一种气溶胶测量仪器标定系统的设计及性能评估

对气溶胶测量仪器进行准确标定是保证大气环境及污染源颗粒物测量数据质量的重要前提.本研究搭建了一套多分散在线标定气溶胶测量仪器的系统,该系统采用超声气溶胶发生装置产生多分散颗粒物,并用空气动力学粒径谱仪对颗粒物粒径分布进行测量.评测结果表明该系统干燥腔室内气溶胶稳定、均匀,且符合对数正态分布.以采样器为例,已有研究多使用单分散离线标定方法对采样器切割性能进行标定,该方法操作繁琐、实验周期长.利用多分散在线标定系统对PM_(2.5)和PM_(10)双级虚拟撞击采样器进行标定,并与单分散离线标定方法进行了对比,两套系统的标定结果呈现较好的一致性,但多分散在线方法大大缩短了标定实验周期.     

Grey relational analysis of an integrated cascade utilization system of geothermal water

With the drastic decrease in fossil resources and rapid deterioration of the global environment, the utilization of geothermal resources has been strongly advocated. The combination of heat, power, and cold utility generation is commonly used to increase the utilization efficiency of geothermal resources. In this study, an integrated cascade utilization system of waste geothermal water (ICUWGW) from a flash geothermal power plant in China is established to increase the utilization efficiency of geothermal water. The waste geothermal water leaving the power plant is proposed for further use in cascade for two-stage LiBr/H₂O absorption cooling, agricultural product drying, and residential bathing. Twelve candidate temperature schemes showing different inlet and outlet temperatures of every subsystem are proposed for the ICUWGW. Several criteria are selected for the evaluation and screening of the candidate schemes. Grey relational analysis incorporating analytic hierarchy process is conducted to screen the optimal temperature scheme for the ICUWGW to meet the comprehensive criteria of thermodynamics and economics. Results show that the optimal scheme features significant improvement in energy efficiency, exergy efficiency, and equivalent electricity generation efficiency compared with those of the current geothermal power plant. The investment payback time of the additional subsystems for cooling, drying, and bathing is 1.85 years. Exergy analysis is also conducted to determine the further optimization potential of the optimal ICUWGW. Sensitivity analysis of electricity price on the performance of the optimal ICUWGW is also performed.     

ELPI 测定环境空气 PM2．5的现场比对研究

采用ELPI自动监测方法与手工采样－重量法对环境空气PM2．5监测进行现场比对研究,按照两种方法数据的相对偏差来评价ELPI方法的数据质量。实验结果表明,两种方法数据的相对偏差范围为－12．9％～17．4％,加权平均值为3．0％;相对偏差的绝对值范围为1．1％～17．4％,平均值为9．3％。 ELPI法的数据质量总体较好,方法的准确度尚可。只是随着空气PM2．5浓度测定值的升高,ELPI法与重量法相对偏差的绝对值显著减小,可见,在低浓度下,ELPI法的数据质量相对较差,此时方法的准确度有待进一步验证、提高。     

Comprehensive characterization of ambient nanoparticles collected near an industrial science park: Particle size distributions and relationships with environmental factors

We investigated the characteristics of ambient particles and their relationships with various environmental factors, including gaseous pollutants (CH4, non-methane hydrocarbons (NMHC), total hydrocarbons (THC), NOx, CO, SO2), meteorological parameters (humidity, temperature), and time (day/night, workday/weekend). We used an electrical low-pressure cascade impactor to measure the number and size distributions of ambient particles (0.007–10 m) that were collected approximately 1 km northwest of Hsinchu Science Park in Taiwan between February and May 2007. The number concentrations of particles were enhanced through photochemical reactions during the day. In addition, high traffic flow during workdays increased the formation of particulates. Except for SO2, all of the gaseous pollutants we studied (CH4, NMHC, THC, NOx, CO) correlated positively with the total number concentrations of ambient particles during daytime, indicating that they might contribute to the particulate burden. The poorer relationship between the SO2 level and the total number concentration of particles suggests that SO2 might participate indirectly in the nucleation process during particle formation, The high enrichment factors for Zn, Pb, Cu, and Mn, which mostly comprised the ultrafine particles (diameter: < 0.1 m) and fine particles (diameter: 0.1–1 m), presumably arose from emissions from traffic and high technology factories. Heterogeneous reactions on solid particles might play a role in the removal of SOx and NOx from the atmosphere. Sulfides and nitrides can further react with these local pollutants, forming specific Cu-containing compounds: CuO (39%), CuSO4 (34%), and Cu(NO3)2 (27%), within the ambient particles in this industrial area.     

