The Approach of Compensation of Air Refractive Index in Thermal Expansion Coefficients Measurement Based on Laser Feedback Interferometry

We present the thermal expansion coefficient （TEC） measurement technology of compensating for the effect of variations in the refractive index based on a Nd： YA G laser feedback system, the beam frequency is shifted by a pair of aeousto-optic modulators and then the heterodyne phase measurement technique is used. The sample measured is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams hit perpendicularly and coaxially on each surface of the sample. The reference beams hit on the reference mirror and the high-refiectivity mirror, respectively. By the heterodyne configuration and computing, the influences of the vibration, distortion of the sample supporter and the effect of variations in the refractive index are measured and largely minimized. For validation, the TECs of aluminum samples are determined in the temperature range of 29-748K, confirming not only the precision within 5 × 10-7 K-1 and the accuracy within 0.4% from 298K to 448K but also the high sensitivity non-contact measurement of the lower reflectivity surface induced by the sample oxidization from 448 K to 748 K.

Measurement of Diffusion Coefficients of Air in Silicone Oil and in Hydraulic Oil

一台活塞柱体仪器被建立基于空气和不稳定的一个维的散开方程的答案的 PVT 州的方程在 dimethyl 硅酮油并且在水力的油测量空气的溶解度和扩散性。测量扩散性温度关系能被 Arrhenius 方程很好为设计应用适合。在溶质扩散性 D 和溶剂粘性之间的关联被检验。以 Eyring 的激活理论，在 air-silicone-oil 散开过程的激活在硅酮油的动量运输与那相当不同：当后者的是否定的时，前者的激活熵是积极的。然而，二个过程的激活热含量在一样的数量级，它导致 D/T 是粗略地不变的观察。

Method for acquiring part load distribution coefficient of air conditioning system

This paper presents a method to acquire runtime distribution ratio of building air conditioning system under part load condition (part load coefficient of system) through practical energy consumption data. By utilizing monthly energy consumption data of the entire year as the analysis object,this paper identifies data distribution,verifies distribution characteristics and analyzes distribution probability density for the issue of running time distribution ratio of air conditioning system in part load zones in the whole operation period,thus providing a basic calculation basis for an overall analysis of energy efficiency of air conditioning system. In view of the general survey of public building energy consumption carried by the government of Chongqing,this paper takes the governmental office building as an example,the part load ratio coefficient corresponding to practical running of air conditioning system of governmental office building in Chongqing is obtained by utilizing the above probability analysis and the solving method of probability density function. By utilizing the ratio coefficient obtained using this method,the part load coefficient with any running ratio of air conditioning system can be obtained according to the requirement of analysis,which can be used in any load ratio for analyzing running energy efficiency of air conditioning system.

Effects of Excess Air Coefficients on Combustion Characteristics of N-butanol by a Constant Volume Combustion Bomb

The effects of excess air coefficients on the combustion characteristics have been experimentally investigated by means of a constant volume combustion bomb.N-butanol was tested as the research fuel at different air-fuel equivalence ratios.Through the discussion of the combustion pressure,the combustion temperature,accumulated heat release,ignition delay and combustion duration,the effects of the excess air coefficient on combustion characteristics is clarified.Experimental results show that near the theoretical air-fuel ratio,the combustion rate is the fastest accompanying with shorter combustion duration while the combustion pressure and temperature reach the maximum.With increase or decrease of the excess air coefficient the combustion pressure,the temperature and the heat release reduce.Simultaneously,the combustion timing is deferred and the combustion duration becomes longer.

Role of Atmospheric Boundary Layer(ABL)Height and Ventilation Coefficient on Urban Air Quality--A study based on Observations and NWP Model

Air pollution is an issue of great concern in any urban region due to its serious health implications.The capital of India,New Delhi continues to be in the list of most polluted cities since 2014.The air quality of any region depends on the ability of dispersion of air pollutants.The height or depth of the atmospheric boundary layer(ABL)is one measure of dispersion of air pollutants.Ventilation coefficient is another crucial parameter in determining the air quality of any region.Both of these parameters are obtained over Delhi from the operational global numerical weather prediction(NWP)model of National Centre for Medium Range Weather forecasting(NCMRWF)known as NCMRWF Unified Model(NCUM).The height of ABL over Delhi,is also obtained from radiosonde observations using the parcel method.A good agreement is found between the observed and predicted values of ABL height.The maximum height of ABL is obtained during summer season and minimum is obtained in winter season.High values of air pollutants are found when the values of ABL height and ventilation coefficient are low.

