Diagnosis methodology for the turbocharger groups installed on a 1 MW internal combustion engine

The issue of internal combustion engine (ICE) diagnosis attracts great interest because modern engines need continual control of the operational status, in order to obtain high efficiency in energy conversion and accurate control of the polluting emissions. In particular, in reference to an alternative ICE of 1 MW, the present study relates the development, through the design of neural simulators, of the turbocharger maps to reproduce the operational states characterized by new&clean conditions and allowing the evaluation of particular “health state” indices of such a module. In detail, after an experimental campaign, turbocharger fundamental characteristics referred to new&clean conditions, such as the compressor isoentropic efficiency and the mass flow elaborated by the turbine, were evaluated at different operation conditions of the alternative ICE Subsequently, the neural simulators were developed through the training and test of different neural architectures.     

分布式水电机组故障诊断集成专家系统的研究

针对水电机组故障诊断的多样性和复杂性，将分布式人工智能技术引入机组故障诊断技术的研究，提出一种适用于水电机组的分布式故障诊断专家系统结构和组织方法；并在此基础上，利用神经网络技术、可视化技术和模糊技术，提出了一种新的故障诊断集成知识表示方式和推理生策略，并已应用于某水电厂分布式故障诊断集成专家系统中。     

A single procedure for helping PV designers to select silicon PV modules and evaluate the loss resistances

When a photovoltaic system is to be sized, different PV modules are considered. The optimisation of such systems is always the goal, but the choice of the PV module with best performance should also be considered. Nevertheless, selecting a module from catalogue data has certain inconveniences. First, because those data allow only comparisons with absolute magnitudes, the conclusions about which module is the most appropriate is not easy. Second, data provided in catalogues are not sufficient to know the module behaviour under conditions different from standard. This paper deals with the normalisation of the modules data by considering a base that allows for obtaining a “per unit” representation. For modelling and studying the modules under non-standard conditions it is necessary to know series and shunt resistances, but that is not easy. Then, by simulations, it is possible to show the influence of these resistances in the module behaviour.     

Near-maximum-power-point-operation (nMPPO) design of photovoltaic power generation system

The present study proposes a PV system design, called “near-maximum power-point-operation” (nMPPO) that can maintain the performance very close to PV system with MPPT (maximum-power-point tracking) but eliminate hardware of the MPPT. The concept of nMPPO is to match the design of battery bank voltage V_set with the MPP (maximum-power point) of the PV module based on an analysis using meteorological data. Three design methods are used in the present study to determine the optimal V_set. The analytical results show that nMPPO is feasible and the optimal V_set falls in the range 13.2–15.0 V for MSX60 PV module. The long-term performance simulation shows that the overall nMPPO efficiency η_nMPPO is higher than 94%. Two outdoor field tests were carried out in the present study to verify the design of nMPPO. The test results for a single PV module (60Wp) indicate that the nMPPO efficiency η_nMPPO is mostly higher than 93% at various PV temperature T_pv. Another long-term field test of 1 kWp PV array using nMPPO shows that the power generation using nMPPO is almost identical with MPPT at various weather conditions and T_pv variation from 24 °C to 70 °C.     

Estimation of the energy of a PV generator using artificial neural network

The integration of grid-connected photovoltaic (GCPVS) systems into urban buildings is very popular in industrialized countries. Many countries enhance the international collaboration efforts which accelerate the development and deployment of photovoltaic solar energy as a significant and sustainable renewable energy option. A previous method, based on artificial neural networks (ANNs), has been developed to electrical characterisation of PV modules. This method was able to generate V–I curves of si-crystalline PV modules for any irradiance and module cell temperature. The results showed that the proposed ANN introduced a good accurate prediction for si-crystalline PV modules performance when compared with the measured values. Now, this method, based on ANNs, is going to be applied to obtain a suitable value of the power provided by a photovoltaic installation. Specifically this method is going to be applied to obtain the power provided by a particular installation, the “Univer generator”, since modules used in these works were the same as the ones used in this photovoltaic generator.     

Prospect of RBMK-NPPS strength monitoring system on-line module development

System for strength monitoring and residual lifetime (SMS) assessment of NPP equipment makes it possible to improve safety and effectiveness of operation.

According to SMS concept it includes two main modules: for on-line data acquisition and diagnostic and for off-line date processing and lifetime assessment.

Algorithm for RBMK SMS on-line module is proposed to be based on the basis of “DASHA” expert system shell.

Universal expert shell “DASHA” was created using the original matrix method of image identification theory and can be used for on-line diagnostic system development for any complex technological object of arbitrary physical nature.     

Study of AC-module inverters under extreme desert conditions

We present some results of a high-statistics study of the performance and characteristics of NKF OK4E-100 “AC-module”-type inverters under extreme desert conditions. The work was carried out at the Ben-Gurion National Solar Energy Center, located in the Negev Desert. Twenty inverters were monitored for one complete year. Ten of them were each fed by pairs of 40 W Solarex SX146 PV modules, in order to provide a set of “normal operation” systems. The other 10 were fed by quartets of similar 40 W PV modules, in order to create frequent situations of extreme overload. The paper addresses hourly, daily and seasonal inverter efficiencies; optimal module sizing; overload penalties; temperature effects; light-threshold effects; quality control issues and failure rates.     

