Applied Energy (APPL ENERG)

Publisher: Elsevier

Journal description

Applied Energy provides a forum for information and ideas in the areas of energy conversion, conservation and the optimal management and use of energy and power resources. The journal publishes original papers, reports and reviews, and authors are encouraged to submit manuscripts which bridge the gaps between research, development and implementation. The breadth of coverage ranges from ambient energy, through combustion and processes of electricity release, to the economic use of power in industry. Applied Energy is also concerned with the attendant problems of modelling and forecasting, conservation strategies, and the environmental and social impacts of energy policies and usage.

RG Journal Impact: 5.94 *

*This value is calculated using ResearchGate data and is based on average citation counts from work published in this journal. The data used in the calculation may not be exhaustive.

RG Journal impact history

2019Available summer 2020
20185.94
20175.17
20165.77
20157.00
20147.12
20136.31
20125.63
20117.63
20104.92
20092.84
20081.75
20071.52
20061.35
20050.92
20040.50
20030.56
20020.49
20010.31
20000.42

RG Journal impact over time

RG Journal impact
RG Journal impact over timeGraph showing a linear path with a yearly representation of impact points of the journal

Additional details

Cited half-life3.10
Immediacy index1.64
Eigenfactor0.06
Article influence1.20
Websitehttp://www.sciencedirect.com/science/journal/03062619
Website descriptionApplied Energy website
Other titlesApplied energy (Online)
ISSN0306-2619
OCLC38524766
Material typeDocument, Periodical, Internet resource
Document typeInternet Resource, Computer File, Journal / Magazine / Newspaper

Publications in this journal

Metering, critically examining and if necessary modifying the energy flow through a system is desirable in order to achieve a high efficiency. Systematic procedures for energy management and audit of processes and products are suggested: they involve energy flow charts and assessment questionnaires and thereby facilitate the location, and reduction or elimination, of energy profligate sub-systems. Design rules for the improvement of energy flow systems are listed.
The salt stratified solar pond is found to be a reliable solar collector and storage system. This paper discusses the effect of varying certain design parameters on pond steady-state temperatures. These significant parameters are sizing parameters--pond surface area and depth of the pond; operating parameters--storage volume and the heat extraction fraction; and geo-climatic parameters3solar radiation, water table depth and upper convective zone thickness. Studies indicate that there is an optimum depth and storage volume of the pond for each application in terms of temperature and heat load desired.
The use of flat-plate solar collectors for the generation of electric power is attracting the attention of engineers and scientists for its simplicity in construction and operation. The efficiency of collection is low due to the low operating temperatures of the flat-plate collectors. In the low temperature range applicable to flat-plate collectors, refrigerants can be used as working fluid. The cost of construction can be reduced by the suitable selection of collector and refrigerants. It has been shown that R-114 has suitable characteristics for use as a Rankine cycle working fluid. By using an aluminium tube-plate type collector with 0·005 m tube diameter, 10 risers per metre width of collector, it becomes light and cheap. When the emissivity of the collector is 0·1 and a single cover is used, the maximum efficiency condition is attained. Limited to a pressure drop of 2·5 bar in the collector, 16 collectors can be used in series and the overall efficiency can be as high as 7·8% under 1000 W/m2 insolation conditions and for an outlet temperature of 380 K. Under these conditions 5600 collectors of 1·5 m x 1·5 m size will be required to produce 1000 kW of electricity.
The objective of this paper is to analyze the most up-to-date data available on total greenhouse-gas emissions of a LNG fuel supply chain and life-cycle of city gas 13A1 based on surveys of the LNG projects delivering to Japan, which should provide useful basic-data for conducting life-cycle analyses of other product systems as well as future alternative energy systems, because of highly reliable data qualified in terms of its source and representativeness. In addition, the life-cycle greenhouse-gas emissions of LNG and city-gas 13A in 2010 were also predicted, taking into account not only the improvement of technologies, but also the change of composition of LNG projects. As a result of this analysis, the total amount of greenhouse-gas emissions of the whole city-gas 13A chain at present was calculated to be 61.91Â g-CO2/MJ, and the life-cycle greenhouse-gas emissions of LNG and city-gas 13A in 2010 could be expected to decrease by about 1.1% of the current emissions.
To determine effective surface self-diffusion coefficients of CO2 within type 13X zeolite particles, at various temperatures (25-70 °C), inverse analyses of observed CO2-uptake curves were successfully performed. The obtained effective surface self-diffusion coefficients increase with both the amount adsorbed and the temperature and ranged from 7.8 x 10-10 to 1.95 x 10-9 m2/s under the present experimental conditions.
