Economical Comparisons Research Articles

Economical Comparisons of Interconnection Technology for Asynchronous AC Power Grids

There is growing interest in grid connections between different micro grids, countries, and the selection of interconnection method should be based on an economic analysis. This paper analyses the economics of VFT (Variable Frequency Transformer) and HVDC (High Voltage DC) and proposes an optimal grid interconnection method. The economic evaluation was conducted based on the new investment cost depending on the capacity of the facilities needed for the grid connection, and the feasibility study was carried out to find out which method is more advantageous economically.

A Review of Battery Energy Storage Systems for Residential DC Microgrids and Their Economical Comparisons

In residential DC microgrids integrated with renewable energy sources (RESs), prosumer’s power generation and load demand are not matched due to inherent sporadic nature of RESs. One way to address this issue is to add an energy storage system (ESS). The ESS is useful in fluctuation suppression, load following, time shifting, peak shaving, energy saving and emergency power. Moreover, an ESS will resolve overvoltage issue in utility grids due to exported surplus energy from residential RESs. Therefore, this paper will review battery ESSs that can be used in residential DC microgrids. Three major battery chemistries, i.e. leadacid, lithium ion (Li-ion) and Zinc bromine (ZB) are reviewed. The analysis of the levelized cost of energy reveals that lead-acid batteries are economically less competitive compared with Li-ion and ZB batteries in residential DC microgrid applications.

Date palm seed as suitable filler material in glass–epoxy composites

Natural materials as polymer fillers are proposed for applications in different industries due to their good prices, acceptable mechanical behaviors, and their improved environmental footprint. The aim of this work is to study the mechanical characteristics of glass fiber (G–E) filled with date seed (DS) as potential polymer filler. DS is produced during the processing of fruit plant (Phoenix dactylifera L.). G–E hybrid composite is reinforced with angle-ply [(± 45)4]S using DS powder by applying the semi-automatic technique (SAT). The effects of DS filler on wear rate (Ks) and impact energy at different efficient parameters were investigated. Technical and economical comparisons between the DS filler and inorganic fillers [e.g., silicon carbide (SiC), aluminum oxide (AL2O3)] were carried out. Surface inspection was conducted using scanning electron microscope (SEM) and the nature of reinforcement was investigated using Fourier-transform infra red (FTIR). The results revealed that the addition of 10% DS reinforcement to G–E improved the wear resistance rate and increased toughness by about 71% and 80%, respectively. FTIR results indicated that a physicochemical interaction has occurred between G–E and the organic DS filler contact surfaces. Finally, G–E reinforcement optimization was carried out by minimizing the wear rate, determining the optimum filler load and type, normal load, and abrasive size. The obtained results showed the effectiveness of the DS as filler for G–E fibers from technical and economical point of views.

ESTIMATION OF LONG-TERM INVESTMENT PROJECTS WITH ENERGY-EFFICIENT SOLUTIONS BASED ON LIFE CYCLE COSTS INDICATOR

The starting stage of the tender procedures in Russia with the participation of foreign suppliers dictates the feasibility of the developments for economical methods directed to comparison of technical solutions on the construction field. The article describes the example of practical Life Cycle Cost (LCC) evaluations under respect of Present Value (PV) determination. These create a possibility for investor to estimate long-term projects (indicated as 25 years) as commercially profitable, taking into account inflation rate, interest rate, real discount rate (indicated as 5 %). For economic analysis air-blower station of WWTP was selected as a significant energy consumer. Technical variants for the comparison of blower types are: 1 - multistage without control, 2 - multistage with VFD control, 3 - single stage double vane control. The result of LCC estimation shows the last variant as most attractive or cost-effective for investments with economy of 17,2 % (variant 1) and 21,0 % (variant 2) under adopted duty conditions and evaluations of capital costs (Cic + Cin) with annual expenditure related (Ce+Co+Cm). The adopted duty conditions include daily and seasonal fluctuations of air flow. This was the reason for the adopted energy consumption as, kW∙h: 2158 (variant 1),1743...2201 (variant 2), 1058...1951 (variant 3). The article refers to Europump guide tables in order to simplify sophisticated factors search (Cp /Cn, df), which can be useful for economical analyses in Russia. Example of evaluations connected with energy-efficient solutions is given, but this reference involves the use of materials for the cases with resource savings, such as all types of fuel. In conclusion follows the assent to use LCC indicator jointly with the method of determining discounted cash flows, that will satisfy the investor’s need for interest source due to technical and economical comparisons.

Comparisons between energy carriers' productions for exploiting renewable energy sources

This paper provides comparisons between three different energy carriers that could be produced within areas having cheap electricity. The comparisons were made in terms of the technological efficiencies and economical viabilities for five different scenarios. Economical comparisons were based on IRR (internal rate of return) calculations and sensitivity analyses covering different independent variables such as carbon tax, electricity price and capital costs. It was discovered that SNG (synthetic natural gas) and LNG (liquid natural gas) production is economically uncompetitive compared to ammonia and methanol productions. Ammonia production would be the better choice if there were a carbon tax between 0 and 83EUR/t of CO2. At a carbon tax higher than 83EUR/t, methanol production would be the more economical option.

