Idle Conditions Research Articles

The Impact of Power Quality on VFD Application in Motor Fan Dust Collector

The technology to control the motor speed according to load requirements is variable frequency drive (VFD). The motor fan dust collector operates using a VFD to reduce the speed during idle smelting conditions. In addition to energy efficiency, the power quality of the electrical energy system is important to consider. Nonlinear loads from VFDs cause harmonics in the industry that affect electrical power. Power quality measurement and analysis to determine the harmonic and unbalance values of voltage and current are important for improving power quality. This paper discusses the effect of VFDs on power quality, as a real case study, data from existing VFDs in the steel industry are taken to analyze power quality. A large current harmonic of 45% occurs when the VFD decrease the motor speed during idle smelting operation and drops to 5% when the motor speed returns to full speed during smelting operation on. The average maximum current unbalance value is 10.8% and the voltage unbalance is 0.36%, which is still below the standard maximum limit whether the motor is at full or low speed.

Vehicle Intermittent Idle Shake: Mechanism and Influence Factors

This paper studies the mechanism and influencing factors of the intermittent shaking of a vehicle in idle conditions and explores methods to suppress the idle shake of a vehicle. A full vehicle model including an engine crank-link mechanism is established. Taking a vehicle with intermittent idle shake as an example, the causes of the intermittent idle shake of the vehicle are investigated. The study shows that the intermittent idle shake of the vehicle is caused by the beat vibration, which is due to the unbalance of the crankshaft of the engine and the rotating turbine of the torque converter, and the near rotational speeds of these two rotating parts. In addition, a parametric model of cylinder pressure is presented. The effects of abnormal cylinder pressure (abnormal amplitude, abnormal ignition phase and abnormal fluctuating rate) on the idle shake are analyzed respectively. It is found that changes of combustion pressure in cylinder may also cause intermittent idle shake of the vehicle. Finally, the measures to attenuate the intermittent idle shake of vehicle are presented.

Calibration and Experimental Study of a Self-Developed Particle-Number Measurement Instrument

To accurately evaluate the size and distribution characteristics of the emission particles exhausted from in-use motor vehicle engines, we independently developed a condensation particle counter (CPC) known as BHCPC. It was calibrated by conducting the calibration procedures stated in the International Standard ISO 27981. After calibration, we conducted on-site measurements and offline sampling analysis of soot particles exhausted from different engines at a motor vehicle inspection center. The calibration results show that the detection efficiency is 90% when the particle diameter is 20.6 nm and the startup response time of the instrument is 3.53 s. The experiment results show that the self-developed BHCPC demonstrates good consistency in measuring particle-number concentration (PNC) in motor vehicle exhaust, with significant count fluctuations only occurring when PNC is higher than 25,000 P/cc. Under idle conditions, motor vehicles compliant with China VI emission regulations exhibit markedly lower exhaust emission PNC compared to those adhering to China IV emission regulations. Moreover, the results obtained from the offline electron microscope analysis show that fuel content in particle samples significantly decreases as engine speed increases, and a similar variation was also found in particle size. The micro-characteristics of the particle can give potential support to the combustion diagnostics.

Emission Characteristics of Particle Number from Conventional Gasoline and Hybrid Vehicles

Vehicular particle number (PN) emissions have garnered increasing attention. In this study, nine light-duty vehicles, involving conventional internal combustion engine gasoline vehicles (ICEVs) and hybrid electric vehicles (HEVs), underwent testing on a chassis dynamometer to elucidate key factors influencing PN emissions. We found that with more stringent emission standards Gasoline Direct Injection (GDI) vehicles exhibited a reduction in PN emission factors. Higher PN emissions for GDI vehicles than vehicles with Multi-Port Fuel Injection (PFI) engines were observed; meanwhile, HEV showed lower PN emissions than ICEVs. PN emissions for cold start consistently exceeded warm start across vehicles with different standards and technologies. Notably, China VI HEV exhibited a substantial 19.2-fold increase in PN emissions for cold start compared to warm start. Analysis on a second-by-second basis revealed that cold-start emissions concentrated in low speed, while warm-start emissions were prominent in extra-high speed. Concerning vehicle specific power (VSP), the lowest mean PN emission rate occurred during idle conditions. PN emissions for China IV-VI ICEVs with GDI engines would increase with the increasing VSP, whereas China VI ICEVs with PFI engines and HEV with GDI engines showed varied patterns of PN emissions, especially under cold start. Our study would further facilitate formulating effective strategies for vehicular PN emissions.