GIS-based environmental assessment of wind energy systems for spatial planning: A case study from Western Turkey

Increasing population and life standards causes fossil fuel consumption to increase. Due to this increasing consumption, fossil fuels are being depleted rapidly. In addition to rapid exhaustion, another important problem associated with fossil fuels is that their consumption has major negative impacts on the environment. Therefore, many countries around the world have included renewable energy systems (RES) in their future energy plans so that they can produce reliable and environmentally friendly energy. Parallel to this trend, various RES have been identified and recently integrated into the current energy network of Turkey as well. However, it should be recognized that renewable energy resources are not fully environmentally safe. Different RES are associated with different environmental impacts. In planning the future energy development of a country, evaluation of renewable energy resources potentials together with their associated environmental impacts is critical. The aim of this study is to create a decision support system for site selection of wind turbines using Geographic Information System (GIS) tools. Wind energy potential and environmental fitness/acceptability are used as decision criteria for the site selection process. Potential environmental impacts of wind generation are identified in accordance with Turkish legislations and previous studies; and represented as fuzzy objectives of the decision problem. Wind potential map of Turkey generated by General Directorate of Electrical Power Resources Survey and Development is used to identify economically feasible locations in terms of wind energy generation. A study area composed of Usak, Aydin, Denizli, Mugla, and Burdur provinces in Turkey is selected and divided into 250 m × 250 m grids. Each grid represents an alternative location for a wind turbine or group of wind turbines. Fuzzy environmental objectives such as “Acceptable in terms of noise level”, “Acceptable in terms of bird habitat”, “Acceptable in terms of safety and aesthetics” and “Safe in terms of natural reserves” associated with wind turbines are identified based on previous research and each of these objectives are represented by a fuzzy set. Individual satisfaction degree of each of these environmental objectives for each grid is calculated. Then these individual satisfactions are aggregated into an overall satisfaction degree using various aggregator operators such as “and”, “or”, and “order weighted averaging.” Thus, an overall satisfaction degree of all the environmental objectives is obtained for each grid in the study area. A map of environmental fitness is developed in GIS environment by using these overall satisfaction degrees. Then this map is utilized together with the wind potential map of Turkey to identify both potentially and environmentally feasible wind turbine locations within the study area.     

A simple procedure for assessing thermal comfort in passive solar heated buildings

The Fanger thermal comfort equation is linearized and used to develop a procedure for assessing thermal comfort levels in passive solar heated buildings. In order to relate comfort levels in non-uniform environments to uniform conditions, a new thermal index called the “equivalent uniform temperature” is introduced.     

Decision making in energy planning: the ELECTRE multicriteria analysis approach compared to a FUZZY-SETS methodology

Every planning activity generally requires to make some choices. After a preliminary analysis of the sector under examination, a forecast of trends of input–output items, the planner must define an action plan voted to arrange all the strategies and specific interventions able to fit demand and supply during the planned time. The redaction of an action plan implies a strong effort in order to synthesize either suggestions coming from the analysis phases either all the constraints linked to technical choices. In the same time, a large number of “external” variables plays a role in orienting decision making. Some of these can be handled by numerical models (economic cost-benefit analyses, market penetration strategies, environmental impacts). Other aspects, concerning social and cultural impact, political drawbacks, aesthetic aspects, etc., can be analysed only in a qualitative way, or are subjected to a not-objective judgement. This paper aims of introducing a methodological tool able to “organize” and “synthesize” the large set of variables coming from several specific judgements (or assessments) helping the “decision maker” to read the complex problem, understand it and make choices. Previous works of the authors have presented possible applications of “multicriteria-analysis”. In particular, the ELECTRE methods family, (Roy, B., Me´thodologie multicrite`re d'aide a` la de´cision, Economica, coll. ‘‘Gestion', Paris, 1985) will be presented under the point of view of energy planning application. It consists in a “flexible” ranking method which takes into account the uncertainties of all the specific assessments, the qualitative nature of some indexes, the weight of the preferences or willingness systems of the decision maker. On the other hand, similar results can be obtained through the application of fuzzy sets theory (Zimmermann, H. J., Fuzzy set Theory and its Application. Kluver Academic Publisher, 1987). A decision making support method, based on fuzzy logic is here tested and compared to the previous one. A case study developed by authors will show differences among these two different approachs. It is focused on the development of a renewable energy diffusion strategies plan. Advantages and drawbacks of both methods will be explored and some suggestions will be proposed.     

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.     

Prediction of global daily solar radiation using higher order statistics

The main concern of the present paper is to present and to analyse two procedures for modelling daily global solar radiation. The first one uses the clearness index techniques and the second one uses a totally different type of approach for taking in consideration important properties of such data, including non-Gaussian shape and non-stationarity. This procedure uses the difference between the extraterrestrial and the observed daily global radiation denoted “lost solar component”. Both procedures are based on higher order statistics for generating the global solar radiation using mainly a random process. The prediction results show that the sequences of values generated have the same statistical characteristics as those of sequences observed. The comparison between the two methods used indicates that the developed model based on the “lost solar component” is better than the model obtained using the conventional procedure based on the clearness index.     

