Energy Release Time Research Articles

Prediction of power generation output of compressed air energy storage tank based on temperature limitation

The pressure and temperature of the CAES system drop during the power generation process. This generation will be forced to stop when the temperature reaches the metal material limit. To avert the power generation process from stopping due to the temperature dropping too low, it is necessary to monitor and predict the power output of the CAES system in real time. By setting the relevant control operation logic, according to the temperature limit value of the gas canister, the minimum allowable temperature of the gas canister design, and the maximum value of the minimum allowable temperature of the pipe design between the gas canister and the heat exchanger, the minimum allowable temperature of the gas canister is obtained. the residual energy release energy and residual energy release time of the gas storage tank can be calculated by collecting relevant parameters in real time. It is verified by the simulation experiment of the 10 MW CAES system model. By monitoring the changes in parameters such as the temperature of the gas canister during the energy release process, the prediction model can calculate the compressed gas in the gas canister more accurately, and the power generation output can be predicted in the operation of the CASE system. Mastering the residual energy release energy and residual energy release time of the gas canister can arrange the operation mode in advance and improve the reliability of unit operation.

Uncovering the decomposition mechanism of nitrate ester plasticized polyether (NEPE): a neural network potential simulation.

Nitrate ester plasticized polyether (NEPE) propellants have attracted widespread attention due to their high energy density and excellent low-temperature mechanical properties. However, little is known about the thermal decomposition process of the NEPE propellant, particularly lacking microscale models and interaction mechanisms. This work aims to establish a high-precision and efficient neural network potential (NNP) model covering the NEPE matrix, describing its mechanical behavior and detailed thermal decomposition mechanisms. The model accuracy, including atomic energies and forces, was validated through density functional theory (DFT) results, and the NEPE propellant decomposition model was verified via molecular dynamics (MD) simulations with DFT precision. The results demonstrate that the NNP model accurately predicts the energies and forces of the NEPE matrix for single and mixed systems at the DFT-level precision, and reproduces the mechanical properties consistent with DFT calculations. Meanwhile, the thermal decomposition order of the NEPE matrix predicted by NNP is consistent with the experimental results, accurately capturing complex physical phenomena and detailed decomposition processes among components. It is also revealed that the addition of a binder can improve the stability of the propellant and extend its energy release time. This study applies innovative machine learning algorithms to develop an NNP computational model for the NEPE matrix with DFT precision, which is crucial for practical propellant formulation design.

Dynamic Response Difference of Hydraulic Support under Mechanical-Hydraulic Co-Simulation: Induced by Different Roof Rotation Position and Hysteresis Effect of Relief Valve

As key supporting equipment in coal mining, hydraulic supports are vulnerable to impact pressure from roof movement and deformation. In this paper, a mechanical-hydraulic co-simulation platform for hydraulic supports is established. Moreover, the rationality of the simulation platform is verified. Based on this platform, the rigid-flexible coupling impact dynamics model of hydraulic support is built. Finally, by delaying the opening time of the relief valve, the energy dissipation problem of the relief valve hysteresis effect on the hydraulic support system under the rotary impact is discussed. The results indicate that the rotary load acting on the hydraulic support decreases gradually with the backward movement of the roof rotary position, which causes the peak pressure in the column to decrease (by 69 MPa). The hinge point load of different parts shows different load transfer laws. The hysteresis effect of the relief valve prolongs the energy release time of the system, increasing the pressure in the column by 23 MPa. The instantaneous opening speed of the relief valve spool reaches 15.7 m/s, and the hinge point between the top beam and the column is most sensitive to the hysteresis effect (impact coefficient increases by 0.63).

Gurney model for non-standard cylinder with increased wall thickness and its application in aluminized explosives

To meet the requirements of an aluminized explosive cylinder test with a longer energy release time, a non-standard cylinder structure with a larger wall thickness was designed, which can not only extend the effective expansion time of detonation products but also avoid a great increase in the test charge mass. The non-standard cylinder was filled with TNT explosives for its relatively stable Gurney energy, and the experimentally generated parameters were compared with those of Φ50 and Φ100 mm standard cylinders. Based on this, a more accurate Gurney Model for Non-Standard Cylinder (GM-NSC) was proposed taking into account the influence of shell deformation and axial movement of detonation products compared with the traditional Gurney model. The analysis results show that the proposed GM-NSC model curve is suitable for both non-standard and standard cylinders. Finally, the method was applied to DNAN-based aluminized explosives, and the experimental results show that the method can characterize more thoroughly the effect of the detonation product expansion enhanced by the rapid reaction of aluminum powders.

