energy conversion efficiency can reach values of 10–20%, by an order of magnitude higher than the conversion efficiencies achieved with other laser-based methods used so far.

scholarly journals A high energy density solar rechargeable redox battery

2016 ◽  
Vol 4 (9) ◽  
pp. 3446-3452 ◽  
Author(s):  
Mohammad Ali Mahmoudzadeh ◽  
Ashwin R. Usgaocar ◽  
Joseph Giorgio ◽  
David L. Officer ◽  
Gordon G. Wallace ◽  
...  
Keyword(s):  
Energy Density ◽  
Solar Energy ◽  
Energy Conversion ◽  
Storage System ◽  
Solar Energy Conversion ◽  
High Energy ◽  
High Energy Density ◽  
Dye Sensitized ◽  
Energy Conversion And Storage ◽  
And Storage

An integrated solar energy conversion and storage system is presented using a dye sensitized electrode in a redox battery structure.

scholarly journals Supercritical CO2 Synthesis of Freestanding Se1-xSx Foamy Cathodes for High-Performance Li-Se1-xSx Battery

2021 ◽  
Vol 9 ◽  
Author(s):  
Chengwei Lu ◽  
Ruyi Fang ◽  
Kun Wang ◽  
Zhen Xiao ◽  
G. Gnana kumar ◽  
...  
Keyword(s):  
High Performance ◽  
Specific Capacity ◽  
Three Dimensional ◽  
Rate Capability ◽  
Carbon Matrix ◽  
High Energy ◽  
Rechargeable Batteries ◽  
High Energy Density ◽  
Rechargeable Lithium Batteries ◽  
Practical Applications

Selenium-sulfur solid solutions (Se1-xSx) are considered to be a new class of promising cathodic materials for high-performance rechargeable lithium batteries owing to their superior electric conductivity than S and higher theoretical specific capacity than Se. In this work, high-performance Li-Se1-xSx batteries employed freestanding cathodes by encapsulating Se1-xSx in a N-doped carbon framework with three-dimensional (3D) interconnected porous structure (NC@SWCNTs) are proposed. Se1-xSx is uniformly dispersed in 3D porous carbon matrix with the assistance of supercritical CO2 (SC-CO2) technique. Impressively, NC@SWCNTs host not only provides spatial confinement for Se1-xSx and efficient physical/chemical adsorption of intermediates, but also offers a highly conductive framework to facilitate ion/electron transport. More importantly, the Se/S ratio of Se1-xSx plays an important role on the electrochemical performance of Li- Se1-xSx batteries. Benefiting from the rationally designed structure and chemical composition, NC@[email protected] cathode exhibits excellent cyclic stability (632 mA h g−1 at 200 cycle at 0.2 A g−1) and superior rate capability (415 mA h g−1 at 2.0 A g−1) in carbonate-based electrolyte. This novel NC@[email protected] cathode not only introduces a new strategy to design high-performance cathodes, but also provides a new approach to fabricate freestanding cathodes towards practical applications of high-energy-density rechargeable batteries.

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