Design of the measurements validation procedure and the expert system architecture for a cogeneration internal combustion engine

A research activity has been initiated to study the development of a diagnostic methodology, for the optimization of energy efficiency and the maximization of the operational time in those conditions, based on artificial intelligence (AI) techniques such as artificial neural network (ANN) and fuzzy logic.The diagnostic procedure, developed specifically for the cogeneration plant located at the Engineering Department of the University of Perugia, must be characterized by a modular architecture to obtain a flexible architecture applicable to different systems. The first part of the study deals with the identifying the principal modules and the corresponding variables necessary to evaluate the module “health state”.Also the consequent upgrade of the monitoring system is described in this paper. Moreover it describes the structure proposed for the diagnostic procedure, consisting of a procedure for measurement validation and a fuzzy logic-based inference system. The first reveals the presence of abnormal conditions and localizes their source distinguishing between system failure and instrumentation malfunctions. The second provides an evaluation of module health state and the classification of the failures which have possibly occurred. The procedure was implemented in C++.     

Conditioning of utilizable energy by a thermostatic control of the thermosyphonic flow in solar systems

A considerable increase in the available useful energy from a thermosyphonic solar water heater which is equipped with a thermostatically flow control device is demonstrated. Such a device may reduce the system efficiency, nevertheless, it may increase the output of useful energy. The term “load utilizability” is defined and used to analyse such systems. A simulation procedure is used to evaluate the dependence of the load utilizability as function of load temperature and time. The high temperature yield of such systems facilitates their use beyond the limitation of domestic hot water supply such as industrial process and space heating. A potential reduction of the price of such systems is obtained by operating them at higher temperatures and therefore smaller water tank storage capacity. Such operational strategy increases the operational flexibility without significant loss of overall thermal efficiency.     

Electricity generation from renewable energy : The French experience

Besides its traditional and large scale involvement in hydro power, EDF has recently taken a significant interest in “new” renewable energy sources. The present paper describes the reasons and the field of application of this interest.     

CAFE compliance by light trucks: economic impacts of clean diesel engine

With the popularity of light trucks increasing in the United States, their share of the US light vehicle market had doubled between 1980 and 1996, climbing from 20 to 40%. By 1996, annual energy consumption for light trucks had risen to 5.97×10¹⁵ Btu [5.97 quadrillion Btu, or “quad,” or 6.30×10¹⁸ joule (J)], compared to 7.94 quad (8.38×10¹⁸ J) for cars. In recent years (since 1995), the fuel economy of US - manufactured light trucks (almost 99% of which use gasoline engines) has been below the Corporate Average Fuel Economy (CAFE) standards. This paper analyzes a strategy to reduce the CAFE shortfalls by adopting the new, highly energy-efficient clean diesel engine. Research on such engines has been funded by the US Department of Energy, Office of Heavy Vehicle Technologies, under its Light Truck Clean Diesel Engine Program. A clean diesel engine market penetration trajectory is developed, representing an industry response to meet the CAFE standards. Whether the engine will be produced inside the country or imported remains uncertain, so two cases are defined. Values of exports/imports of clean diesel engines/trucks under these cases are estimated. The macroeconomic benefits are estimated by using a model of the US economy developed by Standard & Poor's Data Resources, Inc. On the basis of gains in the gross domestic product projected under the alternative cases, domestic production of the clean diesel engine is favored over importing it.     

Well-testing in travale-radicondoli field. Part V. Concluding statement on pressure transient studies made from well tests in the Travele-Radicondoli reservoir