Characteristics of Infrared Radiation in the Failure of Phosphate Rock at Different Loading Rates

Safe and effective mining of phosphate rock plays an important role in the sustainable development of phosphorus resources. The mechanical properties and failure process of phosphate rock under different mining rates remain unclear, further restricting the safe and efficient mining of phosphate rock. In this paper, infrared radiation and uniaxial compression tests of phosphate rock under different loading rates, e.g., 0.0005, 0.001, 0.005, and 0.01 mm/s, were conducted to investigate the failure process of phosphate rock. Energy evolution and infrared radiation characteristics of the phosphate rock damage process were analyzed using nondestructive, real-time, and noncontact infrared thermal imaging technology. The results show that the higher the loading rate of phosphate rock, the more obvious the high-temperature zone and high-temperature point of phosphate rock in the loading process. At failure, the friction and slippage between internal cracks are intense, showing that the infrared radiation temperature difference increases with the increase of loading rate. As loading rate increases, the energy release time of phosphate rock before damage is reduced, resulting in more energy stored in the rock as evinced by its infrared radiation characteristics, finally resulting in greater damage. The increase of loading rate reduces the dissipation energy of phosphate rock before failure so that more energy remains in the rock mass through the weak surface of the grain boundary. The results of this work will be helpful in enhancing theoretical support for prevention and control of dynamic disasters in phosphate mines.

Research on Evolution Characteristics of Unloading Energy in Excavation Face of High-Stress Pillar

In the mining process of the stage empty field subsequent filling mining method, aiming at the problem of unloading failure and instability of the excavation face of the high-stress ore pillar, the theory of unloading stress component is introduced and combined with the energy release theory to explore the unloading failure mechanism of the excavation face of the ore pillar. The results show the following. (1) The degree of accumulation of strain energy in the pillar is related to the tangential stress. After the peak of the tangential stress, the energy changes from accumulation to release, indicating that energy release is the main cause of pillar damage. (2) In pillar unloading, there are 4 typical characteristic areas of stress during the loading process: crushing area, shaping area, elastic area, and original rock stress area. The energy accumulation area and the stress component area show good correspondence, and they all appear from the top to the bottom of the pillar. At 1/4, the starting point of unloading failure can be determined. (3) The mutation mechanism in the process of energy release is related to the time effect of tangential stress. On the contrary, the greater the tangential stress is, the longer the elastic zone lasts, and the more significant the energy accumulation is. Also, the increase in tangential stress will lead the energy release time becomes shorter, and a large amount of accumulated energy is released in a short time, causing local instability and destruction of the pillar, and eventually spreads to the whole.

Optimization of shaped pulses for radio frequency excitation in NMR logging.

The radio frequency (RF) excitation pulse of the nuclear magnetic resonance (NMR) logging tool can realize slice measurement by designing shaped pulses. In the case of a certain main magnetic field, the accuracy of the shaped pulse designhas a very important impact on the signal-to-noise ratio (SNR) of the NMR signal and the measurement of the short relaxation signal. Hard pulse excitation will produce an undesirable infinite number of side lobes that may perturb the spins in unwanted regions. Soft pulse can achieve selective excitation and has a better slice profile and shorter energy release time while it is not conducive to the measurement of short relaxation signals. This article focuses on the designof shaped pulses in extreme downhole environments and analyzes the characteristics of the three shaped pulses in the two cases of equivalent bandwidth and equivalent pulse duration. At the same time, a kind of RF-shaped pulse transmitting circuit with phase difference control is realized. According to the pulse type optimization strategy, the appropriate shaped pulse is selected. When echo spacing (TE) >0.6ms, the SNR can be increased to more than 12%. When TE is small, it will automatically switch to the hard pulse mode, which is good for short relaxation measurement.

