Energies

571 KiB

Open AccessArticle

Application of the NO_x Reaction Model for Development of Low-NO_x Combustion Technology for Pulverized Coals by Using the Gas Phase Stoichiometric Ratio Index

by Masayuki Taniguchi, Yuki Kamikawa, Tsuyoshi Shibata, Kenji Yamamoto and Hironobu Kobayashi

Energies 2011, 4(3), 545-562; https://doi.org/10.3390/en4030545 - 23 Mar 2011

Cited by 3 | Viewed by 8073

Abstract

We previously proposed the gas phase stoichiometric ratio (SRgas) as an index to evaluate NO_x concentration in fuel-rich flames. The SRgas index was defined as the amount of fuel required for stoichiometric combustion/amount of gasified fuel, where the amount of [...] Read more.

We previously proposed the gas phase stoichiometric ratio (SRgas) as an index to evaluate NO_x concentration in fuel-rich flames. The SRgas index was defined as the amount of fuel required for stoichiometric combustion/amount of gasified fuel, where the amount of gasified fuel was the amount of fuel which had been released to the gas phase by pyrolysis, oxidation and gasification reactions. In the present study we found that SRgas was a good index to consider the gas phase reaction mechanism in fuel-rich pulverized coal flames. When SRgas < 1.0, NO_x concentration was strongly influenced by the SRgas value. NO_xconcentration was also calculated by using a reaction model. The model was verified for various coals, particle diameters, reaction times, and initial oxygen concentrations. The most important reactions were gas phase NO_x reduction reactions by hydrocarbons. The hydrocarbon concentration was estimated based on SRgas. We also investigated the ratio as an index to develop a new low-NO_x combustion technology for pulverized coals. We examined the relation between local SRgas distribution in the fuel-rich region in the low-NO_xflame and NO_x emissions at the furnace exit, by varying burner structures. The relationship between local SRgas value and local NO_x concentration was also examined. When a low-NO_x type burner was used, the value of SRgas in the flame was readily decreased. When the local SRgas value was the same, it was difficult to influence the local NO_x concentration by changing the burner structure. For staged combustion, the most important item was to design the burner structure and arrangement so that SRgas could be lowered as much as possible just before mixing with staged air. Full article

(This article belongs to the Special Issue Coal, Biomass & Solid Refuse Combustion)

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230 KiB

Open AccessArticle

Simultaneous Optimization for Hybrid Electric Vehicle Parameters Based on Multi-Objective Genetic Algorithms

by Lincun Fang, Shiyin Qin, Gang Xu, Tianli Li and Kemin Zhu

Energies 2011, 4(3), 532-544; https://doi.org/10.3390/en4030532 - 18 Mar 2011

Cited by 70 | Viewed by 10669

Abstract

Compared to conventional vehicles Hybrid Electric Vehicles (HEVs) provide fairly high fuel economy with lower emissions. To enhance HEV performance in terms of fuel economy and emissions, and ensure user satisfaction with driving performance, the need for simultaneous optimization for the main parameters [...] Read more.

Compared to conventional vehicles Hybrid Electric Vehicles (HEVs) provide fairly high fuel economy with lower emissions. To enhance HEV performance in terms of fuel economy and emissions, and ensure user satisfaction with driving performance, the need for simultaneous optimization for the main parameters of powertrain components and control system is inevitable. However, this problem is challenging due to the large amount of coupling design parameters, conflicting design objectives and nonlinear constraints. Considering the defect of the methods which convert multi-objective optimization problems into single-objective ones, a comprehensive methodology based on the non-dominated sorting genetic algorithms II (NSGA II) to achieve parameter optimization for powertrain components and control system simultaneously and successfully find the Pareto-optimal solutions set is presented in this paper. A case simulation is carried out and simulated by ADVISOR, The simulation results show that this method can produce many Pareto-optimal solutions and a satisfactory solution can be selected by decision-makers according to their requirements. The results demonstrate the effectiveness of the algorithms proposed in this paper. Full article

(This article belongs to the Special Issue Hybrid Vehicles)

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402 KiB

Open AccessArticle

CFD Investigation into Diesel PCCI Combustion with Optimized Fuel Injection

by Zhijun Peng, Bin Liu, Weiji Wang and Lipeng Lu

Energies 2011, 4(3), 517-531; https://doi.org/10.3390/en4030517 - 18 Mar 2011

Cited by 31 | Viewed by 11419

Abstract

A multi-pulse injection strategy for premixed charge compression ignition (PCCI) combustion was investigated in a four-valve, direct-injection diesel engine by a computational fluid dynamics (CFD) simulation using KIVA-3V code coupled with detailed chemistry. The effects of fuel splitting proportion, injection timing, spray angles, [...] Read more.

