External Electrical Power Research Articles

Numerical study on a heat-driven piston-coupled multi-stage thermoacoustic-Stirling cooler

This work investigates a novel heat-driven multi-stage thermoacoustic cooler that can satisfy cooling requirements in the applications of natural gas liquefaction and high-temperature superconductivity. The proposed system consists of a compressor, multiple thermoacoustic units (engines and coolers) coupled by piston-cylinder assemblies. The acoustic power input by the compressor is successively multiplied in the thermoacoustic engine units, and the amplified acoustic power is then consumed to produce cooling power in the thermoacoustic cooler units. The proposed system overcomes the limitations of the traditional thermoacoustic systems owing to high efficiency, compact size, and ease of control. Analyses are first performed to explore the influence of the number of stages. The design method of the pistons is presented based on acoustic impedance matching principle.Based on the optimized system, simulations are then conducted to investigate the axial distribution of the key parameters, which can explain the reason for improved thermodynamic performance. At heating and cooling temperatures of 873 K and 130 K, the system achieves a cooling power of 2.1 kW and a thermal-to-cooling relative Carnot efficiency of 23%. This represents significant increases by over 60% in efficiency and 80% in cooling capacity when compared to existing systems. Simulations further demonstrate how controlling the input acoustic power and frequency via the compressor enables control of the system under various conditions. Further discussions are made considering a potential combined cooling and power system, indicating an overall thermal-cooling-electricity efficiency of 34% without any external electric power required for the compressor.

Utilization of thermoelectric technology in converting waste heat into electrical power required by an impressed current cathodic protection system

Supplying an energy source for impressed current cathodic protection is considered as the main challenge for pipelines corrosion protection in remote areas. The purpose of this study is to construct and evaluate the performance of an impressed current cathodic protection system using waste heat to replace the external electrical power supply. The system consists of four thermoelectric modules producing the electrical power from the hot combusted gas stream. Mathematical modeling and Buckingham Pi theorem were applied to obtain five dimensionless parameters and several models to estimate the system performance. According to the experimental results, the generated voltage, electrical current, and temperature difference have been increased rapidly during the experiment up to 201 mV, 44 mA, and 20 K, respectively. Moreover, mathematical modeling and Buckingham Pi theorem were also utilized to obtain three equations, two nonlinear and one dimensionless equation, to calculate the generated electrical voltage with the maximum error of 1.22%, 9.11%, and 10%, respectively. The results indicate that the temperature difference (between inlet gas and environment) and the figure of merit have a direct effect, and heat sink thermal resistance has an inverse effect on the generated electrical voltage.

Organic Semiconductors for Optically Triggered Neural Interfacing: The Impact of Device Architecture in Determining Response Magnitude and Polarity

The use of organic semiconductor devices as photocapacitors is an innovation with promising applications in neural interface technologies, particularly for retinal prosthetics. Here we report the characterization of four distinct photocapacitor device architectures that were fabricated by depositing ultra-thin layers of poly-3-hexylthiophene and C60 fullerene in various combinations on tin-doped indium oxide (ITO) electrodes. We used electrophysiological recordings to measure the intrinsic photoresponse at 470 nm, and also to determine light-induced voltage perturbations in electrolyte solutions interfaced with these semiconductors. We also determined the light-induced intracellular voltage changes in co-cultured sensory neurons. Electrochemical impedance spectroscopy was used to establish the photocapacitive response mechanism of the intracellular changes upon illumination. The largest amplitude photocapacitive response was elicited from a neuron/acceptor-donor bilayer/ITO device architecture, whilst reversing the donor and acceptor layer order enabled a neuron response of the opposite polarity. The photoresponse in the neuron/acceptor/donor/ITO bilayer device configuration was significantly enhanced in both amplitude and time duration by electrical grounding of the indium tin oxide layer. We describe the advantages and limitations of each configuration of these device and discuss pathways towards the creation of optically triggered neural interfaces that do not require an external electrical power supply.