The theory and applications of pressure transient (well test) analysis have been studied intensively for more than 40 yr by petroleum reservoir engineers and groundwater hydrologists. Only in the past decade, however, have geothermal-fluid wells been tested for the purpose of making pressure transient studies. Results of these studies disclose various well conditions, for example, restrictions to fluid flow into the wellbore. They also disclose reservoir heterogeneities, boundaries and permeability-thickness products of reservoir rocks. Probably most important, they can be used in estimations of energy reserves. This powerful analytical tool is discussed with special reference to the Travale reservoir.This reservoir is complicated geologically and hydrologically. It lies on the margin of a graben near a widespread outcrop of the reservoir rocks, which also form an absorption area for the meteoric waters. The area explored can be divided into three zones: in one of these (the nearest to the absorption area) some noncommercial wells produce two-phase water-steam mixtures; in the second zone the wells produce superheated steam, while a well drilled in the graben itself produces a fluid with an uncondensable gas content of about 80%. The reservoir is described in relation to defining areas for further exploration. The nature of the reservoir has affected the design of programs for collecting pressure-production data and other well performance data. The performance history prior to the advent of pressure transient studies pertains mainly to what is known as the ‘old’ Travale reservoir to the southwest of the ‘new’ Travale-Radicondoli reservoir in which the more recent wells are drilled and in which modern well test analysis methods have been applied. Data on the “old” reservoir are discussed first.Because of its initial performance and relationship to nearby wells the most important well in the “new” reservoir is Travale well 22. It has been subjected to extensive well testing. Nearly all the wells in the “new” reservoir have been involved, however, through well-interference tests. In these tests the wells surrounding Travale well 22 are shut in and their pressure responses to different Travale well 22 production rates are measured. Well interference tests indicate the characteristics of fluid flow in the reservoir between test wells and in a qualitative way the heterogeneous nature of the reservoir itself.Pressure transient theory is developed from ideal system behavior: one vertical, fully-penetrating well producing at a constant rate from a horizontal reservoir of uniform thickness and of infinite extent in any direction from the wellbore. A great deal of research has been done to aid well-test analysts in their interpretation of pressure buildup and pressure drawdown curves constructed from data taken on wells in actual reservoirs. This research generally is accomplished with model studies. Some of the models developed in the present research fit reasonably well with the build-up behavior of Travale well 22.The research done on the Travale reservoir is summarized here with the objective of showing what has been learned, how it can be applied, and what should be done next. Confidence in applications of pressure transient analyses in the Travale reservoir has been gained. New concepts of the reservoir system have emerged as a result of the research. Additional testing and more precise measurements in the field should lead to good engineering estimates of energy reserves.     

Performance assessment of an internal combustion engine at varying dead (reference) state temperatures

This study deals with investigating the effect of varying dead state temperatures on exergy efficiency of a high-oleic methyl ester (HOME) fueled internal combustion engine (ICE). This engine is a 4.5L, four-stroke, four-cylinder, turbocharged, 66.5 kW maximum power capacity John Deere 4045T diesel engine run with HOME, which is genetically modified with a high-oleic soybean oil methyl ester. The test speed is 1400 min⁻¹ at a full load. In the analysis, actual operational data obtained from a study conducted by one of the co-authors at Iowa State University, USA are used. Exergy efficiency values at various dead state temperatures are calculated for comparison purposes since these types of engines may be operated under different outdoor air conditions. The results obtained are discussed from the exergetic point of view. It was found that exergetic efficiency increased as dead state temperature decreased. As a result, exergy efficiency values ranged from 29.78% to 34.93% based on dead state temperatures between −5 °C and 30 °C.     

Recent improvements and arising challenges in dye-sensitized solar cells

Work demand for energy is expected high and finding sufficient route to produce clean energy is an ever more pressing problem. Science had identified the key research challenges if solar energy is to provide a significant fraction of our energy needs. The huge gap between our present use of solar energy and its enormous undeveloped potential defines a grand challenge in energy research. One of the most attractive methods currently being developed is “dye sensitization” in solar cells in order to increase the efficiency of conversion of solar radiation into electricity. Although large improvements in present technology will be required, the review points to progress in nanoscience, in particular as a reason to be optimistic.     

