Energy Storage Mode Research Articles

Heating and energy storage characteristics of multi-split air source heat pump based on energy storage defrosting

In recent decades, multi-split air source heat pump (M-ASHP) unit has been widely used for space heating. Similar to the split-ASHP unit, frost would accumulate on its outdoor coil surface under frosting condition, which significantly deteriorates its heating performance. In the previous study, a novel reverse-cycle defrosting method based on phase change energy storage was developed and investigated, and the study demonstrated that the novel defrosting method could significantly improve defrosting performance. To provide guidelines for designing the M-ASHP units with phase change energy storage, it is necessary to investigate the characteristics of heating and energy storage for M-ASHP units, which is presented in this paper. Experimental results showed that there was no frost on outdoor coil when only the indoor unit with heating capacity of 7.1 kW was turned on under frosting condition. In addition, the energy storage period increased as the number of operating indoor unit increased, namely the load rate. Furthermore, the optimal starting time of the energy storage operation was around 10 min after the start-up of M-ASHP unit. Even though, compared with the conventional heating mode with three turned-on indoor units, the energy storage mode shortened the heating period by 8 min and decreased the average heating capacity and COP by 4.4% and 1.9%, respectively. The above negative impacts of energy storage operation on the heating performance of the M-ASHP unit could be neglected by considering its positive impacts on defrosting performance, for a periodic heating-defrosting condition.

Study of the modes of operation of capacitive energy storage in the automobile engine start systems

The article presents data on the study of the operating modes of capacitive energy storage (ES) in the start systems of a modern automobile engine. Experimental dependencies of the main parameters of the electric starter start systems (SSS) using ES are presented. A comparative analysis of alternative energy storage devices revealed that the best performance indicators for specific power are ES, which is achieved due to lower internal resistance. ES are able to quickly give away and accumulate energy. The discharge and charge time is determined by the electricity consumers and the parameters of the charging circuit of ES. Studies of ES in SSS for automotive internal combustion engines (ICE) were carried out, when, instead of the standard battery the battery with a smaller capacity is used, and the ES is located in the remaining part of the volume of battery. At high specific rates of ES, the reliability of the start can be increased with the same total volume and weight of the SSS at low temperatures. The theoretical and experimental studies have allowed to obtain the dependence of the instantaneous and average parameters of the SSS on the time of the engine scrolling, as a result of which the required capacity of the ES and its internal resistance, the initial energy of the ES, as well as the necessary volume and mass of the ES are determined. The volume and mass of batteries can be determined from the reference literature or by known methods by specific energies of batteries in volume and mass. On the experimental dependences it was shown that the time of the crankshaft scrolling, the number of working strokes and the angle of rotation of the crankshaft to a complete stop Nрх depend on the capacity and charge voltage of the ES. The studies were conducted in the Cold Start Laboratory of the Federal State Unitary Enterprise Research and Experimental Institute of Automobile Electronics and Electrical Equipment together with the Department “Electrical Equipment and Industrial Electronics” of Moscow Polytechnic University, where an experimental assessment of the possibility was made of starting gasoline engines at low temperatures of SSS with ES of high-voltage (capacitors with a voltage of 200 V - 290 V) and low-voltage ESs with a voltage of 12 V - 16 V.

A Review on Capacity Optimization of Hybrid Renewable Power System with Energy Storage

With the rapid development of the global economy, there is a sharp shortage of fossil energy sources. Therefore the development of renewable energy technologies such as wind power and solar power has become a hot issue nowadays. However, due to the randomness, intermittency and instability of renewable energy, it is difficult to provide continuous and stable electricity when it runs independently. Hybrid renewable power systems with energy storage can improve the reliability of power supply. Capacity optimization is the key of hybrid renewable power system design and the basis of optimal scheduling. In this paper, the capacity optimization of hybrid renewable power system with energy storage is summarized and classified. According to the different energy storage modes of the hybrid renewable power systems, the capacity optimization models, optimization methods and the software used are introduced.

Analysis of the Development of DC Distribution Network with Renewable Energy and Flexible Energy Storage

In order to meet the increasing demand for DC load of electric vehicles, information equipment and semiconductor lighting systems in today’s increasingly urbanized distribution networks, and to prevent the deterioration of environmental problem, a large number of intermittent, unstable renewable energy are integrated into the DC distribution network. According to the characteristics of renewable energy, the mixed energy storage mode can be used to realize the separation of power generation and electricity utilization in the space and time. It is reasonably planned to realize the safety, economy, high quality and reliability of the DC distribution in the future.

