System Efficiency Factor Research Articles

Hybrid powertrain efficiency improvement by using electromagnetically controlled double-clutch transmission

This paper proposes a new type of hybrid powertrain with a specially designed double-clutch transmission. Compared with the existing hybrid powertrains, the proposed solution with double-clutch transmission, based on innovative double-clutch and mechanical gear sets, has the potential to achieve higher levels of performance efficiency at a lower production cost. The impact factors of system efficiency are analysed on a dynamic non-linear simulation model. The control strategies of powertrain and the double-clutch transmission gear ratios are studied by simulation results. Additionally, the double-clutch transmission can increase the efficiency of regenerative braking.

Hybrid powertrain efficiency improvement by using electromagnetically controlled double-clutch transmission

This paper proposes a new type of hybrid powertrain with a specially designed double-clutch transmission. Compared with the existing hybrid powertrains, the proposed solution with double-clutch transmission, based on innovative double-clutch and mechanical gear sets, has the potential to achieve higher levels of performance efficiency at a lower production cost. The impact factors of system efficiency are analysed on a dynamic non-linear simulation model. The control strategies of powertrain and the double-clutch transmission gear ratios are studied by simulation results. Additionally, the double-clutch transmission can increase the efficiency of regenerative braking.

Improving energy recovery efficiency by retrofitting a PCM-based technology to an ORC system operating under thermal power fluctuations

Energy-intensive industrial processes, such as those occurring in steel billet reheating furnaces, usually release waste heat characterised by a fluctuating and/or intermittent nature, which limits the efficiency of current waste heat recovery systems. In fact, current waste heat recovery systems are usually designed for one single operating point, which forces them to operate at off-design conditions when subjected to power fluctuation of the waste heat.This paper investigates the impact of retrofitting a technology based on high temperature phase change materials (PCM-based technology) in an existing waste heat recovery system – composed of an air preheater and an Organic Rankine Cycle (ORC) system – installed downstream of a steel billet reheating furnace. The analysis was carried out by using real data from a billet reheating furnace and ORC system to develop and validate a model in Modelica language; a comparison between the ORC system efficiency and capacity factor with and without the PCM-based technology was then performed.The results showed that the introduction of the PCM-based technology allows the capacity factor to increase from 38% to 52% and the average thermal efficiency to increase from 15.5% to 16.4%. The cost-benefit analysis shows that electric energy priced between 83 and 120 €/MWh could guarantee a payback period between 3 and 5years.

Efficiency analysis of moving-magnet linear oscillating motor with dual-resonance for linear electro-hydrostatic actuator

More-electric aircraft draws considerable attention due to its high efficiency, high reliability, and easy maintenance. Linear electro-hydrostatic actuator is a novel linear actuation system suitable for more-electric aircraft, and offers many advantages over traditional rotary electro-hydrostatic actuator. However, it requires high-frequency reciprocate actuation of linear oscillating motors with both high efficiency and high power factor. In this study, a novel moving-magnet tubular linear oscillating motor with dual-resonance is proposed for linear electro-hydrostatic actuator applications to achieve high efficiency and high power factor simultaneously. Firstly, system impedance model is set up analytically, which helps to analyze the influence of structure parameters on system performance. Based on this model, working efficiency and power factor are compared with the nonresonance design, and validated by experimental results. In order to take real scenario into considerations, the nonlinearity of motor and rectangular-type load is also analytically derived and analyzed with effective resonant frequency tracking method proposed. It shows that dual-resonance design does increase system efficiency and power factor, and can be applied in linear electro-hydrostatic actuator system for more-electric aircraft effectively.

Research on Influence Factor of System Efficiency and Power Loss Factor for DC Power Supply System of Data Center

In order to increase system efficiency and decrease the power loss factor of power supply system of data center, the influence factor should be researched under different conditions. On one hand, system efficiency and power loss factor are compared under different load factors. On the other hand, DC power sources with different voltage level and capacity are implemented into power supply system. Many tables and curves of test results are presented in this paper to help us analyze the influence factor under different conditions of power sources and load factor of data center. Finally, many useful conclusions are drawn and operation suggestion for economic operation of data center is also given in this paper.

