Experimental study and prediction of liquid nitrogen pool evaporation process on concrete surface

The vaporization rate of pool boiling process of a liquid nitrogen spilled on concrete surface was investigated by a visual experiment platform. The boiling curve for liquid nitrogen on concrete cooling process was obtained. The shapes of bubbles in three typical boiling regimes were observed. Based on the experimental results, the coefficients of the empirical formulas for nuclear boiling and film boiling are modified, and the empirical formulas for boiling of liquid nitrogen-concrete surfaces are obtained. Combined with the calculation formula of the non-steady-state semi-infinite one-dimensional heat conduction temperature, a coupled calculation model for the heat transfer and vaporization process of liquid pool on the liquid nitrogen-concrete surface is proposed. Application of this model can better predict the quality of liquid nitrogen vaporization.     

Characterisation of prompt and delayed atmospheric radioactivity releases from underground nuclear tests at Nevada as a function of release time

A database with information on about 500 cases of atmospheric radioactivity releases from underground nuclear tests is analysed. The data are statistically evaluated and systematically aggregated in order to characterise prompt uncontrolled as well as delayed operational releases of radioactivity into the atmosphere. The focus is put on the latter. The reported data compare well with theoretically derived xenon activities for reasonable nuclear test scenarios. Conclusions are drawn on the main features of releases that can be expected from underground nuclear tests as a function of release time. These findings are relevant for developing and validating methods to be applied in global monitoring of atmospheric radioactivity with respect to indications of an underground nuclear explosion.     

New subjects in the politics of energy transition? Reactivating the northern German oil and gas infrastructure

The global circulation of the word ‘fracking’ seems to testify to a setback for energy transitions, a nexus that has not yet received much scholarly attention. In light of this, the controversy over fracking is understood as furthering infrastructural changes that are central to energy transitions. Infrastructure should not be understood as materiality per se but instead as sedimented but ultimately discursive elements that can be reactivated and rearticulated. Examining ‘infrastructure’ from the point of view of discourse theory places the focus on infrastructural change. Prior to 2011, the oil and gas infrastructure in northern Germany was largely invisible to the public. The subsequent reassembling of production with fracking facilitated the politicization not just of that term but also of the whole infrastructure. Instead of routinely reproducing the infrastructure, subjects that had formerly dominated the field were confronted with new and heterogeneous voices that challenged their agency.     

Food Security: Crops for People Not for Cars

Humankind is currently faced with the huge challenge of securing a sustainable energy supply and biofuels constitute one of the major options. However, the commercially traded edible crops are barely sufficient to meet food demand of the present world population. Certain regions, for example EU-27, do not even have a sufficient indigenous crop production. Of this follows that motor biofuels based on edible crops should be avoided. To replace more than some percent of the fossil motor fuels, non-edible biomass—rest products and wastes—should instead be considered for conversion to biofuels. In this way, about 10% of the current fossil fuels can be replaced. Feeding a world population expected to grow by some 50% during the next 50 years will be a major challenge. For environmental reasons it seems that agricultural land cannot be expanded very much, maybe not at all. The solution to the increasing food demand seems therefore to be using the present crop production more efficiently and increasing output from present agricultural land, maintaining biodiversity and climate stability within reasonable limits. In the future, agriculture will need more energy and more water irrigation. Food production is, however, already very energy demanding, requiring several times more externally provided energy than the energy content of the food itself. A sufficient energy supply will be a key issue for the future farming!     

朝阳市农村能源现状与开发利用途径

朝阳市农村能源资源十分丰富 ,但农村能源却普遍短缺。根据朝阳市农村能源供需矛盾 ,本文提出发展农村能源的措施     

厌氧发酵系统温度的选择和热量平衡

本文分析了厌氧发酵温度的选择和厌氧系统中热量平衡的关系。并运用此关系对薯干酒糟过滤液在冬季最低温度为0℃,夏季最高温度为35℃的地区进行中温和高温厌氧发酵处理中的热量平衡关系分别进行了讨论,证明了对温度为50℃,COD浓度为23g/L的废液进行中温发酵能得到更大的经济效益,但也必须使用所产生的沼气作为能源加热或冷却废液。所需的热量和气温的关系为:Q_t=4.73×105to-3.73×106 (KJ/d)。      

Effects of sludge characteristics on electrical resistance and energy consumption during electro-dewatering process