LES Modeling of the DLR Generic Single-Cup Spray Combustor: Validation and the Impact of Combustion Chemistry

AbstractTurbulent spray combustion in a generic kerosene-fueled single-cup combustor at typical idle and cruise conditions of an aeroengine are studied with Large Eddy Simulations (LES) using Lagrangian spray and finite-rate chemistry combustion modeling. Three reaction mechanisms of varying complexity are used to model the combustion chemistry. The choice of turbulence-chemistry interaction model is shown to affect the results significantly. The impact of the choice of chemical reaction mechanism and the difference in operating conditions are gauged in terms of time-averaged flow, spray, and combustion characteristics as well as unsteady behavior. Good agreement between LES predictions and experimental results are generally observed but with a notable dependence on the choice of chemical reaction mechanism. The mechanism specifically targeting Jet A displays the best agreement. The choice of reaction mechanism is further demonstrated to influence the flow and thermoacoustics in the combustor, resulting in different thermoacoustic modes dominating. The spray cone is found to be too narrow and thin, an inaccuracy which could be remedied by either making the injection method more empirical or by introducing additional models.

Enhancement of energy, exergy and soot characteristics with the utilization of MEK in diesel engine

This study investigated the effects of methyl ethyl ketone (MEK) on a diesel engine’s energy, exergy and emissions. The evaporation of a bi-component droplet of MEK and heptane was modeled. Furthermore, the soot morphology and nanostructure were quantified. Different blends were examined at other engine conditions. Running the engine under idle conditions and optimum speed considerably reduced engine emissions. MEK noticeably decreased the maximum reachable load of the diesel engine. Both specific fuel consumption and thermal efficiency increased with MEK. The exergetic efficiency increased while the fuel exergy decreased at the same work exergy. The effects of MEK on combustion characteristics were insignificant. However, a stronger premixed combustion phase was obtained where MEK evaporated first and caused a slightly longer droplet lifetime. Low percentages of MEK reduced CO emissions, while NOx emissions increased consistently with the MEK addition. The engine conditions noticeably influenced the unburned hydrocarbon emissions with MEK. Both smoke opacity and primary particle diameter decreased. The fringe analysis emphasized that MEK decreased fringe length, soot intensity, and alignment, increasing fringe tortuosity and spacing. Clearly, methyl ethyl ketone suppressed soot formation in a diesel engine and decreased its reactivity.Graphical abstract

One year monitoring of an offshore wind turbine: Variability of modal parameters to ambient and operational conditions

This paper presents the variation of identified modal parameters of an offshore wind turbine (OWT) over one year of continuous monitoring. The considered OWT is a Haliade 150–6 MW GE turbine on a jacket substructure at the Block Island Wind Farm in Rhode Island, U.S. The turbine was instrumented with a monitoring system including accelerometers, strain gauges, inclinometers, and a data acquisition system with automatic data transfer to cloud storage. Continuous vibration measurements of the OWT have been collected over one year from April 2021 to April 2022. An automated output-only operational modal identification approach is developed to extract modal parameters of the OWT over this one-year period using windows of 10-min data. The identified modal parameters of the first few vibration modes show variability and correlation with several ambient and operational conditions. It is observed that the identified natural frequencies and damping ratios of the first side-to-side (SS) mode are stable over time and have very small variation, but those of the first fore-aft (FA) mode show significant variability. The second FA/SS modes can only be identified with reasonable accuracy when the turbine is in idle condition. Similar to the first FA/SS modes, the second FA mode has larger variability in frequencies and damping ratios than the second SS mode because of the aerodynamics effects. The system identification results over one full year verify the effectiveness and robustness of the proposed approach for long-term monitoring of this OWT and serve as the reference database.

