Comparison Of Dynamic Performance Research Articles

Tuning of Mixing Zone Parameters in a Dynamic Mixer and Performance Comparison with Screw-based Mixers

A new dynamic mixer has been designed for the mixing of two incompatible polymer melts. Three main design parameters (number of circles of holes (N), number of holes (M) per circle, and diameter of the holes (d3)) for the mixing zone of the dynamic mixer were selected to study their influences on the pressure drop (Δp) and the segregation scale (S) using Orthogonal tests. The influences of flow rate and rotational speed were also investigated. In addition, the mixing effect was compared with that of screw and slotted-screw mixers. The results showed that the most significant factor influencing S and S∙Δp is N. Both Δp and S increased with increasing flow rate, and decreased with increasing rotational speed. Compared to the screw and slotted-screw mixers, the dynamic mixer had a better mixing effect and shorter length.

Comparison of Dynamic Performance of an All-Metallic Vibration Isolator by Elliptic Method and Frequency Sweeping Method

A horizontally symmetric all-metallic vibration isolator (AM-VI) is proposed to further investigate the dynamic mechanical performance. The novel AM-VI was constructed by combining hat-shaped metal rubber and oblique springs, which were connected in parallel. The springs were arranged symmetrically relative to the support. The elliptic method and the frequency sweeping method were used to compare the dynamic stiffness and the loss factor of the AM-VI. The results demonstrated that the dynamic stiffness and the loss factor calculated by two distinct test methodologies were considerably different, indicating that the inertial force effect of the dynamic testing equipment should be taken into count when adopting the elliptic method. Furthermore, when the vibration isolation performance was evaluated by utilizing mechanical impedance and force transmissibility, the AM-VI achieved excellent vibration isolation performance within a broad frequency range.

Comparison of Dynamic Balance Performances of Adult Runners With Intellectual Disability Versus Their Sedentary Peers.

Our aim in this study was to compare the dynamic balance between runners (100 sprint) and non-runners with intellectual disability (ID). Our participants were 36 healthy male adults with ID aged 17-29years, divided into runners (n = 18) and sedentary non-runners (n = 18). We assessed dynamic balance in these participants, using the Y-Balance Test (YBT), the Expanded-Timed Up and Go Test (ETUGT) and the Functional Reach Test (FRT). Runners with ID had significantly better balance scores than their sedentary counterparts on YBT (p < .001), the two walking phases of the ETUGT (p < .05) and the FRT (p <.05). Thus, running training (100m sprint) was associated with better dynamic balance in this sample.

Cake layer reformation rates on self forming dynamic membranes and performance comparison with microfiltration membranes

Dynamic membranes (DMs) keep on attracting attention progressively as an alternative to conventional membranes because they can be operated with relatively higher fluxes and lower fouling rates. However, there are many factors affecting the performance of DMs, such as DM pore size, structure, and operating conditions. In this study, mainly focused on the investigation of cake formation rates both in initial formation and reformation rates after physical/chemical cleaning. In this context, it has been evaluated the performances of DMs with different pore sizes (171 μm, 90 μm, and 30 μm) and different structures under the same conditions and compared their performances with microfiltration (MF) membranes (0.45 μm and 0.22 μm) in a single reactor. In the study, the effects of different fluxes (15-, 20-, 25 L/m2·h (LMH), SADm (1-, 0.8-, 0.5 m3-air /m2·h) and F/M (0.095, 0.125, 0.19 g-COD/g-MLSS·day) conditions on the treatment and filtration performance of DMs were investigated. High COD (>95%) and turbidity (<10 NTU) removals were obtained in this study. In particular, the 30 μm DM (0.65 ± 0.47 NTU) produced quite close effluent turbidity compared to MFs (0.12 ± 0.05 NTU). Low SADm and high F/M values resulted in increased effluent COD concentrations and turbidity values. By decreasing the SADm, the cake formation rate and the fouling rate increased, which showed that there is a definite relationship between the cake formation rates and the fouling rates. Additionally, considering all the results, the most stable operation was obtained in the 30 μm DM, although it has been occurred the least fouling in the 90 μm membrane in the study. This study, focused on cake reformation rates, attempts to show that DMs can be used as an alternative to MBRs. Especially, when taking into account the results of the reformation rate of 30 μm DM (6.09 NTU/h) and other high filterability features.

