Power Loss Coefficient Research Articles

Particle motion characteristics of vertical pipe on a the horizontal-vertical pneumatic conveying system installed dune models in the different curvature elbows

To minimize energy consumption in transportation, a dune model is developed and installed in elbow with varying radii of curvature in the horizontal-vertical pneumatic conveying system in this study. The experimental study focuses on the effect of dune model in elbow with different radius of curvature on the pneumatic conveying system in terms of pressure drop, additional pressure drop coefficient, and the power loss coefficient. Furthermore, the particle concentration and velocity distribution are measures by using the electrical capacitance tomography (ECT) and the high-speed particle image velocimetry (PIV) technology. Finally, the particle pulsation velocity is analyzed to reveal the particle motion mechanism of vertical pipe with dune model by using the fourier transform and wavelet transform. The results indicate that the minimum gas conveying velocity is reduced by installing the dune model, with a maximum reduction rate of 10.36 %, and the maximum reduction rate of power loss coefficient decreased is 11.56 %. At the same time, the particle concentration near the outside and inside wall of the pipe with dune is lower and higher than of without dune, and the particle axial velocities with dune are larger than the case of no dune, and the particle axial pulsation intensity with dune are larger than the case of no dune. Otherwise, the peak value of power spectrum of with dune is lower than that of no dune model in the low frequency region, and the wavelet fluctuation energy of low frequency has a great influence on the axial velocity of particles near the inside wall of pipe for the case of dune model.

Optimizing Thermomechanical Processing of Bimetallic Laminates.

Thermomechanical processing combining plastic deformation and heat treatment is a favorable way to enhance the performance and lifetime of bimetallic laminates, especially those consisting of metals, which tend to form intermetallic layers on the interfaces when produced using methods involving increased temperatures. The presented work focuses on optimizing the conditions of thermomechanical treatment for an Al + Cu bimetallic laminate of innovative design involving a shear-strain-based deformation procedure (rotary swaging) and post-process heat treatment in order to acquire microstructures providing advantageous characteristics during the transfer of direct and alternate electric currents. The specific electric resistivity, as well as microhardness, was particularly affected by the structural features, e.g., grain size, the types of grain boundaries, and grain orientations, which were closely related to the applied thermomechanical procedure. The microhardness increased considerably after swaging (up to 116 HV02 for the Cu components), but it decreased after the subsequent heat treatment at 350 °C. Nevertheless, the heat-treated laminates still featured increased mechanical properties. The measured electric characteristics for DC transfer were the most favorable for the heat-treated 15 mm bimetallic laminate featuring the lowest measured specific electric resistivity of 22.70 × 10-9 Ωm, while the 10 mm bimetallic laminates exhibited advantageous behavior during AC transfer due to a very low power loss coefficient of 1.001.

Transformer-customer relationship identification for low-voltage distribution networks based on joint optimization of voltage silhouette coefficient and power loss coefficient

Transformer-customer relationship identification for low-voltage distribution networks based on joint optimization of voltage silhouette coefficient and power loss coefficient

Unsteady conjugate heat transfer characteristics in hexagonal cavity equipped with a multi-blade dynamic modulator

