A new type of refrigerator and its cycle

The world is facing an energy and climate crisis. Globally, the energy sector emits 26 billion tonnes of CO₂ each year, and electricity production alone accounts for 41% of emissions (European Wind Energy Association. 2008. Pure Power: Wind Energy Scenarios up to 2030. European Wind Energy Association. p. 6). Currently, reducing CO₂ emissions and curbing climate change have become global priorities, and we only have a narrow window of time left in which to act. The new type of refrigerator can offer an immediate and concrete solution to the many energy and climate challenges that we are facing. This is an account of a new type of refrigerator and its cycle for use in the refrigeration industry. For its cycle, the working substance is air or other gases; its cycle is very similar to that of the reverse Brayton cycle (Hou, Y., Zhao, H. L., Chen, C. Z., and Xiong, L. Y. 2006. “Developments in Reverse Brayton Cycle Cryocooler in China.” Cryogenics 46 (5): 403–407). In the cycle of the new type of refrigerator, the isochoric exothermic process and the isothermal exothermic compression process replace the isobaric exothermic compression process of the reverse Brayton cycle. The new type of refrigerator can produce a net electrical energy, and it is not a perpetual motion machine, because the environmental enthalpy and atmospheric pressure can be utilized as the external energy sources, which cannot be performed by any other conventional refrigerators; therefore, the reliability and significance of this new type of refrigerator is self-evident.     

A new type of Stirling heat engine

This is a new technique for operating a Stirling heat engine. Theoretically, its thermal efficiency should be greater than 100%. However, it does not violate the first and second laws of thermodynamics; it is not a perpetual motion engine, because the atmospheric pressure can be utilized as the external energy source, which no other existing heat engines can do. This means that the new type of heat engine can offer an immediate and concrete solution to the many energy and climate challenges that we are facing; therefore the reliability and significance of this new type of Stirling heat engine is self-evident.     

Total concentrations and speciation of heavy metals in soils of the Shenyang Zhangshi Irrigation Area, China

The Shenyang Zhangshi Irrigation Area (SZIA) was used for the spreading of municipal and industrial waste water, which is an economic way of irrigating crops, recycling nutrients and water treatment. Long-term irrigation resulted in a severe metal contamination of soils. To identify the soil phases implicated in retaining the metals, sequential extractions were performed. The most predominant metal was cadmium which was mainly associated with mobile, easily soluble and easily reducible fractions. Copper was mainly associated with the residual, EDTA extractable and moderately reducible fractions. Lead was bound to organic matter and poorly crystalline Fe-oxides. Nickel and zinc were mainly associated with the residual and strongly reducible fractions. Although copper, lead, nickel and zinc concentrations were of minor importance mobile metal concentrations of these metals as well as of cadmium exceeded German trigger values for plant production and plant growth.     

Spatial distribution,temporal variation,and sources of heavy metal pollution in groundwater of a century-old nonferrous metal mining and smelting area in China

This study first presents the spatial distribution, temporal variation, and sources of heavy metal pollution in groundwater of a nonferrous metal mine area in China. Unconfined groundwater was polluted by Pb, Zn, As, and Cu, in order, while confined karst water in the mines showed pollution in the following sequence: Zn, Cd, Cu, Pb, and As. Pollution by Pb was widespread, while Zn, As, Cu, and Cd were found to be high in the north–central industrial region and to decrease gradually with distance from smelters and tailings. Vertically, more Pb, Zn, Cu, and Cd have accumulated in shallow Quaternary groundwater, while more As have migrated into the deeper fracture groundwater in the local discharge area. Zn, Cd, and Cu concentrations in groundwater along the riverside diminished owing to reduced wastewater drainage since 1977, while samples in the confluence area were found to have increasing contents of Pb, Zn, As, Cu, and Cd since industrialization began in the 1990s. Sources of heavy metals in groundwater were of anthropogenic origin except for Cr. Pb originated primarily from airborne volatile particulates, wastewater, and waste residues and deposited continuously, while Zn, Cd, and Cu were derived from the wastewater of smelters and leakage of tailings, which corresponded to the related soil and surface residue researches. Elevated As values around factories might be the result of chemical reactions. Flow patterns in different hydrogeological units and adsorption capability of from Quaternary sediments restricted their cross-border diffusion.     

基坑外设置隔离桩对土体水平位移的隔断效果分析

目前对于隔离桩是否能有效减小基坑外地下结构的变形问题仍存在争议。为研究隔离桩对基坑开挖引起的土体水平位移的隔断效果,结合二阶段分析方法及地层补偿法,提出了求解基坑开挖后隔离桩外土体位移的三阶段分析方法,并对其合理性进行了验证。结果表明:基于该方法的计算,不同基坑开挖深度和不同围护墙变形模式下,隔离桩的存在可减小坑外地坪下一定深度范围内的土体水平位移,但可能增大深层土体水平位移;隔离桩刚度越大,对土体上部水平向位移的隔离效果越好,但同时深层土层位移增大的情况也越明显;合理的隔离桩桩顶埋深可一定程度减小隔离桩对深层土体的牵引作用。为保护基坑外的地下结构而设置隔离桩时,应根据模拟计算结果、工程实际情况及当地经验综合分析其可行性。     