Low-cost Wireless Lamp Socket and Power Plug for Smart Homes and Its Comparison with Available Commercial Competitors

Smart home manufacturers widely produce Wireless Lamp Socket and Power Plug devices, which offer various features ranging from basic on/off control to more complex functionalities such as monitoring energy consumption, power losses, and harmonics. However, these devices tend to be expensive, as indicated by market surveys. To address this issue, the current study aimed to develop low-cost wireless control nodes for smart homes that operate using relays. The two nodes consisted of lamp socket and power plug built with lowcost electronic components, including a Wi-Fi built-in Microcontroller ESP8266 (Wemos D1 mini model) as the backbone to create ESP-Mesh wireless network and to provide control ports for high/low logic, a relay module, an AC-to-DC converter module, and terminals (E27 screw for lamp socket node and C-type plug for the power plug node). This paper primarily focuses on the hardware aspects. In order to evaluate the effectiveness of the nodes, the following tests are conducted: (1) product demonstration to assess the product functions, (2) power measurement in idle and active conditions, (3) ESP-Mesh connection testing, and (4) RSSI measurement. Functional testing is done using a smartphone with the UPISmartHome version 2.0 Android application, which successfully controlled the nodes wirelessly. In idle conditions, power plug and lamp socket nodes consume 426.36 mWatt and 418.275 mWatt of power, respectively. Further, in active conditions, power plug and lamp socket nodes consume 435.704 mWatt and 440.583 mWatt of power, respectively. RSSI testing results show that both nodes can be controlled within an optimal range of 60 meters (with reference to RSSI below –85 dBm) without the Internet, utilizing the ESP-Mesh feature of ESP8266. This range is deemed reasonable for smart homes of 21, 36, or 45 square meters. Both nodes could be controlled under the ESP-Mesh network that gets build. We also present the comparison with other products of competitors in this paper.

Dynamic Test and Evaluation Analysis of an Advanced Fuel Cell Vehicle

Power performance is one of the key parameters to evaluate the whole vehicle. For fuel cell vehicles, because the energy is composed of electric hybrid mode, its power performance is paid more attention. In this paper, the power performance of an advanced fuel cell vehicle is tested and evaluated comprehensively. First of all, the initial state of the fuel cell vehicle test is defined, and then the typical dynamic conditions such as long idle condition, maximum speed condition and beyond acceleration condition are selected for testing. By analyzing the test results and analyzing the energy distribution under different working conditions, the results show that the power performance of the fuel cell vehicle is excellent, accelerating from 80km/h to 140km/h in only 13.3s. The test results have a certain significance for the research and development of fuel cell vehicles.

Technical modeling challenges for large idling wind turbines

This paper presents comprehensive investigations into idling instability occurring on the IEA 15 MW reference turbine. The systematic studies are carried out by means of Blade Element Momentum (BEM) and free wake vortex (Vortexline) methods. Two state-of-the-art dynamic stall models are tested in the present investigations, namely the Beddoes-Leishman and the IAG dynamic stall models, implemented into a development version of the wind turbine design code Bladed. The studies highlight the importance of unsteady aerodynamic modeling to predict idling instabilities and emphasize the characteristics of each modeling strategy. It is demonstrated that the IAG dynamic stall model predicts a more physically reasonable idling instabilities. Furthermore, Vortexline enables the calculations of the induced velocities even under idling conditions in contrast to BEM. The combination of the Vortexline method and the IAG model is considered to provide the most reasonable turbine response. The studies will be helpful for load engineers to select appropriate modeling strategies and shed some light into future engineering modeling improvements of wind turbines.

Monopile Foundation Stiffness Estimation of an Instrumented Offshore Wind Turbine through Model Updating

Rapid development of offshore wind foundation models has resulted in a large number of built structures with generally underestimated foundation stiffness properties and a need to update and validate both the individual structural models and the underlying foundation design frameworks. This paper outlines a structural health monitoring approach, based on the combination of output only structural health monitoring methods and model updating, to estimate foundation stiffness parameters using field monitored data. Field monitoring data from an offshore wind turbine under idling conditions, over a large monitoring period, are presented and operational modal analysis is applied to estimate the modal parameters. Those are compared to modal properties predicted by finite element models, employing either old (API/DNVGL) or new (PISA) foundation design properties, which are calibrated using geotechnical site investigation data. A new approach to interpret seabed level statically equivalent foundation stiffness, in terms of effective lateral and rotational stiffness against load eccentricity, is presented. Seabed level statically equivalent foundation properties are updated by comparison against the observed modal behaviour and the optimised foundation parameters are presented, demonstrating a close match to the predictions of the PISA method.