PurposeThe transient analysis of the thermal response and frictional loss characteristics for flow-modulated conjugate heat transfer phenomena has been investigated in the present study. The flow domain is a partitioned cavity of a hexagonal structure equipped with a multi-blade flow modulator. The clockwise rotating blade is adiabatic and stirrers the internal flow along with the natural convection caused by the bottom heated floor of uniform heat flux. The conjugate behavior is introduced through the solid subdomains consisting of two brick-made partitions and one glass partition of uniform thickness. The material of the partition wall reflects the physical aspects of industrial applications. ApproachThe two-dimensional unsteady continuity, momentum, and energy equations are expressed in a non-dimensional form where the buoyant force is modeled through the Boussinesq approximation. The Arbitrary Lagrangian Euler (ALE) finite element is adopted to solve the moving mesh problem by formulating a free triangular discretization scheme. Parametric computational investigations are carried out for air as the working fluid (Pr = 0.71) and 3 different configurations of the rotating modulator while varying the other parameters, i.e., Reynolds number (Re) and Rayleigh number (Ra) for a fixed Biot number (Bi = 104). This dynamic mesh problem encompasses a wide range of parameters, i.e., (100 ≤Re≤ 103), and (104≤Ra≤ 106) for Bi = 104 to evaluate the thermodynamic response of the present thermo-fluid system. Various thermo-fluid system responses are visualized through the spatially average Nusselt number evaluated on the heated surface, system effectiveness, average thermal storage capacity, and frictional power loss of the flow domain. The thermal response is fragmented into individual responses in terms of component signal frequency by the Fast Fourier Transform (FFT) analysis. FindingsAccording to the current analysis, increasing the number of blades increases the rate of heat transfer by a negligible amount. On the other hand, among three different types of modulators, the three-blade modulator shows the lowest power loss coefficient and the lowest power instability. Thus, a three-blade modulator qualifies as the optimum design to impart external motion to the working fluid to introduce forced convection. LimitationsThis research has some scope for improvement. Future studies can be conducted on the improvement of blade designs, thickness, and size of the blades. Practical ImplicationsThe present study can shed light on the modeling of a better storage system where heat transfer and moisture control are integrated for the proper functioning of the storage, such as food storage, cold storage, garment inventory, etc. OriginalityThis study is original, and no previous research has been conducted considering the hexagonal domain and variation of the number of blades. ConclusionThe present study reveals that a modulator best serves its purpose at low Rayleigh and high Reynolds numbers. Moreover, the three-blade modulator has the lowest power loss coefficient and lowest power instability, making it the most suitable modulator to impart external excitation to the working fluid.

Gear and bearing power losses: from dip to minimum quantity lubrication

PurposeThis paper aims to address the influence of lubrication methods on operational characteristics, power losses and temperature behavior of gears and bearings. It contributes to the improvement of resource and energy efficiency of geared transmissions.Design/methodology/approachExperimental investigations were performed at a gear and bearing power loss test rig. Thereby, dip lubrication, injection lubrication with injection volumes from 0.05 to 2.00 l/min and minimum quantity (MQ) lubrication with an injection volume as little as 28 ml/h were considered. Measurements were evaluated in terms of no-load and load-dependent power loss, bulk temperatures and mean gear coefficients of friction.FindingsResults show strongly reduced no-load gear and bearing losses for lubrication methods with low lubricant quantities. Load-dependent losses are similar to conventional lubrication methods and tend to be lower at high speed. This is related to higher bulk temperatures, as the heat dissipation of lubrication methods with low oil quantities is limited. Limited thermal load limits were shown to be extended by LowLoss gears.Originality/valueSystematic investigations were conducted to evaluate the influence of dip, injection and MQ lubrication on power loss and temperature behavior of gears and bearings. The results of this study support further research on needs-based lubrication methods for gearboxes.

Turbine power loss during yaw-misaligned free field tests at different atmospheric conditions

This paper presents an analysis of the power loss of the upstream turbine for yaw misalignment depending on the inflow condition. High-quality experimental field data, obtained from a lidar wind profiler, met mast, GPS based yaw sensor, turbine data, and load data is used. To reduce the spreading of the power loss during yaw misalignment, the rotor effective wind speed is estimated using load data. Furthermore, the so-called power loss coefficient currently used in most engineering models, for yaw misalignment, is assessed at various inflow conditions. As main finding, the power loss coefficient increases for stronger vertical wind shear. In addition, there is an asymmetry with respect to the direction of the yaw misalignment that is enhanced by the wind shear exponent and the wind veer. Neglecting these two effects could result in in-conservative wake-steering decisions at stable stratification

The 0.38 kV “Green Network” Operating Modes Simulation with Multi-Level Unbalanced Power Consumption