Performance evaluation of an air-cooled heat exchange system for hybrid nanofluids

This study used an acetylene flame synthesis system to prepare hybrid carbon nanofluids (HCNFs) containing amorphous carbon, graphene oxide, and graphite-2H as a working fluid for heat exchange applications. In addition, sodium dodecyl sulfate was added to the prepared HCNFs as a dispersant to reinforce their dispersion and suspension performance. The basic characteristics of the HCNFs were measured and analyzed. Finally, the HCNFs were applied in a cooling system with an air-cooled heat exchanger (ACHE) to evaluate the pumping power consumption, heat exchange capacity (Q̇ex), and system efficiency factor (SEF) of the ACHE under turbulent flow. The results show that the pumping power and Q̇ex of the ACHE cooling system increased with the HCNF concentration under all experimental conditions. The maximum enhancements in Q̇ex and SEF for the HCNFs at 0.02wt.% were respectively approximately 13.0% and 11.7% at a flow rate of 2.0L/min (compared with those of water).

Prediction of flat-bottom hole signals received by a spherically focused transducer for an ultrasonic pulse echo immersion testing

The spherically focused transducer has been widely used for nondestructive evaluation of micrometer-scale inner defects in material and microelectronic devices due to its outstanding transverse resolution and high beam intensity. In this paper, by combining the beam model, the flaw scattering model and the system efficiency factor, an ultrasonic measurement model is developed for the spherically focused transducer in an ultrasonic pulse-echo immersion testing and is used to predict the ultrasonic flaw signal for flat bottom hole (FBH). The multi-Gaussian beam (MGB) model and the Gaussian beam equivalent point source (GBEPS) model are extended to evaluate the beam fields radiated by the spherically focused transducer in water and transmitted into solid through a planar interface. Results show that the MGB model is more excellent considering both the accuracy and efficiency. Experiments are performed to determine the system efficiency factor and the experimental measured flaw signal is compared with the model predictions to validate the accuracy of the proposed model. Effects of the depth and size of the FBH are further studied using the established model.

Energy analysis of green office buildings in the tropics—Photovoltaic system

This research is to conduct energy analysis of green office buildings in the tropics. According to International Performance Measurement and Verification Protocol (IPMVP), there are four options available in the IPMVP, namely Option (A) Retrofit Isolation: Key Parameter Measurement, Option (B) Retrofit Isolation: All Parameter Measurement, Option (C) Whole Facility and Option (D) Calibrated Simulation. The current research is using Option (A) Retrofit Isolation: Key Parameter Measurement to study the Building Integrated Photovoltaic (BIPV) systems of Malaysia Green Technology Corporation (MGTC) Green Energy Office (GEO) Building. There are four types of BIPV systems being studied, namely System A (polycrystalline silicon), System B (amorphous silicon), System C (monocrystalline glass-glass, semi-transparent) and System D (monocrystalline silicon). The aims of the study are to examine the energy performance and quantify the energy savings of BIPV systems. The key parameters being evaluated are the system efficiency, reference yield, final yield, performance ratio and capacity factor. The methodology used is the actual data collection and analysis. The energy analysis result has shown that System B is having the best performance among all systems, whereas System C has the lowest performance.