Dynamic Performance Comparison of the Different PV Modules with Real Data

Nowadays, the photovoltaic panel is an important source for electricity production and one of the preferable renewable resources. Many companies have started to produce for increasing PV panel demand. It is a fact that the performance of PV panels under real environmental conditions in the application area will affect the benefit to be obtained from the application and investment to be made. In this study, Istanbul, Turkey, for the five most widely sold in the market PV panels of MATLAB/Simulink models using performance comparison minutes and measured weather data created in the environment is made. With the related study, the effects of using dynamic analysis to be obtained from more detailed simulation studies have been revealed instead of feasibility calculations to be made using only the data specified in the technical document.

Dynamic performance comparison of different types of ballastless tracks using vehicle-track-subgrade coupled dynamics model

This paper contributes to evaluate the dynamic performance of different types of ballastless tracks, including the CRTS II, CRTS III as well as CRTS DB, subjected to a moving high-speed railway vehicle. To this end, a vertically vehicle-track-subgrade coupled dynamics model appropriating for both the longitudinally connected-type track structure and the element slab-type track structure is constructed by introducing the Green’s function method, so as to achieve a full characterization of the vehicle-track-subgrade system with accurate and efficient solutions. The time-spatial distributions of the displacement and velocity Green’s functions of the track-subgrade system are analyzed to ascertain the values of the truncation parameters employed in the model. Numerical examples are presented to illustrate and compare the dynamic characteristics of the three types of track structures under various track irregularities, vehicle speeds, fastener stiffnesses and subgrade elastic moduli. It is shown that the discrepancy among different track structures exerts an ignorable influence on the vertical wheel-rail force, but its effect on the vertical displacement, acceleration and stress of the track-subgrade system is noteworthy. Besides, the attenuation characteristics of the track-subgrade system with respect to track depth are further investigated. It is concluded that the system displacement against the track depth presents an approximately linear attenuation, whereas the system stress reveals an approximately exponential attenuation.

Dynamic performance and control strategy comparison of a solar-aided coal-fired power plant based on energy and exergy analyses

Solar-aided coal-fired power generation is a hybrid technique to generate power with the coal and solar energy. The performance of solar-aided coal-fired power plant (SACFPP) with solar irradiance fluctuations received little attention in previous studies. Dynamic and exergy analysis models of SACFPP are developed to evaluate the SACFPP performance in transient processes caused by solar irradiance disturbances and the consequent system regulation. An SACFPP integrating the trough collector system (TCS) in parallel with HP2 and HP3 heaters of a 660 MW coal-fired power plant is simulated. Influences of solar irradiance and feedwater ratio to TCS disturbances on SACFPP performance are analyzed, including step cases and typical solar days. The solar-to-power exergy efficiency fluctuates sharply in the dynamic process. It increases from 32.62% to 57.25% and decreases to 28.1% when solar irradiance step decreases from 700 to 400 W m−2. Accumulations of additional power and exergy destruction are the highest in Autumn Equinox. Then, control strategies of feedwater flow to TCS are proposed and compared to obtain maximal solar-to-power exergy efficiency during transients. Results indicate that the feedwater flow to TCS should follow the solar irradiance decrease with a dynamic period of less than 200 s; otherwise, extra exergy destruction occurs.

