Application of Exergoeconomics to the Analysis and Optimization of Process Systems

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New Type of Basic Functions of FEM in Application to Solution of Inverse Heat Conduction Problem

The work presents the application of heat polynomials for solving an inverse problem. The heat polynomials form the Treffetz Method for non-stationary heat conduction problem. They have been used as base functions in Finite Element Method. Application of heat polynomials permits to reduce the order of numerical integration as compared to the classical Finite Element Method with formulation of the matrix of system of equations.     

Development of Wavelet Image Compression Technique to Particle Image Velocimetry

IntroductionParticle Image Velocimetry (PIV) is a non-intrusiveflow visualization technique and is now firmly established as a powerful fluid dynandcs tool to measure flowvelocity in the area of fluid mechanics. Even moreimportant than this remarkably improved performance ofthe PIV technique, is its unique ability to captureinstantaneous full-field flow and thus to allow thequantitative detection of spahal stfuctllres in unsteadyflows, which is not possible with other experimentaltechniques…     

Experimental Investigations of Micro Air Injection to Control Rotating Stall

Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be aneffective method to delay the inception of rotating stall in a low speed axial compressor.Considering the practicalapplication a new type of micro injector was designed and described in this paper,which was imbedded in thecasing and could be moved along the chord.In order to verify its feasibility to other cases,such as high subsonicaxial compressor or centrifugal compressor,some other cases have been studied.Experimental results of the samelow speed axial compressor showed that the new injector could possess many other advantages besides success-fully stabilizing the compressor.Experiments performed on a high subsonic axial compressor confirmed the ef-fectiveness of micro air injection when the relative velocity at the blade tip is high subsonic.Meanwhile in orderto explore its feasibility in centrifugal compressor,a similar micro injector was designed and tested on a lowspeed centrifugal compressor with vaned diffuser.The injected mass flow was a bit larger than that used in axialcompressors and the results showed micro injection could also delay the onset of rotating stall in the centrifugalcompressor.     

Application of Mechanical Similarity Laws to the Collection Efficiencies of Geometrically Types of Uni—Flow Cyclone Dust Collectors

From the mechanical similarity point of view, the centrifugal effect, Ar, and the Stokes number, St, as well as the Reynolds number, Re_c for the motion of solid particles in the cyclone are the relevant parameters. In order to apply these similarity laws for the prediction of the characteristics of the collection efficiency, ηc, geometrically similar types of uni-flow cyclones were used. The body diameters of the cyclones were D_1=30, 50, 69 and 99 mm, respectively. The feed particle concentration of the fly-ash particles was up to C_o = 60g/m~3. From the experimental results: (1) the pressure drop, △pc, in the cyclones was a function of not only the Reynods number, Re_c, but also the body diameter, D_1; (2) the collection efficiency, η_c, did not always increase with decreasing body diameter but there existed an optimal body size; (3) application of the mechanical similarity laws to the collection efficiency was not always sufficient for estimating the collection efficiency, since the feed particle concentration was an additional important factor; (4) a new parameter which was the ratio, E_(pf), of the apparent separation energy, W_p, of the solid particles to the energy loss, E_c, of the gas flow in the cyclone was introduced for discussing the collection efficiency; (5) Fuchs theory, used to estimate the collection efficiency, was examined. Fuchs theory may be applied for high feed particle concentration.     

The following announcement is recommended to the reader Bulletin of National Natural Science Foundation of China

Bulletin of the National Natural Science Foundation of China is an informational as wellas a scientific periodical in Chinese(each issue contains table of contents and abstractsin English)published by the National Natural Science Foundation of China(NSFC).Thepurpose of this publication is to disseminate its work to the society,carry comments on     

Application of Numerical Simulation Method to Predict the Performance of Wave Energy Device with Impulse Turbine

This paper presents the work carried out to predict the behavior of a 0.6 m Impulse turbine with fixed guide vanes with 0.6 hub-to-tip (H/T) ratio under real sea conditions. In order to predict the true performance of the actual Oscillating Water Column (OWC), the numerical technique has been fine tuned by incorporating the compressibility effect. Water surface elevation verses time history based on Pierson Moskowitz Spectra was used as the input data. Standard numerical techniques were employed to solve the non-linear behavior of the sea waves. The effect due to compressibility inside the air chamber and turbine performance under unsteady and irregular flow condition has been analyzed numerically. Considering the quasi-steady assumptions, unidirectional steady flow experimental data was used to simulate the turbine characteristics under irregular unsteady flow conditions. The results show that the performance of this type of turbine is quite stable and efficiency of air chamber and the mean conversion     