A 1-kW Contactless Energy Transfer System Based on a Rotary Transformer for Sealing Rollers

This paper introduces an innovative contactless energy transfer system for power supplying rotatable parts of automatic machineries as a robust alternative to sliding contacts. The design procedure of the key system devices, such as the dc/ac converter and the rotary transformer with its windings, is discussed. Different configurations in terms of switching network, number of turns, wire, and compensation are discussed with respect to their impact on the system efficiency and power factor. A thermal model to account for the core temperature is also introduced. Two setups, operating at 50 kHz and able to transfer up to 1.3 kW in a contactless fashion, are realized and tested to supply sealing roller resistors of automatic machineries. The system prototypes are then experimentally tested to validate the analytical models and the finite element simulations of the entire wireless power transfer link. Trade-offs emerge from the setups, in particular concerning efficiency, power factor, and electro-magnetic compatibility. As a consequence, we discuss the choice of the optimal configuration depending on the final application.

Nonlinear Decoupling Control of DFIG

DFIG (Double Fed Induction Generator) becomes a competitive wind power form due to it needs small capacity converter and the controllable of system efficiency and power factor. Aiming at back to back three-phase voltage-type PWM converter of the doubly-fed VSCF wind turbine, the nonlinear mathematical model of the controller of rotor side and network side is constructed, the strategy of feedback linearization of nonlinear control is proposed, the decoupling control of active and reactive power of DFIG is achieved. The simulation results indicate that: this control strategy has good dynamic characteristics, and the quality of power supply of DFIG is improved.

포물면 집광거울 방식의 태양광 집광채광시스템 개발

We developed a parabolic reflector based daylighting system which can be used as an alternative indoor daytime lighting device such as for fluorescent lamps. The system comprises three main components : a daylight concentrator made of 4 pairs of parabolic reflectors and mirrors, a silica optical fiber bundle based light transmitter, and 4 light diffusers for the final indoor delivery of the collected daylight. We analyzed the performance of the system and revealed the system efficiency and daylighting factor. All test methods follow the rule, NR PV601 : 2007-daylighting system, governed by Korea Energy Management Corporation.

고성능 DCM-ZVS 스텝 업-다운 AC-DC 컨버터에 관한 연구

본 논문에서는 고효율과 고역률을 위한 새로운 DCM-ZVS 스텝 업-다운 AC-DC 컨버터에 대해 연구된다. 제안한 DCM-ZVS 컨버터에 사용된 스위칭 소자들은 새로운 유사공진 회로에 의해 소프트 스위칭 기법으로 동작되고, 펄스폭변조(PWM) 방식에 의한 전류불연속모드(DCM)로 구동된다. 제안한 컨버터의 유사공진 회로는 스텝 업-다운 인덕터와 무손실 스너버 커패시터로 구성되고, 또한 DCM에 의해 제어회로 기법과 제어회로 구성이 간단한 장점이 주어진다. 입력 교류 전류파형은 일정 스위칭 주파수에 의한 교류 입력전압의 크기에 비례한 유사 정현파형으로 된다. 그 결과, 제안한 DCM-ZVS 컨버터는 낮은 스위칭 손실과 고효율을 얻을 수 있으며, 컨버터의 입력역률은 거의 단위역률로 된다. 해석적 결과의 타당성은 다양한 컴퓨터 시뮬레이션과 실험 결과를 통해 입증된다. This paper is studied on a new DCM-ZVS step up-down AC-DC converter of high performance, that is, high system efficiency and power factor correction (PFC). The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit, and are driven with discontinuous conduction mode (DCM) according to pulse width modulation (PWM). The quasi-resonant circuit uses a step up-down inductor and a loss-less snubber capacitor. The proposed converter with DCM also simplifies the requirement of control circuits and reduces the number of control components. The input AC current waveform in the proposed converter becomes a quasi-sinusoidal waveform proportional to the magnitude of input AC voltage under constant switching frequency. As a result, the proposed converter obtains low switching power loss and high efficiency, and its input power factor is nearly in unity. The validity of the analytical findings is confirmed by some computer simulation results and experimental results.

