Regenerative System Research Articles

Damping force and energy recovery analysis of regenerative hydraulic electric suspension system under road excitation: modelling and numerical simulation.

The regenerative hydraulic electric suspension (RHES) is a new type of energy regeneration damper system based on the principle of vibration energy harvesting. This system can recover the vibration energy of suspension dissipated in the form of thermal energy when vehicle travels on the road. In previous studies about RHES system, the vehicle suspension displacement is defined as varieties of periodic waves, such as sinusoidal and so on. The energy harvesting performance of damper system can be explained and evaluated to some extent, but the influence of the actual excitation condition of the road is not fully considered when studying the RHES. This paper builds models of road profiles, quarter car and power regeneration based on the proposed RHES system. Furthermore, the change laws of performance with the varies of road class, motor displacement, accumulator capacity and electrical load are summarized and the corresponding optimization suggestions are proposed, which realize the prediction and evaluation of RHES system performance under the excitation of different road profiles. Simulation suggests that this system can recover 100-400 W of power under road excitation. The findings of system analysis indicate that the component design can satisfy the damping characteristics and power performance required for specific application. The results also show that adjusting the electrical load and accumulator capacity is highly beneficial for controlling suspension behaviours, improving system reliability and increasing power regeneration.

Taking into account the efficiency of turbine plant flow path compartments in design calculations of their energy characteristics

Development of regulatory energy characteristics of TPP equipment is a mandatory and resource-intensive proce-dure. A mathematical model of the turbine plant (the turbine plant itself and its regenerative feed water heating system) was developed earlier based on the matrix formalization of calculations of the energy and mass exchange installations. The analysis of the modeling results has shown that the model adequately de-scribes the real characteristics of a turbine plant only at low bleeding load. At higher load, the accuracy of description is much lower and the model cannot be used for practical analysis of real equipment. All this means that the turbine model needs to be refined by introducing stage-dependent efficiency indicators for more accurate determination of the equipment energy characteristics and, based on them, developing of computer aided methods for optimizing regimes of technological systems and sub-systems of thermal power plants. Methods of mathematical programming were used to investigate the multi-flow heat and mass exchange systems and sub-systems of thermal power plants on the basis of heat and mass balance equations. The energy characteristics and efficiency indicators of TPP equipment were determined in accordance with the existing normative approach. The turbine plant model has been refined by the matrix formalization method by introducing stage-dependent efficiency indicators. Model solutions have been obtained and analysed in order to calculate energy characteristics of the combined cycle turbine plant. The calculaiton results have been compared with the energy characteristics of a turbine unit in operation. It has been shown that the proposed approach is reliable and reasonable. The obtained results can be used for increasing the validity degree of equipment energy characteristics calculation, creating computer simulators and software tools for optimizing modes of technological systems and subsystems of heat power plants.

Generation of femto-laser induced micro shock wave and its measurement for regenerative medical system

Generation of femto-laser induced micro shock wave and its measurement for regenerative medical system

A standardized rat burr hole defect model to study maxillofacial bone regeneration

With high incidence rate and unique regeneration features, maxillofacial burr hole bone defects require a specially designed bone defect animal model for the evaluation of related bone regenerative approaches. Although some burr hole defect models have been developed in long bones or calvarial bones, the mandible has unique tissue development origins and regenerative environments. This suggests that the defect model should be prepared in the maxillofacial bone area. After dissecting the anatomic structures of rat mandibles, we found that creating defects in the anterior tooth area avoided damaging important organs and improved animal welfare. Furthermore, the available bone volume at the anterior tooth area was superior to that of the posterior tooth and ascending ramus areas. We then managed to standardize the model by controlling the age, weight and gender of the animal, creating standardized measurement instruments and reducing the variations derived from various operators. We also succeeded in deterring the self-rehabilitation of the proposed model by increasing the defect size. The 6 × 2 mm and 8 × 2 mm defects were found to meet the requirements of bone regenerative studies. This study provided a step-by-step standardized burr hole bone defect model with minimal tissue damage in small animals. The evaluations resulting from this model testify to the in vitro outcomes of the proposed regenerative approaches and provide preliminary screening data for further large animal and clinical trials. Therefore, the inclusion of this model may optimize the evaluation systems for maxillofacial burr hole bone defect regenerative approaches. Statement of SignificanceUnremitting effort has been devoted to the development of bone regenerative materials to restore maxillofacial burr hole bone defects because of their high clinical incidence rate. In the development of these biomaterials, in vivo testing in small animals is necessary to evaluate the effects of candidate biomaterials. However, little has been done to develop such defect models in small animals. In this study, we developed a standardized rat mandible burr hole bone defect model with minimal injury to the animals. A detailed description and supplementary video were provided to guide the preparation. The development of this model optimizes the maxillofacial bone regenerative approach evaluation system.