Self‐Powered Stretchable Mechanoluminescent Optical Fiber Strain Sensor

Strain sensors that can work sustainably and continuously without any external power supply are highly desirable for future wearable and implantable devices. Herein, a self‐powered stretchable strain sensor based on the integration of mechanoluminescent phosphors with an elastomer optical fiber is proposed and developed. This mechanoluminescent optical fiber is capable of emitting light just driven by external strain, without the need of an external light source or electric power. The strain‐induced emitted light can be collected and guided along the mechanoluminescent optical fiber. The sensor exhibits linear strain response up to 50% and high‐accuracy strain measurement (±1%). Moreover, this optical fiber strain sensor displays consistent signals over 10 000 stretch–release motion cycles, which demonstrates the good durability of the sensor. Due to the excellent light confinement of the elastomer optical fiber, this strain sensor is demonstrated in both bright‐ and dark‐field measurements, wearable gloves, and an implantable sensing device, thereby demonstrating potential as a promising technology for future self‐powered optical sensor systems.

Feasibility analysis of a steam-water supercharger for small-scale Rankine cycle

For the traditional Rankine cycle, mechanical pump driven by electricity is the only power-consuming part. Based on this, a steam-water supercharger is proposed in this paper, which can realize the pressurization of low-pressure condensate only using high-pressure and high-temperature steam. In the structural design, the crank slider mechanism is selected to realize automatic control of steam-intake and steam-exhaust passages. Besides the overview of principle, the mathematical modeling for performance analysis is also conducted. Then the theoretical study, including pressurizing performance and parameters study, and experimental verification are carried out to prove the feasibility of the proposed supercharger. The results show that: the proposed supercharger can be an alternative to the mechanical pump, and there is no requirement for external electric energy or power transmission, which is conducive to the promotion of small-scale portable solar power generation systems.

The Socio-Economic aspects of Laparoscopic Approach in the Treatment of Inguinal Hernia by Mesh in Cameroon

Background: In Sub-Saharan Africa (SSA), economic conditions often do not always permit the use of modern surgical techniques, especially for hernia treatment. Aim of the study: To demonstrate that a modern technique such as Laparoscopic Total Extraperitoneal inguinal hernioplasty (TEP) can be performed at a significantly lower cost thanks to the use of a less expensive mesh material. Settings: The study was performed in Douala at the Gynaecology-Obstetric and Paediatric University Hospital and at governmental Regional Hospitals of Ayos and Edea in Cameroon. Material and methods: Prospective, randomised, double-blind, controlled trial (RCT) including consecutive adult patients presenting with primary inguinal hernia treated by TEP, with implantation of either sterilised mosquito net mesh (MNM) or conventional polypropylene mesh (CPM). Results: 62 patients were enrolled; randomization allocated 32 to MNM and 30 to CPM. Both groups were comparable for age and professional activities. Significant perioperative differences pertained to conversion rate (2/32 MNM), due to external (electrical power) factors and mesh removal for early obstruction (1/30 CPM). Hospital stay was less than 2 days in both groups. All patients resumed their activities after 3 weeks. Costs were significantly lower in the MNM group. No recurrences were noted with a follow-up of median 21(12-30) months. Conclusion: This RCT shows that TEP with MNM is feasible, cost-effective with good outcomes in SSA hospital setting.

Electroless Production of Fertilizer (Struvite) and Hydrogen from Synthetic Agricultural Wastewaters.

The drive toward sustainable phosphorus (P) recovery from agricultural and municipal wastewater streams has intensified. However, combining P recovery with energy conservation is perhaps one of the greatest challenges of this century. In this study, we report for the first time the simultaneous electroless production of struvite and dihydrogen from aqueous ammonium dihydrogen phosphate (NH4H2PO4) solutions in contact with either a pure magnesium (Mg) or a Mg alloy as the anode and 316 stainless steel (SS) as the cathode placed in a bench-scale electrochemical reactor. During the electroless process (i.e., in the absence of external electrical power), the open circuit potential (OCP), the formation of struvite on the anode, and the generation of dihydrogen at the cathode were monitored. We found that struvite is formed, and that struvite crystal structure/morphology and precipitate film thickness are affected by the concentration of the HnPO4n-3/NH4+ in solution and the composition of the anode. The pure Mg anode produced a porous 0.6-4.1 μm thick film, while the AZ31 Mg alloy produced a more compact 1.7-9.9 μm thick struvite film. Kinetic analyses revealed that Mg dissolution to Mg2+ followed mostly a zero-order kinetic rate law for both Mg anode materials, and the rate constants (k) depended upon the struvite layer morphology. Fourier-transform infrared spectrometry, X-ray diffraction, and scanning electron microscopy indicated that the synthesized struvite was of high quality. The dihydrogen and Mg2+ in solution were detected by a gas chromatography-thermal conductivity detector and ion chromatography, respectively. Furthermore, we fully demonstrate that the reactor was able to remove ∼73% of the HnPO4n-3 present in a natural poultry wastewater as mainly struvite. This study highlights the feasibility of simultaneously producing struvite and dihydrogen from wastewater effluents with no energy input in a green and sustainable approach.

