先进吸收式制冷循环构建理论及其应用研究

该研究提出了制冷能力的新概念,并将其用于吸收式制冷循环性能的分析及其新循环的构建。针对中低温大温降余热利用不充分的技术难题,该报告创建了一种结构形式简单、能高效利用该类热源的先进吸收式制冷循环,理论研究结果显示,在所研究的工况范围内,新循环单位质量热源流体的制冷量比传统单效循环高20%以上。针对低温余热难以高效利用的技术难题,该报告通过合理利用或者改变溶液的现实扩散制冷能力,根据不同工况的需求,分别构建了3个新的先进吸收式制冷循环。理论研究表明:新构建的循环比传统循环具有更高的效率。针对中温余热难以高效利用的技术难题,该报告分别构建了两个1.x效吸收式制冷循环。理论研究表明,在所研究工况范围内,新提出的1.x效吸收式制冷循环的COP比传统单效循环可以提高20%左右。为了验证所提出的新循环及其所采用的理论模型,该课题设计并搭建了1.x效吸收式制冷循环实验装置。实验研究表明,当蒸发温度为5℃、吸收温度和冷凝温度为40℃、发生温度为135.3℃的时候,新循环的COP比传统单效循环的COP提高20%左右,当发生温度为127℃、冷凝温度和吸收温度为40℃、蒸发温度为10℃时,新循环的COP能达到1左右,比传统单效循环COP高30%左右,从而在实验上验证了新循环具有比传统循环高得多的效率。     

天然气CO2转化化学回热热力循环

提出了一种由天然气CO2转化化学回热动力循环和氨吸收制冷循环构成的新型O2/CO2热力循环系统.其中,采用天然气CO2转化化学回热回收较高温度的燃气透平排气热量,采用氨吸收制冷循环回收较低温度的排气热量,并利用制冷循环产生冷量作CO2循环压气机进气冷却.研究了该循环的热力学性能及其影响参数,考察了循环压比和进气冷却温度对系统循环的影响规律.新循环的系统模拟结果表明,基于1 kg/s的CH4进料流量及透平初温1 573.15 K条件,系统产功24.799 MW,发电效率达到49.6%,并可输出冷量0.609 MW.系统综合火用效率达到47.9%.同时,可回收2.246 kg/s的水,捕集2.743 kg/s液态形式的CO2,实现了循环系统的CO2和NOx准零排放.     

船用燃气轮机超临界CO_2/有机闪蒸余热回收循环的热力学分析

为了提高船用燃气轮机效率并降低排烟温度,提出一种由超临界CO_2循环和有机闪蒸循环组成的新型余热回收循环:该循环中超临界CO_2循环回收高温烟气,有机闪蒸循环回收低温烟气。对该系统进行了热力学分析和以循环净功率为目标函数的优化分析,结果表明:在基本工况下,接入该余热回收循环后的燃气轮机热效率和■效率高达50.4%和68.93%,比未接余热回收循环的燃气轮机热效率提高了44%,■效率提高了43.6%;冷凝器■损最大,为842.04 kW,占余热回收循环总■的6%;当CO_2压气机压比越大、加热器1和加热器2的端点温差越小时,余热回收循环的净功率越大;有机闪蒸循环的蒸发温度处于最佳值时,余热回收循环净功率最大;当有机工质为对二甲苯时,该余热回收循环的净功率最高,为9 759.64 kW,最终排烟温度最低,为177.6℃。     

烧结余热发电高温烟气阀门设计

烧结工序的能耗指标与先进国家相比差距较大,每吨烧结矿的平均能耗要高20千克标准煤,节能潜力很大.烧结工序的能耗约占冶金总能耗的10%～12%.而其排放的余热约占总能耗热能的49%.在烧结矿生产过程中,特别是烧结矿由鼓风式环冷机冷却过程中会排出大量温度为250～400℃的低温烟气,其热能量大约为烧结矿热耗量的30%左右.实现能源梯级利用的高效性和经济性角度分析,余热发电是最为有效的余热利用途径,平均每吨烧结矿产生的烟气余热回收可发电20千瓦时,折合吨钢综合能耗可降低8千克标准煤.余热发电烟气阀门烧结余热发电重要的辅机设备,直接影响烧结和余热电站运行稳定、废气的充分利用以及整个系统运行效率和可靠性,做好高温烟气阀门对烧结余热发电具有重要意义.     

