A new miniaturized engine based on thermomagnetic effect of magnetic fluids

A new engine system, essentially consisting of a permanent NdFeB magnet, a kerosene-based magnetic fluid and a rotor, is proposed based on the thermomagnetic effect of a temperature-sensitive magnetic fluid. The rotor was driven by the thermal convection of the magnetic fluid in the presence of a homogeneous external magnetic field. A digital camera was used to record the rotation speed of the rotor to investigate the performance of the engine system under varying conditions such as heat load, heat sink temperature, and magnetic field distribution. The peak angle velocity obtained for the rotor was about 2.1 rad/min. The results illustrate that the rotation speed of the rotor increases as the input heat load increases, or as the heat sink temperature decreases. The performance of the motor is considerably influenced by the magnetic field imposed. Therefore, the performance of such an engine can be controlled conveniently by changing the external magnetic field and/or the temperature distribution in the fluid.     

Forecasting the transport energy demand based on PLSR method in China

Transportation sector accounts for a major share of energy consumption in China, especially the petroleum products, which experienced rapid increases in energy demand. The purpose of this study is to forecast transport energy demand for 2010, 2015 and 2020 based on partial least square regression (PLSR) method under two scenarios. Transport energy demand is analyzed for the period of 1990–2006 based on gross domestic product (GDP), urbanization rate, passenger-turnover and freight-turnover. This method suggests that transport energy demand for 2020 will reach to a level of around 433.13 Mtce and 468.26 Mtce, respectively. Those figures are very close to the estimation obtained by Energy Research Institute of China. Thus this study provides an effective tool, which can be used as an alternative solution and estimation techniques for the transport energy demand.     

Surface cooling based on the thermomagnetic convection: Numerical simulation and experiment

In this paper we present the results of our numerical and experimental investigation of thermomagnetic convection in a temperature sensitive ferrofluid under the influence of strong non-uniform magnetic field. The convection is studied in a rectangular cell with permanent magnets attached to the cell walls. When the cell is heated from below, the observed intensification of heat transfer is significantly higher than that in the case of simple thermogravitational convection. The predictions of the numerical simulations are compared with the experimental results with good correspondence.     

一种基于可靠出力的储能容量的配置方法

储能系统在大型风电场中可用于"削峰填谷",使风电输出平滑可调度,从而提高风电并网率,解决风电难消纳的问题。但大型风储联合发电系统受场地、储能成本以及储能材料的制约并未得到广泛应用,研究如何在适当的"弃风"情况下同时保证风电持续输出以及储能经济性势在必行。文中提出一种大型风储系统(风力-压缩空气储能系统)储能容量配置方法,研究风储系统在不同置信度下的储能容量配置,通过实例来验证储能装置用于提高风电输出可靠性,结果表明风电输出可靠性与储能容量有正比关系。最后,通过简单储能成本分析,验证该系统的经济性。     

Development of rank ordering techniques based on the analytical hierarchy process for evaluation of energy conversion devices

Both producers and consumers of electric energy have challenging decisions to make. In some cases, these decisions are related to the selection of specific equipment for energy production or energy conversion. The important financial and operational decisions that face these companies merit the use of an analytic approach to decision making. Of special interest is the purchase of high volume equipment used in the daily operation of energy production or conversion. This paper presents a method that utilizes all available information when making a decision, regardless of the size of the problem. The method is based on the analytical hierarchy process (Saaty, 1980). An example is shown demonstrating the selection of one of the most common energy conversion devices, namely a distribution transformer. Distribution transformers are rank ordered according to manufacturers using this decision support technique. Finally, a user friendly software package implementing this method is fully developed on a personal computer.     

基于海洋能的离岸监测服役件供能系统设计

海洋能作为可再生清洁能源,近年来已有多种转换开发方法与装置设计方案提出,但大多集中于装置原理优劣以及供能量大小对比的研究,缺乏针对海洋公共平台及其服役件供能服务的集分析、设计、智能管理、固联以及安全保护等系统化研究。针对不同尺度的服务对象,文章提出了基于海洋可再生潮流能、波浪能的转换、储备以及服务一体化供能应用系统,分析设计了海洋能转换装置原理,提出总体设计思路。在此基础上,给出了电机效率匹配、供能与数据采集智能管理、多装置集成固联以及极端海况自适应保护分析原则与设计方法。结合现场实验验证系统的有效性,为海洋可再生能源的应用与服务提供帮助和参考。     