In each pensioner's home investigated, the living room was heated during the afternoons and evenings to between 17 and 24°C. The rate of heating in the rest of the flat was influenced by weekly income. Temperatures there were very much lower than in the living room, generally being less than 12°C in the bedroom(s) and bathroom during average winter conditions. The lowest temperatures in these rooms were 5°C and 2°C respectively. Medical research shows that such cold conditions can be harmful to health, especially of the elderly or very young. The total annual rate of fuel expenditure was largely determined by other fuel use (e.g. for providing hot water and cooking). The rate of financial expenditure on space heating the living room was dependent upon its size, the chosen comfort temperature, and the weather conditions experienced. Financial income and the location of the flat affected the rate of expenditure on heating in the rest of the flat; the number of occupants and the use of the immersion heater influenced the rate of expenditure for other uses of fuels. The majority of factors which could lead to improvements in the thermal comfort achieved within these flats, notably by up-grading the thermal insulation of the building fabric, improving the heating system, use of better hot-water controls, or increasing the financial income of the occupants, were largely outside the control of the pensioners.
The results of an experimental study of the excess-air-dependent heat losses, as well as gaseous emissions (NOx, SO2 and CO), on a 150 MW boiler firing Thai lignite are discussed. The NOx emissions were found to increase with the higher excess air ratios; the NOx values in the flue gas (at 6% O2) ranged from 257 to 325 ppm, whilst the excess air ratio varied from 1.06 to 1.32 at the economizer outlet. Owing to the highly-efficient operation of the flue gas desulfurization units, the SO2 emissions from the unit were maintained at a relatively low level, 50-76 ppm for the above excess-air ratios, whereas they accounted for about 3100-3300 ppm at the inlet of the FGD units. The CO emissions were determined for the extremely low excess air ratios. Two approaches for the optimization of the excess air ratio were analyzed in this study. For the first, i.e. the conventional approach, the optimization was carried out based on minimizing the total excess-air-dependent heat losses. The second, the environmentally friendly approach, proposed in this work, was aimed at minimizing the "external" costs (or the costs of damage done by the boiler emissions to the environment and humans). As shown in this paper, the lignite firing at the optimal excess air results in a lower environmental impact by the boiler unit.
Changes in labour productivity can bring about economic growth or decline of a region. The factors that explain increases or decreases in labour productivity, if identified, can help policy makers control them so as to mitigate explosive changes in productivity and their concomitant effects on the utilisation of capital, employment, prices, welfare payments and social services. This paper attempts to identify these variables for five coal-producing regions in the US. Section 2 describes these regions, identifies the relevant variables and presents an econometric methodology of regression equations for underground and surface mines. These variables are the non-captive mines, continuous mining technologies in underground mines and medium- and large-sized power shovels and draglines in surface mines, capacity utilisation, accident rates and mining regulations. The literature on regional labour productivity is critically reviewed in Section 3 and it is concluded that none of the five available studies help in comparing inter-regional productivity of labour. Section 4 presents empirical results of equations estimated for underground and surface mines and concludes that the selected variables explained variation in labour productivity significantly. In particular, the results revealed that the regional variations in productivity were explained by technological changes, mine ownership and regulatory laws passed by the Federal and the State governments.
This paper analyses technological change in coal mines in five regions--the Northern and Southern Appalachians, the Rocky Mountains, the Interior and Gulf and Northern Great Plains. Such an analysis can help identify the regions that are growth centres of the future and those that are the declining centres, so that an orderly transfer of manpower and resources from the latter to the former can be brought about efficiently and expeditiously. Section 2 deals with changes in production profiles, over time, of the regions by dividing coal mines into underground and surface mines. It concludes that the Appalachian regions are the declining regions with lower labour productivity and that the Northern Great Plains, with its increasing labour productivity, is the expanding region. Technological changes (TC) in underground mines consist of replacement of conventional mining machines by the continuous miners and the replacement of the latter by the long-wall machines. The TC in the surface mines is the substitution of intermediate- and large-sized power shovels and draglines (PS and Ds) for their smaller size counterparts. Section 3 presents a methodology of S-shaped growth curves. Section 4 reports empirical results for growth rates of adoption of the newer techniques across regions. These results reveal that the Northern Great Plains region is not absorbing the manpower and resources released by the Appalachian regions so that there are shortages in the former in the face of unemployment in the latter. There is, therefore, an opportunity for the declining Appalachian regions to inform their surplus manpower and resources about the growth centre in the north and prepare them for relocation, retraining and readjustment to the changes.
This paper presents estimates of what a monopoly would set natural gas prices at in the inter- and intra-state markets of the United States over the period 1960-1966. The predictions are accurate but not perfect. This paper cannot conclusively prove that price setting in these markets was done in this manner, however, due to lack of assumptions on the supply side. The estimates are close enough to be interesting though, and a model of the supply side should be developed.
This paper deals with the causal relationship analysis between Gross Domestic Product, Energy Intensity and CO2 emissions in Greece from 1977 to 2007, by means of Johansen cointegration tests and Granger-causality tests based on a multivariate Vector Error Correction Modeling. Results indicate that there is a set of uni-directional and bi-directional causalities among the selected time series. We performed a model Variance Decomposition Analysis using Choleski technique and we provided a comparison with other studies. The findings of the study have significant policy implications for countries like Greece as the decoupling of CO2 emissions and economic growth seems quite unlikely.