矩形喷嘴PM2.5惯性冲击采样器的研制

惯性冲击器是最重要的颗粒物采样器之一,被广泛用于大气颗粒物的分级采样。设计了一种中流量的矩形喷嘴PM2.5惯性冲击采样器。根据Marple准则设计了冲击器的结构参数,用CFX软件进行了惯性冲击器内部气固两相流场的CFD模拟,得出了惯性冲击器的最优结构参数。根据得出的最优设计参数,进行了PM2.5惯性冲击器样机的结构设计,并在实验室用APS气溶胶空气动力学粒度仪进行了标定。实验标定和CFD数值模拟的结果基本吻合,当采样流量为100L/min,冲击器的切割粒径dp50=2.55μm,切割锐度σg=1.4,满足设计要求。     

Comparative thermodynamic performance analysis of a cascade system for cooling and heating applications

In this study, a comparative thermodynamic performance analysis of cascade system (CCS) for cooling and heating applications is presented and compared for different refrigerant couples. The CCS consists of the low-temperature cycle (LTC) and high-temperature cycle (HTC). The CO₂ was used as working fluid in LTC, whereas the HFE 7000, R134a, R152a, R32, R1234yf, and R365mfc refrigerants were used in HTC. The heating and cooling coefficients of performance (COP_ht, COP_cl) and exergy efficiency of CCS are investigated parametrically according to various factors such as the evaporator, condenser, and reference temperatures. After thermodynamic analyses are completed, the COP_cl of CCS is obtained as 1.802, 1.806, 1.826, 1.769, 1.777, and 1.835 for CO₂-HFE7000, CO₂-R134a, CO₂-R152a, CO₂-R32, CO₂-R1234yf, and CO₂-365mfc refrigerant couples, respectively. Furthermore, the heat exchanger has the highest exergy destruction rate, whereas the expansion valves have the lowest of exergy destruction rate.     

梯级电站开发对生态环境的影响及保护措施——以瓦岗河水电规划为例

采用现场调查及类比分析等方法,结合瓦岗河水电规划成果,本文围绕小型河流水电梯级开发对环境影响的特点,重点分析瓦岗河水电梯级开发对植被、水土保持、水生生物、水质的影响。针对不利的影响,本文提出适合小型河流水电开发的环境减缓和补救措施。通过对环境不利影响采取相应的保护措施后,如下泄生态流量、外购鱼苗放流等,规划实施带来的不利环境影响将得以有效控制和减缓。     

冲击采样器设计参数分析

在颗粒物研究中 ,分级采样是一种常用的监测方法 ,而冲击采样器是颗粒物分级采样的重要仪器。从颗粒物的受力分析着手 ,得到了冲击采样器重要参数———斯托克斯数的表达式 ,并对TSP、PM1 0 和PM2 5冲击采样器设计参数进行了详细分析 ,得到了采样器设计参数的关系式及相关曲线     

固定污染源排气中PM2.5采样方法综述

我国新的环境空气质量标准已于2012年颁布并将自2016年起全面实施.为使新标准规定的细颗粒物(PM2.5)达标,各地需对固定污染源排气中PM2.5进行监测和控制,但目前国内尚无固定源PM2.5采样标准方法.本文系统地介绍了国内外固定源PM2.5采样方法及相应的国际标准,包括直接采样法和稀释采样法,并分析了这些方法的优缺点及用于我国固定源PM2.5测量的可行性.为了便于环境管理和监测,建议确立基于虚拟惯性撞击原理的烟道内直接采样方法为标准方法,用于测定固定源排气中的可捕集PM2.5;为了评估固定源PM2.5排放对大气环境质量和健康的影响,建议同时确立以烟道外稀释采样为基础的标准方法,用于测定固定源排气中包括可捕集和可凝结的PM2.5.     

调水及梯级开发对汉江襄阳段水环境容量影响

汉江是襄阳市主城区唯一水源地和纳污水体,其水质状况对襄阳市和汉江中下游的社会经济发展和人民生活影响重大。对南水北调中线调水及汉江梯级崔家营建成后的汉江襄阳段环境容量进行了预测,为该区域的水污染物总量控制提供科学依据。结合汉江襄阳段的水质、水文条件以及排污状况,采用零维和二维水质模型相结合,对该江段的水环境容量进行了计算。结果表明:与现状相比,2015年汉江襄阳段主要污染物COD和NH1-N的水环境容量在多数江段呈下降的趋势,尤其是丰水期和平水期下降较为明显。