Environmental and economic assessment of a greenhouse waste heat exchange

As the economic costs of energy and the negative externalities associated with the combustion of fossil fuels threaten the economic viability of greenhouses in northern climates there is a renewed interest in the use of waste heat. This paper presents a technical and economic methodology to determine the viability of establishing waste heat greenhouses using the waste heat from industrial processes in northern climates. A case study is presented of an exchange between a tomato greenhouse and a flat glass manufacturing plant, which found the waste heat system is significantly more economic to operate than a purely natural gas system.     

动力与热力抬升对烟气抬升高度的影响分析

通过模式选择和计算,得出烟气抬升高度的增加与动能和热能的关系,表明当烟囱出口处风速分别为3 m/s、2 m/s和1 m/s时欲增加同样大小的烟气抬升高度,需要的动能比热能要高,结论认为烟气的热力提升比动力提升的贡献大。     

环评监测现场采样中应注意的问题

根据环境影响评价监测的要求,提出了环评监测中方案的细化、点位布设方面存在的问题,阐述了如何合理设置监测点位、准确把握采样方法、科学选择分析方法等问题。     

Microstructure of 2205 duplex stainless steel joint in submerged arc welding by post weld heat treatment

The 2205 duplex stainless steel (DSS) is of both good properties austenitic steel and ferritic steel, which applies to the shipbuilding industry usually. In this paper, the OM, XRD and microhardness test methods are used to analyze the variation of submerged arc welded (SAW) joints with and without post weld heat treatment (PWHT). The research results show that the σ phase disappear in the fusion edge zone near heat affect zone (HAZ) and an increase in the welded center zone during the follow-up PWHT, while the amount of γ phase is decreased in the welded center zone with PWHT. A segregation distribution of some second phases is also found in the welded center zone after PWHT. There have two pick values of microhardness arise in the fusion edge zone and the welded center zone separately without PWHT. However, a maximum value of microhardness at the fusion edge zone near HAZ is disappeared and the other is still held at the welded center zone during PWHT. It can be attributed to the changes of second phases, element diffusions and particle segregation during PWHT. A developing mechanism is issued to demonstrate the second phases transferring of the 2205 DSS SAW joints by PWHT.     

Improvement of welding heat source models for TIG-MIG hybrid welding process

Tungsten inert gas-metal inert gas (TIG-MIG) hybrid welding process is an effective way to improve welding productivity and quality due to advantages of the two processes. Mathematical analysis is crucial to fundamentally understand this synergetic welding process. In this study, based on experimental visualization of arc behaviors, some assumptions are proposed to deduce adaptive plane and volumetric heat source models separately for each involved welding method first. The influence of torch angles on distribution of temperature and geometry of weld bead are calculated and compared with experimental results. It shows that this developed algorithm of heat source can be employed to accurately predict welding process whether the electrode gun is slanted backward or forward to the direction of welding. Then TIG-MIG hybrid welding process is simulated and analyzed without considering the attractive or repulsive force of two arcs. The characteristic of TIG-MIG welding process is discussed compared to single MIG. It lays the foundation for the further research on the interaction of the two arcs during TIG-MIG hybrid welding.     

秸秆压块与燃煤供热系统生命周期环境排放对比研究

为证明采用秸秆压块燃料替代煤炭进行供热的可持续性,对秸秆压块和燃煤供热系统的生命周期环境排放进行了对比分析.基于我国2012年投入产出表,构建了投入产出生命周期评价(IO-LCA)和过程生命周期评价(PLCA)相结合的混合生命周期评价(Hybrid-LCA)模型,核算了玉米秸秆压块和燃煤供热系统供应1 GJ热的生命周期CO2、SO2、NOx和PM2.5排放.结果显示,秸秆压块供热系统的生命周期CO2排放量为7 kg·GJ-1热,比燃煤供热排放减少121 kg.此外,秸秆压块供热系统比燃煤供热系统可以分别减少SO2排放98%、NOx排放76%和PM2.5排放58%.控制原料水分,通过减少原料收集和能源转化过程中的耗损,减少能源转化过程的电力消耗以及控制原料收集半径等可以有效改进秸秆压块供热系统环境表现.     

城市热岛效应下浅层土中混凝土的酸腐蚀试验研究

针对城市热岛效应引起城区浅层土地温场升高这一观测结果,采用室内快速模拟试验方法,对城区酸性土壤腐蚀混凝土材料的温度效应开展了试验研究.试验研究了在温度为5℃、20℃和40℃条件下,混凝土试样在酸浓度分别为0%、5%和10%的沙土介质中放置30 d、90 d后的抗压强度变化规律,并对混凝土试样在腐蚀过程中的腐蚀系数变化规...     

微波诱导AC/Cu、AC/Fe催化非均相Fenton 反应催化降解垃圾渗滤液

采用活性炭载体负载Cu、Fe为催化剂,在微波诱导作用下,对垃圾渗滤液污染物进行降解。实验结果表明,活性炭负载金属前经适当浓度硝酸浸泡处理后,催化剂对COD去除率提高可超过15%,过高硝酸盐浓度对COD去除有不利影响;催化剂对COD去除率随Cu、Fe金属负载量增加呈先增加后降低的趋势,催化剂对Cu、Fe的最佳负载量分别为质量百分比2.11%和1.12%。对于AC-Cu体系,在初始pH=3,H2O2投加量为4.98×103mg/L,催化剂用量为5.0×103mg/L,420 W功率下微波辐射10 min时,垃圾渗滤液COD去除率可达到84.13%;对于AC-Fe体系,当H2O2投加量为0.33×103mg/L,催化剂AC-Fe用量为2.0×104mg/L,420 W功率下微波作用10 min时,垃圾渗滤液COD去除率为60.16%。分析2种催化剂对COD去除差异的原因,可能是催化剂AC-Cu表面单分子分布的阈值比AC-Fe高。降解液的pH值对AC-Cu体系、AC-Fe体系COD去除影响存在拐点,最高COD去除率点对应的降解液pH值为3。微波辐射功率较低时,体系COD去除率随辐射功率增加而增加;辐射功率较高时,高温下垃圾渗滤液中有机硫化物分解成小分子硫化物,对催化剂活性存在一定抑制作用。     

基于分段式电压采集法的天线绝缘检测技术研究

如今,短波发信伸缩天线、插拔鞭天线等大量应用于通信台站与舰船上,天线绝缘性能是其重要的考核指标,该参量关乎到天线的持久性与通信的稳定性。以天线绝缘电阻检测技术为研究对象,分析了天线绝缘检测手段的必要性与存在的不足,在普通绝缘检测技术的基础上,提出了一种基于分段电压采集法的绝缘检测方法,对信台站与舰艇上天线的设计、施工、调试、维修、以及现场系统联调等环节起到保障作用,改善了天线绝缘性能检测技术智能化、模块化、高精度等问题。     

The impact of the electricity tariff reform on renewable energies and energy efficiency investments: The case of the Italian residential market

This article investigates the impact that the electricity tariff reform is likely to have on investments in renewable energies (i.e., photovoltaics) and the adoption of energy efficiency measures (i.e., installation of heat pumps and efficient home appliances) in the residential market in Italy. The study develops detailed cost comparisons and simulations considering two different investment scenarios (before and after the reform) to conclude that the reform will: (i) have a negative impact on investments in photovoltaic systems; (ii) favor the adoption of energy efficiency measures, such as efficient home appliances.