Air tightness of compressed air storage energy caverns with polymer sealing layer subjected to various air pressures

During the operation of compressed air storage energy system,the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer.To calculate and properly evaluate air tightness of polymer sealing caverns,the air-pressure-related air density and permeability must be considered.In this context,the high-pressure air penetration in the polymer sealing layer is studied in consideration of thermodynamic change of the cavern structure during the system operation.The air tightness model of compressed air storage energy caverns is then established.In the model,the permeability coefficient and air density of sealing layer vary with air pressure,and the effectiveness of the model is verified by field data in two test caverns.Finally,a compressed air storage energy cavern is taken as an example to understand the air tightness.The air leakage rate in the caverns is larger than that using air-pressure-independent permeability coefficient and air density,which is constant and small in the previous leakage rate calculation.Under the operating pressure of 4.5-10 MPa,the daily air leakage in the compressed air storage energy cavern of Yungang Mine with high polymer butyl rubber as the sealing material is 0.62%,which can meet the sealing requirements of compressed air storage energy caverns.The air tightness of the polymer sealing cavern is mainly affected by the cavern operating pressure,injected air temperature,cavern radius,and sealing layer thickness.The cavern air leakage rate will be decreased to reduce the cavern operating pressure the injection air temperature,or the cavern radius and sealing layer thickness will be increased.

热风加热沥青路面冲击射流共轭传热特性

为提高热风加热沥青路面的就地再生加热效果,基于热风冲击射流对流换热和沥青路面内部导热的共轭传热过程,建立了热风加热沥青路面的冲击射流共轭传热理论模型,选取有限容积法得到了共轭传热模型的通用离散方程,采用压力-速度耦合半隐式算法(semi-implicit method for pressure linked equations,SIMPLE)获得了整个求解域内温度场分布,选取平均热流密度和平均换热系数反映沥青路面加热效果,通过正交试验研究了热风出口速度和热风出口温度对路面加热效果的影响程度。仿真和试验结果表明:理论计算与实验温度场分布趋势吻合度高,两者平均误差为8.4%;平均热流密度和平均换热系数在加热初期均从最大值急剧下降,而后下降幅度逐渐减小趋于平衡,两者的仿真计算与实验结果趋势相同,平均误差分别为6.4%和7.8%;热风出口速度和热风出口温度对平均热流密度均有显著影响,热风出口速度对平均换热系数有显著影响,热风出口温度对平均换热系数的影响相较于平均热流密度指标表现为不显著。研究结果为后续沥青路面就地热再生热风加热温度控制和加热器设计提供了理论依据。

拱架送/回风方式对日光温室冬季作物冠层区热环境的影响

传统日光温室被动的热环境调控模式难以满足温室作物冠层区空气温度和速度调控需求,且能源利用效率低下。为了改进日光温室热环境精准调控方法和提高温室能源利用效率,该研究结合日光温室围护结构特点,提出了一种日光温室拱架的送/回风方法,并基于温室作物多孔介质模型,建立了拱架送/回风系统温室的数值传热模型。采用空气温度与速度不均匀系数、气流速度适宜区面积比、能量利用系数以及累计有效积温等评价参数,研究了下送上回、中间回风和上送下回等3种温室拱架送/回风方式对日光温室冬季作物冠层区热环境的影响。结果表明,与中间回风和上送下回通风方式相比,下送上回通风方式对不同作物冠层高度处的空气温度和速度调控的结果最优,且不同作物冠层高度处气流速度适宜区面积比和累计有效积温都最大。当采用下送上回通风方式时,与送风干管风速为9、11和12 m/s相比,送风干管风速为10 m/s的能量利用系数最大,在作物冠层高度0.4、0.6、0.8和1.0 m处的能量利用系数分别为0.976、0.982、0.985和0.987,并且不同作物冠层高度处的空气温度不均匀系数和速度不均匀系数也都最小。因此,下送上回通风方式的推荐送风干管风速为10 m/s。该研究可为日光温室热环境的精准调控提供参考。

影响流量管流量系数的因素分析

对某航空发动机整机试验装置的流量管三维流场进行数值模拟,通过布置虚拟测点,建立流量管虚拟试验校准和测量的仿真方法,研究流量管流量系数获取方法、校准试验测试布局,分析来流雷诺数、壁面粗糙度、流量管圆度对流量系数的影响。结果表明,附面层位移厚度法和校准试验法获取的流量系数接近。在同一流向布置测量截面,流量系数随流量管内雷诺数的减小而减小,随流量管壁面粗糙度的增大而减小;低雷诺数工况下,流量系数对粗糙度变化不敏感。对于低雷诺数工况或者在流量管壁面粗糙度较大时,应采用附面层位移厚度法或校准试验法获取流量系数。流量系数对流量管圆度的变化不敏感,建议采用校准试验方法获得有变形的流量管的流量系数。尽量采用校准试验法获取流量管宽雷诺数范围的流量系数,采用实际测量工况下的雷诺数对应的流量系数,修正流量管测量数据,才可保证流量管测量精度。