A multi-pulse injection strategy for premixed charge compression ignition (PCCI) combustion was investigated in a four-valve, direct-injection diesel engine by a computational fluid dynamics (CFD) simulation using KIVA-3V code coupled with detailed chemistry. The effects of fuel splitting proportion, injection timing, spray angles, and injection velocity were examined. The mixing process and formation of soot and nitrogen oxide (NO_x) emissions were investigated as the focus of the research. The results show that the fuel splitting proportion and the injection timing impacted the combustion and emissions significantly due to the considerable changes of the mixing process and fuel distribution in the cylinder. While the spray, inclusion angle and injection velocity at the injector exit, can be adjusted to improve mixing, combustion and emissions, appropriate injection timing and fuel splitting proportion must be jointly considered for optimum combustion performance. Full article

(This article belongs to the Special Issue Advancement in Combustion Sciences and Technology)

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659 KiB

Open AccessArticle

Building Space Heating with a Solar-Assisted Heat Pump Using Roof-Integrated Solar Collectors

by Zhiyong Yang, Yiping Wang and Li Zhu

Energies 2011, 4(3), 504-516; https://doi.org/10.3390/en4030504 - 14 Mar 2011

Cited by 16 | Viewed by 8029

Abstract

A solar assisted heat pump (SAHP) system was designed by using a roof-integrated solar collector as the evaporator, and then it was demonstrated to provide space heating for a villa in Tianjin, China. A building energy simulation tool was used to predict the [...] Read more.

A solar assisted heat pump (SAHP) system was designed by using a roof-integrated solar collector as the evaporator, and then it was demonstrated to provide space heating for a villa in Tianjin, China. A building energy simulation tool was used to predict the space heating load and a three dimensional theoretical model was established to analyze the heat collection performance of the solar roof collector. A floor radiant heating unit was used to decrease the energy demand. The measurement results during the winter test period show that the system can provide a comfortable living space in winter, when the room temperature averaged 18.9 °C. The average COP of the heat pump system is 2.97 and with a maximum around 4.16. Full article

(This article belongs to the Special Issue Advances in Solar Energy)

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562 KiB

Open AccessArticle

A New Neural Network Approach to Short Term Load Forecasting of Electrical Power Systems

by Nima Amjady and Farshid Keynia

Energies 2011, 4(3), 488-503; https://doi.org/10.3390/en4030488 - 10 Mar 2011

Cited by 73 | Viewed by 10119

Abstract

Short-term load forecast (STLF) is an important operational function in both regulated power systems and deregulated open electricity markets. However, STLF is not easy to handle due to the nonlinear and random-like behaviors of system loads, weather conditions, and social and economic environment [...] Read more.

Short-term load forecast (STLF) is an important operational function in both regulated power systems and deregulated open electricity markets. However, STLF is not easy to handle due to the nonlinear and random-like behaviors of system loads, weather conditions, and social and economic environment variations. Despite the research work performed in the area, more accurate and robust STLF methods are still needed due to the importance and complexity of STLF. In this paper, a new neural network approach for STLF is proposed. The proposed neural network has a novel learning algorithm based on a new modified harmony search technique. This learning algorithm can widely search the solution space in various directions, and it can also avoid the overfitting problem, trapping in local minima and dead bands. Based on this learning algorithm, the suggested neural network can efficiently extract the input/output mapping function of the forecast process leading to high STLF accuracy. The proposed approach is tested on two practical power systems and the results obtained are compared with the results of several other recently published STLF methods. These comparisons confirm the validity of the developed approach. Full article

(This article belongs to the Special Issue Intelligent Energy Demand Forecasting)

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549 KiB

Open AccessArticle

Analysis of a Residential Building Energy Consumption Demand Model

by Wei Yu, Baizhan Li, Yarong Lei and Meng Liu

Energies 2011, 4(3), 475-487; https://doi.org/10.3390/en4030475 - 10 Mar 2011

Cited by 40 | Viewed by 9754

Abstract

In order to estimate the energy consumption demand of residential buildings, this paper first discusses the status and shortcomings of current domestic energy consumption models. Then it proposes and develops a residential building energy consumption demand model based on a back propagation (BP) [...] Read more.

