跨临界二氧化碳汽车空调特性分析

本文建立跨临界循环汽车空调装置的数学模型,通过样机实验数据对模型进行检验,用此模型分析了跨临界循环汽车空调装置的变工况特性,以及吸气回热结构对于装置工作性能的影响。本文的研究结果可用于指导跨临界循环汽车空调装置的设计改进。     

基于二氧化碳传感器的气密性检测方法

针对当前工业上泄漏检测方法存在检测精度低、成本高等缺点,设计一种微量泄漏检测方法。该方法利用二氧化碳气体作为示踪物质,充满纯二氧化碳气体的被测件通过标准漏孔产生泄漏,气体进入检测容器中,通过二氧化碳气敏传感器测量检测容器内二氧化碳浓度的变化得到微量气体泄漏的泄漏率。与工业生产中传统的气密性检测方法相比,该方法在提高准确度的同时保证测试的准确性,并且能降低成本。试验结果表明:该检测方法测试的准确性不受温度和湿度变化的影响;在不同压力测试条件下,实测值与标准漏孔参考值误差3%,验证方法的准确性;在相同压力测试条件下,测试结果相对标准偏差5%,实验重复性良好。     

Mixed waste ferrite as a novel sorbent for carbon dioxide derived from flue gases

Ferrite is a potential sorbent for flue gases such as CO₂, H₂S and SO₂. This paper discusses the adsorption and decomposition of CO₂ into carbon by hydrogen-activated waste ferrites prepared from Berkeley Pit acid mine water (Butte, MT). The decomposition effectiveness of these waste ferrites was studied at 300 °C and compared with the synthetic magnetite obtained from ferrous sulfate solution in our laboratory. The decomposition was measured by two methods: indirectly by measuring the adsorption rate of CO₂ and directly by analysing the carbon deposited on the samples. The results indicated that the mixed waste ferrite had good affinity for the adsorption and decomposition. The CO₂ decomposition data of both sorbents fitted the first-order reaction kinetics. Even though the surface area of the magnetite was higher than that of waste ferrite, the CO₂ decomposition rate of the waste ferrite was estimated to be 2.5 times higher than that of magnetite under identical conditions. The carbon analysis deposited on the sample indicated that the CO₂ was 100% decomposed into carbon and other carbon/hydrogen compounds by the waste ferrite, whereas the conversion was 43% by the magnetite. In terms of specific adsorption of carbon, ferrite was three to five times more efficient than magnetite.     

Surfactants and self-assembly in carbon dioxide

Amphiphilic compounds have played a vital role in the emergence of carbon dioxide in both its liquid and supercritical states as a versatile, environmentally benign solvent. This review serves to describe recent efforts in three major areas of the field: (1) polymeric amphiphile self-assembly in carbon dioxide solutions, (2) use of surfactants as stabilizing agents for polymerizations, and (3) studies involving ‘small molecule’ surfactant assemblies in carbon dioxide.     

Solubilities of ethylene,ethane, and carbon dioxide in mixed solvents consisting of methanol,acetone, and water

The amount of gas absorbed in a liquid solvent or solvent mixture is measured with a high-precision gas burette. Solubility coefficients (Henry and Ostwald coefficients) of C₂H₄ and C₂H₆ are determined at ambient temperature and atmospheric pressure (1) in the pure solvents C₃H₆O, CH₃OH, and H₂O; (2) in the three binary mixtures of the solvents as a function of the composition of the solvent mixture; and (3) in several ternary mixtures of arbitrary composition. The experimental data are presented in diagrams and tables.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Emissivity of carbon dioxide

This paper presents a new correlation for the emissivity of carbon dioxide gas, suitable for extrapolating existing nomograms to large optical thickness values and high temperatures.     

An inverse problem of simultaneously estimating contact conductance and heat transfer coefficient of exhaust gases between engine's exhaust valve and seat

The conjugate gradient method using two search step sizes is used to solve the inverse problem of simultaneously estimating the periodic thermal contact conductance, h_c(t), and the heat transfer coefficient of the exhaust gases, h_g(t), between the exhaust valve and seat in an internal combustion engine. The importance of the determination of h_c(t) and h_g(t) lie in that they are the critical factors for designing the cooling system and the insulation of the exhaust valve. The inverse analysis is based on the temperature measurements taken from the sensors placed in both the valve and seat regions during the transient process of operation. In this study two unknown timewise-varying functions h_c(t) and h_g(t) are to be estimated at the same time, thus two search step sizes with each one corresponding to each unknown function are derived. The results show that the CPU time for the inverse solutions using two search step sizes are greatly reduced than using just one search step size¹ for the determination of two unknowns, besides, it also shows that the inverse solutions are reliable even when the measurement errors are considered. The advantage of the conjugate gradient method is that no a priori information is needed on the variation of the unknown quantities, since the solution automatically determines the functional form over the domain specified. The successful development of the present technique can be applied to any kind of two-dimensional periodic contact problems, such as the determination of a two-dimensional contact conductance problem² and the temperature or heat flux behaviour on the inside wall of internal combustion engines³.     

Optimized measurement uncertainty and decision-making in the metering of energy,fuel, and exhaust gases

Risks of incorrect decision-making in conformity assessment associated both with sampling and measurement uncertainties are tackled with a decision theory approach, earlier used in analytical measurement, where the costs of testing are balanced against the costs associated with the consequences of incorrect decision-making. Examples cover the metering of energy, fuel, and environmental emissions; all areas of increasing societal importance where costs are rising at the same time as more stringent accuracy requirements are successfully introduced. Published in Izmeritel’naya Tekhnika, No. 4, pp. 18–22, April, 2008.     

纳米级稀土材料在汽车尾气净化中的应用

汽车尾气是当今大气污染的主要来源之一 ,催化净化是国际普遍采用的汽车尾气净化法。本文根据我国贵金属贫乏而稀土资源丰富的国情 ,以及稀土纳米材料特有的性质和功能 ,综述了纳米级稀土材料在汽车尾气净化中的应用及其发展前景