Electroactive polymer-based inner vessel-wall pressure transducer capable of integration with a PTA balloon catheter for examining blood vessel health.

This study presents a state-of-the-art soft and biocompatible transducer capable of detecting vessel inner-wall pressure for biomedical applications. The device includes a 3D electroactive polymer core element encapsulated by polydimethylsiloxane with an ellipsoidal structure. The device produces a voltage output when its sensing mechanism experiences different pressures, resulting in deformation at different orientations. Thus, it can be employed to detect the pressure exerted by inner vessel walls of different stiffness values. The output voltage is induced by the strain experienced by the sensing mechanism of the device without the need for any external electrical power source. The core element, which is made of an ionic polymer-metal composite, possesses a unique hollow design; this allows a catheter to pass through, and the core element can be anchored at an arbitrary position on the catheter. We also demonstrate that the fabricated device can be integrated with a medically used percutaneous transluminal angioplasty balloon catheter to form a smart sensing module. This module can detect different levels of fat accumulation around the inner wall of a blood vessel phantom. Evaluating vessel blockage and stiffness using the signals acquired from the developed device is discussed.

Manipulating dehydrogenation kinetics through dual-doping Co3N electrode enables highly efficient hydrazine oxidation assisting self-powered H2 production

Replacing sluggish oxygen evolution reaction (OER) with hydrazine oxidation reaction (HzOR) to produce hydrogen has been considered as a more energy-efficient strategy than water splitting. However, the relatively high cell voltage in two-electrode system and the required external electric power hinder its scalable applications, especially in mobile devices. Herein, we report a bifunctional P, W co-doped Co3N nanowire array electrode with remarkable catalytic activity towards both HzOR (−55 mV at 10 mA cm−2) and hydrogen evolution reaction (HER, −41 mV at 10 mA cm−2). Inspiringly, a record low cell voltage of 28 mV is required to achieve 10 mA cm−2 in two-electrode system. DFT calculations decipher that the doping optimized H* adsorption/desorption and dehydrogenation kinetics could be the underlying mechanism. Importantly, a self-powered H2 production system by integrating a direct hydrazine fuel cell with a hydrazine splitting electrolyzer can achieve a decent rate of 1.25 mmol h−1 at room temperature.

Structure orderliness assessment of grid development to improve the reliability of coal mine external electrical power supply

State-of-the-art reliability assessment methods require a large amount of initial statistical data, which does not always have the necessary degree of accuracy for accurate assessment. Moreover, this data is often difficult to obtain, which can ultimately delay the execution of calculations and increase error within results. This paper explores an alternative assessment method using the “structural orderliness indicator” and minimal initial data to calculate the change in reliability indicators in connection with reinforcement decisions. This paper includes the cost of reconstruction associated with the introduction of a new unit cost indicator for increasing the structure orderliness index. As a real-world application, the following discussion proposes improvements to external electrical power supply reliability for coal-mining enterprises within the Russian Federation, such as in the Kemerovo region (the biggest coal-producing region of Russia). In recent years, the number of production process suspensions and emergency shutdowns of life support facilities has increased due to external power supply disruptions. The performed calculations made possible qualitatively comparison the proposed method and state-of-the-art method based on the determination of reliability indices (SAIDI, SAIFI, etc.).

