天然气改制工艺[火用]分析及优化方向

从[火用]平衡的角度分析了天然气改制工艺系统的能量转换与利用过程，计算了各项[火用]收入、[火用]支出及[火用]效率，指出了天然气改制工艺系统运行参数优化的方向。     

热电冷联产系统节能性的[火用]分析

利用[火用]分析的方法，定义了等效发电[火用]效率，对常用热电冷联产系统形式的节能性进行了分析。认为相对于全国平均供电煤耗而言，热电冷联产系统的节能是有条件的，应选取合理的方式，优化设计和运行方案；相对于当前有些热电厂夏季负荷不足的情况，热电冷联产是节能的，在不同的情况下节能率在7．8％～39％之间。建议利用现有的热电联产条件，发展热电冷联产系统，提高现有热电厂的设备利用率和运行经济性。     

预分解窑系统的[火用]分析

分析比较了[火用]分析法与热平衡法,指出[火用]分析法比热平衡法更能深入、科学地阐述能的本质,更真实地反映系统能量的量和质的转化及损失情况,为系统节能指明方向．通过对乌兰2500t／d预分解窑系统进行的热平衡及[火用]平衡计算,分析了造成系统[火用]损失的原因及其影响程度,确定了系统耗能的薄弱环节,找出了节能途径,并指出余热发电是现阶段减少[火用]损失最有效的方法．     

太阳能光伏光热-热泵系统能量与[火用]分析

针对太阳能光伏光热-热泵系统是否具有节能优势,利用TRNSYS软件建立了太阳能光伏光热-热泵系统仿真模型,并利用实测数据进行了验证。与单一光伏发电系统、单一空气源热泵系统进行了全年运行对比,并进行了能量分析与[火用]分析。结果表明,太阳能光伏光热-热泵系统的全年平均电效率、全年总发电量、热泵机组COP、能耗及[火用]损均优于单一光伏发电系统加单一空气源热泵系统。     

天然气管网压力能利用工艺的[火用]分析

论述了天然气管网压力能的计算方法，利用天然气压力能进行储气调峰、发电、天然气液化、膨胀制冷的工艺流程。采用透平膨胀机回收利用天然气管道的压力能时，压力[火用]转换为机械功和冷[火用]，机械功大于冷[火用]，充分利用转换的机械功和冷[火用]有利于提高天然气管道压力能的利用效率。     

太阳能热泵多功能复合机系统(火用)分析

在制热工况下,对太阳能热泵多功能复合机（SAHPM）进行了系统[火用]分析。结合实例,计算了压缩机、冷凝器、毛细管、蒸发器的[火用]损失系数,压缩机、蒸发器的[火用]损失系数较大,是降低系统、[火用]损失的关键。     

海水源热泵系统的(火用)经济分析

利用(火用)经济分析方法建立了海水源热泵系统的(火用)经济分析模型,并对海水源热泵系统流程的(火用)成本进行计算,结果表明热泵机房的(火用)流成本最高,因此可以通过提高热泵效率等途径来减小(火用)流成本.建议以(火用)流成本最小作为约束函数,并将(火用)经济分析法用于海水源热泵系统的优化设计中.     

基于[火用]分析的太阳能喷射制冷系统运行参数优化

(火用)分析是用来分析制冷系统性能的一种工具.本文分析基于下列假设:太阳辐射为750W/m2,制冷量为10 kW,采用R141b作制冷剂,周围环境温度为31℃.对太阳能喷射制冷系统(火用)分析结果表明,不可逆损失产生于各个部件,随运行温度而变化.其他条件不变时,系统((火用))效率随着蒸发温度的升高而升高,随着冷凝温度的升高而降低.在一定的蒸发、冷凝温度下,(火用)效率最大时,可以得到最佳发生温度.     