Control Strategy for the Energy Optimization of Hybrid Regenerative Braking Energy Utilization System Used in Electric Locomotive

The braking process of electric locomotive is featured by short braking time, large braking power, large voltage fluctuations, etc. Faced with the problem of low utilization of braking energy and high investment cost of the current regenerative braking energy utilization systems, an energy optimization scheme is proposed in this paper by combining the control strategy for energy storage and energy optimization. The regenerative braking energy utilization system is modeled by analyzing the braking process of electric locomotive. The instantaneous absorption reference powers of the energy storage subsystem and energy feedback subsystem in braking process are obtained according to the established mathematical model. The energy storage subsystem uses super capacitor and adopts a power-current dual closed-loop control strategy. The energy feedback subsystem adopts a voltage-current dual closed-loop control strategy. Through the tracking control of the instantaneous power, a reasonable distribution of the regenerative braking energy is achieved between the energy feedback subsystem and energy storage subsystem, thereby increasing the utilization efficiency of the two subsystems. Finally, the performance of the proposed scheme is verified by simulation and experiment.

Cooling water mass flow optimization for indirect dry cooling system of thermal power unit under variable output load

The analysis was conducted for the optimal operation under off-design conditions of the indirect dry cooling thermal power generating unit. The numerical model of natural draft dry cooling tower (NDDCT), as well as the off-design performance model of whole thermal system of a supercritical power generating unit, including that of turbine, condenser and regenerative system, were combined together. An iterative procedure was adopted so that the operating parameters of dry cooling system with cooling water mass flow rate and output power load were obtained. The total coal consumption of power generation, which considered both effects of back pressure of turbine and power consumption of circulating pump, was taken as the optimization object. The results indicated that the pump power consumption increased, while the back pressure decreased with circulating cooling water mass flow rate. There was the optimum cooling water mass flow rate corresponding to the lowest coal consumption of power generation. For the objective power generating unit, 4.83 ton standard coal per hour at most can be saved by adjusting the circulating cooling water flow rate to the optimum value.

Active Control of Regenerative Brake for Electric Vehicles

Looking at new trends in global policies, electric vehicles (EVs) are expected to increasingly replace gasoline vehicles in the near future. For current electric vehicles, the motor current driving system and the braking control system are two independent issues with separate design. If a self-induced back-EMF voltage from the motor is a short circuit, then short-circuiting the motor will result in braking. The higher the speed of the motor, the stronger the braking effect. However, the effect is deficient quickly once the motor speed drops quickly. Traditional kinetic brake (i.e., in the short circuit is replaced by a resistor) and dynamic brake (the short circuit brake is replaced by a capacitor) rely on the back EMF alone to generate braking toque. The braking torque generated is usually not enough to effectively stop a rotating motor in a short period of time. In this research task, an integrated driving and braking control system is considered for EVs with an active regenerative braking control system where back electromagnetic field (EMF), controlled by the pulse-width modulation (PWM) technique, is used to charge a pump capacitor. The capacitor is used as an extra energy source cascaded with the battery as a charge pump. This is used to boost braking torque to stop the rotating motor in an efficient way while braking. Experiments are conducted to verify the proposed design. Compared to the traditional kinetic brake and dynamic brake, the proposed active regenerative control system shows better braking performance in terms of stopping time and stopping distance.

Regenerative semi-active vortex-induced vibration control of elastic circular cylinder considering the effects of capacitance value and control parameters

A regenerative semi-active control system based on self-tuning Fuzzy proportional-derivative (PD) control strategy is applied to suppress the vortex-induced vibrations (VIV) of an elastically supported circular cylinder at low Reynolds numbers. Of particular interest was the effect of control parameter and capacitance on the VIV reduction and energy regeneration capabilities of adopted semi-active control system. A collaborative simulation which couples a Fuzzy PD controller along with the adjustable electromagnetic (EM) damper and corresponding energy harvesting circuit (implemented in MATLAB/Simulink) to the computational fluid dynamic (CFD) plant model (implemented in Fluent) is employed. It appears that the cylinder displacement amplitude, capacitor charging speed, and maximum stored electrical energy vary with the controller parameters and capacitance value. It is shown that the selected regenerative semiactive control system can store maximum energy in a capacitor in prescribed limiting time, along with the highest level of cylinder oscillation reduction which is the primary goal of current work.