A self-powered flexible-vision electronic skin based on piezophototronic GaN nanowires for rapid image recognition

A self-powered flexible-vision electronic skin for rapid image recognition has been fabricated from piezophototronic GaN nanowires. The basic structure of each photodetecting pixel consists of horizontally-aligned GaN nanowires crossing a cross-finger electrode, and 6 × 6 photodetecting pixels that form a patterned sensing matrix. The working mechanism is based on the piezophototronic effect, and the device can harvest a tiny amount of mechanical energy and directly output photodetecting signals without any external electrical power. The output piezoelectric voltage is significantly dependent on UV illumination, and the response is up to ~76 for 80 µW cm−2 light. The response and recovery times are very short. A practical application of the device for rapid image recognition has been simply demonstrated, and this shows the potential for realizing an artificial intelligent retina. This work can promote the development of wearable flexible electronics and expand the scope of self-powered nanosystems.

The dual-function of hematite-based photoelectrochemical sensor for solar-to-electricity conversion and self-powered glucose detection

Photoelectrochemical (PEC) glucose sensing has been developed as a novel promising electrochemical approach for advanced analysis due to the advantages of high sensitivity and selectivity as well as good stability. Here, we present a Fe2O3 nanorod (Fe2O3NR)-based PEC sensor, which shows excellent performance in glucose detection for the concentrations in the range of 0.2–2.0 mM with a linear correlation coefficient of 0.997 and a sensitivity of 100.46 μA cm−2 mM−1. Furthermore, the glucose determination can be achieved without inputting external electrical power via a photo fuel cell (PFC) which is fabricated by the Fe2O3NR photoanode and platinum cathode. The generated maximum power density (Pmax) shows a linear sensitivity of 3.53 μW cm−2 mM−1 to the variation of glucose concentrations from 0.5 to 2.5 mM with correlation coefficient of 0.990. Therefore, the Fe2O3NR-based PEC sensor not only realizes the electricity generation from renewable solar energy and bioenergy but also accomplishes the detection of glucose by self-power.

Reliability comparison of natural convection and forced circulation configurations of a FBR thermo-siphon decay heat removal system

Natural convection based passive decay heat removal systems are increasingly being deployed in the newer designs of nuclear reactors with the expectation that they enhance reliability and robustness owing to the elimination of reliance on human operators and external electrical power supply. In the absence of demonstrated experience with passive systems, difficulty in testing them on the field and possible range of phenomena which can degrade their performance, in some designs part of the redundant passive circuits are fitted with pumps to alleviate concerns regarding passive system performance. In this study the two types of designs, one with a set of 4 passive thermo-siphon loops and another with electro-magnetic pumps in part or all of the thermo-siphon loops are studied to bring out the reliability aspects. The decay heat removal function failure frequency is analyzed considering, electromagnetic pump integrity, changes in human interaction aspects for the two different configurations. It is observed that the introduction of electromagnetic pumps in two out of four loops increases the decay heat removal function failure frequency by approximately 64%. If electromagnetic pumps are introduced in all the four loops, the decay heat removal function failure frequency increases by an order. The results are highly sensitive to electromagnetic pump reliability. This study indicates that, there is no change in the uncertainty propagated from input parameters to response parameters, there is no significant advantage in terms of flexibility gained for certain operator actions and higher levels of reliability need to be achieved for the electromagnetic pump if it is to be introduced in all the four loops as compared to introduction in only two loops.

Energy Harvesting and Storage by Water Infiltration of Eggshell Membrane

As a domestic waste in daily life, eggshell membrane (ESM) is a unique biomaterial due to its biocompatibility, bioadsorption, and the structure of interwoven and coalescing fibers with many pores which can be utilized in many fields. Herein, a new kind of potentially biocompatible energy harvesting and storage device based on polymer polyaniline/carbon nanotube (PANI/CNT) composite electrodes and ESM is designed. Without external electric power, a single device can extract a maximal output voltage of 0.26 V from water osmosis. The energy can be stored directly and released circularly, and the output voltage can achieve superposition by integrating devices in series. This self‐charging bioelectric phenomenon can be explained by the membrane potential of the ESM induced by water movement. Due to the biocompatible feature of the ESM, and sufficiently high electric output, this study provides a new idea for sustainable and biocompatible energy harvesting and storage devices.