火花辅助对多缸汽油机HCCI燃烧及排放的影响

采用优化动力技术手段,利用发动机冷却水和排气余热加热进气,在多缸汽油机上实现了均质混合气压缩(HCCI)燃烧,研究了火花辅助点火对HCCI燃烧及其排放特性的影响.结果表明：当进气温度未达到HCCI稳定燃烧条件时,火花辅助有助于HCCI燃烧,并可增大平均指示压力、最大气缸爆发压力以及最大压力升高率,降低循环波动率,提高燃烧稳定性;火花辅助使得HCCI燃烧出现了2个放热阶段,当点火提前角增加时,主燃烧阶段的放热率峰值增大,燃烧起始点提前;在发动机转速为1 200~1 600 r/min的小负荷范围内,火花辅助可以适当降低NOx和HC的排放量.     

温度对增压二甲醚发动机性能的影响

以一台增压二甲醚发动机为研究对象,研究进气温度和燃料温度对二甲醚发动机性能的影响。试验结果表明,进气温度升高,燃烧滞燃期缩短,放热率曲线往前移,预混合燃烧的峰值降低,预混合燃烧在整个燃烧过程中所占比例减小;进气温度升高会导致发动机油耗率上升,排温升高,NOx排放增加。二甲醚燃料温度的影响比进气温度升高,燃料温度增加会导致发动机功率下降。额定工况点下,当燃料温度由28℃升高到40℃时,发动机的功率由192.1 k W下降到168 k W,下降12.0%。二甲醚温度每升高1℃,二甲醚发动机功率平均下降1.0%。     

双工况燃机进气冷却测控系统设计

为了提高燃机在酷热夏季的出力,研发了具有双工况工作模式的进气冷却系统.该系统利用烟气余热作为动力,不仅在夏天制冷工况下能对燃机进气进行充分冷却,有效提高燃机效率;而且在冬天低压加热工况下驱动低压加热器产生热水,提升余热锅炉的给水温度,以提高汽轮机的功率.该系统的测控系统基于DCS框架构建,并根据实际情况简化为两层结构:集中控制层和过程控制层.上位监控软件用DELPHI软件自主开发,通过自主开发的OPC控件,实现了对下位PLC控制器的实时读写操作.使用结果表明,该套测控软件不仅界面美观,操作方便,而且对数据处理具有独到的优越性.     

吸附式制冷系统运行参数动态特性

针对燃料电池汽车余热驱动的吸附式制冷循环过程吸、脱附特性,采用动态的分析方法,对吸附式制冷系统的主要部件吸附床在不同阶段（等容加热、等压解吸、等容冷却、等压吸附）的工作过程建立动态方程,同时对制冷系统的蒸发器及冷凝器建立相应的动态模型。利用数值方法对数学模型进行求解,分析吸附速率、吸附床温度、冷凝温度、蒸发温度、制冷功率等参数随时间的动态变化规律。研究结果表明：吸附速率在吸附过程进行到5min时达到峰值,吸附床温度达到350K后其升温速率开始减慢,吸附床温度降到315K后的降温速率开始减慢,冷凝温度在解吸阶段进行到8min时存在1个峰值,蒸发温度的变化趋势与制冷功率的变化趋势相反。     

发电机组凝汽器背压的优化计算

结合某电厂350 MW发电机组运行数据和凝汽器变工况计算,运用控制变量法分别定性与定量分析了机组负荷、循环水流量、循环水温度对凝汽器背压的影响,并进一步得到这些参数对机组热耗率、机组净功率、全厂供电煤耗率的影响规律。以机组净出力为目标函数,寻找机组运行最佳背压和最佳循环水流量,并给出机组在常用负荷(75%)运行时,循环水泵优化调整方案及优化调整前后全厂供电煤耗率的对比。经优化,循环水泵单泵运行向双泵运行切换的温度点由16℃调整至18℃;通过循环水泵运行方式调整,该台机组全厂平均供电煤耗率可节约0.25 g/(kW·h)。     

涡旋制冷压缩机外部冷却的研究

为具有外冷结构的涡旋制冷压缩机的工作过程建立了热力学模型,并研制了实验室样机,该压缩机的冷却结构可以深入到样机内部,其冷却效果更好.在搭建的相关冷却水循环回路中对无水冷和不同进口水温下的性能参数进行了测试,结果表明:相对于无水冷的工况,当进口水温为25℃时,输入功和排气温度分别降低了11.9%和36%,制冷量和容积效率分别提高了11%和12.7%,系统的制冷系数COP提高了26.2%;对于有水冷的工况,当进水温度从55℃降低到15℃时,系统的COP约提高1.5%,排气温度从86℃降低到64℃,降低了22℃,水和压缩机的换热量从1 261W升高到2 507W,提高了1 246W.模拟结果与实验结果吻合良好.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that