Study on the Control Strategy of Regenerative Braking for the Hybrid Electric Vehicle under Typical Braking Condition

In this paper, a parallel regenerative braking control strategy and fuzzy PID control algorithm for series-parallel hybrid electric vehicles are developed based on the analysis of the existing regenerative braking control strategy and control algorithm, indicating a reasonable and effective regenerative braking control strategy for series-parallel hybrid vehicles. The simulation model of regenerative braking control system is established by MATLAB/Simulink software, and the parametric model of each component of regenerative braking system is established by AVL CRUISE software. The joint simulation under the typical braking condition of 30, 60 and 90km/h under the moderate braking intensity (z = 0.3) is conducted. The results show that the braking energy recovery rate is the largest (reaching 24%) and the energy recovery effect is obvious in the initial speed of braking of 60km/h.

Mild temperature hydrothermal oxidation of anaerobic fermentation filtrate for carbon and nitrogen recovery in a regenerative life support system

Hydrothermal oxidation of fermentation filtrate was conducted in a tubular reactor to recover carbon (as CO2) and nitrogen (as NH4+ or NO3−) at mild temperature destined for use in a regenerative life support system. Temperature, residence time (tR), and the oxidizer equivalence ratio (OER) were the experimental variables in the oxidation tests. The highest carbon recovery achieved was 68.2%, with 80.1% of the total nitrogen being retained in the form of NH4+ or NO3− at 380 ℃, tR = 48 s and OER = 4.0. The effect of temperature, residence time and OER on carbon and nitrogen distribution were discussed. Moreover, a first-order reaction rate was applied by means of regression analysis to estimate the carbon conversion rates. Prolonging the residence time at 380 ℃ with OER = 3.0 is proposed to be a promising modification to increase both carbon and nitrogen recovery from the filtrate.

Modeling and Control of a Diesel Engine With Regenerative Hydraulic-Assisted Turbocharger

Diesel engines are of great challenges due to stringent emission and fuel economy requirements. Compared with the conventional turbocharger system, regenerative assisted system provides additional degrees-of-freedom for turbocharger speed control. Hence, it significantly improves control capability for exhaust-gas-recirculation (EGR) and boost pressure. This paper focuses on modeling and control of a diesel engine air-path system equipped with an EGR subsystem and a variable geometry turbocharger (VGT) coupled with a regenerative hydraulic-assisted turbocharger (RHAT). The challenges lie in the inherent coupling among EGR, turbocharger performance, and high nonlinearity of the engine air-path system. A control-oriented nonlinear RHAT system model is developed; and a linear quadratic (LQ) control design approach is proposed in this paper to regulate the EGR mass flow rate and boost pressure simultaneously and the resulting closed-loop system performance can be tuned by properly selecting the LQ control weighting matrices. Multiple LQ controllers with integral action are designed based on the linearized system models over a gridded engine operational map and the final gain-scheduling controller for a given engine operational condition is obtained by interpreting the neighboring LQ controllers. The gain-scheduling LQ controllers for both traditional VGT-EGR and VGT-EGR-RHAT systems are compared with the in-house baseline controller, consisting of two single-input and single-output (SISO) controllers, against the nonlinear plant. The simulation results show that the designed multi-input and multi-output LQ gain-scheduling controller is able to manage the performance trade-offs between EGR mass flow and boost pressure tracking. With the additional assisted and regenerative power available on the turbocharger shaft for the RHAT system, engine transient boost pressure performance can be significantly improved without compromising the EGR tracking performance, compared with the baseline control.

Continuous power output criteria and optimum operation strategies of an upgraded thermally regenerative electrochemical cycles system

In order to utilize the low-grade thermal energy efficiently, a more realistic model of thermally regenerative electrochemical cycles system with continuous power output is proposed in which the heat transfer irreversibility, external heat leakage and non-ideal regeneration losses are taken into account. Besides, the symmetry of cells, which is necessary for a practical thermally regenerative electrochemical cycles system operated at steady state, is considered. Analytic expressions for the efficiency and power output of the system are derived. The design and operation criteria of the system for achieving continuous power output are obtained. The general performance characteristics and the optimally operating regions of several parameters are reported. The influences of the external heat leakage on the system performance and the upper and lower bounds of efficiency at maximum power output at different situations are evaluated and discussed.