Performance analysis of distributed coordination function with early collision detection in In-band Full-duplex wireless networks

In-band Full-duplex (IB-FD) wireless has the potential to double the spectral efficiency offering its innate capability to resolve conventional problems emerge owing to the imperfect medium access control (MAC) in In-band half-duplex (IB-HD) wireless networks. IEEE 802.11 distributed coordination function (DCF), a binary slotted exponential back-off with carrier sense multiple access scheme, has been used extensively in literature as the fundamental contention resolution technique to devise MAC protocols for IB-FD wireless networks. Unlike IB-HD, an IB-FD network can contain two simultaneously active transmission links within a single collision domain. This phenomenon invalidates the applicability of existing IB-HD models of the DCF to compute its performance (i.e., saturation throughput) accurately in IB-FD wireless networks. We have proposed two MAC protocols for two types of network scenarios taking early collision detection capability of an IB-FD wireless transceiver into consideration. This paper also presents a distinct analytical model to quantify the performance of the DCF in the context of IB-FD wireless assuming finite number of stations and idle channel conditions. We have applied the concept of primary–secondary transmission links and, thoroughly derived the probability that a station transmits either as primary or secondary in a randomly chosen time-slot taking secondary transmitter’s back-off counter into account. We have also investigated the effect of inter-station interference free IB-FD link on the performance of the DCF. Our protocol, when applied to network without hidden stations, has obtained the highest throughput gain of 1.59, 1.61, 1.68 while the DCF is configured with CWmin of 16, 32, 64, respectively than IEEE 802.11 basic access scheme. We have observed increased throughput gain with hidden stations, thanks to inter-station interference free transmission region, and achieved 2.12, 2.14, 2.16 times higher throughput, respectively than that of IEEE rts-cts access scheme.

Reducing particulate emissions by using advanced engine oil nanoadditives based on molybdenum disulfide and carbon nanotubes

Nanoadditives can be used to enhance lubricating properties of engine oils. Although many additives have been developed, molybdenum disulfide and carbon nanotubes have attracted significant attention. In this study, we demonstrate that hybrid nanostructures based on these unique materials (MoS2/CNTs) positively affect engine oil lubricating properties. Hybrid nanostructures were produced via wet chemical synthesis in impinging jet reactor. This method is characterized by easy scalability and possible continuous operation, which are crucial in material commercialization. The application of 0.5 wt% suspension exhibited the best results, reducing the friction coefficient at the engine operating temperature by up to 26%. Nanoadditives protected the lubricated parts, causing their wear to be considerably lower than the base oil. The effect of nanoadditives on the quality of exhaust gases was also investigated, which has not yet been researched. The application of the oil with MoS2/CNT reduced the emissions of solid particles in the gasoline engine exhaust gas. The total volume of particles in the exhaust gas was reduced by 91% and 49% under idling and load-running conditions. This research showed that MoS2/CNTs can be successfully used as nanoadditives in engine oils for improving tribological properties, enhancing anti-wear performance, and reducing particle emissions in exhaust gas.

Aero-Engine Preliminary Design Optimization and Operability Studies Supported by a Compressor Mean-Line Design Module

An approach for preliminary aero-engine design, incorporating a mean-line code for the design of axial-flow, multi-stage compressors, is presented. The compressor mean-line code is developed and integrated within a framework for the preliminary design and assessment of aero-engine concepts. It is then combined with modules for compressor map generation, multi-point engine design, steady-state and transient engine off-design performance and aircraft mission analysis. Implementation examples are presented, demonstrating the determination of the optimal combination of compressor and engine design parameters for achieving minimum fuel burn over a specific aircraft mission, while obeying constraints that guarantee operability over the entire flight envelope. Constraints related to compressor stability during transient maneuvers between idle and static take-off conditions and engine temperature limits at maximum take-off are respected by the final design. The results demonstrate the potential for design trade-offs between engine performance at the aircraft mission level and compressor aerodynamic stability.