The increase of electrical resistance (ER) and energy consumption (EC) during the later stage of dewatering is a major problem hindering the development of electro-dewatering (EDW) technology. As the variations of sludge characteristics are significant during the EDW process, the relationships between sludge characteristics and ER and EC during EDW remain unclear. In this study, the effects of moisture content (MC), thickness, pH, conductivity, zeta potential, temperature, and gas volume on the ER and EC during the EDW process were statistically investigated using correlation and multiple linear regression analyses. Herein, the results showed that the ER of the sludge near the anode was primarily affected by pH, whereas the sludge near the cathode was primarily affected by the MC and conductivity. Further, sludge temperature and conductivity were the most reliable indicators to predict the EC near the anode and cathode, respectively. The results of this study provide theoretical guidance useful for solving the increase of ER and EC during the later stage of the EDW process.     

Adoption of European Union's IPPC Directive to a textile mill: Analysis of water and energy consumption

The present study was undertaken as part of the first application and evaluation of the BREF (Best Available Techniques; BAT Reference Document) Textile Document within the context of the European Union's Integrated Pollution Prevention and Control (IPPC) Directive to a large scale textile mill in Turkey. The BAT requirements for the denim manufacturing textile mill were selected in cooperation with the factory management. Detailed mass balance calculations were conducted to evaluate the overall effect of the selected BAT options. The initial findings indicated that the adoption of the selected BAT options resulted in considerable savings in water and energy consumption in the mill. Besides the installation of flow meters and use of semi-counter current rinsing in the most water-intensive processes, minimization of wash waters in the water softening plant, reuse of the concentrate stream from the reverse osmosis plant and compressor cooling waters provided a 29.5% reduction in the total specific water consumption of the mill, reaching the lower limits suggested by the BREF Textile Document. In terms of energy consumption, use of waste heat from finishing wastewater streams in heating up the wash waters, heat insulation and maintenance applications in addition to BAT measures taken for water minimization reduced specific energy consumption by 9% achieving the limits set by the BREF Textile Document.     

Substituting energy crops with organic wastes and agro-industrial residues for biogas production

In this study, industrial and agro-industrial by-products and residues (BRs), animal manures (AMs), and various types of organic wastes (OWs) were analyzed to evaluate their suitability as substitutes for energy crops (ECs) in biogas production. A comparison between the costs of the volume of biogas that can be produced from each substrate was presented with respect to the prices of the substrates in the Italian market. Furthermore, four different feeding mixtures were compared with a mixture of EC and swine manure (Mixture A) used in a full-scale plant in Italy. Swine manure is always included as a basic substrate in the feeding mixtures, because many of the Italian biogas plants are connected to farms. When EC were partially substituted with BR (Mixture B), the cost (0.28 € Nm⁻³) of the volume of biogas of Mixture A dropped to 0.18 € Nm⁻³. Furthermore, when the organic fraction of municipal solid waste (OFMSW) and olive oil sludge (OS) were used as possible solutions (Mixtures C and D), the costs of the volume of biogas were −0.20 and 0.11 € Nm⁻³, respectively. The negative price signifies that operators earn money for treating the waste. For the fifth mix (Mixture E) of the OFMSW with a high solid substrate, such as glycerin from biodiesel production, the resulting cost of the volume of biogas produced was −0.09 € Nm⁻³. By comparing these figures, it is evident that the biogas plants at farm level are good candidates for treating organic residues of both municipalities and the agro-industrial sector in a cost-effective way, and in providing territorially diffused electric and thermal power. This may represent a potential development for agrarian economy.     

Externalities of Fugitive Dust

It is known that fugitive dust can cause human health and environmental problems, alone or in combination with other air pollutants. These problems are referred to as ‘external costs’ that have been traditionally ignored. However, there is a growing interest towards quantifying externalities to assist policy and decision-making. With this in mind, the present study aimed at discussing the environmental regulations that deal with fugitive dust, the impact of fugitive dust on human health and global climate system, and the available methods for calculating fugitive dust externalities. The damage cost associated with human health and global environmental problems was predicted based on the environmental strategy priority model. The damage cost estimated by the model ranged from 40 to 374 EUR/kg of emitted fugitive dust with a mean value of 120 EUR/kg of emitted fugitive dust. It was also found that PM_2.5 and PM₁₀ have contributed to about 60% and 36% of the estimated damage cost, respectively. The remaining 4% was attributed to both nitrate and sulfate aerosols.