A novel structured nanosized CaO on nanosilica surface as an alternative solid reducing agent for hydrogen fluoride removal from industrial waste water

In the semiconductor industry, perfluorinated compound removal is a major concern owing to the formation of highly toxic and hazardous hydrogen fluoride (HF) as a by-product. Calcium oxide (CaO) can be considered a promising material for HF sorption reaction process. However, the easier reaction between CaO and H2O results in the formation of Ca(OH)2, which ultimately limits the usefulness of CaO. The objective of the research work is preparation of CaO nanoparticles on hydrophobic silica (SiO2) to use as a alternative solid reducing catalyst for efficient HF removal process. High-resolution transmission electron microscopy micrographs confirmed that the as-prepared CaO particles are <5 nm in size and the smaller sized CaO nanoparticles are homogeneously anchored on the entire surface of ∼100 nm spherical SiO2 nanoparticles. The reaction-enhanced regenerative catalytic system (RE-RCS) was used to measure the HF removal efficiency. HF is removed more efficiently using CaO on SiO2 than using CaO alone. At the outlet of the RE-RCS, the obtained HF concentrations are 2811.4 and 2166.1 ppm after a 3 h reaction using CaO and CaO on SiO2 as the sorbent, respectively. The lower concentration of HF at the outlet of the system using CaO on SiO2 indicates that HF sorption is remarkably enhanced using CaO on SiO2 inside the RE-RCS. In addition, the presence of a hydrophobic region in the catalyst sorbent prevents the reaction between CaO and water, which leads to avoiding the formation of Ca(OH)2. These phenomena significantly enhance the HF removal efficiency and CaF2 formation process.

An innovative self-adaptive method for improving heat sink utilization efficiency of hydrocarbon fuel in regenerative thermal protection system of combined cycle engine

A highly efficient regenerative thermal management system of combined cycle engine can realize the energy balance between the high power requirement of the vehicle and severe thermal environment of the engine, therefore, the heat sink utilization efficiency of supercritical hydrocarbon fuel in regenerative thermal protection system needs to be improved. In this paper, an innovative self-adaptive method using mini-structure to improve the mass flow rate distribution in thermal protection system with parallel cooling channels is proposed based on the engine’s extremely nonuniform thermal load. The effectiveness of this novel method is numerically studied, and the effects of adaptive mini-structure’s location and number are also investigated. The results demonstrate that the existence of adaptive mini-structure improves the mass flow uniformity between parallel channels by forming a jet flow through the mini-structure and the backward recirculation region created by the jet flow, these two characteristics adaptively change the flow area in the low heat flux channel and create a virtual throat after the adaptive mini-structure which decreases the mass flow rate in low heat flux channel and achieves better uniformity. Among the various cases in the present paper, the location with X = 200 mm improves the uniformity of parallel channels with 10% deviation of heat flux from 26.6% to 78.8%, and for the 20% deviation of heat flux, the uniformity is improved from 23.5% to 63.4%.

Modular Regenerative Emulation System for DC–DC Converters in Hybrid Fuel Cell Vehicle Applications

This paper proposes a novel emulation system for emulating the power system in the fuel cell electric vehicle. The major purpose of the proposed emulation system is to test the dc-dc converter between the fuel cell and high-voltage powertrain. The bidirectional buck-boost type dc-dc converter is applied in the emulation system as the basic elements. A modularized approach is presented for easily scaling up and down the power level of the emulation system. Meanwhile, an energy loop structure is implemented in the proposed emulation system for power capability boosting purpose. Because of the proposed energy loop configuration, the emulation system offers long-term running capability with high power rating without the grid connection. A neutral current control mechanism is applied in this paper to further enhance the long-term testing capability as well as extending the lifespan for the battery packages. The simulation studies are proposed in this paper to validate the control mechanisms of the emulation system. A 10 kW hardware prototype has been built and the experimental tests are presented for validating the functionalities of the emulation system.

A quantitative analysis of 3D-cell distribution in regenerative muscle-skeletal system with synchrotron X-ray computed microtomography

One of the greatest enigmas of modern biology is how the geometry of muscular and skeletal structures are created and how their development is controlled during growth and regeneration. Scaling and shaping of vertebrate muscles and skeletal elements has always been enigmatic and required an advanced technical level in order to analyse the cell distribution in 3D. In this work, synchrotron X-ray computed microtomography (µCT) and chemical contrasting has been exploited for a quantitative analysis of the 3D-cell distribution in tissues of a developing salamander (Pleurodeles waltl) limb – a key model organism for vertebrate regeneration studies. We mapped the limb muscles, their size and shape as well as the number and density of cells within the extracellular matrix of the developing cartilage. By using tomographic approach, we explored the polarity of the cells in 3D, in relation to the structure of developing joints. We found that the polarity of chondrocytes correlates with the planes in joint surfaces and also changes along the length of the cartilaginous elements. Our approach generates data for the precise computer simulations of muscle-skeletal regeneration using cell dynamics models, which is necessary for the understanding how anisotropic growth results in the precise shapes of skeletal structures.