Application of nickel–lanthanum composite oxide on the steam reforming of ethanol to produce hydrogen

Nickel–lanthanum composite oxides, LaNiO_x, were used for steam reforming of ethanol (SRE). The composite oxides (with 3:1, 1:1, 1:3 M ratios, assigned as 3La–1Ni, 1La–1Ni, and 1La–3Ni, respectively) were prepared by co-precipitation-oxidation (PO) and assisted with ultrasonic irradiation (240 W). Meanwhile, the as-prepared 1La–1Ni sample was further calcined at 300 and 700 °C for 2 h (assigned as C300 and C700). All samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and temperature programmed reduction (TPR). Catalytic activities towards the SRE reaction were tested from 300 to 450 °C in a fixed-bed reactor. The study focused on deriving optimized composition of composites and compared the effect on the reduction pretreatment under 200 °C [assigned with (H)]. The results indicated that the ethanol conversion reached completion around 325 °C for the 1La–1Ni(H) sample while it required 400 °C for the 1La–1Ni sample with a minor CO distribution for both samples under an H₂O/EtOH molar ratio of 13 and 22,000 h⁻¹ GHSV. The yield of hydrogen (YH₂$Y_{{\text{H}}_2}$) approached 5.2 around 375 °C for the 1La–1Ni(H) sample.     

Prediction of condensation characteristics of alternatives to R-502 inside air–refrigerant enhanced surface tubing

In this paper, an experimental study on the heat transfer characteristics of two-phase flow condensation of alternative azeotropic refrigerant mixtures to R-502, on air/refrigerant horizontal enhanced surface tubing, is presented. The condensation data indicated that the heat transfer coefficient on the blend R-408A has the highest heat transfer rate among the blends under investigation. The condensation data also showed that R-502 and R-407B have similar heat transfer rates when plotted against the refrigerant mass flow rate. It also can be observed that, as the mass flux increases, heat transfer coefficient increases. Correlations were proposed to predict the heat transfer characteristics such as average heat transfer coefficients, as well as pressure drops of alternatives to R-502; such as R507, R404A, R407B and R408A in two-phase flow condensation inside enhanced surface tubing. In addition, proposed correlations were found to fairly predict the two-phase flow heat transfer condensation data.     

Correlation models of diffuse solar-radiation applied to the city of São Paulo,Brazil

Measurements of global and diffuse solar-radiation, at the Earth's surface, carried out from May 1994 to June 1999 in São Paulo City, Brazil, were used to develop correlation models to estimate hourly, daily and monthly values of diffuse solar-radiation on horizontal surfaces. The polynomials derived by linear regression fitting were able to model satisfactorily the daily and monthly values of diffuse radiation. The comparison with models derived for other places demonstrates some differences related mainly to altitude effects.     

Comparison of mode-Ⅰ crack propagation of tube subjected to internal hydrogen static and detonation loading

An elaborate numerical model with progressive damage and failure and fluid-structure coupling was developed to study the crack propagations of tubes under hydrogen static and detonation loads. The numerical model was verified with experiment in terms of crack behaviors and fracture patterns. The tube responses, crack propagations, pressure histories, crack lengths and speeds as well as the energy storages were obtained and analyzed in detailed. It was found the static load case has higher stored energy inside the tube, which causes the larger crack length and speed, as well as the severer bending deformation of tube. The forward crack first run faster under detonation load, but it will be caught up by the backward crack in the late period. The crack growths are incremental under both types of loads. However, the crack growth under detonation load has certain regular patterns, where the oscillating crack speed has a dominant frequency that can be calculated by the proposed formula. Moreover, the quantitative relationship between detonation load speed and the incremental crack growth length was revealed, which is fundamentally and practically useful.     

