重庆市大气细颗粒物中多环芳烃组分与男性精子DNA损伤的关联研究

目的探讨重庆市大气细颗粒物(PM2.5)中的多环芳烃(polycyclic aromatic hydrocarbons,PAHs)暴露对男性精子DNA的损害效应。方法研究对象来源于2013、2014年重庆市大学生男性生殖健康研究队列(male reproductive health in Chongqing college students,MARHCS),检测采样期间大气PM2.5中的低环PAHs(2~4环)和高环PAHs(5~6环)各组分的含量;采用单细胞凝胶电泳实验检测精子DNA损伤;采用混合效应模型探讨PAHs各组分的暴露程度与男性大学生精子DNA损伤水平之间的关联。结果2013年大气细颗粒物中的PAHs组分以低环PAHs为主,其中菲、芴、芘的占比最高,而2014年大气细颗粒物中则以高环PAHs为主,如茚并[1,2,3-cd]芘、苯并[g,h,i]苝、苯并[a]芘等。在2014年,男性大学生的精子DNA损伤指标如彗星尾长、尾矩和Olive尾矩较2013年明显增加(P<0.05)。混合效应模型结果显示:低环PAHs中的荧蒽、苊烯、芘和总低环PAHs与精子DNA损伤指标中的彗星尾长和尾矩呈负相关。高环PAHs中的苯并[k]荧蒽、苯并[b]荧蒽和二苯并[a,h]蒽与精子DNA损伤指标中的彗星尾长呈正相关[β(95%CI):108.987(43.754~203.820)、158.700(65.957~303.272)、185.708(67.350~387.775),校正P均<0.05];与彗星尾矩呈正相关[β(95%CI):449.204(260.066~737.695)、683.108(374.515~1192.387)、683.108(374.515~1192.387),校正P均<0.05]。结论重庆市大气细颗粒物中的高环PAHs组分暴露,可能导致精子DNA损伤效应增加。

基于太阳能热化学的分布式供能系统热力学性能及碳排放分析

分布式供能系统临近用户,具有灵活消纳可再生能源的优势。集成太阳能与清洁燃料互补的分布式供能系统,旨在实现太阳能与燃料的高效互补利用。提出了基于太阳能热化学的分布式供能系统,该系统集成了太阳能热化学转化与分布式冷热电联供系统,将太阳能与甲醇以热化学的形式进行源头互补,把太阳能转化为合成气燃料化学能,进而通过内燃机发电机组和余热回收单元输出冷、热、电产品,以满足用户的负荷需求。通过数值计算的方法,对所集成的系统开展了热力学性能及CO2排放性能分析,研究了设计工况及变工况下运行性能,结果表明所集成的太阳能与燃料热化学互补供能系统具有显著的节能减排优势。

某地区戒毒人群HBV、HCV、HIV和TP标志物检测结果分析

目的分析山东济宁地区戒毒人群乙型肝炎病毒(HBV)、丙型肝炎病毒(HCV)、人类免疫缺陷病毒(HIV)和梅毒(TP)的感染现状。方法对2014-2016年该院收治的1 003例戒毒人员传染病标志物乙型肝炎5项指标、HCV抗体(HCV-Ab)、HIV抗体(HIV-Ab)和TP抗体(TP-Ab)进行检测和结果分析。结果戒毒人群HBs-Ag阳性率7.38%,HCV-Ab阳性率0.40%,TP-Ab阳性率8.87%,HIV-Ab阳性未检出,总阳性率15.75%。不同年龄组间HBs-Ag阳性率和TP-Ab阳性率差异均有统计学意义(P<0.01),>40岁年龄组有较高的HBs-Ag阳性率和TP-Ab阳性率;不同性别间TP-Ab阳性率差异有统计学意义(P<0.01),女性高于男性;不同职业HCV-Ab阳性率差异有统计学意义(P<0.05);农民组HCV-Ab阳性率较高;强制/自愿戒毒组间TP-Ab阳性率差异有统计学意义(P<0.05),强制戒毒人群TP-Ab阳性率高于自愿戒毒人群。结论该地区内吸毒人群HBV、HCV和HIV感染率较低,TP感染率较高;不同的年龄、性别、职业、地市是HBV、HCV和TP感染的影响因素。

槽式太阳能聚光器能流密度测试系统研制技术

设计一种用于槽式太阳聚光器焦线能流密度测试系统,系统主要由余弦反射体、CCD光学测量系统、导轨及调整系统等组成。首先在实验室内采用辐射标定装置对余弦反射体和CCD光学测量系统进行精密标定,得到CCD光学测量系统灰度与能流密度定量关系;然后再用该系统对槽式太阳聚光器焦线能流密度进行测试。介绍该测试系统的标定方法和各部分设计关键技术,通过外场定量测试的方式对该测试系统进行检定后,能流密度测试误差优于5%。