The article considers modeling, parameters calculation and analysis of the rural electric networks operating modes, containing power take-off units with multi-level unbalanced power consumption. At the same time, a low-voltage electrical network section fragment is considered as a certain cluster in the structure of an extensive and heterogeneous 0.38 kV network. The model is made for a certain “green network” cluster variant, containing several nodes of highly unbalancing power consumption with a balancing device (BD). Connecting options the BD in various power take-off nodes, including power supply buses, are considered. As a balancing technical means, a device is presented that has a minimum resistance to zero-sequence currents with its power automatically control in a zero-sequence currents function. The main criteria for assessing the currents and voltages unbalanced level are the zero-sequence voltage unbalance coefficient, which characterizes the power quality, as well as the power loss coefficient, which characterizes the increase in power and energy losses in the unbalanced mode. Based on the developed method, algorithm and computer program “Unbalance”, the calculation was made and the changes characteristics in the studied indicators were constructed using modern the Matlab graphics editor technologies. The analysis of the studied indicators was carried out, on the which basis the most appropriate node in the electrical network model was determined, where the functioning efficiency of the balancing device will be the greatest.

Impact of Wi-Fi network coverage planning on the logistics objects’ location accuracy

The use of Wi-Fi networks to construct a system for determining the object’s location inside warehouses is the simplest and most cost-effective way of solving the logistical problems. The positioning in such a system is based on measuring the received signal strength level with the application of the lateration (trilateration) method to calculate the target’s coordinates. This method requires taking into account the electromagnetic environment in the room and the fulfillment of certain requirements for the construction of a network serving as a positioning tool. Incorrect access points placement in the premises leads to a significant positioning error, unacceptable in most cases of the system’s application. The article isdevoted to the improvement of the positioning accuracy by the network structure correction in accordance with the coverage and frequency planning. To implement the lateration algorithm for the determination of the distances between a mobile object and an access point, three radio wave propagation models were used, selected from a variety of similar models after the preliminary analytical and experimental studies. The power loss coefficients used in the models for the signal’s passing through partitions and floors were adapted to the configuration and features of the rooms in which the experiments were conducted.

On the issue of occurrence of fire-hazardous situations with unbalanced power consumption

The influence of phase current unbalance on the probability of occurrence of fire-hazardous situations in industrial premises that receive power in various power supply systems is considered. The theoretical prerequisites for the occurrence of fire-hazardous situations are described. It is shown that zero-sequence flows flowing through a neutral conductor in an unbalanced mode significantly heat it, which can lead to short circuits and conditions for the occurrence of fires. The results of studies of unbalanced conditions in Russia and abroad are presented. It is shown that the zero-sequence flows resulting from current unbalance lead to an increase in additional losses of active power and electrical energy. It is proved that additional heat losses caused by unbalanced power consumption can destroy the insulation of neutral and phase conductors, which is the main cause of short circuits and, as a result, fires. Based on the use of the Matlab graphical editor, dynamic characteristics of variations in phase and interphase currents and voltages, as well as the power loss coefficient, which characterizes the increase in heat losses, are constructed. The analysis of fires and their consequences for various objects in the Russian Federation is made. A computational unit has been developed in Matlab, which is used for calculating and plotting the dynamics of fires and their consequences over the investigated period of time. It is shown that the occurrence of fires and their consequences due to violations of the rules of operation of electrical installations occurs in any premises and sometimes reaches more than 20% of all possible causes of fires. Methods and technical means of minimizing zero-sequence currents as a means of preventing the occurrence of fire-hazardous situations are considered. The principle of operation of an automatically controlled shunt-symmetric device with a minimum resistance to zero-sequence currents is described.

Surface virtual texturing of the journal bearings of a three-cylinder ethanol engine

PurposeThis paper aims to numerically investigate the surface texturing effects on the main bearings of a three-cylinder ethanol engine in terms of the power loss and friction coefficient for dynamic load conditions.Design/methodology/approachThe mathematical formulation considers the Partir-Cheng modified Reynolds equation. The mass-conserving Elrod-Adams p-θ model with the JFO approach is used to deal with cavitation. A fluid-structure coupling procedure is considered for the elastohydrodynamic lubrication. Accordingly, a 3-D linear-elastic substructured finite element model obtained from Abaqus is appliedFindingsSimulations were carried out considering different dimple texture designs in terms of location, depth and radius. The results suggested that there are regions where texturing is more effective. In addition, distinct journal rotation speeds are studied and the surface texture was able to reduce friction and the power loss by 7%.Practical implicationsThe surface texturing can be a useful technique to reduce the power loss on the crankshaft bearing increasing the overall engine efficiency.Originality/valueThe surface texturing performance in a three-cylinder engine using ethanol as fuel was investigated through numerical experimentation. The results are supported by previous findings.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2019-0380/