Self-contained Electrochemical Process to Produce Pure Compressed Hydrogen from Hydrocarbons and Steam Without an External Energy Supply

This paper describes and analyzes a system that tightly couples an electrochemical oxidation cell (EOC) with a protonic-conducting ceramic separation cell (PSC) to produce compressed pure hydrogen from a hydrocarbon feedstock and water. The EOC introduces oxygen through its membrane-electrode assembly (MEA) into the fuel chamber, enabling partial oxidation and reformation of the fuel to produce a hydrogen-rich mixture within the anode microstructure. At the same time, the EOC generates the electric power needed to drive the PSC for hydrogen separation and compression. On the other hand, removing hydrogen from the fuel stream by PSC can thermodynamically promote the catalytic conversion of the fuel stream. The concept leads to a self-contained integrated system, being independent of any external electrical power source, and being capable of producing pressurized hydrogen with potentially high energy-conversion efficiency.

Simulation modeling balancing current in the traction network of a substation group

This article is devoted to assessing the transit of electricity from an external electrical power supply system through the traction network of a railway district that includes nine traction substations. Substation transformers has star-delta-11 connection. The paper presents a simulation model of the railway district implemented in the MATLAB/Simulink software package. Various options of loading the external power supply system are modeled including into account the symmetrical load of the external network and the single-phase load of traction substations. The values of the voltage difference on the traction windings of power transformers of adjacent substations that occurs at different loads, the balancing currents that this difference creates and real power losses in the inter-substation areas are calculated.

Concept Design of the Underwater Manned Seabed Walking Robot

In this paper, a novel concept designed of a multi-legged underwater manned seabed walking robot is presented. The robot will be used in both shallow water current (1–2 m/sec) and deep water up to 500 m. It is powered by an external electric power source through tether cable. It walks on the seabed with six legs, which makes it distinct from conventional screw-propelled underwater robots. It can walk calmly without making the water turbid. Two anterior arms act as manipulators. All leg joints and manipulators are controlled by Brushless Direct Current Motors. Motivation for this concept comes from soldier crab that walk mostly forward and has an egg-shaped body. It is operated by a pilot sitting in a pressurized cabin, and promptly control operations of the robot and manipulator. Preliminary design of the pressurized cabin, using an empirical formula, “ASME PVHO-1 2007” standard, and validation was carried out through ANSYS Workbench. Hydrodynamic forces acting on the robot body and legs are utilized to withstand the water current and external forces to adjust legs and body posture for stability. Buoyancy rules are employed to control its rising and diving motion. All key technologies employed in the development of the robot and their approaching methods are explained. It will provide a safe operation space for humans in underwater operations.

An Unpowered Flexible Lower Limb Exoskeleton: Walking Assisting and Energy Harvesting

Powered exoskeletons are used to assist human walking, but it is inconvenient for a user to carry a bulky energy-supply system. During walking, human lower limbs accelerate and decelerate alternatively, during which period the human body does positive and negative work, respectively. Therefore, if the negative work performed during deceleration can be harnessed using some assisting device to then assist the acceleration movement of the lower limb, the total metabolic cost of the human body during walking can be reduced. In this work, an unpowered flexible lower limb exoskeleton is proposed; it is worn in parallel to the lower limbs to assist human walking without consuming external electrical power. The flexible exoskeleton imitates the physiological structure of a human lower limb, consisting of elastic and damping components. When worn on the lower limb, the exoskeleton can partly replace the function of the lower limb muscles, which can scavenge kinetic energy during lower limb deceleration to assist the acceleration movement, so that the biomechanical power consumption can be reduced during walking. In addition to the walking assistance, the generator in the exoskeleton, serving as a damping component, can harvest kinetic energy to produce electricity for powering wearable electronics. A prototype of the flexible exoskeleton was developed, and experiments were conducted to validate the effectiveness. The experiments showed that the lower limb exoskeleton could reduce the metabolic cost by 3.12% at the walking speed of 4.5 km/h, and a maximum electrical power of 6.47 W was generated at the walking speed of 5.1 km/h.