An Electrochemical Generator Containing Cylindrical Aluminum-Air Cells

The article considers matters concerned with optimizing the design and technology of aluminum-air electrochemical generators for emergency and backup power supply to different consumers. The physicochemical principles used to construct such generators are briefly described. Owing to the absence of self-discharge in the energy storage mode, aluminum-air generators can remain in the waiting mode for a longer period of time as compared with electrochemical storage batteries or hydrogen-air fuel cells. The source is activated by adding water to it. To obtain better specific parameters of aluminum-air cells and improve their manufacturability, a cylindrical cell design is proposed. One-off cells and a battery have been developed, fabricated, and tested. The obtained results are compared with the data from testing a battery and cells having a flat design. The possibility of obtaining essentially better specific characteristics due to making a shift to a cylindrical design is shown. Owing to the proposed design, more efficient use of aluminum has been achieved along with simplifying the system for maintaining the thermal balance of the cell and battery. The article presents the results from testing a single aluminum-air cell and a four-cell battery, which showed the need to adjust the concentration of electrolyte in cells and batteries of this type. The obtained data are compared with the results from tests of previously fabricated aluminum-air elements of the classical flat design. For determining the prospects for using generators of this type, their technical and economic characteristics were compared with those of the main competing sources of emergency and backup power supply, including lead-acid and lithium-ion storage batteries, and with hydrogen-air electrochemical generators. The characteristic time of power source operation and the frequency of its coming into action for which the use of aluminum-air electrochemical generators is economically justified are determined, and recommendations on extending the range of these parameters are given.

Theoretical investigation on energy storage characteristics of a solar liquid desiccant air conditioning system in Egypt

This work presents theoretical study of a standalone outdoor liquid desiccant air conditioning (LDAC) system assisted by solar energy. The liquid desiccant dehumidification cycle was integrated with a double indirect evaporative air cooler and a regenerative air heat recovery. The double indirect evaporative air cooler was used to recover heat from the return air, while air-air heat exchanger was used to recover heat from air leaving the regenerator. A water-in-glass evacuated tube solar collector was used to supply the system with solar heat. The remaining required heat is provided by natural gas fired boiler. The system was simulated by transient model under thermal energy storage, thermochemical energy storage and combined thermal and thermochemical energy storage modes.The theoretical results show that the mean daily thermal coefficient of performance (TCOP) is a strong function of the difference between absolute humidity ratio of outdoor air and saturated air. Results also show that, each tube of solar collector can deliver 30-Watt to operate the LDAC system under thermal energy storage mode for 16 h daily. While in the LDAC system under thermochemical energy storage mode, each tube would deliver 38.5-Watt for 16 h operation.It has been found that, to rise the solar fraction from 90% to 100% in the thermal energy storage mode, the required size of tubes array will be increased by 20%. Also, an analysis was carried out on the TCOP and required storage volume of the different energy storage modes. It shows that the combined energy storage method is the most energy efficient method.Finally, life cycle cost analysis (LCCA) was carried out for the LDAC system using various types of energy storage modes. The comparison indicated that 90% solar fraction LDAC system is the most economic system related to unit prices of solar collector and gas prices in Egypt. The total annual cost for the 90% solar assisted LDAC system is found to be lower than that of a vapor compression cycle (VCC) by about 50.5%. At the second order, the thermal energy storage mode by 49%. On the other side, the thermochemical energy storage mode is the least cost saving energy storage mode.

Объемные гидравлические приводы с частотным управлением и несколькими энергетическими каналами

The article presents possible circuit engineering solutions for pump-controlled hydraulic drives with frequency control (FC PCHD), the use of which makes it possible to obtain an essentially wider stable stepless adjustment range of the system output member’s speed from its “crawling” to maximum values. In addition, better reliability and robustness of the drives are achieved owing to the use of two-channel arrangements for transmitting energy flows to the system output member. Criteria and parameters for evaluating the competitiveness of two-channel FC PСHDs equipped with mechanical differential reduction gears and hydraulic adding units are formulated. The article analyzes the advantages and drawbacks of two-channel FC PСHD versions involving closed and open liquid circulation schemes, a differential connection arrangement of electric pump sets, and the hydraulic motor unit’s mechanical differential, all featuring extended functional abilities, including, in particular, energy storage and recuperation modes. Different kinds of machines and apparatuses that can be used in the FC PСHD composition are subjected to a comparative analysis, and preferable modifications of their components are suggested. It is shown that, owing to the attained advantages, adjustable multichannel FC PСHDs are successfully used as actuating modules of various power systems of important engineering facilities as a replacement of or supplement to conventional hydraulic and electromechanical drives.