Comparative investigation of the costs and performances of torsional irregularity structures under seismic loading according to TEC

The poor seismic performance of reinforced concrete buildings during the latest earthquakes has become a serious issue in the building industry in Turkey. This case, designing new buildings without structural irregularities against earthquake loads reveals to be quite significant. This study mainly is focused on the effects of different torsional irregularities on construction costs and earthquakes performance of reinforced concrete buildings. In that respect, structural torsional irregularities are investigated based on the Turkish Earthquake Code. The study consists of major eight main parametric models. In this models consist of totally 49 models together with the variations in the number of storey. With this purpose, the earthquake performances and construction costs (especially steel quantities) of reinforced concrete buildings which having different structural torsional irregularities were obtained with the help of Sta4-CAD program. Each model has been analyzed by both the methods of equivalent earthquake loading and dynamic analysis. The obtained results reveal that the model-1 which has lower torsional irregularity coefficient shows the best earthquake performance owing to its regular plan geometry. Also, economical comparisons on costs of the torsional irregularity are performed, and results-recommendations are given.

Economic value analysis of Galanthus sp. in Turkey

The economic value analysis has been carried out by detecting the production, good and service value functions of Galanthus sp. in Turkey. In the analyses, economical valuation techniques, group comparisons, ecological and socio-cultural valuation criteria had been used. Total flow value for goods and service functions of Galanthus sp. had been calculated as $68/year/unit per Galanthus sp. and the potential flow rate per Galanthus sp. had been estimated at $137/year. The total value of Galanthus sp. had been calculated as $544,000,000/year for annual export of 8 million Galanthus. When the positive added value, which was included in ecological and sociological processes and created by non-pecuniary values and the wealth and heritage value were added, it was easily seen that the economic value of the Galanthus was considerably high. Moreover, it had been determined that especially, the medical source value ($23/year) was a crucial factor among this value. DOI: http://dx.doi.org/10.3329/bjb.v43i1.19748 Bangladesh J. Bot. 43(1): 65-71, 2014 (June)

Prospective of Applications of Superconducting Fault Current Limiters in Chinese Power Grids

China is home to the world's second largest electric power industry, and has plans to modernize its power network into a robust and efficient grid. Short-circuit fault current control becomes increasingly important to the power grid modernization process. Superconducting fault current limiters (SFCLs) may contribute significantly to the solution to the fault current problem. This paper discusses the demands and challenges in the application of SFCLs to Chinese power grids, from the perspective of the present situation and taking into consideration future developments of the electric power industry. Technical and economical comparisons with conventional fault current control technologies are presented

Effects of Relative Volatility Ranking on Design and Control of Reactive Distillation Systems with Ternary Decomposition Reactions

Design and control of reactive distillation systems of ternary decomposition reactions with two different relative volatility rankings, IK ↔ LK + HK and HK ↔ LK + IK, have been explored. Systems with intermediate boiling reactant have a behavior that is similar to that of the quaternary system with intermediate boiling reactants, if not simpler. Systems with heavy reactant are quite different. Two possible flowsheets (two-column and one-column configurations) have been discussed. The two-column flowsheet is workable for a wide range of chemical equilibrium constants. The one-column configuration is feasible for systems with high chemical equilibrium constants. Economical comparisons reveal that the one-column configuration is preferred for systems with large equilibrium constants while the two-column configuration is more economical in the region of low equilibrium constants. For the control of nonlinear reactive distillation systems, fast measurement (temperature measurement) is essential for tight control. Control performance deteriorates if significant measurement delay is present. Thus, parallel cascade control offers an attractive alternative for the control of reactive distillation systems in an offset free manner.

Economical Supporting System Design for Laying Hen Poultry Houses

Poultry houses should be economical and should demonstrate adequate resistance and safety. In poultry houses, generally truss systems or frames are used as the supporting systems and reinforced concrete and steel sections are used as construction materials. In this study, 45 poultry houses from 25 commercial enterprises within the study area were selected as the material. They were evaluated based on their capacities, system designs and construction material used in their supporting system. Initially, construction materials selected for supporting systems and their dimensions were determined and their structural sufficiencies were evaluated. Then, seven model poultry house were developed by taking the current conditions of the enterprises and related literatures into consideration. Three different material combinations were considered for supporting system of each model developed: Steel truss - reinforce d concrete column, steel truss - steel column and frame system. Thus, total of 21 different combinations for 7 models were evaluated. Depending on supporting system characteristics, load analysis and statical calculations were carried out for each model and supporting systems were dimensioned based on results obtained from statical solutions and economical comparisons were carried out among them. It is believed that results of this study may contribute significant perspectives for the project engineers in poultry housing systems.