A novel EFHAT system and exergy analysis with energy utilization diagram

In this paper, a new type of gas turbine cycle has been proposed based on an innovative combination of a newly designed HAT cycle with an externally fired heater. In this manner, “dirty” fuels such as coal and biomass can be more efficiently used than before and the water in this cycle can be recycled. This is radically different from the conventional HAT cycle. In particular, the temperature of the clean humid air out of the turbine is not restricted by the dew point of gas. Hence, some amount of latent heat can be utilized to generate hot water being supplied to the humidifier. This will enhance the humidification ability for improving performance of the system. The new system is also analyzed by using the graphical exergy methodology based on energy-utilization diagrams (EUDs). As a result, for a turbine inlet temperature (TIT) of 1073 K, the thermal efficiency of the new system may be as high as 45.37%. The new system will effectively recover both the energy quality and quantity at the low- and middle-temperature ranges.     

Control concepts for direct steam generation in parabolic troughs

A new prototype parabolic-trough collector system was erected at the Plataforma Solar de Almería (PSA) (1996–1998) to investigate direct steam generation (DSG) in a solar thermal power plant under real solar conditions. The system has been under evaluation for efficiency, cost, control and other parameters since 1999. The main objective of the control system is to obtain steam at constant temperature and pressure at the solar field outlet, so that changes in inlet water conditions and/or in solar radiation affect the amount of steam, but not its quality or the nominal plant efficiency. This paper presents control schemes designed and tested for two operating modes, “Recirculation”, for which a proportional-integral-derivative (PI/PID) control functions scheme has been implemented, and “Once-through”, requiring more complex control strategies, for which the scheme is based on proportional-integral (PI), feedforward and cascade control. Experimental results of both operation modes are discussed.     

The influence of distance from landfill and population density on degree of wood residue recycling in Australia

Governments use numerous policy instruments to encourage both “upstream” and “downstream” sorting of residues into different recycling streams. Wood waste in particular takes up a large amount of landfill space, and its anaerobic decomposition contributes to global warming through the emission of carbon dioxide and methane. In Australia the wood residue stream, such as used pallets from the commercial and industrial sector, is of particular concern to various states and territories. Diverted wood residue can provide an important resource for use in bioenergy or biofuel production.This study attempted to identify whether there is a difference between wood separating and non-separating waste facilities. This study also attempted to determine whether there is a relationship between the amount of general (total) waste collected and variables indicating general waste generation in surrounding areas, including distance to nearest population centre, distance to nearest capital city and population “catchment” of the waste facility location.It was found that a high percentage of landfills accept wood residue (80%). The results suggest that the availability of recycling is not dependent upon the relative size of the landfill and that economies of scale are not a driving factor behind wood residue recycling opportunity, but that other factors may drive or contribute to the availability of wood residue recycling.Finally, there was no clear relationship between the amounts of general waste passing through the facilities and other variables such as distance to nearest population centres, nearest capital city and population within a given radius.     

The performance results of Trombe-Wall passive systems under Aegean Sea climatic conditions

Since 1977, at the “Solar Energy Thermal Applications Laboratory of M.T.A.” in Marmaris, Turkey, an experimental study of a “Trombe Thermal Storage Wall” passive system continues in operation; two analogous houses have been built, one of which is serving as a reference system. The incident solar radiation on a vertical surface, the temperature changes of the internal and external surfaces of the wall, at interval of thirty minutes, and the convective flow through the “Trombe-Wall” have been measured in order to determine the solar fractions transmitted by the processes of radiation, convection and thermocirculation. In the present study, the variation of the “Trombe-Wall” efficiency has been calculated during the period of a year using a computer evaluation model in which the half hour measurement data have been introduced. The experimental results show that, according to the months, 15–35 per cent of the incident solar radiation over the south facade is transmitted to the interior through the “Trombe-Wall”, while the reference house transmits from the south facade 8–19 per cent of solar radiation received. Finally, it can now be confirmed that the results of the “Trombe-Wall” system without any special type insulation, contributes to practically the total heating load of the village houses under the sunny Aegean Sea Climatic conditions.     