Justification for Unscheduled Maintenance of Solar Panels Used as a Power Supply for Sprinkler Machines

The modern level of agriculture is described by the introduction of renewable energy sources. New generation sprinkler machines are being put into production, in the power system of which solar panels are used. One of the factors that negatively affect the performance of solar cells in an open field is their dusting, which is formed as a result of dust storms and wind. Cleaning of the battery panels is carried out in various ways: manual, semi-automatic and automatic. Dust cleaning is included in maintenance. (Research purpose) The research purpose is to determine the conditions for performing the maintenance, which consists in cleaning solar panels in the field. (Materials and methods) Theoretical (analysis, hypothesis design), empirical (observation, testing), experimental (ascertaining experiment) methods has been used during research. (Results and discussion) The article describes an introduced parameter for estimating the level of dusting. The power loss indicator shows the ratio of the power of the dusted module to the power of the clean module. Unscheduled maintenance is affected by the distance of the solar module from the repair point, the power of the solar module, the loss from dusting, the frequency of maintenance and cost indicators. (Conclusions) It has been found the dependence of maintenance period of the solar module of the sprinkler machine on the distance to the sprinkler machine, to the point of maintenance and repair, the power loss coefficient in case of dusting of the solar module, the cost of performing maintenance, as well as the frequency of maintenance. Article describes the boundaries of the choice of operating mode of the sprinkler between unscheduled maintenance for cleaning the solar module and the acceptance of additional power of the sprinkler power supply system according to the criterion of minimum operating costs.

Condensation flow at the wet steam centrifugal turbine stage

This paper investigates spontaneous condensation of wet steam in a centrifugal turbine by means of three-dimensional computational fluid dynamics. The flow field and aerodynamic characteristics of the wet steam in the centrifugal turbine are compared and analyzed by using the equilibrium steam and nonequilibrium steam models, respectively, where the latter applies the classical droplet nucleation theory and neglects velocity slip between the liquid phase and the gaseous phase. The state parameters of wet steam are described here based on the IAPWS’97 formulation. It is concluded that under the design condition, the mass flow rate, wetness fraction, and flow angle of the wet steam centrifugal turbine in the nonequilibrium steam model all change compared with the equilibrium steam model, with values of 4.4%, 0.5%, and 10.57%, respectively. Then the performance variation of the wet steam centrifugal turbine is analyzed under different steam conditions and different outlet back-pressure conditions. The results show that the change law of the mass flow rate, shaft power, and wetness fraction in the centrifugal turbine are basically identical in both models, and the mass flow rate, shaft power, wheel efficiency, and entropy loss coefficient of the centrifugal turbine in the nonequilibrium steam model are all higher than those in the equilibrium steam model, whereas the outlet wetness fraction is lower than that in the equilibrium steam model.

Complex power economic dispatch with improved loss coefficients

Standard economic dispatch (ED) of power generating units traditionally considers only real power generation and real power losses. Real power losses are often treated using the approximate B-loss coefficients, which are pre-calculated for a power system using load flow solution for certain base-case loading conditions. These coefficients do not assure accuracy for large deviations from the base-case loading conditions, as they are derived with few assumptions that assure an adequate accuracy for small deviations from the base-case conditions. Reactive power loss is unlike the real part as it does not have straightforward closed-form expressions for ED involving reactive power concerns. Inspired by old Kron’s loss formula derivations, this paper presents new original closed-form expressions for active and reactive power loss formulas, which are derived mainly to improve the deficiencies of the traditional ED formulations that use less accurate real power loss expressions and ignore reactive power demands and losses. The obtained coefficients are tested on four different-size test systems, and the results are compared with those obtained from solutions of both the load flow and B-coefficients for wide deviations from the base-case operating conditions. Then, the paper presents the mathematical model of the combined active-reactive complex power ED (CPED) including complex power losses using the new derived improved complex power loss coefficients that guarantee more accurate real power losses while considering reactive power concerns. The proposed CPED scheme using the new coefficients is then tested on the four test systems and compared for five costing methods of reactive power. Results and comparisons presented in this paper will show that the active and reactive power loss formulas can achieve more realistic results and accuracy for different system sizes and operating conditions, in addition to showing that reactive power consideration can significantly change outcomes of the standard ED.