XFEM study of crack propagation in logs after growth stress relaxation and drying stress accumulation

There are crack-prevention mechanisms in living trees. However, in the felled logs, relaxation of growth stress and accumulation of drying stress may cause crack propagation. To investigate the crack propagation behavior and crack patterns in log cross sections, theoretical and simulation models are developed in this paper. In the theoretical model, global stability and local instability of cracks are considered in logs. In the simulation models, energy release rate is calculated based on FEA J-integral calculation models; crack patterns on log cross sections are investigated by the XFEM and fracture mechanics simulation models. Simulation results suggest that various crack patterns may develop in log cross sections, and there are several representative patterns. The existence of the simulated crack patterns can also be verified in real logs. The results of parameterization indicate that the crack bifurcation has a close relationship with energy storage and release modes. The pattern of main cracks is related to the damage initiation–evolution parameters. These phenomena can be explained by the energy principle of crack propagation and the stability principle of energy storage systems.

Memory and Energy Storage Dual Operation in Chalcogenide-Based CBRAM

In this paper, we demonstrated memory and energy storage dual operation in GeS2/Ag conducting bridge RAM. Both operations are based on electrochemical reactions and Ag diffusion in the GeS2 electrolyte. Depending on specific bias and current conditions, the same device can be used for data or energy storage: in memory mode, Ag-based filament is formed in GeS2, while in energy storage mode, Ag bulk diffusion is achieved. Voltage sweep and constant current stress cycling modes for energy storage are evaluated, and the total stored charge is quantified. These obtained results open the path for new autonomous or ultra-low power circuits, integrating dual operation devices composed of the same stack, where energy storage devices could provide energy to the memory array.

Study of the Lifetime of High-Power GaAs PCSSs Under Different Energy Storage Modes

This paper presents an experimental study on the lifetime of high-power gallium arsenide photoconductive semiconductor switches (PCSSs) under different energy storage modes. Under the capacitive energy storage mode, the lifetime of a PCSS was increased by a factor of 10 through a reduction in the capacitor size, which reduces the hold-time of the carrier avalanche multiplication. Under the transmission line energy storage mode, the lifetime of a PCSS was increased by more than twofold by reducing the bias electric field, which reduces the degree of the carrier avalanche multiplication. Additionally, the influence of various factors on device lifetime and the failure mechanisms are discussed. The experimental results and analysis indicate that electrode erosion and stress damage are the two leading factors that induce the failure of high-power PCSSs.

A Novel High Controllable Voltage Gain Push-Pull Topology for Wireless Power Transfer System

Wireless Power Transfer (WPT) is commonly used to transmit power from a transmitting coil to various movable power devices. In the WPT system, due to a resonant tank inherent characteristic, the system cannot achieve a high output voltage gain. This paper proposes a novel current-fed push–pull circuit to realize high output voltage gain by adding a bi-directional switch between the resonant network and inverter. To obtain a high voltage gain, this paper proposes energy storage and energy injection mode to realize an energy boost function. A duty cycle control method for mode switching is also proposed. The proposed method allows the converter to operate with a variable voltage gain over a wide range with high efficiency. Experimental validation shows that the system gain of a proposed circuit can achieve a variable gain from 2 to 7 of which the converter can be two times higher than the classical system with the same condition.

Economic viability of battery energy storage and grid strategy: A special case of China electricity market

Battery energy storage (BES) plays an important role in the integration of intermittent renewable power and distributed generation. The price arbitrage is a major source of energy storage income. In China, the electricity price is tightly regulated by the government. It's interesting to find out whether the BES is economic viability in such a special electricity market, and what's the optimal response of the grid (or regulator) when facing the arbitrage activities of BES. This research starts with a price arbitrage model to evaluate the feasibility of energy storage in China's electricity market, which can be used to determine the optimal investment scale and operation mode of energy storage. A quantitative assessment is also implemented to discuss the influence when factors change. Following this, an optimal pricing strategy for grid is established. The results reveal that the storage investment can realize positive profit in some districts where the price gap between peak/off-peak periods is high. Appropriate subsidies can be quantitatively described by sensitivity analysis. In terms of social welfare, the energy storage can be deployed on a large-scale at a low social cost under a suitable price mechanism.