Solidification in a shell-and-tube thermal energy storage unit filled with longitude fins and metal foam: A numerical study

In this study, an innovative thermal energy storage design method was developed by adding the combination of metal foam and fin to phase change materials (PCMs). A numerical model was built and verified based on the comparison among the present model prediction, experimental measurements, and numerical results in open literature. To highlight the novel design method, four cases including fin-PCM, foam-PCM, fin-foam-PCM, and PCM unit were compared by means of solidification features. The temperature distribution, solidification front propagation, and buoyancy-induced convection in the liquid PCM were accounted for. Numerical results demonstrated that metal foam outperformed fin regarding the improvement on solidification phase change. The combination of foam and fin achieved the best performance, leading to a 90.5% reduction in complete energy release time in comparison with the PCM unit. The proposed design method provided reference potentials for advancing energy storage engineering. However, buoyancy-induced convection in the liquid PCM before solidification was harmful to the formation of solidification front and its movement. A maximal 11.5% prolonging time for the complete solidification was found.

Experimental study of reaction properties of aluminum/polytetrafluoroethylene powder under laser ablation

Metal particle size and environment will affect the reaction properties of aluminized polytetrafluoroethylene (Al/PTFE) reactive material. This study experimentally investigated the reaction properties of Al/PTFE with different Al particle sizes through time-resolved self-emitting imaging and emission spectroscopy under nanosecond laser ablation in air and an inert argon environment. The results show that the laser ablation causes a continuous combustion characteristic and a long energy release time in Al/PTFE. Furthermore, the reaction properties of Al/PTFE are closely related to the particle size of Al powder. The emission intensities and durations increase as Al particle size decreases, but it no longer conforms to this rule when Al particle size decreases to nanometers. This inconsistency may be due to the oxidation of Al powder and agglomeration of nano-Al powder. The experiments in different gas environments proved that the reactivity of Al/PTFE in the inert gas environment is not as good as that in air because of the lack of the oxidation reaction between Al and oxygen from the air.

First Frequency-time-resolved Imaging Spectroscopy Observations of Solar Radio Spikes

Abstract Solar radio spikes are short duration and narrow bandwidth fine structures in dynamic spectra observed from the GHz to tens of MHz range. Their very short duration and narrow frequency bandwidth are indicative of subsecond small-scale energy release in the solar corona, yet their origin is not understood. Using the LOw Frequency ARray, we present spatially, frequency, and time resolved observations of individual radio spikes associated with a coronal mass ejection. Individual radio spike imaging demonstrates that the observed area is increasing in time and the centroid positions of the individual spikes move superluminally parallel to the solar limb. Comparison of spike characteristics with that of individual Type IIIb striae observed in the same event show similarities in duration, bandwidth, drift rate, polarization, and observed area, as well the spike and striae motion in the image plane suggesting fundamental plasma emission with the spike emission region on the order of ∼108 cm, with brightness temperature as high as 1013 K. The observed spatial, spectral, and temporal properties of the individual spike bursts are also suggestive of the radiation responsible for spikes escaping through anisotropic density turbulence in closed loop structures with scattering preferentially along the guiding magnetic field oriented parallel to the limb in the scattering region. The dominance of scattering on the observed time profile suggests the energy release time is likely to be shorter than what is often assumed. The observations also imply that the density turbulence anisotropy along closed magnetic field lines is higher than along open field lines.

Effect of ignition parameters on detonation initiation using toroidal shock wave focusing

For fast detonation initiation, a novel compact initiator based on shock wave focusing has been proposed in our work. Two-dimensional numerical investigation was performed to understand the fast detonation initiation mechanism in hydrogen-air mixtures. Detailed evolution processes, namely, flame acceleration, shock wave focusing and detonation initiation were analyzed. Moreover, effects of ignition energy and energy release time on detonation initiation have been discussed thoroughly. The numerical results indicate that flame acceleration process can be divided into three stages: a) curling deformation of flame with low speed, b) tensile deformation of flame with medium speed, c) steady propagation of flame with high speed. After shock focusing, a highly compressed and heated region triggers the rapid detonation initiation. Further analysis indicated that detonation initiation time increases with the decrease of ignition energy. And the reason is mainly due to initial ignition delay differences controlled by ignition energy. In particular, once ignition energy is smaller than 12.5 mJ, mixtures will be no longer ignited. Besides, with the increase of energy release time, both the run-up time and distance of detonation initiation increase. The rapid release of energy can not only make mixtures ignited earlier, but also enhance initial flame velocity. As a result, when energy release time is reduced from 200 μs to 50 μs, the run-up time and distance are decreased by 50% and 32.5%.