LNG冷能用于天然气富氧燃烧电厂碳捕获

构建一套将LNG冷能应用于天然气富氧燃烧电厂碳捕获过程的集成系统。该系统采用高压富氧燃烧方式,利用LNG冷能将烟气中的CO_2全部液化回收。一部分CO_2捕获封存,完成碳捕获过程,实现碳的零排放;另一部分CO_2用于富氧燃烧动力循环。由于LNG冷能的输入,碳捕获不需要烟气压缩过程,实现了近零功耗的碳捕获。利用Aspen Plus模拟软件对该集成系统进行模拟计算和优化分析,得到了CO_2循环物质的量流量(直接进入燃烧器与直接进入混合器的CO_2物质的量流量之和)、燃烧压力等参数对系统运行的影响情况。当燃烧器燃烧压力为3.5 MPa时,最佳CO_2循环物质的量流量为28.7 kmol/s,对应的最佳烟气温度(燃气轮机入口处混合烟气温度)为542℃。使用LNG冷能对CO_2进行捕获封存后,碳捕获过程能耗大为降低,系统净发电效率为50.48%。     

关于热泵一次能源利用率的计算与分析

发电环节按燃煤电厂考虑,针对空气源热泵热水供热系统进行了一次能源热效率和[火用]效率的计算和分析,结果表明:热泵机组COP分别为3和4时,其一次能源热效率均大于100%,但热泵机组的一次能源[火用]效率、热泵供热系统的一次能源[火用]效率都远小于100%。热泵供热系统的一次能源[火用]效率表征了热泵供热系统对一次能源[火用]价值的利用程度,可称为热泵供热系统的一次能源利用率。而热泵机组的COP及其一次能源热效率虽然不能直接反映一次能源价值的利用程度,但它们都与热泵供热系统的一次能源[火用]效率呈正比关系,所以也都可以用于对热泵供热系统进行能效比较和评价。合理降低热泵机组输出水温可以提高机组的COP,从而提高热泵供热系统的一次能源[火用]效率,实现相同供暖目标的一次能源消耗量减少。     

Radiation from products of combustion

A simple accurate method to compute emissivities and absorptivities of isothermal, homogeneous mixtures of soot, CO₂ and H₂O is provided. Emissivities and absorptivities so calculated are shown to be in good agreement with detailed spectral calculations and with available experimental data. The results presented lead to the conclusion that, for homogeneous, isothermal mixtures of combustion products, spectral calculations are unnecessary. The method provided in this paper is just as accurate and, being much simpler to execute, more attractive than the spectral calculations.     

Hypolimnetic aeration and dissolved gas concentrations: Enclosure experiments

Two large circular enclosures, each containing approx. 550 m³ of water, 14 m deep, and open to the mud-water interface, were used to monitor the effects of hypolimnetic aeration. One enclosure was held as a control, the other aerated every 3 or 4 days for a period long enough (usually < 2 h) to maintain hypolimnetic O₂ levels at > 4 mg 1⁻¹. Nutrient additions (10 g of 90% H₃ PO₄ and 250 g NaNO₃ per week) to each enclosure were controlled from the commencement of the experiment (17 June 1980) until its completion (2 November 1981). Temperatures in both enclosures were identical. Hypolimnetic O₂ levels in the control fell to zero during both summers, but remained at > 4 mg 1⁻¹ in the aerated enclosure. Free N₂ concentrations in the hypolimnion of the aerated enclosure was higher than in the control. Concentrations of H₂S in the control hypolimnion increased to > 5 mg 1⁻¹ and concentrations of CH₄ increased to > 18 mg 1⁻¹. Both remained at or near zero in the aerated enclosure. Tests of aerator efficiency suggested that the full air-lift design that was employed had an average O₂ exchange efficiency of 42% which is higher than the values reported for most other designs.     

Etude de l'oxydation de chloroethanes en milieu aqueux dilue par H2O2/u.v.Degradation of chloroethanes in dilute aqueous solution by H2O2/u.v.

The destruction of organic pollutants in water can be achieved by the combination of oxidants or of oxidants with u.v. radiation (O₃/H₂O₂;; H₂O₂/u.v.; O₃/u.v.). The efficiency of these advanced oxidation processes is accounted for by the generation of very reactive free radicals such as hydroxyl radicals. In this paper, experimental data are presented to examine the effect of physico-chemical parameters on the efficiency of the H₂O₂/u.v. process for the degradation of chloroethanes in dilute aqueous solution and to test a kinetic model for this oxidation process. The model is based on known reactions of OH radicals in water and on kinetic results obtained in a previous work for the photodecomposition of hydrogen peroxide (Nicole et al., 1990).     