Computational Fluid Dynamics Modeling of a Direct Solar Driven Sulfuric Acid Decomposition Reactor

A hydrogen economy requires primary sources to provide the power required to produce hydrogen from water, fossil fuels, biomass or similar compounds. Water-splitting processes are particularly attractive, since water is abundant around the planet, the unique products from water splitting are hydrogen and oxygen and a variety of primary energy sources can be used to produce the hydrogen. External electric power can be used to produce hydrogen by conventional water electrolysis [1], but it firstly requires the production of electricity to realize the electrochemical splitting of the water molecule. A more efficient and more cost-effective approach is to use thermal power to drive a thermochemical water splitting process. Such cycles break the hydrogen-oxygen bounds through a series of heat-driven chemical reactions, with recirculation of intermediate substances of different type. By this approach the external heat which drives the chemical reactions is converted into chemical energy of the hydrogen produced from water splitting. Among the various water splitting processes, the sulfur-based cycles and in particular the thermo-electrochemical Hybrid Sulfur (HyS) is one of the most appealing cycles. This process has only fluid reactants and is comprised of only two global reaction steps: a low temperature electrochemical exothermic section, operating at temperatures on the order of 100 °C, and a high temperature thermal section operating at max temperatures of about 800 °C. In the electrochemical section SO2 and H2O are combined together to produce electrochemically H2 at the electrolyzer cathode and H2SO4 at the electrolyzer anode. Sulfuric acid is recycled inside the plant, concentrated and decomposed, in the high temperature thermal section, into SO2, O2 and H2O. Oxygen is then separated from SO2 and water and extracted as byproduct of the process. Solar driven HyS process is being studied by the Greenway Energy and the University of South Carolina within the DOE HydroGEN program (part of the DOE Energy Material Network initiative) [2], partnering with the Idaho National Laboratory, the Savannah River National Laboratory and the National Renewable Energy Laboratory. The project focuses on the high temperature sulfuric acid thermal decomposition section, developing new optimized catalyst formulations (i.e. achieving higher activity, lower performance degradation and lower costs), to be integrated in novel solar reactor systems. A new bimetallic catalyst formulation has been developed and synthesized, based on novel composition and support. Compared with the current state of the art sulfuric acid decomposition catalysts, developed by Idaho National Laboratory during the DOE Nuclear Hydrogen Initiative [3], the proposed catalyst shows the potential for higher SO3 conversion yields and very limited sintering effects. Test results, under sulfuric acid environment and operating temperatures on the order of 800 °C, will be shown and discussed. The new catalyst will be placed in a novel solar reactor, being developed within the HydroGEN project. The proposed concept is based on a solar cavity receiver system, realizing the sulfuric acid decomposition and internal heat recovery in a single unit, directly heated by the incident solar radiation. This system, along with the actual H2SO4 decomposition into SO2, allows: (1) efficient internal heat recovery from the decomposition products and (2) connections with the metallic interfaced HyS equipment (e.g. tubing, valves etc) at low temperatures. A novel reactive computational fluid dynamic (CFD) model is presented, integrating mass, energy and momentum balance equations. A new kinetics expression has also been developed to model the behavior of the novel catalytic formulation. The model has been developed for both the high temperature catalytic decomposition process and for the vaporization/condensation of the sulfur mixture process. A novel two-phase model has been developed with the properties of the mixtures (SO2, SO3, H2O, H2SO4, O2) extracted from process models and integrated in the CFD code using numerical modeling approximations. Results are presented and discussed.

Proposal of InGaAs/InAlAs multiple quantum well Mach–Zehnder modulator integrated with array of planar antennas

We propose an InGaAs/InAlAs multiple quantum well (MQW) Mach–Zehnder modulator integrated with an array of gap-embedded planar antennas for 60 GHz band radio-over-fiber system. The modulator enables us to directly convert from wireless millimeter-wave (MMW) signals to light-wave signals without any connection cables. A newly designed MQW for the modulator exhibits a large refractive index change at low electric field owing to its unique quantum confined Stark effect, which can achieve push-pull driving in modulation without any external electrical power supply. In addition, by introducing a PIN structure to waveguides, an electric field induced in the antena gap can be applied to a core layer of the waveguide efficiently under the irradiation of MMW signals. The modulator with a 2-element array planar antenna can be driven under an MMW power density of 98 W m−2. We theoretically discuss designs and characteristics of the MQW, planar antenna, and modulator.