供热系统中动力设备的节能问题分析

分析了供热系统中动力设备能耗偏高的原因,主要为低负荷率运行和阀门调节造成的节流损失;比较了不同流量调节方法的特点;指出应通过动力设备容量的合理配置配合合适的调速方法以保证动力设备高效运行;分析了不同设备的合理调节范围;并利用具体方案比较分析了变频调节的节能幅度。     

变频技术在电厂循环水泵中的应用

针对目前主要采用阀门调节管路流量而造成能源浪费的问题,介绍了变频调速技术的主要原理、汽轮机最佳真空的计算方法,指出在电厂循环水系统中应用变频调速技术具有较大的节能潜力。     

变频技术在泵与风机系统中应用的节能分析

根据泵与风机在不同工况下运行的性能与特点，分析了变流量运行时，泵与风机流量、扬程(压头)、功率与转速间的关系。介绍了变频器在泵与风机调速上的应用现状，及使用变频器变频调速与挡板节流对比，阐述了变频调速节能原理及经济效益。提出了变流量运行时，泵与风机应采用变频技术，合理配备，并举例分析比较了电厂鼓风机采用变频调节时的特性、耗能情况及其经济性。     

变频技术与空调节能

分析了空调系统流量调节方式与能耗的关系,根据变频调速技术的节能原理,通过实例说明变频调速装置用于空调的变流量调节可显著节能,提高空调系统的经济性。     

变频技术与空调节能

分析了空调系统流量调节方式与能耗的关系,根据变频调速技术的节能原理,通过实例说明变频调速装置用于空调的变流量调节可显著节能,提高空调系统的经济性。     

流量泵变频调速的技术经济分析及投资决策方法

通过对流量泵的工况分析、功率分析,提出了变频调速调节流量的节能潜力估计及实施变频调速项目的投资决策方法。     

空调中流体输送系统变频节能经济分析

介绍了变频调速技术及在空调系统中的节能原理,分析了空调流量调节方式与能耗的关系,通过实例说明变频调速装置用于空调的变流量高节可显著节能,提高空调系统的经济性。     

锅炉脱盐水系统变频节能改造

在化工生产中,离心泵使用较为普遍,其出口压力往往要高于生产系统所需压力,常见做法是采用阀门降压,能耗较高.相比而言,变频调速能够降低离心泵出口压力过高问题,且能够节省阀门降压带来的能量损耗.针对兖矿国宏公司脱盐水系统,收集离心泵出口管道阀门前后压力数据,进行相关计算后得出节能效果.结合现场情况和运行经验,编制变频改造方案.改造完成后,再次收集相关数据,经过比较节能效果明显,达到预期目的.     

变频调速器在化工企业中的应用

在分析异步电动机调速运行方式的基础上结合采用变频调速而进行了节能分析 ,并通过实际事例指出了采用变频调速后的实际节能效果和社会经济效益     

变频调速技术在锅炉风机上的应用

简述实际生产中锅炉风机运行情况及发现的主要问题,锅炉风机采用变频调速的原因,介绍了锅炉风机变频调速节能原理.通过变频改造后的实际应用效果及节能分析论证了采用变频调速达到了节能的目的和效果.     

炼油工业节能仍有许多细致扎实的工作要做

介绍了中国石化炼厂近几年节能取得的成效,炼油综合能耗从2001年的78．86kg标油/t降低到2007年的65．91kg标油／t,炼油单因耗能从2001年的13．1kg标油,（t·因素）降低到2007年的10．11kg标油,（t·因素）。通过炼油能耗评价和节能潜力分析,对中国石化炼油企业节能现状作出了基本评价,指出了今后节能任务艰巨,节能空间较大。分析了中国炼油业面临的新问题和新挑战,对新建和改扩建炼厂能耗进行了剖析。最后对炼油企业挖掘节能潜力提出了建议,包括合理选择原油、生产优化、提高全厂加热炉热效率、深化装置间的热联合、蒸汽系统的优化、低温热能的合理利用、采用高效节能设备、节电、回收凝结水、加强节能管理。     

热水器污垢实时监测及其节能潜力估算

热水器的实测结果表明了热水器的污垢不可忽视.水质和垢样分析结果则指出了垢的成因,为了消除垢的不良影响,建立了热水器污垢(热阻)实时监测模型用以监测污垢的积聚状态,并进而据以估算热水器污垢对策的潜在节能价值.     

Integrated modelling of material flows and energy systems (MIMES)

A comprehensive nonlinear programming model, MIMES, for the optimization of linked material and energy flow systems is presented. The model is generic, intended for systems that can be described by materials and energy balances but where the details of phase transitions and chemical reactions can be omitted. It fills a niche between energy systems engineering and process flowsheeting models. Issues suitable for analysis by the model range from energy conservation in industrial plants, specific industries or industrial subsectors to municipal waste management and fuels and materials life cycle analysis. MIMES is implemented on PC (386/486). The model is demonstrated for a paper production line in a paper mill. This example shows how the model can be used for joint analysis of energy and water conservation, substitution of energy carriers, and utilization of waste heat outside the system.     