Technique for measuring metallic salt effects upon the indigenous heterotrophic microflora of a natural water

The effects of several concentrations of the metallic salts Ag₂SO₄, NaAsO₃, BaCl₂2H₂O, CdCl₂2.5 H₂O, CrCl₂6H₂O, CuCl₂, HgCl₂, NaCl, NiCl₂6H₂O, PbCl₂ and ZnCl₂ upon the indigenous heterotrophic microflora of a natural water were studied. Effects of these salts upon the heterotrophic activity of the microbes were assayed using the heterotrophic technique whereas lethal effects upon the heterotrophic bacteria were determined using nutrient agar plate counts. The heterotrophic activity method is based upon the uptake and mineralization of a radioactively labeled metabolite (in these experiments ¹⁴C-glucose) by the indigenous aquatic microbes and data analysis is by Michaelis—Menten enzyme kinetics equations. Concentrations of metallic salts which resulted in bacterial death also caused erratic uptake and mineralization rates of ¹⁴C-glucose whereas sub-lethal concentrations, as determined by nutrient agar plate counts, caused a non-competitive inhibition of maximum heterotrophic activity and markedly increased the turnover time of the glucose substrate.     

Effect of electrolyte composition, and of added iron(III) in the presence of selected organic complexing agents, on nickel(II) precipitation by lime

The effect of effluent composition involving the common anionic species Cl⁻, SO₄²⁻ and CO₃²⁻ on the efficiency of nickel(II) precipitation, modelling lime (CaO) as the precipitant, has been investigated using the solubility domain approach. Solubility domains were based on the phases that were found to limit metal solubility for systems representing potential effluent composition limits. These phases were found to resemble their mineralized counterparts, but with a lower degree of structural order. At higher SO₄²⁻ and CO₃²⁻ concentrations both gypsum (CaSO₄·2H₂O) and calcite (CaCO₃) were formed, but these had little effect on the observed residual nickel solubility. The calculated solubility domains were found to generally encompass the experimentally determined solubilities, thereby providing quality assurance ranges for hydroxide precipitation. The effect of the complexing anions tartrate and EDTA⁴⁻ on residual Ni(II) in solution as well as the effects of the addition of Fe(III) on the removal of Ni(II) complexed by these species are described.     

Electrochemical Treatment of Acidic Aqueous Ferrous Sulfate and Copper Sulfate as Models for Acid Mine Drainage

Acid mine drainage (AMD) is a serious environmental problem in the mining industry. The present work describes electrolytic reduction of solutions of synthetic AMD, comprising FeSO₄/H₂SO₄ and CuSO₄/H₂SO₄, in flow-through cells whose anode and cathode compartments were separated using ion exchange membranes. In the case of FeSO₄/H₂SO₄ at constant flow rate, the pH of the effluent from the catholyte increased progressively with current at a variety of cathodes, due to electrolytic reduction of H⁺ ions to elemental hydrogen. Near-quantitative removal of iron was achieved by sparging air into the catholyte effluent, thereby precipitating iron outside the electrochemical cell, and avoiding fouling of the electrodes. The anode reaction was the oxidation of water to O₂, a proton-releasing process. Using cation exchange membranes and sodium sulfate as the supporting electrolyte in the anode compartment, the efficiency of the process was compromised at high currents by transport of H⁺ competitively with Na⁺ from the anode to the cathode compartments. Higher efficiencies were obtained when anion exchange membranes were used, and in this case no additional supporting electrolyte other than dilute H₂SO₄ was needed, the net reaction being the electrochemically driven transfer of the elements of H₂SO₄ from the cathode to the anode compartments. Current efficiencies 50% were achieved, the loss of efficiency being accounted for by ohmic heating of the solutions. In the case of CuSO₄/H₂SO₄ and anion exchange membranes at high currents, reduction of Cu²⁺ and H⁺ ions and transport of SO₄²⁻ ions out of the catholyte caused unacceptably high potentials to be generated.     

The role of temperature on carbon monoxide production in compartment fires

The objective of this study was to assess the effect of temperature on carbon monoxide production in compartment fires in order to resolve the difference between global equivalence ratio-yield correlations obtained in simplified upper layer environments and more realistic compartment fires. The chemical reactivity of upper layer gases was studied using a detailed chemical kinetics model. An analysis of the modeling and experimental data in the literature provided insights into the effect of temperature on carbon monoxide production.