The current automobile fuel economy standards were established in June 1977. Several studies completed since then recommended that the Department of Transportation (DOT) modify the current schedule. However, all of the studies were completed before the 1979 gasoline shortage. This paper compares the studies performed to assess alternative schedules and identifies major differences. Major differences among the studies include the definition of[`]economic practicability', cost estimates, estimates of automobile sales losses, and the impact of EPA test procedures. The results of the comparison, along with an analysis of the mix of new cars sold and used car prices since the gasoline shortage, are used to determine if the current schedule can be achieved. Observations regarding improvements to the fuel economy programme for establishing post-1985 standards are also presented.
The object of this paper is to analyse economic efficiency and equity aspects of the auto-gasoline mileage regulations for 1981-1984. The paper uses data available from the US Department of Transportation to estimate both the direct benefits of gasoline and maintenance cost savings and the cost of compliance by the manufacturers. The direct benefit/cost ratios exceed unity and it is concluded that the regulations are cost-effective. The equity aspects are analysed by grouping families according to income groups in the Consumer Expenditure Survey data of the US Bureau of Labor Statistics. The analysis shows that lower income groups owning fewer cars derive fewer benefits, relative to upper income groups, from fuel economy regulations. Income compensating measures such as [`]fuel stamps' are suggested as a way of mitigating this inequity.
The present work deals with the creation, on the basis of experimental data, of the regulation maps for the 1Â MW cogenerative internal combustion engine (ICE) installed at the Engineering Faculty of Perugia University. The regulation logic mapping is necessary for the development of a thermodynamic model of the engine behaviour to simulate the effects of possible malfunctions occurrence, such as deterioration or fouling not directly experienced on the engine. Such a work is carried out as a part of a more general research activity concerning the development of a diagnosis system for the cogenerative plant. Therefore, a first phase of the present work relates to the experimental data gathering campaign and the consequent data analysis to individuate the characteristic parameters of regulation. In the second phase, instead, a neural simulator of the control logic was developed on the basis of the experimental data for the engine operation at full load (initially considered at 980Â kW) and during transitory. Consequently, through such a simulator the regulation maps of the engine were determined considering the variation range of all the characteristic parameters. Finally, a more accurate analysis of the experimental data relative to the dependence of the produced electric power at regimen on the fuel valve position, encouraged the authors to develop a further neural simulator able to reproduce the regulation commands for different values of the target power set for the regimen operation. Consequently, also the regulation mapping was revised obtaining a synthetic representation of the regulation logic useful for the implementation in the thermodynamic model of the engine dynamic behaviour.
This paper contributes to the development of a thermo-dynamic model of the 1 MW cogenerative internal combustion engine (I.C.E.), including also an artificial neural network simulator of the electronic control module. Such a study is part of a more wide research activity, concerning the development of a diagnosis and monitoring system specifically for power plants. In particular, the engine model was realized to simulate the engine functioning also in the case of malfunctions and failures occurrence, taking in consideration the compensation effect operated by the regulation system.The complete model was tested in reference to several experimental conditions, in particular in a first phase relative to different values of the target electrical power and, subsequently, concerning the case of compressor fouling. Therefore it was validated both the thermo-dynamic model and the regulator operation in reference to the experimental data.
The two-stage heat transformer (TSHT) is an advanced heat–transformer which can widen the operating range compared to that which can be achieved with a single-stage heat–transformer (SSHT). This paper analyzes three kinds of two-stage heat transformers and puts forward the two-stage heat–transformer with H2O/LiBr for the first stage and 2,2,2-trifluoroethanol (TFE)/N-methy1-2-pyrrolidone (NMP) for the second stage. The results show that it can reach the same high delivered temperature as the two-stage heat–transformer with only TFE/NMP as working–fluid combinations and can achieve a higher system performance than the two-stage heat transformer with TFE/NMP.
This paper presents rigorous experimental outdoor performance of a 2.32Â kWP stand-alone photovoltaic (SAPV) system in New Delhi (India) for four weather types in each month such as clear, hazy, partially cloudy/foggy and fully cloudy/foggy weather conditions respectively. The daily power generated from the existing SAPV system was experimentally found in the range of 4-6Â kWÂ h/day depending on the prevailing sky conditions. The number of days and daily power generated corresponding to four weather types in each month were used to determine monthly and subsequently annual power generation from the existing SAPV system. There are three daily load profiles with and without earth to air heat exchanger suitable for three seasons like summer (3.75-6.15Â kWÂ h/day), winter (2.79-5.19Â kWÂ h/day) and rainy (3.75Â kWÂ h/day). The hourly efficiency of the SAPV system components are determined and presented in this paper. The life cycle cost (LCC) analysis for the existing typical SAPV system is carried out to determine unit cost of electricity. The effect of annual degradation rate of PV system efficiency is also presented in this paper. The energy production factor (EPF) and the energy payback time (EPBT) of the SAPV system was also determined and presented in this paper.