Comparison of dynamic performances for heat integrated reactive distillation considering safety

The heat integrated reactive distillation is beneficial on energy saving and economy compared with conventional reactive distillation. However, the dynamic controllability is unfavorable due to the complexities of system. In this paper, five different control structures for the isopropyl acetate synthesis are presented as considering both product purities and safety. The integral of absolute error (IAE) and process stream index (PSI) are used to quantify the dynamic performances. The result shows that four enhanced control schemes can achieve better dynamic performances compared with the basic control structure. Based on the four improved control structures, the control structure with temperature difference controller shows the best performance, as involving the overshoot, recovery time, IAE, and PSI, since it improves the tuning stability and adjusts the temperature difference of exchange heat process between the high-pressure column and the low-pressure column.

Dynamic Performance Comparison between STATCOM and SVC

This paper presents an investigation to the dynamic performance of a PI-type controlled STATCOM for various faulty conditions as well as for different system short circuit ratios SCR. Furthermore, the performance of the STATCOM is thereby simulated using the PSCAD/EMTDC software. The obtained results reveal superior dynamic performance and reduced system short circuit ratio SCR.

Thermal and Fluid Dynamic Performance Comparison of Three Nanofluids in Microchannels Using Analytical and Computational Models

The fluid dynamic and thermal performance of three nanofluids containing aluminum oxide, copper oxide, and silicon dioxide nanoparticles dispersed in 60:40 ethylene glycol and water base fluid as a coolant in a microchannel heatsink are compared here by two methods. The first is a simple analytical analysis, which is acceptable for very low nanoparticle volumetric concentration (1–2%). The second method is a rigorous three-dimensional finite volume conjugate heat transfer and fluid dynamic model based upon a constant heat flux boundary condition, which is applicable for cooling electronic chips. The fluids’ thermophysical properties employed in the modeling are based on empirically derived, temperature dependent correlations from the literature. The analytical and computational results for pressure drop and Nusselt number were in good agreement with the nanofluids showing a maximum difference of 4.1% and 2.9%, respectively. Computations cover the practical range of Reynolds number from 20 to 200 in the laminar regime. Based on equal Reynolds number, all of the nanofluids examined generate a higher convective heat transfer coefficient in the microchannel than the base fluid, while copper oxide provided the most significant increase by 21%. Based on the analyses performed for this study, nanofluids can enhance the cooling performance of the heatsink by requiring a lower pumping power to maintain the same maximum wall temperature. Aluminum oxide and copper oxide nanofluids of 2% concentration reduce the pumping power by 23% and 22%, respectively, while maintaining the same maximum wall temperature as the base fluid.

Dynamic performance comparison of two configurations of middle vessel batch distillation column for the separation of ethanol/propanol/butanol mixture

AbstractThis paper deals with Aspen Plus and Aspen Dynamics of the middle vessel batch distillation for the separation of mixtures of ethanol/propanol/butanol. Two configurations of middle vessel batch distillation have been considered, namely, the conventional middle vessel batch distillation (Configuration 1) and the modified middle vessel batch distillation column (Configuration 2). Steady‐state simulations have been performed in Aspen Plus and exported to Aspen Dynamics for dynamic simulation. Dynamic studies show that Configuration 1 requires less time than Configuration 2 to obtain more than 95% of the compositions of ethanol, propanol, and butanol. The efficacy of the two controllers is assessed by the performance indices of integral of square error, integral of absolute error, and integral of time‐weighted absolute error. Configuration 1 is found to have better performance than Configuration 2.

Comparison of Dynamic Performance of Solar PV fed BLDC Motor Drive with P&amp;O and I.C. - MPPT Algorithm

Comparison of Dynamic Performance of Solar PV fed BLDC Motor Drive with P&amp;O and I.C. - MPPT Algorithm

Dynamic Performance Comparison of CO2 Mixture Transcritical Power Cycle Systems with Variable Configurations for Engine Waste Heat Recovery