Injectable in Situ Shape-Forming Osteogenic Nanocomposite Hydrogel for Regenerating Irregular Bone Defects.

The in situ forming injectable hydrogels are appealing for irregular bone defects because of the ease of administration and the addition of ceramics, molecules, and proteins into the hydrogel. We have developed in situ shape-forming hydrogel using oxidized alginate and gelatin as the hydrogel matrix. Whitlockite bioceramic nanoparticles (WH NPs) were incorporated, as they provide enhanced osteogenic stimulation compared to hydroxyapatite via providing higher local ion concentration. The drug simvastatin was also incorporated into the hydrogel system, as it increases the expression of BMP-2 thereby provide environment for bone regeneration. The presence of both WH nanoparticles and simvastatin would enhance bone regeneration potential. The whitlockite nanoparticles (80 ± 8 nm) were synthesized by precipitation method and were characterized. The nanocomposite hydrogel system was characterized by SEM, FTIR and rheologically. The gelation time of the in situ nanocomposite hydrogel was determined by rheological analysis as 28 s, whereas hydrogel alone showed 132 s. Addition of WH NPs not only shortened the gelation time but also increased the gel strength. The in vitro release of simvastatin from the nanocomposite hydrogel showed a release over a period of 28 days. The alkaline phosphatase (ALP) level also showed a significant increase. RUNX2 and BMP2 expressions showed that nanocomposite hydrogel enhanced the osteogenic differentiation. In vivo bone regeneration studies in mice cranial defect studies showed nanocomposite hydrogel was effective in regenerating the bone compared to controls. Thus, the simvastatin-incorporated oxidized alginate-gelatin/WH NPs hydrogel system has the potential to be used as a repairing and regenerative system in cranial bone defects.

Plastic pollution and potential solutions.

Plastic pollution and potential solutions.

Development and Control of Active Suspension System with Energy Regeneration Implementation Scheme

Active suspension systems have been used in the recent years as they provide better ride comfort, road handling and safety. The effect of vehicle vibration caused by road roughness is effectively reduced by active suspension system which plays an important role in improving the vehicle performance indices. The application of active suspension system is limited because it consumes high amount of energy. From the point of energy saving, a regenerative active suspension system is designed and its working principle with two modes switched in different conditions was implemented. In this implementation scheme, operating electric circuits are designed based on different working status of the actuator and power source. In the first stage an electromotor mode in which an active suspension system uses a linear electric actuator controlled by constrained PID controller. In the generator mode, under certain circumstances using linear motor as actuators enables to transform mechanical energy of the car vibrations to electrical energy and accumulated to charge the energy-storage capacitor and fed back into the power source when needed.

A novel indirect-drive regenerative shock absorber for energy harvesting and comparison with a conventional direct-drive regenerative shock absorber

Energy harvesting from the shock absorbers is now becoming an important technology in developing the electrical vehicles. Compared with other kinetic energy sources such as engine and brake systems which are continuous or periodic, the shock absorber is subjected to the fluctuated linear motion with relatively small displacement. This paper presents a novel indirect-drive regenerative shock absorber system that utilizes an arm-teeth mechanism to achieve linear to rotary motion conversion and to amplify its input speed for increasing energy harvesting output. The fluctuation of road randomness can be smoothed out through the flywheel. The proposed design has the advance of achieving all the targets with less number of components. Two prototypes of the direct-drive and indirect-drive regenerative shock absorbers have been built. The simulation models have been developed and validated by experimental results. The performance of this new indirect-drive system has been compared, through experimental testing and analytical modeling, with that of a conventional direct-drive system of the same generator configuration. The results show that this indirect-drive system can achieve greater peak power output and broader frequency bandwidth than the conventional direct-drive system. The indirect-drive system also presents a better ride comfort up to 13 Hz. Using Monte Carlo simulation, a parameter sensitivity analysis of both the indirect-drive and direct-drive systems has been carried out to compare their energy harvesting performances in terms of increasing the peak power output and broadening the energy harvesting frequency bandwidth. In both the systems, choosing the right tyre stiffness and electromechanical coupling constant is beneficial to increasing the peak power output ratio and the harvesting frequency bandwidth. The right choice of the gear ratio can further improve the peak power output ratio of the indirect-drive system. The variation of these parameters will allow for possibility of achieving higher power output when vehicle is driven on random road surfaces.