A novel dual-nozzle ejector for enhancement of hydrogen recirculation applied to proton exchange membrane fuel cell system

The ejector enables hydrogen recycling, offering advantages of non-parasitic power and low noise. However, traditional ejector falls short in operating the proton exchange membrane fuel cell(PEMFC) system across various operating points efficiently. To overcome this limitation, a novel dual-nozzle ejector is proposed for optimal hydrogen recirculation at different power. The computational fluid dynamics(CFD) method is utilized to simulate and verified by experimental results. Firstly, nozzle structure is optimized to address unstable flow phenomena such as vortex generated at nozzle outlet. Subsequently, analysis of flow field is conducted by different structure under idle and full-load conditions. Results show that initial optimization resulted in an 18.8% increase of recirculation ratio under idle condition. Overall performance of constant-section mixing chamber diameter (Dm) of 6.5 is optimal within the output current range from 31.1A to 559.8A. Under idle condition, highest recirculation ratio is achieved when constant-section mixing chamber length is 4Dm, nozzle exit position is at 1.1Dm, diffuser chamber angle is 3°. While under full-load condition, the energy loss caused by wall flow resistance is more significant. By exploring the mechanism of different structure changes under two conditions, particularly under idle condition, this study provides a reference for optimization of ejectors in the future.

Biological postural oscillations during facial expression of pain in virtual characters modulate early and late ERP components associated with empathy: A pilot study

There is a surge in the use of virtual characters in cognitive sciences. However, their behavioural realism remains to be perfected in order to trigger more spontaneous and socially expected reactions in users. It was recently shown that biological postural oscillations (idle motion) were a key ingredient to enhance the empathic response to its facial pain expression. The objective of this study was to examine, using electroencephalography, whether idle motion would modulate the neural response associated with empathy when viewing a pain-expressing virtual character. Twenty healthy young adults were shown video clips of a virtual character displaying a facial expression of pain while its body was either static (Still condition) or animated with pre-recorded human postural oscillations (Idle condition). Participants rated the virtual human's facial expression of pain as significantly more intense in the Idle condition compared to the Still condition. Both the early (N2–N3) and the late (rLPP) event-related potentials (ERPs) associated with distinct dimensions of empathy, affective resonance and perspective-taking, respectively, were greater in the Idle condition compared to the Still condition. These findings confirm the potential of idle motion to increase empathy for pain expressed by virtual characters. They are discussed in line with contemporary empathy models in relation to human-machine interactions.

Effects of noise intensity on concentration levels of chainsaw operators and harvesting workers in industrial forest plantation, North Sumatera, Indonesia.

Noise has the potential to affect the comfort and health of workers. The objective of this research was to determines the effects of noise on the concentration levels of both chainsaw operators and harvesting workers in industrial forest plantation, North Sumatra, Indonesia. This experimental study included 20 respondents which consisted of 10 chainsaw operators/helpers and 10 harvesting workers. All respondents were exposed to the sound of a chainsaw in three different conditions (idle, half gas and racing conditions) with and without personal protective equipment (PPEs: earmuffs, ear plugs and without PPE). The sound intensity produced by the chainsaw and the noise received by the respondents were measured using a sound level meter. Respondents' perception toward noise was recorded using a Likert scale. Respondents' concentration level was assessed by giving 25 math-questions to be answered within 10 minutes. Wilcoxon sign rank test was used to analysed paired data. The average sound intensity received by respondents' left and right ears were lower than the average sound intensity produced by the chainsaw. The use of earmuffs leads to better perception towards noise when compared with the use of earplugs and the absence of any PPE. Based on Wilcoxon test, the noise did not have significant impact on the concentration level of chainsaw operators, whilst the contrary result is true for harvesting workers. The research indicated that although the noise produced by the chainsaw was considered noisy for both chainsaw operators and harvesting workers, it did not have a significant effect on the concentration level of chainsaw operators and only affected the harvesting workers. Therefore, given that the harvesting workers were still affected by the noise, noise control measures are still needed to ensure occupational safety and health for the workers.