Carbon dioxide transcritical power cycle (CTPC) is suitable for engine waste heat recovery owing to its advantages, such as compact construction and high decomposition temperature. In addition, the addition of refrigerant can further improve the performance of pure carbon dioxide (CO2). Because there are limited studies considering the dynamic performance of CTPC systems with CO2 mixture as the working fluid (CMTPC), let alone the dynamic performance comparison of different structures of the CMTPC system, the object of the current work was to compare the dynamic performance, including the off-design performance and dynamic response speed, of four kinds of CMTPC systems, as well as their sensitivity to system input parameters. The dynamic models of four CMTPC systems were established and validated against experimental data, which includes basic CMTPC (B-CMTPC), CMTPC with a preheater (P-CMTPC), CMTPC with a recuperator (R-CMTPC), and CMTPC with both a recuperator and preheater (PR-CMTPC). Based on the dynamic models, the off-design performance and dynamic response speed of four CMTPC systems were compared by changing the engine load. The fluctuation amplitude and response time of a R-CTPC system are the maximum under off-design conditions. Moreover, the sensitivity analysis demonstrates that different output parameters of four CMTPC systems have differing sensitivity to input parameters. It is necessary to pay attention to the more sensitive input parameters under the specific working condition to avoid system damage or unsafe operation.

Dynamic performance comparison of different cascade waste heat recovery systems for internal combustion engine in combined cooling, heating and power

The internal combustion engine is an important prime mover in combined cooling, heating and power systems. However, approximately 30–40% of the input energy is discharged by exhaust; thus, it is significant to recover the exhaust waste heat. Cascade energy-utilisation systems have high efficiencies for exhaust recovery with a large temperature drop. However, waste heat-recovery systems usually work under different conditions and therefore, it is meaningful to study the dynamic performance of cascade systems. In this work, by developing a model library of common components in thermodynamic systems, dynamic simulation models of three cascade systems are established: an electric-cooling cogeneration system (ECCS), a double-effect absorption refrigeration system, and a double-stage organic Rankine cycle. The dynamic response speed and off-design performance of each system are analysed and compared. The results indicate that all the cascade systems respond considerably more slowly than any single-stage cycle, and the ECCS achieves the best off-design performance because both its upper and lower stages (high-temperature organic Rankine cycle and absorption refrigeration) exhibit perfect working condition adaptability, especially the lower stage. Furthermore, the structure of the ECCS is more beneficial for the lower stage to maintain satisfactory off-design performance.

A comparison of static and dynamic balance performance in adolescent male wrestlers and judoists

Summary Objectives The purpose of this study was to compare the dominant and non-dominant legs in respect of dynamic and static balance and to examine the effect of sport type, sportive experience and BMI on the static and dynamic balance of adolescent male judoists and wrestlers. The results of the study could be beneficial for the prevention of injury to the athletes and could be applied to training management. Methods The study included 54 healthy, male, adolescent wrestlers and judoists (mean age: 15.81 ± 0.87 years; height: 165.01 ± 8.73 cm; weight: 62.01 ± 11.94 kg). Static and dynamic balance were assessed using the flamingo balance test (FBT) and the star excursion balance test (SEBT) in an institution-based sports sciences department. Results No statistically significant differences were determined between the dominant and non-dominant leg in the normalized SEBT reach distances (P > 0.05). The static balance performance scores were compared between the groups and the judoists were found to have higher static balance performance than the wrestlers (P Conclusion Both adolescent judoists and wrestlers were found to have higher static and dynamic balance scores compared to other sports branches, and the judoists were determined to have better static and dynamic balance performances than the wrestlers.

Dynamic performance comparison of DFIG and FCWECS during grid faults

Among several types, variable speed-based wind turbine generator (WTG) is the most popular type installed worldwide. This type of WTG is able to extract 5% more energy from wind speed compared to the fixed speed WTG. There are two kinds of variable speed based WTG; Doubly Fed Induction Generator (DFIG) and Full Converter Wind Energy Conversion System (FCWECS). DFIG and FCWECS are placed at the first and second topWTG installation worldwide since 2004. However, both of them are very sensitive to the grid dip fault and may violate the allowable margins identified by various international Fault Ride Through (FRT) codes. This paper aims to investigate the responses of DFIG and FCWECS during certain level of grid dips and compare their performanceunder such event. Results show some differences of the performance of DFIG and FCWECS during voltage sag event, however the voltage profile at the point of common coupling is much better in case of DFIG. Results also recommend that DFIG can be effective when connected to weak grids whilst FCWECS is preferably to be connected to strong grids.