Some economical comparisons between aluminium and copper squirrel cages

Serious thought is being given to the use of die cast copper cages; this is why the cost of copper for cage manufacture might become reasonable, even for small motors. Eight optimum designs are presented; two different powers, two different objective functions (initial price or total price including the price of future losses), and two cage materials (copper and aluminium) have been considered. Various components of prices are compared.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A combined RO/freezing system to reduce inland rejected brine

A combined RO/DCF system is proposed as an efficient system which would reduce the problem of the disposal of the rejected brine from inland desalination plants. Governing equations and thermodynamic relations are shown. Economical and energy comparisons between the combined system and separate RO and DCF units for 200 m 3/h are presented. Results showed that the combined system can reduce the energy consumption by about 13 percent and 17 percent compared to separate RO and DCF plants respectively. The combined system can reduce the rejected brine by over 90 percent of that of separate RO plant at the same water production.

Hydrog�nation �lectrochimique du dinitronaphtal�ne: comparaison avec le proc�d� catalytique

The electrochemical reduction of dinitronaphthalene to produce diaminonaphthalene has been optimized. The synthesis of diaminonaphthalene by the electrolysis of a suspension of dinitronaphthalene in sulphuric acid with a titanium salt gives a yield and purity similar to the synthesis by catalytic hydrogenation. Technical and economical comparisons of the two processes show that for large capacities (several hundred tons per year), reduction by catalytic hydrogenation is more feasible. However, for smaller quantities (several tons per year) the flexibility of exploitation by electrolysis has economic advantages.

Large Enterprise Process Control Policy

Selecting and priority rating of future computer control applications is an acute problem in many process industry companies. To facilitate the selection between potential applications and implementation of alternatives simple decision rules have been constructed. The procedure takes into account company goals, economical comparisons between alternatives, the limits of available resources, and technical progress in the control field.

Fatigue Failure Distributions for Ball Bearings

High reliability requirements of aircraft gas turbine mainshaft ball bearings necessitate reliable methods for estimating fatigue lives in the early failure region of the life dispersion. Economical and rapid comparisons of surface fatigue lives of modern track materials demand extrapolation from limited numbers of rig results, using a statistical distribution which gives reasonable rectification of early failures. The investigation indicates that lognormal distributions are more satisfactory than Weibull distributions for low failure probabilities.

Peltojen salaojituksesta

In Finland the underdrainage of fields has been of small importance, although the need of draining the soil is great. The weightiest reason for this are the high costs of underdrainage which for ex. in 1950 made on an average 60.000 mks per hectare. The costs depend principally on the lenght of drains per hectare, which in Finland is principally considered to be dependent on the kind of soil. Table No. 1 shows the costs of drainage and the number of drains per hectare, in different soils. Besides the costs also technical restrictions have been an impediment to the advance of drainage in our country. Among other things the production of tile-pipes is quite insufficient. The costs of drainage in heavy clay are divided according to table No. 2. Examinations as to the possibilities of reducing in some respect the said costs have resulted in the conclusion that these possibilities are very small at the most expensive point, viz. the tile- pipes 45%. The greatest saving possibilities are to be found in the digging costs. Big digging machines may not have a decisive influence on the question in Finland, this fact being due to the high rate of interest and the scarcity of capital. It would be desirable to develop inexpensive digging machines for underdrainage, because in Finland the season suitable for drainage is very short. A great obstacle in this respect is, however, the fact that the demands for depth of the drains now in force in Finland are so great —in South-Finland the digging depth is 125 and in North Finland 145 cm. In the article the possibilities of reducing the depth of the drains are examined, and according to the experiences and researches made in Sweden, such possibilities could be imagined. In order to further a rapid advance of underdrainage in Finland cheaper methods of drainage than the tile and the board drainage now in use ought to be adopted. Also the possibilities offered by the hills as well as the old plot-trenches ought to be observed and made use of. The author presents a new method which he has tested in mineral soils. A small channel filled with sifted gravel or macadam is made at the bottom of old plot-trenches. The ability of such a channel to conduct water can be exactly estimated (picture No. 13) and so the quantity of gravel or macadam and the grain size can be made dependent on the quantity of water to be conducted. Across such trenches will be made tile-drains at a distance of 50—100 m from each other. By this method the costs can be reduced to about 50 % of the present costs. The gravel or the macadam will be safeguarded against silting up by peat or moss. In peat soil the author has experimented with the arch-drain shown in picture No. 16, which is also made at the bottom of an old trench. Special shovels have been developed for the preparation of this kind of drains. Although the duration of such drains is shorter than the duration of the woodpipe drains, they are to be recommended, at least in certain kinds of peat soil, on account of their cheapness. Besides, although the conducting material would be resistant, the sinking of the peatlands (see picture No. 17) will set a limit to the duration of the wood pipe drainage, because the deep-dug drains will, at the beginning, reduce the crops. Finally the article contains economical comparisons between the expensive and the cheap method.