背压机组热电平衡改造的一个途径

1 前言80年代以来在国家能源政策的推动下,各地热电联产项目得到有力扶持,纷纷建成投产,取得了极好的社会效益和经济效益。但80年代末和90年代初的有关政策,对机组的选型进行了严格限制,规定只能建背压机组。这在当时强调了背压机组的经济性,但却脱离了热负荷的实际,带来了副作用。

天然气冷热电联供系统能量平衡和系统发电机组容量选择方法的探讨

冷热电三联供系统发电机组容量的选择对三联供工程的经济性、节能性有很大的影响。在《燃气冷热电三联供供技术规程》中只作了原则的规定。本文提出通过冷、热、电年负荷延时图计算冷、热、电平均负荷率,并以此为依据计算出发电机组装机容量的推荐值,此时,在全部运行时间内,发电机组均处于满负荷状态下,然后根据建筑物的特点和燃机的性能,采用热电平衡方法确定燃机装机容量。提出通过设计日冷、热、电负荷计算出冷、热、电的最大装机容量。提出通过夏季、冬季、过渡季的冷、热、电负荷计算推荐合理的运行策略,提出通过能量平衡计算三联供系统的年平均综合利用率和三联供全系统的节能率。通过实际工程的应用,说明该方法是合理的、可行的。

热电负荷平衡及运方分析软件的开发

热能与电能的平衡是热电厂运行和生产调度中需考虑的问题,文章主要介绍热电厂机炉故障时如何调节,将这些调节步骤理论化、方程化,进一步得出调整步骤流程图,并根据流程图进行编程。采用N-1校验,即给出了任意一台机炉故障时的调整方式,从而完成机炉故障情况下的热电平衡辅助分析软件设计。

内蒙古西部电网热电负荷平衡及安全状况分析

分析了内蒙古西部电网各供热电厂不同运行方式下热电平衡问题,并对供热和发电之间的关系给予了评价,同时对热网的安全状况提出了建议。

连蒸运行转速与浆板系统热电负荷平衡关系

探讨了浆板生产系统以连蒸运行转速为基础的热电负荷平衡关系,确定经济热电运行方式。

青山纸业热、电动平衡与炉、机运行方式的确立

阐述年产 2 5万t硫酸盐制浆造纸厂热、电动平衡的特点 ,充分利用引进的高效率碱炉和抽背式机组的能力 ,在实际生产过程中 ,因地制宜 ,合理调度 ,正确选择炉、机运行方式 ,使碱炉。

Heat Transfer Analysis on Wire Icing and the Current Preventing from Icing

This study concerns the heat transfer processes during ice accretion on wires. The steady state heat balance equation assumed to describe the thermodynamics at the surface of a current heated wire subjected to icing is obtained by analyzing and computing each terms of heat flux. The surface temperature of wire is derived from the heat balance equation, which gives out a proposed estimation of the current intensity to prevent the wire icing

谈楼宇型燃气三联供系统设计思路

燃气三联供系统是一种节能的分布式能源系统,是近年来国家鼓励推广的一种新型的能源供应系统,现根据对典型医院冷热电负荷需求进行能耗分析,最终确定设备配置原则,保证能源梯级利用。达到节能环保的目的。

Kinetics Study on O2 Adsorption and OHad Desorption at Pt（111）, Its Implication to Oxygen Reduction Reaction Kinetics

Kinetics of dissociative O2 adsorption, OHad desorption, and oxygen reduction reaction （ORR） at Pt（111） electrode in 0.1 mol/L HClO4 has been investigated. Reversible OHad adsorption/desorption occurs at potentials from 0.6 V to 1.0 V （vs. RHE） with the exchange current density of ca. 50 mA/cm^2 at 0.8 V, the fast kinetics of OHad desorption indicates that it should not be the rate determining step for ORR. In the kineticor kinetic-mass transport mix controlled potential region, ORR current at constant potential displays slight decrease with reaction time. ORR current in the positive-going potential scan is slightly larger than that in the subsequent negative-going scan with electrode rotation speed （〉800 r/min） and slow potential scan rate （〈100 mV/s）. The open circuit potential of Pt/0.1 mol/L HClO4 interface increases promptly from 0.9 V to 1.0 V after switch from O2 free- to O2-saturated solution. The increase of open circuit potential as well as ORR current decays under potential control due to the accumulation of OHad from dissociative adsorption of O2. It indicates that at Pt（111） the net rate for O2 decomposition to OHad is slightly faster than that for OHad removal, one cannot simply use the assumption of rate determining step to discuss ORR kinetics. Instead, the ORR kinetics is determined by both the kinetics for O2 decomposition to OHad as well as the thermo-equilibrium of OHad＋H^＋＋e→←H2O.