Dynamic performance comparison involving grid‐connected PV systems operating with active power‐line conditioning and subjected to sudden solar irradiation changes

This study presents a comparative performance analysis involving single- and double-stage photovoltaic (PV) systems, which are connected to a three-phase four-wire electrical system by means of a four-leg inverter topology. The double-stage PV system is composed of a step-up DC/DC converter and a four-leg grid-connected inverter, while in the single-stage PV system the PV array is directly connected to the inverter DC bus. In addition to the active power injection into the grid, both PV systems have two attractive features, described as follows: (i) power quality improvement due to their capability to perform active power-line conditioning, such as load harmonic current suppression, reactive power compensation, and load unbalance compensation; (ii) dynamic improvement in the occurrence of abrupt solar irradiation variations, which is achieved through the implementation of a feed-forward control loop (FFCL) acting directly in the inverter DC-bus voltage control loop, resulting in speeding up of the dynamics of both the DC-bus voltage and the injected grid-inverter currents. The referred comparative analysis addresses the static and dynamic performances considering the PV systems operating under the action of the FFCL, as well as performing active power-line conditioning. Simulation and experimental results are presented to evaluate and validate the proposed study.

Application of Fractal Contact Model in Dynamic Performance Analysis of Gas Face Seals

Fractal theory provides scale-independent asperity contact loads and assumes variable curvature radii in the contact analyses of rough surfaces, the current research for which mainly focuses on the mechanism study. The present study introduces the fractal theory into the dynamic research of gas face seals under face-contacting conditions. Structure-Function method is adopted to handle the surface profiles of typical carbon-graphite rings, proving the fractal contact model can be used in the field of gas face seals. Using a numerical model established for the dynamic analyses of a spiral groove gas face seal with a flexibly mounted stator, a comparison of dynamic performance between the Majumdar-Bhushan (MB) fractal model and the Chang-Etsion-Bogy (CEB) statistical model is performed. The result shows that the two approaches induce differences in terms of the occurrence and the level of face contact. Although the approach distinctions in film thickness and leakage rate can be tiny, the distinctions in contact mechanism and end face damage are obvious. An investigation of fractal parameters D and G shows that a proper D (nearly 1.5) and a small G are helpful in raising the proportion of elastic deformation to weaken the adhesive wear in the sealing dynamic performance. The proposed research provides a fractal approach to design gas face seals.

Modelling and simulation of ZDC controlled PMSG based wind energy conversion system

This paper presents the comparison of dynamic performance and steady state operation of PMSG wind energy conversion systems with two modulation techniques. Voltage oriented control (VOC) is used for grid-connected converter along with sinusoidal pulse width modulation (SPWM) and Space Vector Modulation (SVM) schemes. The generator is controlled by using zero d- axis current (ZDC) control scheme along with optimal torque control (OTC). Performance comparison with two pulse width modulation schemes through simulation results are presented for 2MW/ 690V/ 9.75Hz Non-Salient Pole PMSG using MATLAB/SIMULINK.

Modern Reactive Power Generators

The paper reviews main stages of development of reactive power generators, describes the 1-st and 2-nd generation of synchronous condensers with conventional cooling systems and a new generation – superconductive synchronous condensers. Asynchronous non- salient pole condensers expand the class of rotating compensating devices. Comparison of dynamic performance of conventional synchronous condensers, cryogenic condensers and SVC is presented. The variant of a model 5 MVA HTSC synchronous condenser intended for wind power plants is described.