Design and performance investigation of modified dual reflector parabolic trough collector with double planar mirrors

In a typical parabolic trough collector(PTC), sunlight is concentrated at the bottom of the absorber tube. This concentrated solar flux leads to uneven heat distribution, resulting in high local temperatures and significant thermal stress on the absorber tube.These limitations have restricted the application of PTCs in solar thermochemistry and other fields and have impacted their safe operation. In this study, a new PTC with dual planar mirrors(DPMS) is proposed to homogenize the circumferential solar flux distribution of the absorber tube. A design method and single-objective optimization of the new PTC with a DPMS are proposed,and an uncertainty analysis of the operational and structural parameters is performed. A coupled light-heat-structure numerical model was developed to study the heat transfer performance and structural mechanical properties. The thermodynamic properties of the PTC with DPMS under different boundary conditions were analyzed. The results show that the circumferential temperature difference of the new PTC is within 2.6 K, and the circumferential thermal deformation is within 0.9 mm under typical working conditions(the inlet velocity of the heat transfer fluid is 3 m/s, inlet temperature is 573.15 K, and the direct normal irradiance is 1000 W/m^(2)). Compared with conventional PTCs, the circumferential temperature difference is reduced by 74%–90%, and the maximum thermal deformation along the y-axis is reduced by more than 95% under all working conditions(1–5 m/s, 373.5–675.15 K, 200–1000 W/m^(2)). The new PTC maintains the uniformity of the circumferential solar flux distribution for different operating parameters(sun incident angle of 0°–3°) and installation errors(±3 mm), is suitable for solar energy applications in various fields, and has the potential for large-scale applications.

New Hybrid CHP System Integrating Solar Energy and Exhaust Heat Thermochemical Synergistic Conversion with Dual-Source Energy Storage

For the efficient use of solar and fuels and to improve the supply-demand matching performance in combined heat and power(CHP)systems,this paper proposes a hybrid solar/methanol energy system integrating solar/exhaust thermochemical and thermal energy storage.The proposed system includes parabolic trough solar collectors(PTSC),a thermochemical reactor,an internal combustion engine(ICE),and hybrid storage of thermal and chemical energy,which uses solar energy and methanol fuel as input and outputs power and heat.With methanol thermochemical decomposition reaction,mid-and-low temperature solar heat and exhaust heat are upgraded to chemical energy for efficient power generation.The thermal energy storage(TES)stores surplus thermal energy,acting as a backup source to produce heat without emitting CO_(2).Due to the energy storage,time-varying solar energy can be used steadily and efficiently;considerable supply-demand mismatches can be avoided,and the operational flexibility is improved.Under the design condition,the overall energy efficiency,exergy efficiency,and net solar-to-electric efficiency achieve 72.09%,37.65%,and 24.63%,respectively.The fuel saving rate(FSR)and the CO_(2) emission reduction(ER_(CO_(2)))achieve 32.97%and 25.33%,respectively.The research findings provide a promising approach for the efficient and flexible use of solar energy and fuels for combined heat and power.

Performance Enhancement of Parabolic Trough Collector by Using Homogenizer and Spiral

In conventional parabolic trough collectors(PTCs),sunlight is concentrated at the bottom of the absorber tube,resulting in a significant circumferential temperature gradient across the absorber tube,heat loss and thermal deformation,which affects the safety and thermal performance of PTCs.In this study,a new receiver with homogenizer and spiral(RHS) is proposed,achieving the optical and thermal synergy to ameliorate the thermal deformation of the absorber tube and enhance thermal efficiency.A plane structure homogenizer is designed to improve uniformity of the concentrated solar flux of absorber tube through second reflection.In combination with the spiral,it improves the optical-thermal efficiency of the PTC by enhancing heat exchange between the fluid and the backlight side of the absorber tube.The performance of the collector is numerically studied by building a three-dimensional coupled light-thermal-structure model.The results show that the thermal deformation of the RHS is reduced by more than 96% and the optical-thermal efficiency is improved by 1.2%-0.63% compared with conventional receivers(CRs) under the same inlet temperature conditions.The proposed receiver is validated to be effective in reducing thermal deformation and improving optical-thermal efficiency.