The effect of column-shaped discharge duration on induced high-speed flow dynamics

Energy deposition from pulsed plasma-based devices is of research interest due to their promising flow control applications. Here, we report on a combined experimental and numerical study of a high-speed flow induced by a column-shaped, pulsed discharge at low pressure. The energy release time is analyzed based on the relative dynamics of the shock and contact fronts. Time-resolved shadow imaging is performed to capture the evolution of two cylindrical flow discontinuities—a shock wave and a contact surface—from 4 µs up to 25 µs after discharge pulse. The comparison of the experimental data with the numerical predictions confirms that the heating of gas by the pulsed plasma occurs within one microsecond after nanosecond discharge initiation.

Unified Approach for Meso-Informed Burn Models in Shocked Energetic Materials

Reactive hydrocode calculations of shock-to-detonation transition in heterogeneous energetic (HE) materials need to be closed with burn models. One requirement of burn models is to supply a macroscale control volume with an energy release rate due to chemical reactions that reflects the subgrid physics of hotspot ignition and growth. Energy localization at hotspots delivers chemical energy at a rate , where is the heat of reaction and is a meso-scale energy localization time scale. This energy deposition rate is much larger than nominal Arrhenius-form chemical energy deposition rates in a homogeneous sample subjected to the same shock loading. To develop meso-informed energy deposition rate models, this paper identifies a meso-scale energy release time scale that is common to burn models based on the hotspot ignition and growth concept. The identification of a common time scale allows for a unified microstructure-aware, physics-based reactive burn model; high-fidelity meso-scale numerical simulations are used to construct a surrogate model for . The surrogate model is shown to capture the effects of microstructural parameters on and can be used for meso–macro coupling in a multiscale model to predict the sensitivity of HE materials.

Numerical investigation of an innovative discontinuous distribution of fins for solidification rate enhancement in PCM with and without nanoparticles

Energy storing is one of the most vital needs in the energy industry. This paper aims to solve the problem of long energy release time in phase change material (PCM) energy storage system. In the present study, continuous longitudinal fin that had been traditionally used in literature is transformed into a new three-dimensional distribution of discontinuous strip fins. Effects of the geometric distribution of the strip fins, fins material and adding nanoparticles (NPs) to the PCM on heat transfer enhancement and energy discharge time are investigated by testing 17 different cases. According to the results, the use of discontinuous fins can improve the energy release time up to 89% and 84% comparing to continuous copper and aluminum fins, respectively. Moreover, the results indicate that effect of fin material on the thermal performance is insignificant in cases of continuous fins. The results confirmed that the optimal distribution for cases of discontinuous aluminum fins with and without NPs is different. Besides, the maximum of saving discharge time is 77.8% and 59.5% for combination of NPs with copper and aluminum discontinuous fins, respectively. Besides, the results show that the application of nanoparticles alone cannot lead to a significant discharge time improvement.

Study of the Stability of Triggering of a Controlled Multigap Spark Switch for Capacitive Energy Storage with Charging Voltage up to 100 kV and Energy Release Time on the Order of 100 ns

Results are presented of a study of the stability of triggering of a six-channel seven-gap spark switch intended for switching a capacitive energy storage with a charging voltage of up to 100 kV and energy release time on the order of 100 ns. The working medium of the spark switch is air at atmospheric pressure. In the controlled triggering regime, we measured the breakdown delay time of all of the discharge gaps relative to the arrival of the voltage trigger pulse and calculated the mean square deviation of the delay time (jitter) under variation of the charging voltage and growth rate of the voltage trigger pulse. Jitter less than 1 ns was obtained for a charging voltage of 90–100 kV and a growth rate of the voltage trigger pulse ~650 kV/μs. When the growth rate of the trigger pulse is decreased, the jitter of the spark switch grows significantly. Thus, for a charging voltage of 100 kV and a trigger voltage pulse with growth rate ~200 kV/μs the jitter exceeds 20 ns, and for a voltage trigger pulse with growth rate ~100 kV/μs the jitter exceeds 30 ns. To reduce the jitter when using trigger pulses with low growth rate, blade electrodes were inserted into the spark switch, ensuring ignition of a corona discharge in the gaps during charging of the capacitive storage. It has been shown that for a growth rate of the trigger pulse of 100–200 kV/μs the corona discharge reduces the jitter by 2–3 times.