INFLUENCE OF THE OPERATIONAL MODE OF THE HIGH-TEMPERATURE BOREHOLE THERMAL ENERGY STORAGE ON ITS EFFICIENCY

Ponte Academic JournalJan 2017, Volume 73, Issue 1 INFLUENCE OF THE OPERATIONAL MODE OF THE HIGH-TEMPERATURE BOREHOLE THERMAL ENERGY STORAGE ON ITS EFFICIENCYAuthor(s): Michal Porzer ,Adam Pytlik, Petr Bujok, David Grycz, Martin Klempa, Ondrej MalekJ. Ponte - Jan 2017 - Volume 73 - Issue 1 doi: 10.21506/j.ponte.2017.1.10 Abstract:The purpose of the research was to analyse the influence of the operational mode of the borehole thermal energy storage (BTES), used for balancing heat generation in gas-fuelled cogeneration unit, on its efficiency. The pioneering project took place in the premises of Green Gas DPB, a.s., Paskov, the Czech Republic, during the 2012 2014 period. During these years, 11 operational cycles were conducted and thoroughly analysed in order to identify the correlations between the BTES operational parameters and the its energetic balance. Operational cycles varied in: the overall duration (long-, medium-, short-term); the character (continual, alternating); the operational mode (charging, discharging, resting); the borehole heat exchangers thermal output; and the length of sub-cycles (charging/discharging) in the alternating cycles (8h/16h, 16h/8h, 24h/24h). The results revealed that the BTES efficiency is not constant and should be optimized by adequate operational parameters adjustment. To properly evaluate given cycle, the natural heat dispersion rate must be considered. During the unique cycle II, with a half-year undisturbed resting mode, the rate of natural heat dispersion of the BTES Paskov was evaluated. The obtained results are crucial for the maximization of BTES efficiency. The collected data base is worth further scientific exploitation and analysis. Download full text:Check if you have access through your login credentials or your institution Username Password

Flux balance analysis of photoautotrophic metabolism: Uncovering new biological details of subsystems involved in cyanobacterial photosynthesis

We have constructed and experimentally tested a comprehensive genome-scale model of photoautotrophic growth, denoted iSyp821, for the cyanobacterium Synechococcus sp. PCC 7002. iSyp821 incorporates a variable biomass objective function (vBOF), in which stoichiometries of the major biomass components vary according to light intensity. The vBOF was constrained to fit the measured cellular carbohydrate/protein content under different light intensities. iSyp821 provides rigorous agreement with experimentally measured cell growth rates and inorganic carbon uptake rates as a function of light intensity. iSyp821 predicts two observed metabolic transitions that occur as light intensity increases: 1) from PSI-cyclic to linear electron flow (greater redox energy), and 2) from carbon allocation as proteins (growth) to carbohydrates (energy storage) mode. iSyp821 predicts photoautotrophic carbon flux into 1) a hybrid gluconeogenesis-pentose phosphate (PP) pathway that produces glycogen by an alternative pathway than conventional gluconeogenesis, and 2) the photorespiration pathway to synthesize the essential amino acid, glycine. Quantitative fluxes through both pathways were verified experimentally by following the kinetics of formation of 13C metabolites from 13CO2 fixation. iSyp821 was modified to include changes in gene products (enzymes) from experimentally measured transcriptomic data and applied to estimate changes in concentrations of metabolites arising from nutrient stress. Using this strategy, we found that iSyp821 correctly predicts the observed redistribution pattern of carbon products under nitrogen depletion, including decreased rates of CO2 uptake, amino acid synthesis, and increased rates of glycogen and lipid synthesis.

Energy Blocks — A Physical Model for Teaching Energy Concepts

Most physics educators would agree that energy is a very useful, albeit abstract topic. It is therefore important to use various methods to help the student internalize the concept of energy itself and its related ideas. These methods include using representations such as energy bar graphs, energy pie charts, or energy tracking diagrams. Activities and analogies like Energy Theater and Richard Feynman's blocks, as well as the popular money (or wealth) analogy, can also be very effective. The goal of this paper is to describe a physical model of Feynman's blocks that can be employed by instructors to help students learn the following energy-related concepts: The factors affecting each individual mechanical energy storage mode (this refers to what has been traditionally called a form of energy, and while the Modeling Method of instruction is not the focus of this paper, much of the energy related language used is specific to the Modeling Method). For example, how mass or height affects gravitational energy;Energy conservation; andThe graphical relationships between the energy storage mode and a factor affecting it. For example, the graphical relationship between elastic energy and the change in length of a spring.