A novel approach to analyse incomplete design of experiments – Application to the study of the influence of operational parameters on the performance of a solid oxide fuel cell based micro-combined heat and power system

A SOFC based commercial μ-CHP system is characterized by Electrochemical Impedance Spectroscopy, using a 2⁴ full factorial test plan. The studied factors are: natural gas input power, ratio between oxygen and natural gas flow rates at the reformer inlet, stack average temperature and average operating cell voltage. Six replicates are performed in the domain centre. We performed equivalent circuit analysis and extracted three responses from each spectrum: ohmic resistance together with the two parameters of the CPE used in the model.However, one of our experiment is an outlier. To circumvent this problem, two methods described in the literature were applied: recalculation of missing response and introduction of a dynamic variable. Due their unsatisfactory results, we developed an innovative approach combining an iterative fitting of the multilinear model underlying any factorial design and an N-way ANOVA. Our method is successfully validated on the different 2⁴⁻¹ fractional designs deriving from the full factorial one.The only impacted response is the ohmic resistance. It increases as temperature decreases or as applied voltage increases. It is impacted by a strong synergistic effect of pressure and temperature and a compensating effect of pressure and applied voltage. No significant quadratic effect is observed.     

Thermoeconomic modeling and parametric study of hybrid SOFC–gas turbine–steam turbine power plants ranging from 1.5 to 10 MWe

Detailed thermodynamic, kinetic, geometric, and cost models are developed, implemented, and validated for the synthesis/design and operational analysis of hybrid SOFC–gas turbine–steam turbine systems ranging in size from 1.5 to 10 MWe. The fuel cell model used in this research work is based on a tubular Siemens-Westinghouse-type SOFC, which is integrated with a gas turbine and a heat recovery steam generator (HRSG) integrated in turn with a steam turbine cycle. The current work considers the possible benefits of using the exhaust gases in a HRSG in order to produce steam which drives a steam turbine for additional power output. Four different steam turbine cycles are considered in this research work: a single-pressure, a dual-pressure, a triple pressure, and a triple pressure with reheat. The models have been developed to function both at design (full load) and off-design (partial load) conditions. In addition, different solid oxide fuel cell sizes are examined to assure a proper selection of SOFC size based on efficiency or cost. The thermoeconomic analysis includes cost functions developed specifically for the different system and component sizes (capacities) analyzed. A parametric study is used to determine the most viable system/component syntheses/designs based on maximizing total system efficiency or minimizing total system life cycle cost.     

Application of Optimization Technology for Ratio of Air to Fuel Combining Feedforward with Feedback in Heating Furnace

The thermal characteristics of heating furnace using gas as fuel are discussed in detail in this paper. Combining the technique of fuzzy control with calorific value of feedforward and oxygen concentration of waste gas feedback, the optimization model for ratio of air to fuel is developed and utilized in practice. According to the practical operation, the model can effectively control the oxygen concentration of waste gas, enhance the quality of product and decrease the fuel consumption.     

A new approach to micro-level energy planning—A case of northern parts of Rajasthan,India

The gap in demand and supply of energy can be met by optimal allocation of energy resources. In developing countries like India, demand for energy is constantly rising. Conventional energy supply options have failed to cope up with this increase. Therefore, it is required to plan the allocation at micro-level also. A micro-level energy planning thus becomes pragmatic for sustainable development. Micro-level energy planning aims at optimal resource allocation thereby reducing dependence on commercial energy and reducing associated environmental hazards, and opening new avenues for employment generation.This paper considers energy consumption patterns in northern part of Rajasthan, India to arrive at micro-level plan using multi-objective goal programming approach. Optimal energy resource allocation for various end-uses has been deduced. In conventional micro-level energy planning the region is defined as village or taluk or district. Inter-village energy mix have been attempted to define region for energy planning in the present text. The results of inter-village mix show that the energy mix of two villages at micro-level results in better utilization of available energy sources compared to an individual village. The methodology suggested gives the flexibility of defining a region to the energy planner.     

Application of a k-ε Model to Heat Transfer in Impinging Flows

Local heat transfer is predicted in turbulent axisymmetric jets, impinging onto a flat plate. A non-linear k-e model is used, in which both the constitutive law for the turbulent stresses and the transport equation for the turbulent dissipation rate e have an important contribution in the improved heat transfer predictions. The shape of the Nusselt number profiles, expressing dimensionless heat transfer, as well as the stagnation point value, are well predicted for different distances between the nozzle exit and the plate. Accurate flow field predictions are the basis for good heat transfer predictions. For a fixed Reynolds number, the influence of the nozzle-plate distance is well captured. For a fixed distance, the influence of the Reynolds number is correctly reproduced. Comparisons are made to a low-Reynolds standard k-e model and the v2-f model. A thorough discussion is found in [4]. Only a summary of those results is discussed here, while some new results are also presented.