2D finite element analysis of thermal balance for drained aluminum reduction cells

Based on the principle of energy conservation,the applicable technique for drained cell retrofitted from conventional one was analyzed with 2D finite element model. The model employed a 1D heat transfer scheme to compute iteratively the freeze profile until the thickness variable reached the terminating requirement. The calculated 2D heat dissipation from the cell surfaces was converted into the overall 3D heat loss. The potential drop of the system, freeze profile and heat balance were analyzed to evaluate their variation with technical parameters when designing the 150 kA conventional cell based drained cell. The simulation results show that the retrofitted drained cell is able to keep thermal balance under the conditions that the current is 190 kA, the anodic current density is 0.96 A/cm2, the anode-cathode distance is 2.5 cm, the alumina cover is 16 cm thick with a thermal conductivity of 0.20 W/(m·℃ ) and the electrolysis temperature is 946 ℃ .

Electromotive Force for Solid Oxide Fuel Cells Using Biomass Produced Gas as Fuel

The electromotive force （e.m.f.） of solid oxide fuel cells using biomass produced gas （BPG） as the fuels is calculated at 700-1,200 K using an in-house computer program, based on thermodynamic equilibrium analysis. Tour program also predicts the concentration of oxygen in the fuel chamber as well as the concentration of equilibrium species such as H2, CO, CO2 and CH4. Compared with using hydrogen as a fuel, the e.m.f. for cells using BPG as the fuels is relative low and strongly influenced by carbon deposition. To remove carbon deposition, the optimum amount of H2O to add is determined at various operating temperatures. Further the e.m.f, for cells based on yttria stabilized zirconia and doped ceria as electrolytes are compared. The study reveals that when using BPG as fuel, the depression of e.m.f, for a SOFC using doped ceria as electrolyte is relatively small when compared with that using Yttria stabilized zirconia.

A General Thermal Equilibrium Discharge Flow Model

Based on isentropic flow and thermal equilibrium assumptions, a model was derived to calculate discharge flow rate, which unified the rules of room temperature water discharge, high temperature and high pressure water discharge, two-phase critical flow, saturated steam and superheated steam critical flow, and gave a method to calculate critical condition. Because of the influence of friction, the entropy is increased in the actual discharge process, and the discharge flow rate in thermal equilibrium condition can be obtained by the original model multiplied by an appropriate correction coefficient. The model calculated results agreed well with the experiment data of long nozzle critical flow.

Thermo-Magneto-Electric Currents with Dynamical Magnetization Inhomogeneities

We study the effect of potential and thermal gradient induced non-equilibrium magnetization in quasi1-d itinerant magnets.A semi-phenomenological theory is employed in conjunction with the drift-diffusion model forthis study.Using the methods of non-equilibrium thermodynamics,we derive the transport currents correspondingto charge,heat,and magnetization flows in the presence of non-equilibrium magnetization textures.It is shown howtime-dependent magnetic textures give rise to charge and thermal currents even in the absence of external potential andthermal gradients through spin pumping.The presence of dynamical textures also affect the thermodynamic parametersof the system.As an application,we consider the case of a helimagnet.

One Year Minergie-A--Switzerlands Big Step towards Net ZEB

The first available label standardizing a zero-balanced type of building is the Swiss Standard Minergie-A. The standard prescribes an annual net zero primary energy balance for heating, domestic hot water and ventilation. Electricity consumption for appliances and lighting is excluded. Additionally, Minergie-A is the first standard worldwide which includes a requirement in regard to embodied energy. Based on an analysis of 39 Minergie-A buildings, this paper shows that a wide range of different energy concepts and embodied energy strategies are possible in the scope of the label. The basis of all Minergie-A buildings is a well-insulated building envelope. However, the step from the Swiss Standard Minergie-A to a Net ZEB （net zero energy building） standard which includes electricity consumption for appliances and lighting is not a very big one. Increasing the size of the photovoltaic system is sufficient in most cases. Anyway, some of the Minergie-A buildings evaluated are also Net ZEBs. In this paper, it is also shown that the net zero balance during the operational phase of Net ZEBs clearly outweighs the increased embodied energy for additional materials in a life cycle energy analysis.