Design of an energy hub based on natural gas and renewable energy sources

This paper presents a simulation model for an energy hub consisting of natural gas (NG) turbines as the main sources of energy (including both electricity and heat) and two renewable energy sources—wind turbines (WTs) and photovoltaic (PV) solar cells. The hub also includes water electrolyzers for hydrogen production. The hydrogen serves as an energy storage medium that can be used in some transportation applications, or it can be mixed with the NG feed stream to improve the emission profile of the gas‐turbine unit. The capacity of the designed hub is meant to simulate and replace the coal‐fired Nanticoke Generating Station with a NG‐fired power plant. Therefore, the aim of this work is to develop a simulated model that combines different energy generation technologies, which are evaluated in terms of the total energy produced, the cost per kWh of energy generated, and the amount of emissions produced. The proposed model investigates the benefits, both economic and environmental, the technological barriers, and the challenges of energy hubs by developing several scenarios. The simulation of these scenarios was done using General Algebraic Modeling System (GAMS®). Although the software is strongly known for its optimization capability, the mixed complementary problems solver makes it a strong tool for solving equilibrium problems. Excess energy produced during off‐peak demand by WTs and PV solar cells was used to feed the electrolyzer to produce H₂ and O₂. The proposed approach shows that a significant reduction in energy cost and greenhouse gas emissions were achieved, in addition to the increased overall efficiency of the energy hub. Out of the examined three scenarios, Scenario C appeared to be the most feasible option for a combination of renewable and non‐renewable technologies as it did not only produce hydrogen, but also provided electricity at relatively lower prices. Copyright © 2013 John Wiley & Sons, Ltd.     

Design of high-efficiency turbomachinery blades for energy conversion devices with the three-dimensional prescribed surface curvature distribution blade design (CIRCLE) method

The purpose of this paper is to present the advantages of the direct presCrIbed suRface Curvature distribution bLade dEsign (CIRCLE) method for the design of high-efficiency turbomachinery blades. These advantages are illustrated by redesigning several examples of axial turbomachinery blades of interest to energy conversion devices, and discussing in detail the aerodynamic performance and efficiency improvements of the redesigned blades over the original geometries. The two-dimensional (2D) method, originally proposed for turbine blades, has been extended for use with 2D and three-dimensional (3D) turbine, compressor and fan blades, and isolated airfoils. By specification, the method allows joining line segments between the leading edge (LE) and trailing edge (TE) circles or ellipses so that the streamwise distribution of surface curvature and slope of curvature are continuous everywhere from the LE stagnation point to the TE stagnation point. The form of the line segments to prevent the “wiggles” of higher order lines is presented. Also by specification, the CIRCLE method can be integrated with multi-objective heuristic or evolutionary-algorithm optimization methods. The efficacy of the method is examined by: redesigning two 2D turbine blades, one 2D compressor blade, and one 2D isolated airfoil; and by designing one 3D compressor blade row and one 3D turbine blade row. The aerodynamic performance improvements between the original and the sample redesigned blades are discussed in detail, resulting in higher-efficiency blades than the original geometries. Further extension of the method for centrifugal and mixed-flow impeller geometries is a coordinate transformation. It is concluded that the CIRCLE method is a new design environment enabling the original design (or redesign) of high-efficiency 2D and 3D turbomachine blades, with direct applications in a variety of energy conversion devices.     

A method of testing for rating thermal storage devices based on thermal performance

This paper describes a proposed test method for determining the “effective capacity” and heat loss characteristics of thermal storage devices. The prescribed series of tests should provide useful data for the rating of thermal storage devices based on thermal performance. The apparatuses and major components used in the tests have been prescribed so a liquid or air can be used as the transfer fluid. The series of tests to be conducted consist of one steady-state test to determine the heat loss characteristics and eight transient tests to determine the “effective capacity” for both heat storage and heat removal. During the transient tests, the entering fluid temperature is changed in a step-wise manner and amount of energy either stored or removed over a specified test time is determined. Sample experimental data are given in the paper to demonstrate the concept of the transient tests.     

Simulating the dust effect on the energy performance of photovoltaic generators based on experimental measurements

One of the least analyzed side effects of atmospheric air pollution is the degradation of PV-panels’ performance due to the deposition of solid particles varying in composition, size and type. In the current study, the experimental data concerning the effect of three representative air pollutants (i.e. red soil, limestone and carbonaceous fly-ash particles) on the energy performance of PV installations are analyzed. According to the results obtained, a considerable reduction of PVs’ energy performance is recorded, depending strongly on particles’ composition and source. Subsequently, a theoretical model has been developed in order to be used as an analytical tool for obtaining reliable results concerning the expected effect of regional air pollution on PVs’ performance. Furthermore, experimental results concerning the dust effect on PVs’ energy yield in an aggravated - from air pollution - urban environment are used to validate the proposed theoretical model.     

Discrete ordinates method for three-dimensional neutron transport equation based on unstructured-meshes

A discrete ordinates method for a three-dimensional first-order neutron transport equation based on unstructured-meshes that avoids the singularity of the second-order neutron transport equation in void regions was derived. The finite element variation equation was obtained using the least-squares method. A three-dimensional transport calculation code was developed. Both the triangular-z and the tetrahedron elements were included. The numerical results of some benchmark problems demonstrated that this method can solve neutron transport problems in unstructured-meshes very well. For most problems, the error of the eigenvalue and the angular flux is less than 0.3% and 3.0% respectively. __________ Translated from Journal of Xi’an Jiao Tong University, 2007, 41(3): 363–366 [译自: 西安交通大学学报]     

Discrete ordinates method for three-dimensional neutron transport equation based on unstructured-meshes

A discrete ordinates method for a three-dimensional first-order neutron transport equation based on unstructured-meshes that avoids the singularity of the second-order neutron transport equation in void regions was derived. The finite element variation equation was obtained using the least-squares method. A three-dimensional transport calculation code was developed. Both the triangular-z and the tetrahedron elements were included. The numerical results of some benchmark problems demonstrated that this method can solve neutron transport problems in unstructured-meshes very well. For most problems, the error of the eigenvalue and the angular flux is less than 0.3% and 3.0% respectively.     