Forecasting of Global Earthquake Energy Time Series

This paper explores a new method to model and forecast the global earthquake energy release time series. The ISC-GEM catalogue of global events with magnitude [Formula: see text] is used in this study. The magnitudes of individual events are converted into seismic energy using an empirical relation. The annual earthquake energy time series is constructed by adding the energy releases of all the events in a particular year. Then, the energy time series is decomposed into finite number of intrinsic mode functions (IMFs) using empirical mode decomposition (EMD) technique. The periodicities of these IMF’s and their contribution to the total variance of the data are examined to identify the influence of natural phenomenon on earthquake energy release. The artificial neural network technique (ANN) is further used for modeling the energy-time series. The model is verified with an independent subset of data and validated using statistical parameters. The forecast of the annual earthquake energy release is provided for the year 2016.

Deagglomeration of nanostructured aluminum oxyhydroxide upon shock wave impact of electrohydraulic discharge

This article discusses the patterns of deagglomeration of aluminum oxyhydroxide nanosheets upon electrohydraulic discharge. The dispersion efficiency by electrohydraulic discharge is higher than that of ultrasound impact. The highest influence on destruction efficiency is exerted by the time of energy release, which determines the intensity of cavitation processes in water. No disintegration of initial nanostructures is observed under the selected parameters of electric pulses.

Evaluation research of the fracturing capacity of non-explosive expansion material applied to coal-seam roof rock

Goaf caving is an effective measure to prevent disasters caused by large area roof weighting (LARW). This study uses non-explosive expansion material (NEEM) as a crack source to initiate goaf caving. To evaluate the fracturing capacity of NEEM, we prepared similar specimens with and without an included layer, and different numbers of slots were made along the radial direction of the hole. Acoustic emission and static strain gauge were adopted to monitor energy release and fracture strain damage. All the specimens displayed complex fracture phenomena, and there were positive correlations between fracture number and fractal dimension, fracture density, and the degree of faulting. The fractal dimension and fracture density of layer-bearing specimens were greater than those of specimens without a layer. The released cumulative energy was higher for specimens with two slots than for those with no slots, for specimens both with and without layers. Overall, compared to non-layer specimens, layer-bearing specimens showed a more concentrated energy ratio and a longer duration time of energy release. The relative cumulative energy curves showed several stable rising and abrupt rising patterns, which prolonged the action time of rock internal energy accumulation and accelerated the accumulation of internal damage.

Energy storage and release properties of Sr-doped (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric ceramics

Pb0.94−xLa0.04Srx[(Zr0.6Sn0.4)0.84Ti0.16]O3 (x=0,0.02,0.04,0.06) antiferroelectric ceramics were fabricated via conventional solid-state reaction. The increase of Sr content enhanced the stability of antiferroelectric phase, which resulted in the rise of phase transition fields and energy density. When x=0.06, the releasable energy density was 1.52J/cm3 and the efficiency was 93.3% under 129kV/cm. The pulsed discharge current was also measured to evaluate the energy release properties. Under 129kV/cm, the obtained current density could be as high as 165.5A/cm2. The pulsed discharge energy density was 1.21J/cm3 and 90% of that could be released in less than 200ns. The high energy density, high efficiency and fast energy release time indicate that the obtained AFE ceramics are very promising for pulsed power capacitors.

Effect of electro-discharge circuit parameters on the destructive action of plasma channel in solid media

The results of computer blast-hole experiments with copper wire electro-explosion in the polyethylene-concrete media has been analyzed with shock and pressure wave dynamics depending on the spatiotemporal distribution of electrical power deposition in plasma channel. Pressure and stress-wave dynamics of tensely-deformed material state has been analysed by means of physical and mathematical model, which consistently describes the operation of the discharge circuit, plasma channel expansion, generation and propagation of the shock and pressure waves in the condensed media. It has been shown the significant dependence of the stress-wave profile on the pressure pulse wave shape on the borehole wall which is determined by the rate of electrical energy release in the plasma channel and is weakly depended on the time of energy release (at given rate of its release). Analysis of stress-wave dynamics have been shown that the rapid power deposition results to the higher amplitude of compressive stresses in the wave. The lower energy deposition rate in plasma channel leads to the higher amplitude of tensile stresses both in radial and tangential direction.