We measured various operational parameters of a 200-MWe, wall-fired, lignite utility boiler under different loads. The parameters measured were gas temperature, gas species concentration, char burnout, component release rates (C, H and N), furnace temperature, heat flux, and boiler efficiency. Cold air experiments of a single burner were conducted in the laboratory. A double swirl flow pulverized-coal burner has two ring recirculation zones that start in the secondary air region of the burner. With increasing secondary air flow, the air flow axial velocity increases, the maximum values for the radial velocity, tangential velocity, and turbulence intensity all increase, and there are slight increases in the air flow swirl intensity and the recirculation zone size. With increasing load gas, the temperature and CO concentration in the central region of burner decrease, while O2 concentration, NOx concentration, char burnout, and component release rates of C, H, and N increase. Pulverized-coal ignites farther into the burner, in the secondary air region. Gas temperature, O2 concentration, NOx concentration, char burnout and component release rates of C, H, and N all increase. Furthermore, CO concentration varies slightly and pulverized-coal ignites closer. In the side wall region, gas temperature, O2 concentration, and NOx concentration all increase, but CO concentration varies only slightly. In the bottom row burner region the furnace temperature and heat flux increase appreciably, but the increase become more obvious in the middle and top row burner regions and in the burnout region. Compared with a 120-MWe load, the mean NOx emission at the air preheater exits for 190-MWe load increases from 589.5 mg/m3 (O2 = 6%) to 794.6 mg/m3 (O2 = 6%), and the boiler efficiency increases from 90.73% to 92.45%.
An analysis of the pattern of energy use in 44 sub-sectors of manufacturing industry in the UK is presented. It draws on detailed information from published statistics. Account is taken of trends in structural change and likely uptake of energy efficiency measures to examine the prospects for improved energy efficiency up to the year 2000. It is estimated that the uptake of energy saving measures will reduce total energy consumption by 2l 25%, depending on the level of industrial output.
A novel technique for forecasting the supply and extraction life-cycle of depleting fossil-fuel resources has been applied to crude-oil and natural-gas productions in the unified Germany. The supply side utilises a [`]skewed-normal production-profile' model, that yields a better representation than earlier approaches. A simple model for extrapolating crude-oil and natural-gas demands for Unified Germany has also been devised and based on the so-called [`]modified logit function'. The projected crude-oil and natural-gas balances for the period up to ad 2010 indicate the increasing disparities between both the indigenous crude-oil and natural-gas productions and the future consumption requirements for Germany. The magnitudes of these forecasts depend on current estimates of the remaining oil and gas reserves. Therefore it will be necessary to revise periodically the present projections as more reliable reserve-estimates become available.
A novel technique for forecasting the supply and extraction life-cycle of a depleting fossil fuel resource has been developed. The supply side utilises a [`]skewed-normal production-profile' model that yields a better representation than earlier approaches. A simple model for extrapolating crude oil and natural gas demands has also been devised, based on the so called [`]modified logit function'. The predicted crude oil and natural gas balances for the period up to 2010 indicate the disparity between indigenous production and future consumption for France. These forecasts depend on current estimates of remaining oil and gas reserves. It will consequently be necessary to revise periodically the present projections as more reliable reserve estimates become available.
A novel approach to the modelling of the extraction life-cycle of depleting fossil fuel resources has been applied to the case of oil and natural gas production within the UK Continental Shelf. This utilises skewed normal production profiles that yield a better representation than do earlier approaches. Simple methods for extrapolating oil and gas demand in the UK have also been devised. The projected oil and gas balances for the period up to 2010 indicate when oil production will cease to meet indigenous consumption, and the increasing need to import natural gas supplies. These results depend quite heavily on estimates of remaining oil and gas reserves. It will consequently be necessary to revise periodically the present projections as more reliable reserve estimates become available.
The Polish [`]Development Strategy for Renewables', approved by the Council of Ministers in 2000 and by Parliament in 2001, called for a 7.5% contribution of renewable energy to total primary-energy production in 2010, and 14% in 2020 as development targets for renewables. The purpose of this project was to investigate further what this Strategy meant in terms of the types and amounts of renewable-energy (RE) systems that would need to be installed and the support mechanisms that would need to be put in place to enable this to happen. Development scenarios for RE to 2020 were elaborated and their financial, environmental and social implications were calculated with the Strategic Assessment Framework for the Implementation of Rational Energy (SAFIRE) computer model, devised by Energy for Sustainable Development Ltd (ESD, UK).