Efficiency Analysis and Optimization on Magnetic Resonance Coupled Wireless Transfer System

In this paper, a magnetic resonance coupled wireless transfer system is studied to establish the efficiency analysis model. By analyzing the influencing factors of system efficiency indicates that the system transfer power is mainly determined to the resonance frequency, and only near the resonance frequency has achieved a maximum value. With experimentally studying the load received power varied with frequency at the transfer distance from 80cm to 120cm, we believe that the magnetic resonance coupled wireless transfer system’s optimization can be realized by controlling the frequency.

Measured performance of a 1.72 kW rooftop grid connected photovoltaic system in Ireland

This paper presents results obtained from monitoring a 1.72 kW p photovoltaic system installed on a flat roof of a 12 m high building in Dublin, Ireland (latitude 53.4°N and longitude 6.3°E). The system was monitored between November 2008 and October 2009 and all the electricity generated was fed into the low voltage supply to the building. Monthly average daily and annual performance parameters of the PV system evaluated include: final yield, reference yield, array yield, system losses, array capture losses, cell temperature losses, PV module efficiency, system efficiency, inverter efficiency, performance ratio and capacity factor. The maximum solar radiation, ambient temperature and PV module temperature recorded were 1241 W/m 2 in March, 29.5 °C and 46.9 °C in June respectively. The annual total energy generated was 885.1 kW h/kW p while the annual average daily final yield, reference yield and array yield were 2.41 kW h/kW p/day, 2.85 kW h/kW p/day and 2.62 kW h/kW p/day respectively. The annual average daily PV module efficiency, system efficiency and inverter efficiency were 14.9%, 12.6% and 89.2% respectively while the annual average daily performance ratio and capacity factor were 81.5% and 10.1% respectively. The annual average daily system losses, capture losses and cell temperature losses were 0.23 h/day, 0.22 h/day and 0.00 h/day respectively. Comparison of this system with other systems in different locations showed that the system had the highest annual average daily PV module efficiency, system efficiency and performance ratio of 14.9%, 12.6% and 81.5% respectively. The PV system’s annual average daily final yield of 2.4 kW h/kW p/day is higher than those reported in Germany, Poland and Northern Ireland. It is comparable to results from some parts of Spain but it is lower than the reported yields in most parts of Italy and Spain. Despite low insolation levels, high average wind speeds and low ambient temperature improve Ireland’s suitability.

Weld crack testing method using ultrasonic TOFD technique

In this paper, both the forward and inverse problems of crack testing using the ultrasonic time-of-flight diffraction (TOFD) B-scan mode are studied. For the forward problem, the propagation behaviour of the ultrasonic beam is described and the electrical and electromechanical elements of the inspection system are characterised using a system efficiency factor. Based on this, a crack testing model is established by employing Kirchhoff approximation theory. By using the model, the ultrasonic TOFD A-scan line is predicted and the B-scan foreground image is synthesised. For the inverse problem, in order to obtain lateral location and buried depth information about the crack in the weld, the B-scan image reconstruction is studied. According to the dynamic relationship between the probes and the crack tip in the course of B-scan testing, the synthetic aperture focusing (SAF) algorithm for image enhancement is developed. The results show that the simulated data are in good agreement with the measured data and the presented SAF algorithm can be validated by the simulation model. Processed by SAF, a high-resolution image can be obtained using transducers with poor sound directivity and lower frequency. In this way, measurements can be taken on the reconstructed image rapidly and with high accuracy.

Prediction of Side-Drilled Hole Signals Captured by a Dual Crystal Contact Probe

The dual crystal transducer plays an important role in many practical ultrasonic inspections due to its outstanding near surface resolution and signal-to-noise ratio. In order to get a deeper understanding on the characteristics of this kind inspection system, it is essential to develop an ultrasonic measurement model for dual crystal probes. To address such a need, by combining a multi-Gaussian beam model and a scattering model with the separation of variables method, we provide an efficient ultrasonic measurement model for the dual element transducer. This measurement model can be used to determine the system efficiency factor and predict the responses of a side-drilled hole. Furthermore, the comparisons of model predictions with experimental results are presented to certify the accuracy of this provided model.