焦化与焦炉气制甲醇、液氨装置热电联产的探讨

简要介绍炼焦采用干熄焦技术,与焦炉气制甲醇、液氨装置热电联产项目具有产品能耗低、成本低、市场竞争力强等特点,同时提出存在的问题和解决办法。

Thermodynamic analyses and optimization for thermoelectric devices:The state of the arts

Thermoelectric effect is the most efficient way to convert electric energy directly from the temperature gradient. Thermoelectric effect-based power generation, cooling and heating devices are solid-stated, environmentally friendly, reliable, long-lived, easily maintainable, and easy to achieve miniaturization and integration. So they have unparalleled advantages in the aerospace, vehicle industry, waste heat recovery, electronic cooling, etc. This paper reviews the progress in thermodynamic analyses and optimizations for single- and multiple-element, single- and multiple-stage, and combined thermoelectric generators, thermoelectric refrigerators and thermoelectric heat pumps, especially in the aspects of non-equilibrium thermodynamics and finite time thermodynamics. It also discusses the developing trends of thermoelectric devices, such as the heat sources of thermoelectric generators, multi-stage thermoelectric devices, combined thermoelectric devices, and heat transfer enhancement of thermoelectric devices.

Operation characteristics of AMS-02 loop heat pipe with bypass valve

Loop heat pipes （LHPs） were designed for the alpha magnetic spectrometer （AMS-02） to dissipate heat from the cryocoolers. A bypass valve is applied to the LHP to keep the cryocooler temperature above its limit （-20℃） in cold environment. Extensive experiments were performed on operation characteristics of LHPs with the bypass valve for AMS-02 during thermal vacuum and thermal balance （TVTB） test. We found that the bypass valve can start up successfully in cold environment. With the bypass valve, the evaporator temperature is stable and can meet the requirement of the cryocooler. We analyzed three operating modes of the bypass valve. Set point temperature and regulation temperature shifts were observed and their relations with the bypass valve temperature were given.

Realization of non-equilibrium process for high thermoelectric performance Sb-doped Ge Te

Pristine GeTe shows inferior thermoelectric performance around unit due to the large carrier concentration induced by the presence of intrinsic high concentration of Ge vacancy. In this study, we report a thermoelectric figure of merit ZT of 1.56 at 700 K, realized in Sb-doped GeTe based thermoelectric(TE)materials via combined effect of suppression of intrinsic Ge vacancy and Sb doping. The nonequilibrium nature during melt spinning process plays very important role. For one thing, it promotes the homogeneity in Ge_(1-x)Sb_xTe samples and refines the grain size of the product. Moreover the persistent Ge precipitated as impurity phase in the traditional synthesis process is found to be dissolved back into the GeTe sublattice, accompanying with a drastic suppression of Ge vacancies concentration which in combination with Sb electron doping significantly reduced the inherent carrier concentration in GeTe.Low carrier concentration, approaching the optimum carrier concentration ～3.74 × 10^(-20) cm^(-3) and a high power factor of 4.01 × 10^(-3) W m^(-1)K^(-2) at 750 K are achieved for Ge_(0.98)Sb_(0.02) Te sample. In addition,the enhanced grain boundary phonon scattering by refining the grain size through melt spinning(MS)process, coupled with the intensified alloying phonon scattering via Sb doping leads to low thermal conductivity of 1.53 W m^(-1) K^(-1) at 700 K for Ge_(0.94) Sb_(0.06) Te sample. All those contribute to a high ZT value,representing over 50% improvement in the ZT value compared to the Sb free samples, which provides an alternative way for ultrafast synthesis of high performance GeTe based thermoelectric material.

Numerical and Experimental Studies of an Arc-heated Nonequilibrium Nozzle Flow

The arc-heated high-temperature gas is rotationally and vibrationally excited, and partially dissociated and ionized. When such gas flows inside a nozzle, energy transfers from rotational and vibrational energy modes to translational energy mode, and, in addition, recombination reactions occur. These processes are in thermal and chemical nonequilibrium. The present computations treat arc-heated nonequilibrium nozzle flows using a six temperature model (translational, rotational, N2 vibrational, O2 vibrational, NO vibrational and electron temperatures), and nonequilibrium chemical reactions of air. From the calculated flow properties, emission spectra at the nozzle exit were re-constructed by using the code for computing spectra of high temperature air. On the other hand, measurements of N2+(1-) emission spectra were conducted at the nozzle exit in the 20 kW arc-heated wind tunnel. Vibrational and rotational temperatures of N2 were determined using a curve fitting method on N2+(1-) emission spectra, with the vibrational and rotational temperatures for N2 and N2+ being assumed equal. Comparison of the measured and computed results elucidated that the experimental temperatures were larger than the computed ones. At present, we are trying to reveal the main reason for the discrepancy between the computed and measured N2 vibrational and rotational temperatures.