When discussing how society can decrease greenhouse gas emissions, the transport sector is often seen as posing one of the most difficult problems. In addition, the transport sector faces problems related to security of supply. The aim of this paper is to present possible strategies for a road transport system based on renewable energy sources and to illustrate how such a system could be designed to avoid dependency on imports, using Sweden as an example. The demand-side strategies considered include measures for decreasing the demand for transport, as well as various technical and non-technical means of improving vehicle fuel economy. On the supply side, biofuels and synthetic fuels produced from renewable electricity are discussed. Calculations are performed to ascertain the possible impact of these measures on the future Swedish road transport sector. The results underline the importance of powerful demand-side measures and show that although biofuels can certainly contribute significantly to an import-independent road transport sector, they are far from enough even in a biomass-rich country like Sweden. Instead, according to this study, fuels based on renewable electricity will have to cover more than half of the road transport sector’s energy demand.
Four major themes will dominate United States energy-security in the 21st century. One is the need to diversify the fuel mix (i.e., oil, natural gas, nuclear power, hydro-electricity and other renewable and alternative energy resources). Another is the need to diversify the geographic origin of energy. A third theme is conservation and energy efficiency. And the final theme is devising new ways of managing growing dependence on oil imports rather than aiming at achieving “energy independence”. This paper will examine the new frontiers of the United States’ energy security in the 21st century. It will argue that fossil fuels will continue to dominate US energy needs well into the 21st century and that the Gulf region will maintain its strategic importance for US energy security for the foreseeable future. The paper will conclude that US energy-security could be better served by devising ways of managing dependence on oil imports rather than engaging in meaningless debate over energy independence.
Energy experts project that global oil supplies will only meet demand until global oil production has peaked sometime between 2013 and 2020. Declining oil production after peak production will cause a global energy gap to develop, which will have to be bridged by unconventional and renewable energy sources. Nuclear, solar and hydrogen are destined to become major energy sources during the 21st century, but only if their enabling technologies improve significantly to ensure affordability and convenience of use. This paper will argue that global oil production will probably peak between 2004 and 2005, causing a serious energy gap to develop sometime between 2008 and 2010 rather than 2013-2020 as the energy experts projected. It will also argue that a transition from fossil fuels to renewable energy sources is inevitable. The paper will conclude, however, that fossil fuels with a growing contribution from nuclear energy, will still be supplying the major part of the global energy needs for most, perhaps all, of the 21st century.
Les modeles theoriques montrent que de substantielles economies peuvent etre realisees en densifiant les cites plutot qu'en les etirant. La structure spatiale de la maille urbaine est l'element cle. Les villes organiques qui ont pousse pendant de longues periodes semblent optimiser certains aspects fondamentaux de l'utilisation de l'espace et de la facilite de mouvement. Les civilisations denses paraissent devenir une possibilite de plus en plus attractive, ouvrant la voie vers une economie du mouvement
This paper discusses the theoretical differences in performance between using R-12 and R-22 resulting from changes in thermodynamic properties. It also assesses the potential for using R-22 as a replacement for R-12 by considering a case study of an R-12 reciprocating air-conditioning unit conversion to an R-22 unit.
Bio-fuels are important because they replace petroleum fuels. A number of environmental and economic benefits are claimed for bio-fuels. Bio-ethanol is by far the most widely used bio-fuel for transportation worldwide. Production of bio-ethanol from biomass is one way to reduce both consumption of crude oil and environmental pollution. Using bio-ethanol blended gasoline fuel for automobiles can significantly reduce petroleum use and exhaust greenhouse gas emission. Bio-ethanol can be produced from different kinds of raw materials. These raw materials are classified into three categories of agricultural raw materials: simple sugars, starch and lignocellulose. Bio-ethanol from sugar cane, produced under the proper conditions, is essentially a clean fuel and has several clear advantages over petroleum-derived gasoline in reducing greenhouse gas emissions and improving air quality in metropolitan areas. Conversion technologies for producing bio-ethanol from cellulosic biomass resources such as forest materials, agricultural residues and urban wastes are under development and have not yet been demonstrated commercially.
Sugar cane bagasse was submitted to ethanol organosolv pre-treatment using a 50 L pilot scale reactor. The influence of catalyst type (H2SO4 or NaOH), catalyst concentration (1.25–1.50% w/w on dry fiber) and process time (60–90 min) on total solid recovery and solid composition (glucan, xylan and lignin contents) was evaluated by performing a 23 full factorial experimental design. Pretreated sugar cane bagasse was further submitted to enzymatic hydrolysis using a commercial enzyme complex formed by cellulases and β-glucosidases. Glucose concentration in the hydrolysates and glucose yield referred to initial raw material (g glucose/100 g sugar cane bagasse) were used to select the best operational conditions. Concerning the enzymatic hydrolysis, the resulting glucose concentration was found to be dependent on xylan contents of the pretreated material. The modelling equations for glucose concentration and glucose yield as a function of the pre-treatment variables and the statistical analysis are also discussed in this work.