Energy and exergy analyses of ice rink buildings at varying reference temperatures

This study deals with energy and exergy analyses of ice rink buildings. An ice rink building with a net area of 648 m 2, which is considered to be closed type and located in Turkey, is assessed. Based on the capacity of the ice rink area, the refrigeration system consists of two circuits with the same basic system components, where two types of refrigerants R-134A and R-744 (CO 2) are used. Exergy analysis is based on Lowex approach, while the effect of varying reference (dead) state temperatures on the system exergy efficiency is investigated. It includes exergy transmission load, air infiltration load, exergy load room, exergy demand distribution, exergy load generation, total exergy system efficiency and exergy flexibility factor. Total exergy input rate is calculated to be 253.66 kW, while exergy destruction rate is 227.45 kW. The minimum and maximum exergy efficiency values are found to be 1.72% and 19.05% for reference state temperatures of 10 °C and −10 °C, respectively.

A split-pot experiment with sorghum to test a root water uptake partitioning model

Correct modeling of root water uptake partitioning over depth is an important issue in hydrological and crop growth models. Recently a physically based model to describe root water uptake was developed at single root scale and upscaled to the root system scale considering a homogeneous distribution of roots per soil layer. Root water uptake partitioning is calculated over soil layers or compartments as a function of respective soil hydraulic conditions, specifically the soil matric flux potential, root characteristics and a root system efficiency factor to compensate for within-layer root system heterogeneities. The performance of this model was tested in an experiment performed in two-compartment split-pot lysimeters with sorghum plants. The compartments were submitted to different irrigation cycles resulting in contrasting water contents over time. The root system efficiency factor was determined to be about 0.05. Release of water from roots to soil was predicted and observed on several occasions during the experiment; however, model predictions suggested root water release to occur more often and at a higher rate than observed. This may be due to not considering internal root system resistances, thus overestimating the ease with which roots can act as conductors of water. Excluding these erroneous predictions from the dataset, statistical indices show model performance to be of good quality.

Prediction of Ultrasonic Signals Captured from a Side-Drilled Hole Using a Rectangular Transducer

For the proper interpretation of ultrasonic measurement results from a side-drilled hole (SDH) using a rectangular transducer, it is very helpful to have a complete ultrasonic measurement model. A highly efficient ultrasonic beam model of a rectangular transducer and an accurate scattering model of a SDH are currently available. However, to develop such a complete measurement model, a reference model for the system efficiency factor is also needed. In this study a reference model suitable for a rectangular transducer is given and combined with existing models to develop a complete ultrasonic measurement model that can the predict ultrasonic signals from a SDH. Based on this model, we have calculated the ultrasonic signals from a SDH at different transducer orientations and compared the model-based predictions with experiments.

Modeling Angle Beam Ultrasonic Testing Using Multi-Gaussian Beams

This paper proposes a new approach to modeling angle beam ultrasonic testing that can predict pulse-echo signals, in an absolute and computationally efficient manner, from various reflectors in steel welded joints. This approach relies on a model of the entire ultrasonic measurement process, a model which requires one to solve three subsidiary problems; 1) determination of a system efficiency factor, 2) evaluation of the ultrasonic beam field around the flaw, and 3) calculation of the scattering from the reflector. Here, solutions are offered for each of those three subsidiary problems. To solve the first problem we employ the specular reflection from the cylindrical part of a STB-A1 (Standard Test Block in compliance with Japanese Industrial Standards Z 2347) (equivalently IIW (International Institute of Welding) type 1) standard block to determine the system efficiency factor. To solve the second problem, we calculate the ultrasonic wave field at the flaw with a highly efficient multi-Gaussian beam model. For the third problem, we treat the scattering from a reflector by high frequency approximations. We explicitly give the solutions to all three of these subsidiary problems for counter bore, crack, and side-drilled hole reflectors. Experimental results that validate this approach are also given.