In order to estimate the energy consumption demand of residential buildings, this paper first discusses the status and shortcomings of current domestic energy consumption models. Then it proposes and develops a residential building energy consumption demand model based on a back propagation (BP) neural network model. After that, taking residential buildings in Chongqing (P.R. China) as an example, 16 energy consumption indicators are introduced as characteristics of the residential buildings in Chongqing. The index system of the BP neutral network prediction model is established and the multi-factorial BP neural network prediction model of Chongqing residential building energy consumption is developed using the Cshap language, based on the SQL server 2005 platform. The results obtained by applying the model in Chongqing are in good agreement with actual ones. In addition, the model provides corresponding approximate data by taking into account the potential energy structure adjustments and relevant energy policy regulations. Full article

(This article belongs to the Special Issue Energy Savings in the Domestic and Tertiary Sectors 2011)

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1265 KiB

Open AccessArticle

Latest Developments in Numerical Wind Synopsis Prediction Using the RIAM-COMPACT^® CFD Model—Design Wind Speed Evaluation and Wind Risk (Terrain-Induced Turbulence) Diagnostics in Japan

by Takanori Uchida and Yuji Ohya

Energies 2011, 4(3), 458-474; https://doi.org/10.3390/en4030458 - 07 Mar 2011

Cited by 12 | Viewed by 8636

Abstract

Because a significant portion of the topography in Japan is characterized by steep, complex terrain, which results in a complex spatial distribution of wind speed, great care is necessary for selecting a site for the construction of Wind Turbine Generators (WTGs). We have [...] Read more.

Because a significant portion of the topography in Japan is characterized by steep, complex terrain, which results in a complex spatial distribution of wind speed, great care is necessary for selecting a site for the construction of Wind Turbine Generators (WTGs). We have developed a CFD model for unsteady flow called Research Institute for Applied Mechanics, Kyushu University, COMputational Prediction of Airflow over Complex Terrain (RIAM-COMPACT^®). The RIAM-COMPACT^® CFD model is based on Large-Eddy Simulation (LES) technique. The computational domain of RIAM-COMPACT^® can extend from several meters to several kilometers, and RIAM-COMPACT^® can predict airflow and gas diffusion over complex terrains with high accuracy. First, the present paper proposes a technique for evaluating the deployment location of WTGs. Next, wind simulation of an actual wind farm was executed using the high resolution elevation data. As a result, an appropriate point and an inappropriate point for locating WTGs were shown based on the numerical results obtained. This cause was found to be a topographical irregularity in front of WTGs. Full article

(This article belongs to the Special Issue Wind Energy 2011)

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1132 KiB

Open AccessArticle

Plug-in-Hybrid Vehicle Use, Energy Consumption, and Greenhouse Emissions: An Analysis of Household Vehicle Placements in Northern California

by Brett Williams, Elliot Martin, Timothy Lipman and Daniel Kammen

Energies 2011, 4(3), 435-457; https://doi.org/10.3390/en4030435 - 04 Mar 2011

Cited by 25 | Viewed by 11335

Abstract

We report on the real-world use over the course of one year of a nickel-metal-hydride plug-in hybrid—the Toyota Plug-In HV—by a set of 12 northern California households able to charge at home and work. From vehicle use data, energy and greenhouse-emissions implications are [...] Read more.