多次冻融循环人工盐渍土路基模型试验研究∗

青藏铁路西宁至格尔木段为典型的季节性冻土区铁路,冻害频发,严重影响铁路的正常使用和安全运营,为了整治路基体发生冻害,结合成熟的注浆技术和传统撒盐法,提出注盐法整治路基冻害。在室内模型箱中填筑实体模型,进行封闭系统中多次冻融循环条件下人工盐渍土路基模型试验,探究人工盐渍土路基中温度、水分、盐分以及变形规律,验证注盐法整治路基冻害的可行性。试验结果表明：路基土体内温度变化趋势符合环境温度变化趋势的余弦函数变化波动规律,土体内温度变化较环境温度变化推迟36 h左右;温度梯度是引起水分迁移的主要因素,越接近冷端,迁移量越大,在冻结锋面处达到最大;在封闭系统中,盐分随着水分向冷端运移,但是盐分运移量较低,随着周期的推进,盐分呈逐渐降低的趋势;随着温度的周期性变化路基顶面的变形呈现出有规律的冻胀和融沉现象,但是最大冻胀量为0.08 mm,可见路基盐化之后路基土体基本不产生冻胀变形。     

Sugarcane bagasse amendment improves the quality of green waste vermicompost and the growth of Eisenia fetida

•Earthworms were able to convert green waste into more plant-available nutrients. •The part of heavy metals content increased in the compost added by earthworm. •The addition of SCB to GW did enhance earthworm biomass and humic acid content. •The resulting vermicomposts were characterized by neutral pH and lower EC value. Vermicomposting is a feasible method for disposing of lignocellulosic waste while generating a useful product. The current study assessed the potential of vermicomposting green waste mixed with sugarcane bagasse in proportions of 25%, 50%, and 75% (v:v, based on dry weight). The suitability was evaluated based on the agrochemical properties, earthworm biomass, and phytotoxicity. The final vermicomposts exhibited near-neutral pH values (7.1–7.6), and lower EC values (0.43–0.72 mS/cm) and C:N ratios (14.1–19.9).The content of available nutrients and CEC for all the vermicomposts exceeded those of the control compost (without earthworms). For vermicomposts, the average values of NO₃^–-N, AP, AK, and CEC were 53, 517, 1362 mg/kg, and 158 cmol/kg, respectively. The total contents of heavy metals increased in all vermicompost treatments compared to control composts with the following average final percentages: Zn (2.0%), Cr (15.5%), Pb (23.4%), and Cu (44.3%), but these amounts were safe for application in agroforestry. The addition of sugarcane bagasse to green waste significantly increased the content of total humic substance, humic acid and urease activity, acid and alkaline phosphatase activity, and Eiseniafetida reproduction. The addition of 25% sugarcane bagasse to green waste decreased the toxicity to germinating seeds. These results revealed that vermicomposting is a feasible way to degrade green waste into a value-added chemical product.     

Supercritical water oxidation of landfill leachate

In this paper, ammonia as an important ingredient in landfill leachate was mainly studied. Based on Peng-Robinson formulations and Gibbs free energy minimization method, the estimation of equilibrium composition and thermodynamic analysis for supercritical water oxidation of ammonia (SCWO) was made. As equilibrium is reached, ammonia could be totally oxidized in SCW. N(2) is the main product, and the formation of NO(2) and NO could be neglected. The investigation on SCWO of landfill leachate was conducted in a batch reactor at temperature of 380-500 °C, reaction time of 50-300s and pressure of 25 MPa. The effect of reaction parameters such as oxidant equivalent ratio, reaction time and temperature were investigated. The results showed that COD and NH(3) conversion improved as temperature, reaction time and oxygen excess increased. Compared to organics, NH(3) is a refractory compound in supercritical water. The conversion of COD and NH(3) were higher in the presence of MnO(2) than that without catalyst. The interaction between reaction temperature and time was analyzed by using response surface method (RSM) and the results showed that its influence on the NH(3) conversion was relatively insignificant in the case without catalyst. A global power-law rate expression was regressed from experimental data to estimate the reaction rate of NH(3). The activation energy with and without catalyst for NH(3) oxidation were 107.07 ± 8.57 kJ/mol and 83.22 ± 15.62 kJ/mol, respectively.     

基于MATLAB的灰色模型对秦皇岛市区地下水水位的预测

MATLAB是集数学、图形处理和程序设计语言于一体的实用性很高的数学软件。应用该软件编制了一套GM(1,1)灰色预测模型程序,弥补了灰色预测模型在矩阵计算中的问题,并将该程序运用到了秦皇岛市城市区平原地下水水位预测评价中,从实例看出用MAT-LAB所编制的程序可读性强,容易理解,操作简单灵活,直接面向用户,精度较高。     

菜场有机垃圾压缩脱水特性实验研究

为优化菜场垃圾压缩及脱水机械设计参数,获取最佳的压强值和垃圾在压缩仓内的保压时间,进行了菜场有机垃圾压缩脱水特性实验研究。通过压缩实验及对数据的分析,提出了有机垃圾压缩转运时的合理压缩强度范围为1.5～2.4 kg/cm2;通过压缩脱水实验及对数据的分析得到:压强一定时,保压时间越长,出水量越大;而保压时间一定时,压强增大,脱水率也增加,但2组数据变化均为非线性。对大白菜的实验表明,其合理的脱水压强和保压时间分别为2.4 kg/cm2和30 s左右。