花椒热风-微波组合干燥失水特性研究

花椒热风干燥降速期水分含量低,水分扩散慢,导致热风干燥耗时长。为提高干燥效率,并通过热风与微波组合干燥,分别进行热风干燥、微波干燥和热风-微波组合干燥实验,探究不同干燥参数对花椒失水特性的影响,以确定合理的干燥转换临界点和最优组合干燥模型,并将傅里叶准则数(F_(0))引入Fick第二扩散定律方程,求解有效水分扩散系数(D_(eff))。研究结果表明:热风和微波单独干燥时,升高风温风速和增加微波功率均有利于缩短干燥时间;热风-微波组合干燥花椒时,热风段转微波段的最佳目标含水率即为热风干燥的临界点含水率(65%(w.b)),且高热风温度和高微波功率均可使微波干燥段获得高失水速率;热风-微波组合干燥花椒热风段和微波段对应的最优模型分别为Wang and Singh模型和Page模型,D_(eff)范围分别为1.908×10^(-9)~3.547×10^(-9)m^(2)/s和1.883×10^(-8)~3.321×10^(-8)m^(2)/s。热风-微波组合干燥方式能够显著提高干燥效率,促进花椒内部水分扩散,干燥模型可为优化干燥工艺和设计干燥设备提供理论依据。

相变储热技术在空气源热泵供暖中的应用研究现状

空气源热泵技术因具有节能、环保、高效等优点,在我国建筑供暖领域得到了广泛应用。文章分析了空气源热泵系统在供暖过程中存在的问题,介绍了利用相变储热技术优化空气源热泵运行性能的基本方式及原理。通过分析相变材料自身热物性以及相变储热单元在系统中的应用,从材料及系统两方面简述了相变储热技术在空气源热泵供暖中的研究现状及进展。最后,得出结论并针对相变储热技术在空气源热泵供暖中的应用难点,对未来发展进行了展望。

某纯电车型空调PTC不制热故障分析与改进

为分析电动汽车空调系统不制热故障原因,以某车企收到的4S店空调故障案例为例,使用质量管理工程师常用的检测方法和仪器对加热零部件进行分析与诊断,结果表明是由于软件问题导致熔断器开路,造成空调故障,提出对软件控制的临界值进行改进的故障排除建议。

油田注汽锅炉产汽单耗的计算方法与影响因素分析

为有效降低油田注汽锅炉产汽单耗,通过系统分析油田注汽锅炉生产工艺、生产设备、能耗水平及产汽单耗的计算方法,确定影响产汽单耗水平的关键因素包括温度、压力、干度、过热度、运行管理水平、锅炉热效率等,对各项因素的影响效果进行了分析验证。采用实际测试结果与理论计算数据对比的方法,得出了常见工况下油田注汽锅炉产汽单耗的变化规律,在此基础上明确了注汽锅炉节能提效的重点方向和技术措施,分析各项措施提效降耗的基本效果,对油田注汽锅炉的节能提效、降低产汽单耗和企业生产成本提供了良好借鉴。

250~500 kV X射线窄谱辐射质空气比释动能测量及剂量当量转换系数研究

辐射剂量仪表的准确测量是开展辐射防护工作的重要保障,根据ICRU中规定的实用量要求,需要在特定的参考辐射场中对其进行检定或校准。参考ISO 4037-1:2019,建立250~500 kV X射线窄谱系列参考辐射质,对所建辐射场的均匀性以及相应辐射质下的能谱进行研究。将由EGSnrc模拟的X射线能谱得到所建辐射质下的平均能量、分辨率以及实验测量得到的半值层值与ISO标准推荐值进行比较,结果均满足规范要求,表明新建辐射质准确可靠。利用A5电离室对新建辐射场中的空气比释动能进行测量,再根据X射线能谱信息计算得到的空气比释动能到剂量当量的转换系数,实现空气比释动能到周围剂量当量和个人剂量当量的转换,从而为各类辐射剂量仪表在该高能段的能量响应评价提供了测量条件,保证了量值的准确与可靠。