Integrated Analysis of Influence of Multiple Factors on Transmission Efficiency of Loader Drive Axle

In this study, a loader drive axle digital model was built using 3D commercial software. On the basis of this model, the transmission efficiency of the main reducing gear, the differential planetary mechanism, and the wheel planetary reducing gear of the loader drive axle were studied. The functional relationship of the transmission efficiency of the loader drive axle was obtained, including multiple factors: the mesh friction coefficient, the mesh power loss coefficient, the normal pressure angle, the helix angle, the offset amount, the speed ratio, the gear ratio, and the characteristic parameters. This revealed the influence law of the loader drive axle by the mesh friction coefficient, mesh power loss coefficient, and speed ratio. The research results showed that the transmission efficiency of the loader drive axle increased with the speed ratio, decreased when the mesh friction coefficient and the mesh power loss coefficient increased, and that there was a greater influence difference on the transmission efficiency of the loader drive axle.

Renewable Energy Sharing Among Base Stations as a Min-Cost-Max-Flow Optimization Problem

Limited work has been done to optimize the power sharing among base stations (BSs) while considering the topology of the cellular network and the distance-dependent power loss (DDPL) in the transmission lines. In this paper, we propose two power sharing optimization algorithms for energy-harvesting BSs: the max-flow (MF) algorithm and the min-cost-max-flow (MCMF) algorithm. The two proposed algorithms minimize the power drawn from the main grid by letting BSs with power surpluses transmit harvested power to BSs with deficits. The MCMF algorithm has an additional DDPL cost associated with each transmission line. Hence, the MCMF algorithm shares the harvested power over shorter distances and loses less power during the transmission than the MF algorithm. Our numerical results show that for a fully connected cellular network, i.e., every pair of BSs can share power, with a moderate power loss coefficient per ${l}\,\,{{(}{ {\in }}\,\,{\mathbb {R}}^{{+}}{)}}$ meters of transmission line, the MCMF algorithm saves up to 10%, 22%, and 30% more main grid power than the MF algorithm for 5, 10, and 15 BSs uniformly distributed in a square area of ${l^{2}}$ square meters, respectively.

Deconstruct: A scalable method of as-built heat power loss coefficient inference for UK dwellings using smart meter data

Dwellings in the UK account for about 25% of global energy demand, of which 60% is space heating making this a key area for efficiency improvement. Dwelling UK Energy Performance Certificates (EPC) are currently based on surveyed data, rather than energy use monitoring. The installation of smart meters provides an opportunity to develop an EPC based on in situ dwelling thermal performance.This paper presents ‘Deconstruct’ – a method of estimating the as-built Heat Power Loss Coefficient (HPLC) of occupied dwellings as a measure of thermal performance, using just smart-meter and meteorological data. Deconstruct is a steady-state grey box building model combined with a data processing pipeline and a model fitting method that limits the effects of confounding factors. Smart meter data from 780 UK dwellings from the UK Energy Demand Research Project (EDRP), was used to calculate a median HPLC of 0.28 kW/°C (±15%). The stability of the estimate across multiple years of data with different weather and energy use was demonstrated. Deconstruct was found to be suitable for large scale inference of dwelling thermal properties using the UK's new smart metering data infrastructure.