Utilities' role in deploying renewables

The aim of this paper is to review the current status and prospects of the renewable energy sources that are more suitable for the production of electricity, and to present the views of the EURE Group on the role electricity utilities could play in deploying generating plants based on these sources. In the first part of the paper, reference is made both to the renewable sources that have long been used for these purposes, such as hydro power, and to the “new” ones, particularly bioenergy, photovoltaics and wind power. Mention is also made of other technologies that have so far been less developed or can be applied only locally (e.g. geothermal energy). In the second part, the paper advises on the way utilities could contribute to renewable energy research and how they could help promoting these sources.     

Model simplification and optimization of a passive wind turbine generator

In this paper, the design of a “low cost full passive structure” of wind turbine system without active electronic part (power and control) is investigated. The efficiency of such device can be obtained only if the design parameters are mutually adapted through an optimization design approach. For this purpose, sizing and simulating models are developed to characterize the behavior and the efficiency of the wind turbine system. A model simplification approach is presented, allowing the reduction of computational times and the investigation of multiple Pareto-optimal solutions with a multiobjective genetic algorithm. Results show that the optimized wind turbine configurations are capable of matching very closely the behavior of active wind turbine systems which operate at optimal wind powers by using a MPPT control device.     

Cost predictions for photovoltaic energy sources

A preliminary assessment of the solar cell cost prediction art has been made, both in terms of a review and analysis of the prior literature and through an extension of these prior studies. The primary purpose of this study is to establish a basis for judging the relative credibility of the existing cost estimates.The initial step in this evaluation is to develop a self-consistent system of “reaonable” assumptions concerning the future market environment of solar cell energy sources. The second step is to establish the key assumptions which dominate the cost estimates obtained in prior studies. The results from these first two steps form the basis for judging the relative credibility of the existing cost predictions.Finally, an alternative set of cost estimates is generated. These alternative cost predictions are made for single-crystal Si cells (Czochralski vs “ribbon” growth), current technology Cu₂S---CdS cells, and a “generalized” thin-film photovoltaic device.     

Operational modes of solar heating and cooling systems

This paper emphasizes factors associated with the subsystems that are required to extract heat from solar collectors, store this heat, and deliver it to the loads upon demand. While minimum use of auxiliary energy is the general objective, it must be sought with due regard to safety, convenience and cost. Subsystem alterations that improve energy efficiency typically come at added cost in terms of installation and maintenance. In some cases, the advantages of a specified component or arrangement of components are immediately evident. In other cases, such options are less decisive and will require longer periods of comparative operation to arrive at accurate assessments. The Colorado State University Solar House I allows for such comparative operation in several experimental modes. These selected modes of operation provide for different methods of solar heat transfer and employ different arrangements of system components and control functions. The principles underlying these modes as well as results of these studies are presented. In addition, the methods of operation found necessary for efficient and reliable performance are discussed. While this evaluation is an ongoing process, the initial “start up” and “break in” periods have been experienced and serve as a basis for several recommendations concerning subsystem components and component arrangements.     

增压方式对柴油机高原环境下工作特性影响的数值模拟

以一台高压共轨重型柴油机为研究机型,构建了一维热力学模型,首先对比研究了单级增压(single-stage turbocharger,1TC)和二级增压(two-stage turbocharger,2TC)对柴油机变海拔条件下工作特性的影响;然后将2TC的高压级更换为可变截面涡轮增压器,在4 km海拔条件下,分析了叶...     

Prospects for in situ junction formation in CuInSe2 based solar cells

In this paper we describe our research efforts directed towards the understanding of the CdS/CuInGaSe₂ junctions and, specifically, the interaction of the chemical bath with the CuInGaSe₂. Information gained from these studies has been used to develop a set of criteria for forming junctions without the need for chemical bath deposition or CdS. Our approach differs from many others previously used “alternative buffer layer” methods which appear to be somewhat problematic in implementation as well as in the quality of the results. This “buffer-free” technology has resulted in a 13.5% efficiency cell.     