Full-scale experiments were performed on a 300Â MWe utility boiler retrofitted with air staging. In order to improve boiler thermal efficiency and to reduce NOx emission, the influencing factors including the overall excessive air ratio, the secondary air distribution pattern, the damper openings of CCOFA and SOFA, and pulverized coal fineness were investigated. Through comprehensive combustion adjustment, NOx emission decreased 182Â ppm (NOx reduction efficiency was 44%), and boiler heat efficiency merely decreased 0.21%. After combustion improvement, high efficiency and low NOx emission was achieved in the utility coal-fired boiler retrofitted with air staging, and the unburned carbon in ash can maintain at a desired level where the utilization of fly-ash as byproducts was not influenced.
Ambient temperature bin data are used for estimating the energy consumption for heating and cooling of buildings. This well-known method is a steady-state approach and the energy requirements are determined at various outdoor temperatures, in order to account for the effect of outside temperature on the HVAC equipment efficiency. The application of the method requires detailed bin data. In this paper, the dry-bulb temperature bin data for 38 Greek cities are determined by using a reliable estimating methodology, based on monthly-average outdoor temperatures and solar clearness index. The data are calculated from -18 °C to 42 °C with 2 °C increments in six daily 4-h shifts, and are presented in tabular form.
A 3D model that fully couples multi-species and multi-phase transport, electrochemical kinetics, and heat transfer processes has been developed. The non-equilibrium membrane water absorption/desorption processes along with non-equilibrium condensation/evaporation processes have been investigated utilizing this comprehensive model. In addition, the fallacious assumption that water is produced in vapor phase during the half cell electrochemical reaction is addressed for the first time. The difference and relationship of the cell output current density among three water production mechanisms are exhibited to show the potential error induced by vapor or liquid production assumptions. The present model is capable of predicting transient phenomena within the cell as well. Our results show that compared to the liquid production modeling the dynamic response of PEM fuel cells in vapor production modeling is significantly overestimated owing to the sluggish condensation process.
A prototype 3 kW horizontal upwind type wind turbine generator of 4 m in diameter has been designed and examined under real wind conditions. The machine was designed based on the concept that even small wind turbines should have a variable pitch control system just as large wind turbines, especially in Japan where typhoons occur at least once a year. A characteristic of the machine is the use of a worm and gear system with a stepping motor installed in the center of the hub, and the rotational main shaft. The machine is constructed with no mechanical breaking system so as to avoid damage from strong winds. In a storm, the wind turbine is slowed down by adjusting the pitch angle and the maximum electrical load. Usually the machine is controlled at several stages depending on the rotational speed of the blades. Two control methods have been applied: the variable pitch angle, and regulation of the generator field current. The characteristics of the generator under each rotational speed and field current are first investigated in the laboratory. This paper describes the performances of the wind turbine in terms of the functions of wind turbine rotational speed, generated outputs, and its stability for wind speed changes. The expected performances of the machine have been confirmed under real wind conditions and compared with numerical simulation results. The wind turbine showed a power coefficient of 0.257 under the average wind speed of 7.3 m/s.
Inclination of an enclosed, leaktight rectangular, 910mm × 316 mm, 10 mm thick layer of perlite, led to the maximum rate of heat transfer through it occurring with the layer at an angle of 75° to the horizontal.The apparent thermal conductivity of a horizontal layer of perlite, when heated from below, depends upon the velocity of any air draught blowing over the insulant's upper surface as well as upon the permeability of that upper surface. A horizontal air draught of 1·5 ms−1, at 100 mm above the top of a 100 mm thick horizontal layer of perlite (e.g. as could occur in lofts), resulted in an increase exceeding 20 per cent in the rate of heat transmission for a 5°C per centimetre temperature gradient through the insulant. Suppression of convection out of an otherwise open-topped 100 mm thick horizontal layer of perlite (above which no forced convection ensued) by means of the presence of building paper achieved a reduction of about 8 per cent in the rate of heat transfer through the insulant. The present investigation thus emphasises that such layers should be employed above insulant layers to inhibit convection losses, provided interstitial condensation will then not occur within the insulant layer.Leakage of air into the insulant layer from below (as occurs through ceilings beneath attic spaces) enhances buoyancy driven convection, resulting in increased rates of heat loss and hence higher apparent conductivities. Surprisingly, an increase in the thickness of the horizontal perlite layer with an open top, also leads to a significant rise in the mean apparent thermal conductivity of the insulant.Such conclusions cast doubts on the worthwhileness of many ‘economic thickness’ predictions made assuming a commercially supplied value (obtained under no internal convection conditions) for the insulant's apparent conductivity, and its invariance with the thickness of the insulant.