An evaluation method of energy storage technologies based on energetic costs

近年来，中国和世界一直致力于发展储能技术，为电网运行提供调峰、调频、黑启动、需求响应支持，并帮助解决可再生能源间歇性、不稳定性、不可调节性等问题。本文回顾总结了国内目前评价储能技术常用的技术指标和经济效益指标。并站在能源可持续发展的角度介绍了基于“能量”成本评价储能技术的新理念及方法，阐述了基于‘能量’成本评价不同技术节能潜力的必要性，引入了全生命周期能源投入存储回报（energy stored on Investment，ESOI）这一新指标。ESOI比值越高说明该技术“净能量”越高，生产对能源依赖度越低。本文研究对比了不同储能技术的ESOI，结果表明以压缩空气储能（CAES）和抽水储能（PHS）为代表的物理储能技术的ESOI远远大于电化学储能，其中，过去常用的铅酸电池（PbA）的ESOI最小，只有2。     

Field study of the effect of low-cost weatherstripping devices on energy use in single-family (San Diego) residences

We present results obtained in field studies of control and test houses provided with low-cost, retrofit infiltration controls. There are significant estimates of average energy savings during both the heating and cooling seasons; however, the 95% confidence intervals for the heating season span the origin and the probability that savings were actually observed is less than 85% for the heating season. The probability that actual savings were measured during the cooling season is greater than 95%. For installations made by homeowners, estimated average payback periods are well below two years and are therefore justified in terms of economic returns resulting from energy savings.     

Effect of louver shading devices on building energy requirements

External louvers are increasingly used to provide solar protection for building glazed surfaces. In this work, a general study of the effect of louver shading devices applied to different façades of a building is carried out, for different locations (latitudes). Building energy requirements for a building in the cooling and heating seasons is quantified for different window and louver areas, under climatic conditions of Mexico (Mexico), Cairo (Egypt), Lisbon (Portugal), Madrid (Spain) and London (UK). Also, operative and indoor temperatures were calculated through simulations using TRNSYS software, whereas the model for the shading geometry study was solved with EES software. Both horizontal and vertical louver layouts were considered. The results show that the integration of louver shading devices in the building leads to indoor comfortable thermal conditions and may lead to significant energy savings, by comparison to a building without shading devices.     

基于简单能效测试的燃轻油工业锅炉超耗能源量计算方法研究

随着国家节能减排力度的加大,高耗能特种设备锅炉的节能工作日益被引起重视,锅炉能效测试作为一项常规监管工作得以广泛开展。锅炉能效测试可获得锅炉主要能效指标,例如:锅炉热效率、排烟温度、过量空气系数等,并给出锅炉优化运行的措施,但是锅炉用户更关注锅炉能效指标不符合规程值后,引起燃料浪费量。如何根据锅炉热效率、排烟温度和过量空气系数计量超耗能源量,从而快速指导用户有针对性地调整锅炉运行参数,使得锅炉处于最低经济成本运行具有重大的现实意义。     

基于特征聚类的多能源系统负荷预测方法研究

针对多能源系统中不同种类能源负荷特征提取及预测问题,提出基于特征聚类的多能源系统负荷预测方法,利用灰色关联分析系统理论对多种类能源负荷预测模型中的环境因素输入属性进行主控因素关联度分析,分别得到电、气、热、冷负荷受环境因素影响的关联度,利用卷积神经网络提取负荷数据和关联度输入数据的特征向量,利用K-means聚类算法对给定特征向量进行聚类,建立多种类能源负荷的特征聚类模型。算例结果表明,文章所提出的基于特征聚类的多能源系统负荷预测方法,能够有效提高不同种类能源负荷的预测精度。     

基于模糊决策的路灯节电等级控制系统的设计

此节能型路灯照明智能控制系统以单片机为核心,采用了电压、时间及光控制相结合的方法,利用模糊决策理论对节电等级进行控制,可有效改善路灯照明质量,节约电能及延长灯具的使用寿命,达到了很好的节电效果。     

基于主从博弈理论的综合能源系统优化运行方法

综合能源系统作为实现智慧能源的关键技术形式,其优化运行问题是一门重要课题。针对综合能源系统优化运行问题,考虑到系统多能互补协调,基于主从博弈理论进行建模。其中:主体博弈模型以多能互补协调计划为博弈策略,以综合能源系统综合运行成本最小化为博弈支付,计及多能互补协调约束等必要约束条件;从体博弈模型以各个形式能源子网的运行计划为博弈策略,以能源子网运行收益最大化为博弈支付,计及分布式供能设备运行约束等必要约束条件。分析得到主从博弈模型的纳什均衡,基于混沌粒子群算法设计模型求解流程。最后通过仿真算法表明,所建立的模型适用于综合能源系统优化运行方案制定,能够显著降低系统运行成本。