Multiport PV-Assisted Electric-Drive-Reconstructed Bidirectional Charger With G2V and V2G/V2L Functions for SRM Drive-Based EV Application

This paper develops a highly-integrated solar-assisted switched reluctance motor (SRM) drive for electric vehicle (EV) applications with electric-drive-reconstructed grid-to-vehicle (G2V) and vehicle-to-grid (V2G)/vehicle-to-load (V2L) functions. The flexible and efficient multimode energy transmission is realized among SRM, battery pack, solar photovoltaic (PV) panels, and AC grid. Under motoring condition, the standard switch modules are employed to implement bipolar current excitation and regenerative braking, which provides great benefits for balanced heat dissipation design and massive production of SRM drives for EVs. Under idle condition, the G2V and V2G/V2L modes can be well-regulated by multiplexing and reconstructing SRM windings and converter topology. The EV can be completely stationary without extra clamping device under the adopted positioning strategy. The battery pack can be charged by the developed bridgeless interleaved boost converter with excellent power factor correction capability, and can also act as discharging source to power the AC/DC grids/loads flexibly cooperated with the PV panels. A proof-of-concept prototype platform is built and the experiments based on a 1 kW three-phase 12/8 SRM are carried out to validate the feasibility of the proposed SRM system.

Design and Modeling of Hybrid Electric Vehicle Powered by Solar and Fuel Cell Energy with Quadratic Buck/Boost Converter

Considering technological advancements and international standards mandating reduced greenhouse gas emissions, automobile manufacturers have shifted their focus toward innovative technologies related to fuel-cell electric vehicles. Despite having an all-electric powertrain, fuel cell electric vehicles (FCEVs) utilize a fuel cell stack as their energy source, which runs on hydrogen and results in the emission of only water and heat. Due to the absence of tailpipe pollutants, fuel-cell electric vehicles are considered zero-emission vehicles. Among fuel cell types, low-temperature and low-pressure fuel cells, such as Proton Exchange Membrane Fuel Cells (PEMFCs), are well-suited for vehicular applications as they exhibit high power density, operate at lower temperatures (60-80°C), and are less prone to corrosion than other types of fuel cells. The main objective of this paper is to investigate solar-assisted electric fuel cell vehicles that efficiently integrate the fuel cell system with an electrolyzer and solar power to fulfill the fluctuating power demands of the electric motor and auxiliary systems. A novel EV configuration with a fuel cell, electrolyzer and onboard PV cell is proposed. An onboard PV cell can assist the fuel cell when the irradiation is enough to generate the power. During the idle conditions of vehicles, PV-generated power can be converted into chemical energy using an electrolyzer and generated hydrogen can be stored in a hydrogen tank. To match the voltage required by the motor and sources a quadratic bidirectional buck-boost converter is employed. The proposed configuration is examined by considering variable irradiance and variable speed values. To obtain the maximum power output from the photovoltaic (PV) panel, a Maximum Power Point Tracking (MPPT) algorithm is employed to regulate the PV system. To enhance the efficiency and cost-effectiveness of PV systems, an enhanced version of the incremental conductance algorithm is utilized as the MPPT control strategy. Outer voltage and inner current control are adopted to regulate the DC output voltage of the QBBC converter. An indirect vector-controlled induction motor is used as vehicle drive. Simulations are performed to investigate the proposed EV configuration in MATLAB/SIMULINK.

Effect of flow number of pilot-stage centrifugal atomizer on idle performance of internally staged combustor

Idle performance is critical to the combustion stability of internally staged combustors. Five pilot-stage atomizers are compared in an internally staged combustor, and the effects of the flow number (FN) on the combustion characteristics and emissions are investigated under idle conditions. Experimental results show that the maximum outlet temperature is 1.02–1.04 times the average outlet temperature, and the maximum temperature is located at the dimensionless radial location of 0.66. The key influencing mechanism of the temperature distribution lies in the matching between the spray angle of the pilot-stage atomizer and the angle of the recirculation zone. When the flow number (FN) of the pilot-stage atomizers was increased from 1.6 to 10, the combustion efficiency (η) showed a “decrease-increase-decrease” trend, whereas the emission of unburned hydrocarbon (UHC) showed a opposite trend. At the meantime, the emission of CO remained unchanged, and NOx remained at the undetectable level. In addition, the low sensitivity of pressure loss (3.3%-4%) and combustion stability (0.66%-0.85%) to idle conditions is attributed to the influence of combustion efficiency and outlet temperature. After a comprehensive evaluation, it is determined that an intermediate FN of 5.0 possesses the most balanced combustion characteristics and emissions under idle conditions in the pilot-stage atomizer.