Sevan Marine and Siemens have developed a floating power plant - entitled Sevan GTW (gas-to-wire) - based on Sevan's cylindrical platform and Siemens' SCC-800 combined cycle, and SINTEF has adapted a post-combustion CO2 capture process for on board integration including compression and preconditioning of the CO2. Main emphasis has been placed on developing an optimised conceptual design within the structural constraints, and assessing how efficient the capture unit may be operated in consideration of the dynamic behaviour induced by the sea on the absorber and desorber columns via the floating carrier. The rational behind this technology selection is the urgency in making appropriate steps for a quick start for remote power generation at sea with the inclusion of CCS to serve offshore oil and gas operations. This calls for modular power blocks made up by high efficient combined power cycles with post-combustion exhaust gas cleaning. From this point of view a system with four absorption columns and one desorber unit has been determined based on structured packing material. The capture process has been integrated with the power cycle in due consideration of the sea forces. It is shown that a permanent tilt becomes more important than periodic movements provided the harmonic periods are kept within a certain level (<20Â s). Operational conditions and constraints vis-à-vis movements and trimming of the floater have been addressed and discussed with reference to available literature. This also includes the liquid hold-up and gas-liquid interfacial area in the absorption columns linked with tilting. Optimisation reveals that a reboiler duty of 3.77Â GJ/ton CO2 would result in the lowest capture cost. With a energy penalty of 9%-points the Sevan GTW concept presents itself as a realistic concept deemed to be within reach today.
The instability of the thermal characteristics of rotating-blade coupling (RBC), with longitudinal ribbed turbulators, in real-time four-wheel-drive (4WD) vehicles has been investigated. The key parameters approximate to the operating conditions of a real vehicle. The co-axial rotating channel flow exhibits a pattern of unstable Taylor vortices. Longitudinal rib-roughened walls were employed to prevent high temperatures in local regions. The local temperature-distributions of the RBC with longitudinal ribbed turbulators were measured and compared with those with smooth walls. Longitudinal ribbed turbulators can: (i) prevent local increases in temperature, (ii) increase the lives of the parts of a rotational blade connector and (iii) protect the motive sources of 4WD vehicles.
A new type of internal combustion engine with distinct advantages over conventional piston-engines and gas turbines in small power ranges is presented. The engine has analogies with piston engine operation, but like gas turbines it has dedicated spaces and devices for compression, burning and expansion. The engine operates on a modified limited-pressure thermodynamic cycle. The core of the engine is a nutating non-rotating disk, with the center of its hub mounted in the middle of a Z-shaped shaft. The two ends of the shaft rotate, while the disk nutates. The motion of the disk circumference prescribes a portion of a sphere. In the single-disk configuration a portion of the surface area of the disk is used for intake and compression, a portion is used to seal against a center casing, and the remaining portion is used for expansion and exhaust. The compressed air is admitted to an external accumulator, and then into an external combustion chamber before it is admitted to the power side of the disk. The external combustion chamber enables the engine to operate on a variable compression ratio cycle. Variations in cycle temperature ratio and compression ratio during normal operation enable the engine to effectively become a variable-cycle engine, allowing significant flexibility for optimizing efficiency or power output. The thermal efficiency is similar to that of medium sized diesel engines. For the same engine volume and weight this engine produces approximately twice the power of a two-stroke engine and four times the power of a four-stroke engine. The computed sea-level engine performance at design and off-design conditions in the 2 to 500 kW power range is presented.
This paper investigates whether individual (driver) behavior is influenced by the cost of travel. Specifically, concern is focused on the importance of the price of motor gasoline in impacting the frequency with which individuals exceed the 55 m.p.h. speed limit. Other factors accounting for the time cost of travel and the cost in terms of the effort that must be expended are also considered in explaining the observed behavior. The results do suggest that adherence to the 55 m.p.h. speed limit does depend on the time cost of travel, cost in terms of discomfort and irritability, enforment and, for a subset of states, the unit price of motor gasoline.
The increase in installed wind power has brought a number of Grid Code areas into focus. The area of fault ride-through capability is one with serious implications for system security and thus has an impact on the allowed wind energy penetration in the network. There are several wind turbine models that can be used to study the effects of voltage dips and the corresponding wind turbine responses but these models need to be validated by comparing their results with the data obtained during field tests. This paper presents the design of a voltage dip generator that can be used to test wind turbines up to 5 MW and 20 kV. This system is able to adjust voltage dip depth and duration to the standards defined in different countries and also the fault impedance seen by the grid in order not to disturb its operation during the tests. Simulation results are validated using experimental data obtained at a laboratory-scale prototype (400 V, 90 kW). Finally, the actual 5 MW system and the results obtained during field tests are presented.
Gasification based biomass co-firing was an attractive technology for biomass utilization. Compared to directly co-firing of biomass and coal, it might: (1) avoid feeding biomass into boiler, (2) reduce boiler fouling and corrosion problem, and (3) avoid altering ash characteristics. In this paper, CFD modeling of product gas (from biomass gasification) and coal co-firing in a 600Â MW tangential PC boiler was carried out. The results showed that NOx emission was reduced about 50-70% when the product gas was injected through the lowest layer burner. The fouling problem can be reduced with furnace temperature decreasing for co-firing case. The convection heat transfer area should be increased or the co-firing ratio of product gas should be decreased to keep boiler rated capacity.