We report on the real-world use over the course of one year of a nickel-metal-hydride plug-in hybrid—the Toyota Plug-In HV—by a set of 12 northern California households able to charge at home and work. From vehicle use data, energy and greenhouse-emissions implications are also explored. A total of 1557 trips—most using under 0.5 gallons of gasoline—ranged up to 2.4 hours and 133 miles and averaged 14 minutes and 7 miles. 399 charging events averaged 2.6 hours. The maximum lasted 4.6 hours. Most recharges added less than 1.4 kWh, with a mean charge of 0.92 kWh. The average power drawn was under one-half kilowatt. The greenhouse gas emissions from driving and charging were estimated to be 2.6 metric tons, about half of the emissions expected from a 22.4-mpg vehicle (the MY2009 fleet-wide real-world average). The findings contribute to better understanding of how plug-in hybrids might be used, their potential impact, and how potential benefits and requirements vary for different plug-in-vehicle designs. For example, based on daily driving distances, 20 miles of charge-depleting range would have been fully utilized on 81% of days driven, whereas 40 miles would not have been fully utilized on over half of travel days. Full article

(This article belongs to the Special Issue Energy-Friendly Transportation)

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2078 KiB

Open AccessReview

Fluidized Bed Gasification as a Mature And Reliable Technology for the Production of Bio-Syngas and Applied in the Production of Liquid Transportation Fuels—A Review

by Marcin Siedlecki, Wiebren De Jong and Adrian H.M. Verkooijen

Energies 2011, 4(3), 389-434; https://doi.org/10.3390/en4030389 - 01 Mar 2011

Cited by 119 | Viewed by 17565

Abstract

Biomass is one of the renewable and potentially sustainable energy sources and has many possible applications varying from heat generation to the production of advanced secondary energy carriers. The latter option would allow mobile services like the transportation sector to reduce its dependency [...] Read more.

Biomass is one of the renewable and potentially sustainable energy sources and has many possible applications varying from heat generation to the production of advanced secondary energy carriers. The latter option would allow mobile services like the transportation sector to reduce its dependency on the fossil fuel supply. This article reviews the state-of-the-art of the fluidization technology applied for the gasification of biomass aimed at the production of gas for subsequent synthesis of the liquid energy carriers via, e.g., the Fischer-Tropsch process. It discusses the advantages of the gasification technology over combustion, considers the size of the conversion plant in view of the local biomass availability, assesses the pros and cons of different gasifier types in view of the application of the product gas. Subsequently the article focuses on the fluidized bed technology to discuss the main process parameters and their influence on the product composition and the operability of the gasifier. Finally a synthesis process (FT) is introduced shortly to illustrate the necessary gas cleaning steps in view of the purity requirements for the FT feed gas. Full article

(This article belongs to the Special Issue Energy-Friendly Transportation)

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799 KiB

Open AccessArticle

by Roberto Capata, Antonio Coccia and Max Lora

Energies 2011, 4(3), 368-388; https://doi.org/10.3390/en4030368 - 01 Mar 2011

Cited by 11 | Viewed by 9451

Abstract

For years the interest of the University of Roma 1 (UDR1) research group has been focused on the development of a Hybrid Series vehicle (called Lethe^©), different from standard ones, thanks to the use of a Gas Turbine (GT) set as [...] Read more.

For years the interest of the University of Roma 1 (UDR1) research group has been focused on the development of a Hybrid Series vehicle (called Lethe^©), different from standard ones, thanks to the use of a Gas Turbine (GT) set as a thermal engine. The reason for this choice resides in the opportunity to reduce weight and dimensions, in comparison to a traditional Internal Combustion Engine. It’s currently not possible to use the GT engine set directly for the vehicle traction, so the UDR1 HS configuration only shows the GT set connected with the electric generator. The result is that the traction is purely electric. The resulting engine configuration is commonly described as a Hybrid Series Plug In. Several previous studies have been carried out, and this research has allowed us to define the correct ratio (Degree of Hybridization) between the installed power of the battery pack and that of the GT electric generator which simultaneously guarantee the main life for the battery package and the capacity of the vehicle to complete a common mission without lack of energy or stopping. This article reports the final step of the research: once all data has been calculated, how to “hybridize” a commercial city car, passenger sedan or any other vehicle. Full article

(This article belongs to the Special Issue Hybrid Vehicles)

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Energies, Volume 4, Issue 3 (March 2011) – 10 articles , Pages 368-562

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