An experimental investigation on DI diesel engine with hydrogen fuel

The internal combustion engines have already become an indispensable and integral part of our present day life style, particularly in the transportation and agricultural sectors [Nagalingam B. Properties of hydrogen. In: Proceedings of the summer school of hydrogen energy, IIT Madras, 1984]. Unfortunately the survival of these engines has, of late, been threatened due to the problems of fuel crisis and environmental pollution. Therefore, to sustain the present growth rate of civilization, a nondepletable, clean fuel must be expeditiously sought. Hydrogen exactly caters to the specified needs. Hydrogen, even though “renewable” and “clean burning”, does give rise to some undesirable combustion problems in an engine operation, such as backfire, pre-ignition, knocking and rapid rate of pressure rise [Srinivasa Rao P. Utilization of hydrogen in a dual fueled engine. In: Proceedings of the summer school of hydrogen energy, IIT Madras, 1984; Siebers DL. Hydrogen combustion under diesel engine conditions. Hydrogen Energy 1998;23:363–71]. The present investigation compares the performance and emission characteristics of a DI diesel engine with gaseous hydrogen as a fuel inducted by means of carburation technique and timed port injection technique (TPI) along with diesel as a source of ignition [Swain N, Design and testing of dedicated hydrogen-fueled engine. SAE 961077, 1996]. In the present study the specific energy consumption, NO_x emission and the exhaust gas temperature increased by 6%, 8% and 14%, respectively, and brake thermal efficiency and smoke level reduced by 5% and 8%, respectively, using carburation technique compared to baseline diesel. But in the TPI technique, the specific energy consumption, exhaust gas temperature and smoke level reduced by 15%, 45% and 18%, respectively. The brake thermal efficiency and NO_x increased by 17% and 34%, respectively, compared to baseline diesel. The emissions such as HC, CO, and CO₂ is very low in both carburation and TPI techniques compared baseline diesel.     

Solar-assisted absorption heat pumps feasibility

An absorption system can be used for space cooling as well as for space heating. This dual purpose may be achieved by using the system as heat pump in wintertime. Absorption heat pump heating may be an interesting alternative, particularly for countries where there is a shortage of electric power.When an absorption unit is used as heat pump, its mode of operation is not modified: the internal temperatures of the cycle are only raised. Commercially available LiBr units were tested as heat pumps. COP and heating capacity were considered as a function of cold source temperature for different temperatures of the useful heat. The COP arrived at 1.7, which must be considered a high value for a thermally driven heat pump.Simulations were carried out in order to compare the performance of “conventional” solar, solar assisted heat pump and the combined series system under two different climate conditions. The series system showed performance 25–75 per cent better than “conventional” solar alone.     

Experimental investigation of combustion characteristics and NOx emission of a turbocharged hydrogen internal combustion engine

In order to alleviate the contradictions of increasingly prominent environmental pollution, greenhouse gas emissions and oil resource security issues, the search for renewable and clean alternative energy sources is getting more and more attention. Hydrogen energy is known as a future energy source because of its safety, reliability, wide range of resources and non-polluting products. Hydrogen internal combustion engine combines the technical advantages of traditional internal combustion engines and has comprehensive comparative advantages in terms of manufacturing cost, fuel adaptability and reliability. It is one of the practical ways to realize hydrogen energy utilization. In this paper, the combustion characteristics and NOx emission of a turbocharged hydrogen engine were investigated using the test data. The results showed the combustion duration (the crank angle of 10%–90% fuel burned) at 1500 rpm and 2000 rpm was equal and the combustion duration is much bigger than the other loads when the BMEP is 0.27 MPa. The reason is the effect of the turbocharger on the gas exchange process, which will influence the combustion process. The cylinder pressure and pressure rise rate were also investigated and the peak pressure rise rate was lower than 0.25 MPa/°CA at all working conditions. Moreover, the NOx emission changed from 300 ppm to 1200 ppm with engine speed increasing and the maximum value can reach to 7000 ppm when the equivalence ratio is 0.88 at 2500 rpm, maximum brake torque. The NOx emission shows different changing tendencies with different working conditions. Finally, these conclusions can be used to develop controlling strategies to solve the contradictions among power, brake thermal efficiency and NOx emission for the turbocharged hydrogen internal combustion engines.