This paper presents a month of measurements on the feeders connecting a 63 MW wind farm in Zafarana Egypt, to the 22 kV busbars of the 22/220 kV/2X7S MVA Zafarana substation. Voltage variations and frequency harmonics are compared with the acceptable limits of the national grid within the Egyptian standard conditions and specification of the transmission systems.
Industrial experiments were performed for a retrofitted 660 MWe full-scale down-fired boiler. Measurements of ignition of the primary air/fuel mixture flow, the gas temperature distribution of the furnace and the gas components in the furnace were conducted at loads of 660, 550 and 330 MWe. With decreasing load, the gas temperature decreases and the ignition position of the primary coal/air flow becomes farther along the axis of the fuel-rich pipe in the burner region under the arches. The furnace temperature also decreases with decreasing load, as does the difference between the temperatures in the burning region and the lower position of the burnout region. With decreasing load, the exhaust gas temperature decreases from 129.8 °C to 114.3 °C, while NOx emissions decrease from 2448 to 1610 mg/m3. All three loads result in low carbon content in fly ash and great boiler thermal efficiency higher than 92%. Compared with the case of 660 MWe before retrofit, the exhaust gas temperature decreased from 136 to 129.8 °C, the carbon content in the fly ash decreased from 9.55% to 2.43% and the boiler efficiency increased from 84.54% to 93.66%.
This study examines the relationship between natural gas consumption and economic growth for a panel of 67 countries within a multivariate framework over the period 1992-2005. Pedroni's [24] and [26] heterogeneous panel cointegration test reveals there is a long-run equilibrium relationship between real GDP, natural gas consumption, real gross fixed capital formation, and the labor force. The results of the panel vector error correction model reveal bidirectional causality between natural gas consumption and economic growth in both the short- and long-run.
The present investigation involves a unique, 7 year (2001–2007) long study of corrosion and deposits on superheater tubes in a biomass fired circulated fluidized bed boiler. These measurements are correlated against the different fuels used over this period. In the earlier years, the boiler was run with a mixture of different biomass fuels and peat. In later years, recycled wood was introduced into the fuel mix. The deposit growth rate approximately doubled when the recycled wood content of the fuel was increased to 10–20%. Small amounts of chlorine and zinc were found both in the recycled wood and in the deposit layer. These elements together with alkali metals from the biomass, have the potential to form sticky compounds that increase the deposit growth rate. The corrosion rate of the superheater tubes varied over the study period. A number of possible explanations for this phenomenon are discussed.
This study presents a framework to assess the wind resource of a wind turbine using uncertainty analysis. Firstly, probability models are proposed for the natural variability of wind resources that include air density, mean wind velocity and associated Weibull parameters, surface roughness exponent, and error for prediction of long-term wind velocity based on the Measure–Correlate–Predict method. An empirical probability model for a power performance curve is also demonstrated. Secondly, a Monte-Carlo based numerical simulation procedure which utilizes the probability models is presented. From the numerical simulation, it is found that the present method can effectively evaluate the expected annual energy production for different averaging periods and confidence intervals. The uncertainty, which is 11% corresponding to the normalized average energy production in the present example, can be calculated by specifically considering the characteristics of the individual sources in terms of probability parameters.
Research in the field of NOx abatement has grown significantly in the past two decades. The general trend has been to develop new catalysts with complex materials in order to meet the stringent environmental regulations. This review discusses briefly about the different sources of NOx and its adverse effect on the ecosystem. The main portion of the review discusses the progress and development of various catalysts for NOx removal from exhaust by NO decomposition, NO reduction by CO or H2 or NH3 or hydrocarbons. The importance of understanding the mechanism of NO decomposition and reduction in presence of metal ion substituted catalysts is emphasized. Some conclusions are made on the various catalytic approaches to NOx abatement.
Fossil fuel run diesel engines are being favored in light, medium and heavy duty applications as they exhibit higher fuel conversion efficiencies. Direct injection diesels are still facing challenges to obtain trade-off between oxides of nitrogen and particulate emissions. There are sophisticated strategies such as common rail direct injection, particulate filters with associated sensors and actuators but limited to expensive comfort vehicles. In the present experimental study, a mechanically operated simple component, variable timing fuel injection cam, is designed for a 510 cc automotive type naturally aspirated, water-cooled, direct injection diesel engine. Modifications in the fuel injection cam and gear train are carried out to suit the existing engine configuration. Variable speed tests are carried out for testing the efficacy of component on both engine and chassis dynamometers for performance and emissions. It is observed that the engine which is already retarded could further be retarded with variable timing fuel injection cam. Significant reductions in NOx and smoke emission levels are achieved. Combined effect of VIC with 7% EGR could reduce CO by about 88%, HC + NOx by 37% and PM emissions by 90%. The Engine incorporated with the designed component and EGR, successfully satisfied the existing emission norms with improved power and specific fuel consumption.

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