New operation strategy and multi-objective optimization of hybrid solar-fuel CCHP system with fuel thermochemical conversion and source-loads matching

Multi-energy hybrid energy systems are a promising option to mitigate fluctuations in the renewable energy supply and are crucial in achieving carbon neutrality.Solar-fuel thermochemical hybrid utilization upgrades solar energy to fuel chemical energy,thereby achieving the efficient utilization of solar energy,reducing CO_(2)emission,and improving operation stability.For hybrid solar-fuel thermochemical CCHP systems,conventional integration optimization methods and operation modes do not account for the instability of solar energy,thermochemical conversion,and solar fuel storage.To improve the utilization efficiency of solar energy and fuel and achieve favorable economic and environmental performance,a new operation strategy and the optimization of a mid-and-low temperature solar-fuel thermochemical hybrid CCHP system are proposed herein.The system operation modes for various supply-demand scenarios of solar energy input and thermal-power outputs are analyzed,and a new operation strategy that accounts for the effect of solar energy is proposed,which is superior to conventional CCHP system strategies that primarily focus on the balance between system outputs and user loads.To alleviate the challenges of source-load fluctuations and supply-demand mismatches,a multi-objective optimization model is established to optimize the system integration configurations,with objective functions of system energy ratio,cost savings ratio,and CO_(2)emission savings ratio,as well as decision variables of power unit capacity,solar collector area,and syngas storage capacity.The optimization design of the system configuration and the operation strategy improve the performance of the hybrid system.The results show that the system annual energy ratio,cost saving ratio,and CO_(2)emission saving ratio are 52.72%,11.61%,and 36.27%,respectively,whereas the monthly CO_(2)emission reduction rate is 27.3%–47.6%compared with those of reference systems.These promising results will provide useful guidance for the integrated design and operational regulation of hybrid solar-fuel thermochemical systems.

In-Depth Energy and Irreversibility Analysis in the Solar Driven Two-Step Thermochemical Water Splitting Cycle for Hydrogen Production

Hydrogen production via a two-step thermochemical cycle based on solar energy has attracted increasing attention.However,the severe irreversible loss causes the low efficiency.To make sense of the irreversibility,an in-depth thermodynamic model for the solar driven two-step thermochemical cycles is proposed.Different from previous literatures solely focusing on the energy loss and irreversibility of devices,this work decouples a complex energy conversion process in three sub-processes,i.e.,reaction,heat transfer and re-radiation,acquiring the cause of irreversible loss.The results from the case study indicate that the main irreversibility caused by inert sweeping gas for decreasing the reduction reaction temperature dominates the cycle efficiency.Decreasing reduction reaction temperature without severe energy penalty of inert sweeping gas is important to reducing this irreversible loss.A favorable performance is achieved by decreasing re-oxidation rate,increasing hydrolysis conversion rate and achieving a thermochemical cycle with a lower equilibrium temperature of reduction reaction at atmosphere pressure.The research clarifies the essence of process irrrversibility in solar thermichemical cycles,and the findings point out the potential to develop efficient solar driven two-step thermochemical cycles for hydrogen production.

Ce基太阳能热化学循环的不可逆性分析

太阳能热化学制氢是太阳能利用有效途径,太阳能热化学两步循环通过载氧体的氧化还原反应实现间接分解水制氢,降低直接热解水温度并分步分离氢、氧产物,被广泛关注和研究。目前对于以CeO_(2)/CeO_(2−δ)氧化还原反应对为代表的太阳能热化学循环,系统热力学分析尚停留在能量分析层面,不可逆损失分布及原因仍需进一步探索与研究。本文通过对典型Ce基太阳能热化学循环进行不可逆性分析发现,Ce基太阳能热化学循环基于非化学计量比氧化还原特性,通过增加循环载氧体缓解工作在较低氧压下的真空泵机械损失。氧分压提升引入的循环载氧体增量,导致了高温还原与低温氧化切换过程中的较大加热、冷却不可逆损失,以及与这部分循环载氧体增量有关的辐射损失,严重降低了太阳能热化学制氢效率。降低这部分与氧分压有关的不可逆损失是提升非化学计量比太阳能热化学循环效率的关键。研究结果为太阳能热化学循环高效制氢提供了理论依据。

Experimental Investigation on an Absorption Heat Transformer for Production of Hot Water or Steam Generation

The absorption heat transformer is widely used to utilize low-temperature waste heat in the field of distributed energy,industrial processing,and long-distance indoor heating,because it can upgrade energy level and deliver heat to heated medium.In this work,an experimental system of a vertical single-stage LiBr/H2O absorption heat transformer was established to study its performance in the case of producing high-temperature water or low-pressure steam generation under different heating water flow rates.The useful output heat,coefficient of performance,exergy coefficient of performance,and gross temperature lift of the single-stage heat transformer have all been tested.The results show that the absorber cannot directly generate low-pressure steam under the condition of counter-flow heat exchange but can obtain more useful output heat.The largest useful output heat is 20.3 kW,which is higher than that in the case of parallel-flow heat exchange.The generation of low-pressure steam has certain requirements on the mode of heat transfer.The largest internal gross temperature lift of 28.1℃corresponds to the smallest coefficient of performance of 0.22 when the heating water flow rate is 2.1 m3/h.The performance of the single-stage absorption heat transformer can be improved to some extent by increasing the heating water flow rate.