Maximum Efficiency Increase Research Articles

Analysis and Optimization of a Vaned Diffuser in a Mixed Flow Pump to Improve Hydrodynamic Performance

Hydrodynamic analysis and an optimization of a vaned diffuser in a mixed-flow pump are performed in this work. Numerical analysis is carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations using the shear stress transport turbulence model. A validation of numerical results is conducted by comparison with experimental data for the head, power, and efficiency. An optimization process based on a radial basis neural network model is performed with four design variables that define the straight vane length ratio, the diffusion area ratio, the angle at the diffuser vane tip, and the distance ratio between the impeller blade trailing edge and the diffuser vane leading edge. Efficiency as a hydrodynamic performance parameter is selected as the objective function for optimization. The objective function is numerically assessed at design points selected by Latin hypercube sampling in the design space. The optimization yielded a maximum increase in efficiency of 9.75% at the design flow coefficient compared to a reference design. The performance curve for efficiency was also enhanced in the high flow rate region. Detailed internal flow fields between the reference and optimum designs are analyzed and discussed.

Axial-Flow Ventilation Fan Design Through Multi-Objective Optimization to Enhance Aerodynamic Performance

This paper presents an optimization procedure for axial-flow ventilation fan design through a hybrid multiobjective evolutionary algorithm (MOEA) coupled with a response surface approximation (RSA) surrogate model. Numerical analysis of a preliminary fan design is conducted by solving three-dimensional (3-D) Reynolds-averaged Navier-Stokes (RANS) equations with the shear stress transport (SST) turbulence model. The multiobjective optimization processes are performed twice to understand the coupled effects of diverse variables. The first multiobjective optimization process is conducted with three design variables defining stagger angles at the hub, mid-span, and tip, and the second is conducted with five design variables defining hub-to-tip ratio, hub cap installation distance, hub cap ratio, and the stagger angles at the mid-span and tip. Two aerodynamic performance parameters, the total efficiency and total pressure rise, are selected as the objective functions for optimization. These objective functions are numerically assessed through 3-D RANS analysis at design points sampled by Latin hypercube sampling in the design space. The optimization yields a maximum increase in efficiency of 1.8% and a 31.4% improvement in the pressure rise. The off-design performance is also improved in most of the optimum designs except in the region of low flow rate.

Key Environmental Innovations

This paper is based on empirical research on a taxonomy of technological environmental innovations. It draws on a databank with over 500 examples of new technologies (materials, products, processes and practices) which come with benign environmental effects. The approaches applied to interpreting the datasets are innovation life cycle analysis, and product chain analysis. Main results include the following: 1. Innovations merely aimed at eco-efficiency do in most cases not represent significant contributions to improving the properties of the industrial metabolism. This can better be achieved by technologies that fulfill the criteria of eco-consistency (metabolic consistency), also called eco-effectiveness. 2. Ecological pressure of a technology is basically determined by its conceptual make-up and design. Most promising thus are technologies in earlier rather than later stages of their life cycle (i.e. during R&D and customisation in growing numbers), because it is during the stages before reaching the inflection point and maturity in a learning curve where technological environmental innovations can best contribute to improving ecological consistency of the industrial metabolism while at the same time delivering their maximum increase in efficiency as well. 3. Moreover, environmental action needs to focus on early steps in the vertical manufacturing chain rather than on those in the end. Most of the ecological pressure of a technology is no rmally not caused end-of-chain in use or consumption, but in the more basic steps of the manufacturing chain (with the exception of products the use of which consumes energy, e.g. vehicles, appliances). There are conclusions to be drawn for refocusing attention from downstream to upstream in life cycles and product chains, and for a shift of emphasis in environmental policy from regulation to innovation. Ambitious environmental standards, though, continue to be an important regulative precondition of ecologically benign technological innovation.

Improvement of the efficiency of plasma display panels by combining waveform and cell geometry design

A two-dimensional (2D) self-consistent simulation model is used to investigate the effect of several different sustaining voltage waveforms on the luminous efficiency of plasma display panel (PDP) cells. We first show that such a model can reproduce all the major trends of experimental display measurements concerning the effect of waveform on PDP efficiency. We then use this model to put forth new high-efficiency PDP designs. A new sustaining waveform combining assistant voltage pulses with asymmetric pulse driving results in /spl sim/25% maximum increase in efficiency within the voltage margin of the cell. A new plasma display using combined waveform and electrode designs is determined to have a maximum increase in efficiency of /spl sim/40%.

04/02673 HTI coal conversion technologies in China: Zhou, P. and Lee, T. L. K. Preprints of Symposia — American ChemicalSociety, Division of Fuel Chemistry, 2003, 48, (1), 155–157

A series of composite proton-exchange membranes have been prepared via sol-gel modification of commercial Nafion membranes with [N-(2-aminoethyl)-3-aminopropyl]trimethoxysilane. The structure and physico-chemical properties (water uptake, ion-exchange capacity, vanadyl ion permeability, and proton conductivity) of the prepared composite membranes have been studied as a function of the precursor loading (degree of the membrane modification). If the amount of the precursor is below 0.4/1 M ratio of the amino groups of the precursor to the sulfonic groups of Nafion, the composite membranes exhibit decreased vanadium ion permeability while having relatively high proton conductivity. With respect to the use of a non-modified Nafion membrane, the performance of the composite membrane with an optimum precursor loading in a single-cell vanadium redox flow battery demonstrates enhanced energy efficiency in 20–80 mA cm−2 current density range. The maximum efficiency increase of 8% is observed at low current densities.

Magnetic Enhancement of Ultraviolet Radiation Efficiency of Low-Pressure Hg-Ar Discharge

Application of an axial magnetic field has been found to enhance the efficiency of production of resonance radiation in a low-density Hg-Ar discharge. A specialized experimental system was developed to study this effect, and a maximum efficiency increase of about 7% was observed at B = 530 gauss. The temperature for peak efficiency was observed to shift to higher temperatures in the presence of the magnetic field, as predicted by Richardson and Berman.

Improvement of traveling-wave tube efficiency through collector potential depression

This paper describes the design of single-stage and double-stage collectors which can be operated at potentials. When these single-stage and double-stage collectors were used in conjunction with a traveling-wave amplifier, over-all efficiences of 46 and 57 per cent were obtained, respectively. The maximum increase in efficiency which can be obtained by the use of depressed collectors having one to three electrodes is calculated for various traveling-wave tube design parameters.