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.     

Fuzzy logic-based MPPT controllers for three-phase grid-connected inverters

In photovoltaic (PV) applications, a maximum power point tracking (MPPT) module is necessary to extract the whole energy that the PV module can generate depending on the instantaneous conditions of the PV system. A PV module is obtained by connecting a number of solar cells in series and parallel, which causes voltage and current to increase at module terminations. The present work is based on a three-phase grid-connected inverter designed for a 100 kW PV power plant that uses an MPPT scheme based on fuzzy logic controllers. The whole system presented is simulated in MATLAB. The fuzzy logic-based MPPT controllers show accurate and fast responses and are integrated into the inverter, so that the there is no requirement for a dc–dc converter. The inverter allows full control of reactive power.     

Modelling and experimentation of the “Shell” dryer

The “Shell” dryer is an African solar food dryer using natural convection. Its design has been defined by users, in function of local working conditions and of its easy using. But it is necessary for the best behaviour of this dryer to optimize its air flow section design. We present here a theoretical study of a “rustic” process, through mathematical modelisation tools.     

Expert diagnosis of polymer electrolyte fuel cells

Diagnosing faulty conditions of engineering systems is a highly desirable process within control structures, such that control systems may operate effectively and degrading operational states may be mitigated. The goal herein is to enhance lifetime performance and extend system availability. Difficulty arises in developing a mathematical model which can describe all working and failure modes of complex systems. However the expert's knowledge of correct and faulty operation is powerful for detecting degradation, and such knowledge can be represented through fuzzy logic. This paper presents a diagnostic system based on fuzzy logic and expert knowledge, attained from experts and experimental findings. The diagnosis is applied specifically to degradation modes in a polymer electrolyte fuel cell. The defined rules produced for the fuzzy logic model connect observed operational modes and symptoms to component degradation. The diagnosis is then tested against common automotive stress conditions to assess functionality.     

Active desiccant integration with packaged rooftop HVAC equipment

Current research indicates a direct correlation between indoor air quality and fresh air ventilation rates which supports requirements for building ventilation standards calling for continuous supply and increased amounts of ventilation to help assure safe and healthy interior air environments [O. Seppänen, W.J. Fisk, M.J. Mendell, Ventilation rates and health, ASHRAE Journal (August) (2002) 56–58; C.C. Downing, C.W. Bayer, Classroom indoor air quality vs. ventilation rate, ASHRAE Trans., 1993, Vol. 99, Part 2, Paper Number DE-93-19-1, pp. 1099–1103. [1] and [2]]. Off-the-shelf, packaged rooftop equipment used to air condition most facilities is not designed to handle the increased or continuous supply of outdoor air necessary to comply with building ventilation codes written to this new standard [American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. (ASHRAE), Ventilation for acceptable indoor air quality, Standard 62-1989, 1791 Tullie Circle, NE, Atlanta, GA 30329. [3]].Integration of a rooftop, unitary air conditioner with an active desiccant module (ADM) allows the use of a standard rooftop air conditioner with a thermally regenerated active desiccant component to provide a compact, cost-effective, and simple-to-use packaged system for efficiently pre-treating and supplying ventilation air adequate to ensure healthy indoor environments. By designing a combined vapor-compression/active desiccant system with the desiccant component positioned after a conventional cooling coil, the dehumidification effectiveness of the desiccant is significantly enhanced because it operates on cold, saturated, or nearly saturated, air leaving the evaporator. “Post-coil” rather than the normally used, “pre-coil” desiccant arrangement also minimizes the regeneration temperature required for the active desiccant, allows for partial bypass and post-cooling of the desiccated air after recombination, and dramatic decreases in the overall size for the pre-conditioning unit.     

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.     

Design and fabrication of low concentrating second generation PRIDE concentrator

Prototype first generation Photovoltaic Facades of Reduced Costs Incorporating Devices with Optically Concentrating Elements (PRIDE) technology incorporating 3 and 9 mm wide single crystal silicon solar cells showed excellent power output compared to a similar non-concentrating system when it was characterized both indoors using a flash and continuous solar simulator. However, durability and instability of the dielectric material occurred in long-term characterisation when the concentrator was made by using casting technology. For large scale manufacturing process, durability, and to reduce the weight of the concentrator, second generation PRIDE design incorporated 6 mm wide “Saturn” solar cells at the absorber of dielectric concentrators. Injection moulding was used to manufacture 3 kWp of such PV concentrator module for building façade integration in Europe. Special design techniques and cost implications are implemented in this paper. A randomly selected PV concentrator was characterised at outdoors from twenty-four (≈3 kWp) 2nd-G PRIDE manufactured concentrators. The initial PV concentrators achieved a power ratio of 2.01 when compared to a similar non-concentrating system. The solar to electrical conversion efficiency achieved for the PV panel was 10.2% when characterised outdoors. In large scale manufacturing process, cost reduction of 40% is achievable using this concentrator manufacturing technology.