The Modular Augmented Staged Electromagnetic Launcher Operated in the Energy Storage Mode

Railguns use electrical energy to accelerate projectiles to large velocities. The electrical energy for the launching process is provided by a pulsed power unit. A pulsed power unit usually consists of a capacitor, a switching device, a crowbar diode, and a pulse-forming inductance. The pulse-forming inductance is necessary to generate an appropriate current pulselength and amplitude. The idea of the energy storage augmented electromagnetic launcher is to use the magnetic field produced by the pulse-forming inductance to augment the magnetic field between the rails of the launcher. To maximize the augmentation of the magnetic field, it is necessary to place the pulse-forming inductance as close as possible to the rails of the railgun. The additional magnetic field causes not only an increased acceleration of the projectile but also a larger mechanical load of the railgun structure. This requires a reinforced housing compared with conventional railgun housings. In this paper, the design and the experimental setup of a railgun using an energy storage augmentation scheme as well as the results of experiments are presented. The results are compared with the previous results of a nonaugmented railgun configuration. The comparison shows an improvement of the energy efficiency.

Commercial grid scaling of Energy Bags for underwater compressed air energy storage

Large-scale ability to store surplus energy for use during periods of high demand is a formidable asset in reducing the energy cost, improving electric grid reliability and addressing climate change. An Energy Bag is a fabric balloon-like vessel anchored to a sea- or lakebed for the purpose of storing surplus energy in the form of compressed air. This mode of energy storage is attractive because the passive pressure force of the deep-water environment takes on the significant role of pressure vessel structure to maintain pressurization of the air stored within the Energy Bag. Upon further investigation, it becomes evident that particular attention must be given to the storage volume and pressure required to satisfy requirements economically for commercial grid-scale development of this novel technology. This paper provides an introduction to the benefits and prerequisites pertaining to commercial scale energy storage capacity as related to Energy Bag structure, volume and deployment depth.

Probe on Questions and Mode of Renewable Resource Development and Utilization on Small Islands

Aiming at small islands location limits and the established power grid characteristics, the paper analyses some practical problems to be dealt with when renewable resource is utilized. Combined with the characteristics of small islands, the paper puts forward the new mode without energy storage devices, and designs a renewable resource application system driven directly by photovoltaic devices, emphatically analyses the key technology of no energy storage mode. The new mode effectively resolves the battle neck problem of traditional off-net mode.

Switching of Microwave Radiation Storage and Output Modes in Superconducting Resonance-Cavity Compressors with an Interference Switch

UDC 621.37 We propose a commutator for the interference switch of microwave electromagnetic radiation on the basis of a waveguide H-junction made as a cavity with tunable parameters, which is connected to one arm of this junction. The superconducting version of a microwave compressor with such a switch is analyzed. The conditions of effective switch operation in the mode of electromagnetic energy storage and its fast output in the case of controllable manipulation of the Q-factor and resonant frequency of the switching cavity are determined. Estimates of the output parameters of the superconducting compression system are presented for storing- and switching-cavity Q-factors of about 5 · 10 8 . The possibility of increasing the radiated power in such a compression system by 40–60 dB for output microwave pulses with durations of about 5–10 ns is demonstrated. Variants of practical implementation of the system are considered.

Energy reserves of Southern Ocean copepods: Triacylglycerols with unusually long-chain monounsaturated fatty acids

Two of the dominant Southern Ocean copepods, Calanus simillimus and Calanus propinquus, are known for their lipid storage via triacylglycerols indicating year-round activity, as opposed to diapausing species, which accumulate wax esters. We studied the lipid and fatty acid compositions of C. simillimus (CV stages) with focus on its ability to produce unusually long-chain monounsaturated fatty acids. Besides the biosynthesis of high-energy fatty acids with 20 and 22 carbon atoms, the occurrence of fatty acids with 24 carbon atoms accounting for up to 15% of total fatty acids is intriguing. Their double bond positions were unequivocally determined as (n−9), (n−11) and (n−13) by DMOX derivatisation. The dominant isomer was 24:1(n−11) contributing up to 8% to the total fatty acids. The major fatty acids were the isomers 22:1(n−11) and (n−9) averaging 20% and 10%, respectively. A re-evaluation of fatty acid data of C. propinquus also revealed 24:1 fatty acids exhibiting on average 5% with (n−11) and (n−9) as main isomers. The principal fatty acids were also 22:1(n−11) and (n−9), but in contrast to C. simillimus both fatty acids occurred in equally high amounts of about 20%. The de novo biosynthesis of these long-chain monounsaturated fatty acids generally represents a very efficient energy storage mode. Chain elongation to 22 and even to 24 carbon atoms in C. propinquus and further optimised by C. simillimus yields high-energy compounds for these triacylglycerol-storing copepods. Biosynthetic pathways for the fatty acids are proposed and discussed in view of the well-adapted life cycle strategies of the two species, which have to cope with a pronounced seasonal food supply in the Southern Ocean.