Three-dimensional modeling of water transport in PEMFC

A three dimensional two phase flow model is proposed to study transport phenomena in a PEMFC. In order to capture the effects of liquid water on the performance of the fuel cell, all regions are modeled from the anode to the cathode as having finite thickness. The geometry of the bipolar plate is modeled in detail to capture the effect of liquid water accumulation under the channel rib. This model takes into account the effect of temperature and inlet RH of both the anode and cathode. The three-dimensional model uses the finite volume method to solve the equations of mass conservation, momentum, energy, species transfer and protonic potential. These equations include the effect of liquid water on the transport properties as well as the electrochemical source. The effects of water on ohmic losses are presented for different humidity conditions of the anode and cathode at various fuel cell temperatures.     

Heat and mass transfer influence on potential variation in a PEMFC membrane

Water transport in the membrane of a PEM fuel cell is provided essentially by a convective force, resulting from a pressure gradient, an osmotic force, due to a concentration gradient and an electric force caused by the protons migration from the anode to the cathode. Through these three types of force the two-dimensional behavior of electric potential has been studied in this paper. The adopted model in this work is based on the assumption of single phase and multi-species flow, supposed two-dimensional and transient in a porous medium. The species conservation equation is coupled with the energy equation through the diffusion coefficient of water and the heat convective flux. The set of governing equations in the form of convection–diffusion problem has been solved numerically using the finite volume method. The obtained results show the transient two-dimensional effect of heat and mass transfer on the voltage variation within the membrane.     

An analysis of energy conservation possibilities in the residential sector in New Zealand

A model which simulates residential energy use in New Zealand until the year 2000 has been developed. This paper describes some of the energy conservation possibilities and their effect on energy use for space and water heating. an engineering analysis made to determine the effect of various factors on energy use for space heating is first described. the information gained from many computer simulations is used to develop a quantitative relationship between space heating energy and major determinants—climatic location, building type and intensity of use. Results from an engineering analysis of a water heating unit are used to establish the energy savings due to improved cylinder insulation and lower storage temperature. A solar space and water heating system is analysed to determine the fraction of total heating load that can be met by harnessing solar energy. the analyses demonstrate that the potential of conservation measures to reduce energy use can be substantial—by raising the insulation level on the building and on the water heating cylinder, by lowering the water storage temperature, and by installing an optimized solar heating system, the energy requirement can be reduced to 0·37 times what it is today for a typical uninsulated home.     

Household water conservation: The role of indirect energy savings

Recent regulations specify a cost-effectiveness analysis of implementing household water conservation measures to reduce the flow of wastewater as a prerequisite to federal funding of wastewater treatment plant construction. There is a wide variety of devices available to conserve water: hot water as well as water at ambient temperature. In this analysis we use a sample of 23 metropolitan areas to evaluate the indirect household energy savings which results from conservation devices to save hot water.

Devices to conserve hot water are cost-effective in all 23 metropolitan areas up to an equivalent annual cost of $1.50/1000 gal saved under an assumption of no inflation in energy prices, and about $7.00/1000 gal saved under an assumption of 20%/yr inflation in energy prices. The impact of the indirect energy savings can be further illustrated by noting that devices to conserve ambient temperature water are cost-ineffective in all 23 metropolitan areas at equivalent annual costs above $1.00/1000 gal saved. Besides increasing the level of cost-effective household water conservation from 114 gal/day to 146 gal/day for a family of four, while providing significant economic savings, the indirect energy savings from hot-water conservation devices can provide a 46–62% reduction in energy use for residential water heating.     

Computation of practical flow problems with release of latent heat

Practical flow problems with condensation due to phase change from water vapor to water liquid are numerically investigated. Fundamental equations solved in this study consist of conservation laws of mixed gas, water vapor, water liquid, and the number density of water droplets, coupled with the momentum equations and the energy equation. The classical condensation theory is employed for modeling homogeneous nucleation and nonequilibrium condensation. Heterogeneous nucleation is approximately modeled by assuming a constant radius and a constant number density of droplets. These equations are solved by a high-order high-resolution finite-difference method. As external flows, condensate transonic flows around NACA0012 airfoil in atmospheric flow conditions are calculated, and as internal flows, steady and unsteady transonic wet-steam flows through a steam turbine cascade channel are also calculated.     

立窑分析浅析

利用炯分析的方法对立窑系统进行了分析,得出了效率、变质系数,找出了立窑系统能量利用的薄弱环节,提出了节能挖潜措施.     

Energy flow analysis in pulp and paper industry

This work analyzed the energy flow of the pulp and paper industry in Taiwan. The potential technology options that were examined focus on how to capture some of the energy currently lost in the processes and then identifying the areas with energy-saving potential that could also have large impacts across a variety of industries. In addition, the energy-saving potential of these options was evaluated. The energy-saving potential of the pulp and paper industry would be around 6939.9 KLOE/M. The greatest energy-saving potential lies with improving energy distribution and equipment efficiency, which would together potentially comprise 86.8% of total energy conservation. This analysis can serve as a benchmark for current pulp and paper making operations, and as a base case for stimulating changes toward more efficient energy utilization in the pulp and paper industry.