The effect of changing temperature on compartment fire upper layer composition is twofold: (1) the generation of species in the fire plume is changed; and (2) oxidation of post-flame gases in the layer is affected. Elevated compartment temperatures correlate with increased fire plume temperatures and more complete oxidation of the fuel to CO₂ and H₂O within the plume. The layer temperature dictates post-flame oxidation in the layer. For most situations, upper layer temperatures below 800K indicate chemically unreactive layers. As such, combustion within the fire plume dictates final CO production in the compartment. Reactions in the upper layer dictate final CO levels when upper layer temperatures are about 900K and higher.     

Energy-efficient virtual sensor-based deep reinforcement learning control of indoor CO2 in a kindergarten

High concentrations of indoor CO₂ pose severe health risks to building occupants. Often, mechanical equipment is used to provide sufficient ventilation as a remedy to high indoor CO₂ concentrations. However, such equipment consumes large amounts of energy, substantially increasing building energy consumption. In the end, the issue becomes an optimization problem that revolves around maintaining CO₂ levels below a certain threshold while utilizing the minimum amount of energy possible. To that end, we propose an intelligent approach that consists of a supervised learning-based virtual sensor that interacts with a deep reinforcement learning (DRL)-based control to efficiently control indoor CO₂ while utilizing the minimum amount of energy possible. The data used to train and test the DRL agent is based on a 3-month field experiment conducted at a kindergarten equipped with a heat recovery ventilator. The results show that, unlike the manual control initially employed at the kindergarten, the DRL agent could always maintain the CO₂ concentrations below sufficient levels. Furthermore, a 58% reduction in the energy consumption of the ventilator under the DRL control compared to the manual control was estimated. The demonstrated approach illustrates the potential leveraging of Internet of Things and machine learning algorithms to create comfortable and healthy indoor environments with minimal energy requirements.     

CO2 emission consequences of energy measures in buildings

This paper studies the way in which CO₂ emission levels are affected by different measures to reduce energy consumption in a building. A case study is presented which deals with a residential building in Navestad, a suburb of the Swedish city Norrköping. The building is supplied with district heating primarily delivered from a combined heat and power (CHP) plant. Three types of energy measures are studied: extra insulation, new types of window and the introduction of a heat pump. The first perspective is the city of Norrköping, with the system boundary encompassing the residential building and the CHP plants. A second worst case scenario is then presented: a Nordic perspective in which electricity produced in coal condensing power plants is assumed to cover the marginal electricity production. With the former perspective, the measures extra insulation and new windows reduce the CO₂ emissions, and with the latter both measures increase the CO₂ emissions. The measures extra insulation and new windows are ranked, with respect to cost for the first perspective, using a cost reduction curve for CO₂ emissions. In the paper, costs from the ExternE research project are also used.     

CO2在老油田地质封存中的赋存状态

为研究CO₂在老油田地质封存中的赋存状态,采用室内实验的方法,研究了CO₂与地层流体、岩石的相互作用,并结合驱替实验结果明确了地质封存中CO₂的赋存状态。研究表明:油水共存情况下,CO₂主要溶解于原油中,在原油中的相对溶解量是水中相对溶解量的9.61倍;CO₂溶解所形成弱酸的量和浓度对固化作用起决定作用,在含气饱和度60%以下时,固化度随含气饱和度的增加而增加,在含气饱和度高于60%后,固化度急剧降低;驱替实验注CO₂量较小时,孔隙中CO₂主要为自由气、束缚气和油中溶解气,注CO₂倍数较大时,孔隙中自由气最多,束缚气次之;封存的长期性与驱替试验的短期效应有所不同,地质封存CO₂量较小时,CO₂在地层中主要为溶解气,形成以流体溶解为主的封存模式;地质封存CO₂量较大时,CO₂赋存状态中自由气最多,占69%,溶解气次之,占20%,束缚气最少,形成以自由气为主、溶解气为辅的地质封存模式。研究成果为深入研究CO₂的地质封存提供技术支撑,同时也为老油田CO₂驱开发提供重要参考。