送风参数对老化箱内部温湿度场的影响研究

利用老化箱对机械电子元件进行老化筛选,能有效提高产品的可靠性。老化箱内部温湿度场的均匀性决定了其整体性能,这对老化箱功能有至关重要的影响。为了提高老化箱的性能,基于流体力学原理,利用CFD(computational fluid dynamics,计算流体力学)仿真软件对老化箱简化模型进行仿真模拟,并根据仿真结果确定老化箱内部速度场与温度场的分布情况,以优选不同送风温度、送风速度和送风角度组合下的送风方案。仿真试验采用正交试验法,以送风温度、送风速度和送风角度为试验因素,以能量利用系数、温度不均匀系数和相对湿度不均匀系数为评价指标。通过对仿真试验结果进行极差和方差分析可知,送风角度对能量利用系数的影响最显著,送风温度对温度不均匀系数和相对湿度不均匀系数的影响最显著。针对3个评价指标,得到3种最优方案:送风温度为90℃、送风速度为10 m/s、送风角度为0°,送风温度为90℃、送风速度为12 m/s、送风角度为-10°,以及送风温度为90℃、送风速度为8 m/s、送风角度为0°。最后,开展了老化箱内部温湿度测量实验,并与仿真结果进行了对比。结果表明,仿真结果与实验结果的相对误差较小,均在合理范围内,验证了仿真试验的可靠性和有效性。研究以提高老化箱性能和能量利用率为导向,可为同类老化箱的设计及其送风参数的设置提供参考。

冷凝器面积对空气源热泵制热性能的影响研究

目的研究低温条件下空气源热泵的烘干性能。方法论文主要采用焓差法研究在换热面积和室外温度(温度为7、−12、−20℃,相对湿度为65%)不同时,空气源热泵的制热量、输入功率、能效等性能。结果在7℃环境中,增加室内侧换热器面积,热泵的制热量提高了19%,系统能效提升了14%,但输入功率增加了5%;在−12~−20℃环境中,增加室内侧换热器面积,热泵的制热量提升了5%,系统能效提升明显,最大可提升27%,输入功率最大降低为17%。结论增加室内侧换热器面积,系统焓差降低,但是能提高系统在低温下的循环风量,制热性能更加优异。

温度对绿色葡萄干色泽及干燥特性的影响

【目的】研究不同温度条件下热风干燥对葡萄干色泽相关指标、水分扩散系数的影响,为绿色葡萄干的工业化生产加工提供理论和技术支撑。【方法】采用不同温度(30、32.5、35、37.5和40℃)对无核白葡萄进行干燥,分析温度对葡萄色泽、水分扩散系数及制干品质的影响,拟合干燥动力学模型。【结果】干燥温度为35℃时绿色葡萄干比率最高达到64%,色泽与原料的差异最小,色差ΔE仅为6.99,C、h 0、L、a、b等色泽指标分别为18.23、1.4、14.57、2.99、17.95。叶绿素、叶绿素a、叶绿素b、类胡萝卜素、总酚含量分别为0.56、0.19、0.36、0.32、0.18 mg/g。35℃更适宜绿色葡萄干加工。最符合葡萄干燥的模型,决定系数R 2值最大,误差平方和、SSE和均方根误差RMSE均值最小,分别为0.9981、0.0054和0.0077。绿色葡萄干最适宜的有效水分扩散系数为5.3348×10^(-9)。【结论】热风干燥温度为35℃时最有利于无核白绿色葡萄制干,35℃时有效水分扩散系数分别为30、32.5、37.5和40℃的114.13%、110.58%、95.17%和76.58%,Logarithmic模型可以有效的描述热风干燥工艺条件下葡萄果实水分的变化规律。

SOFA对炉膛出口烟气温度的影响研究

远离型燃尽风(SOFA)对炉膛出口烟气温度影响较大。在SOFA改造比较成功时,炉膛出口烟气温度是否升高主要取决于SOFA的过量空气系数,当该值超过其临界值时,炉膛出口烟气温度降低,反之则升高。在炉膛出口烟气温度降低时,适当调整SOFA的风量和炉膛出口过量空气系数,会使NOx排放降低,锅炉效率提高。

悬索桥主缆截面固定网格多孔模型构建与流动特性研究

为研究悬索桥主缆除湿过程中紧束态钢丝束区域截面流动特性,以深中通道伶仃洋大桥为背景进行主缆截面固定网格多孔模型构建与流动特性研究。利用固定网格的方法,考虑钢丝束间隙,构建一种适用于悬索桥主缆截面的精准多孔模型,研究钢丝束间隙、通气方向、阻力系数计算方法、钢丝束阶数对空气流动特性的影响。结果表明:通气方向不同时,精准多孔模型体现了主缆截面内部流速分布的不均匀性以及流动阻力的各向异性;入口速度一定时,垂直通气时两侧间隙流速大于钢丝束内部流速,水平通气时水平间隙流速有所增大,垂直通气进出口压差大于水平通气,两者相差11.29%;对比采用Ergun公式计算的阻力系数模型与采用拟合计算的实际阻力系数模型,进出口压差差异随着入口速度的减小而逐渐增大,在入口速度为0.031 25 m/s时,水平通气和垂直通气下,2种模型进出口压差差异分别为89.5%和95.6%;钢丝束阶数不同时,各个阶数粘性阻力系数值相差小于1%,惯性阻力系数值相差小于2%,可认为阻力系数计算与钢丝束阶数近似无关。