Suboptimal control of circular cylinder wakes using Van der Pol oscillator

In the present study, we develop an energetically efficient suboptimal open-loop strategy to control the wake behind a circular cylinder in the laminar regime. The open-loop suboptimal controller is designed to resemble the feedback integral controller with reference to its dynamical behaviour. Energetic efficiency is measured using the power loss coefficient. The Van der Pol model for the evolution of lift force on the cylinder is chosen as the reduced-order model for the development of an open-loop suboptimal controller. The parameter estimation of the low- dimensional model is carried out using the results from the continuum based Navier - Stokes simulations. It is shown that a subspace identification method can be used to model the relationship between the inputs to the reduced-order model and the inputs to the higher-order computational fluid dynamic model. The development of the suboptimal control is realised by means of solving suitably formulated optimal tracking and regulator problems using the Pontryagin’s minimum principle. The resultant controller is found to be energetically efficient and also successful in the control of vortex shedding.

A theoretical model and experimental investigation to predict and evaluate cutting capability of turning center based on material removal rate

The present work proposes a theoretical model to test and evaluate cutting capability of turning center based on material removal rate (MRR). The cutting capability is deemed to the maximum MRR that a machine tool can provide. A linear relationship between spindle power and MRR has been presented, which is considered as the self-property of machine tool and is used to evaluate its cutting capability. A series of cutting tests were performed to verify the relationship. It is found that a cutting capability coefficient and a power loss coefficient can be defined to describe the cutting performance of machine tool. The floating error of the model is caused by power loss, cutting mechanism, and state of output power. Then, the testing process and evaluation method were specified. This model has been validated satisfactorily in several series of machine tool, such as two lathes of CAK50 and BRT50. It shows that the cutting capability coefficient of BRT50 is 0.026 with the corresponding MRR 420.44 cm3/min, and the power loss coefficient is 0.165 which means the idle run loss power is less than 0.165 kW. The two values show that the cutting performance of BRT50 is excellent than its previews type of CAK50. This method would also be applied as the acceptance basis of machine tool. In addition, two quick testing strategies on cutting capability and some restrictions such as machining chatter and surface quality have been presented.

The effect of macro-bending on power confinement factor in single mode fibers

One of the methods to determine the macro-bending effect in a single mode fiber is by calculating its power loss coefficient. We describe an alternative method by using the equation of fractional power in the fiber core. Knowing the fiber parameters such as its core radius, refractive indexes, and operating wavelength; we can calculate the V-number and the fractional power in the core. Because the value of the fiber refractive indexes and the propagation constant are affected by bending, we can calculate the value of the fractional power in the core as a function of the bending radius. We calculate the fractional power in the core of an SMF28 and SM600 fiber and, to verify our calculation, we measure its transmission loss using an optical spectrum analyzer. Our calculations and experimental results showed that for SMF28 fiber, there is about 4% power loss due to bending at 633 nm, about 8% at 1310 nm, about 20% at 1550 nm, and about 60% at 1064 nm. For SM600 fiber, there is about 6% power loss due to bending at 633 nm, about 11% at 850 nm, and this fiber is not suitable for operating wavelength beyond 1000 nm.

Performance characteristics of a new hybrid solar cooker with air duct

A new hybrid solar box cooker (SBC) has been developed and tested for thermal performance evaluation in climatic condition of western Uttar Pradesh, India. The uniqueness of new box cooker is an integrated trapezoidal duct and its other integrated elements. The objective of the study is to enhance the heat transfer rate and to reduce the cooking timings by consumption of minimum heat energy. For this purpose, a 200 W halogen lamp has been placed inside the duct to enhance the heat transfer. Besides this, 450 of small hollow balls of copper have also been used to improve thermal performance of SBC especially on forced convection mode. The performances testing have been carried to evaluate the thermal efficiency, figures of merit (F1 and F2), cooking power, heat transfer and overall heat loss coefficient. After completion of experiments, thermal efficiency of SBC has been observed 45.11%, cooking power is estimated to be 60.20 W and overall heat loss coefficient is obtained around 6.01 W/m2 C. Results shows that the present design follow the BIS standards and can cook almost edibles in poor ambient conditions by consuming only 210 W. Discussion has also been made on the significance of the use of copper balls, fan and halogen lamp over the performance of SBC. The present solar cooker has been found as first kind of SBC which can efficiently perform on forced convection in any type of climatic conditions.