Numerical simulation research of heating chamber for high performance hydrogen bell-type annealers

The mathematic model of heating chamber for implementing the prediction of the annealing craft and improving the self adapting with the expansion of the new annealing furnace form, new annealing crafts and new kinds of steel coil has been established. The model developed which including the temperature for gas in heating chamber and the heating cover is based on the characteristics of anneal craft and the situations of locale production run. Firstly, the characteristic of the heating cover which limits the temperature was considered. Secondly, the locale production run condition and dispatching condition were considered. Finally, combining with the models and the simulation system, the numerical simulation research of the anneal process for the high performance hydrogen bell-type annealer as well as the spot experiment test were carried out. The results obtained from the developed models, usually finished less than thirty seconds, are in fair agreement with the test values, such as the relative errors of annealing times were within ±5%, and the quality＇ of the annealed steels were guaranteed.

Fundamental Laws of Physics and Calculation of Heat Transfer in Combustion Chambers of Gas-Turbine Plants

The laws of heat radiation from black body, the laws of Stefan-Boltzmann, Planck, and Wien are fundamental laws of physics. All in all, a little more than 30 fundamental laws of physics, studied by pupils and students worldwide were disclosed. Scientific disclosure of fundamental laws influences mainly power technology, fuel and energy resources saving. In the late XIX century the laws of heat radiation from gas volumes and the laws of Makarov were disclosed. Since the radiation laws from blackbody are fundamental laws of physics, then the laws of heat radiation from gas volumes are fundamental laws of physics. Effect of using laws of heat radiation from gas volumes on fuel saving, reduction of development pressure on the environment in many countries of the world is shown. Calculation results from heat transfer in combustion chamber of gas-turbine plant are described. The torch in a combustion chamber is modeled by cylindrical gas volumes. Fluxes data from the torch and convective fluxes of cooling air are confirmed by measuring data from chamber-wall temperature.

Design and Structure Optimization of Plenum Chamber with Airfoil Baffle to Improve Its Outlet Velocity Uniformity in Heat Setting Machines

The plenum chamber of a heat setting machine is a key structure for distributing hot air to different air channels.Its outlet velocity uniformity directly determines the heating uniformity of textiles,significantly affecting the heat setting performance.In a traditional heat setting machine,the outlet airflow maldistribution of the plenum chamber still exists.In this study,a novel plenum chamber with an airfoil baffle was established to improve the uniformity of the velocity distribution at the outlet in a heat setting machine.The structural influence of the plenum chamber on the velocity distribution was investigated using a computational fluid dynamics program.It was found that a chamber with a smaller outlet partition thickness had a better outlet velocity uniformity.The structural optimization of the plenum chamber was conducted using the particle swarm optimization algorithm.The outlet partition thickness,the transverse distance and the longitudinal distance of the optimized plenum chamber were 20,686.2 and 274.6 mm,respectively.Experiments were carried out.The experimental and simulated results showed that the optimized plenum chamber with an airfoil baffle could improve the outlet velocity uniformity.The air outlet velocity uniformity index of the optimized plenum chamber with an airfoil baffle was 4.75%higher than that of the plenum chamber without an airfoil baffle and 5.98%higher than that of the conventional chamber with a square baffle in a commercial heat setting machine.

Numerical Investigations on Fluid Flow and Heat Transfer Characteristics of an Ultra-Thin Heat Pipe with Separated Wick Structures

Thermal and fluid-flow characteristics were numerically analyzed for ultra-thin heat pipes.Many studies have been conducted for ultra-thin heat pipes with a centered wick structure,but this study focused on separated wick structures to increase the evaporation/condensation surface areas within the heat pipe and to reduce the concentration of heat flux within the wick structure.A mathematical heat-pipe model was made in the threedimensional coordinate system,and the model consisted of three regions:a vapor channel,liquid-wick,and container wall regions.The conservation equations for mass,momentum,and energy were solved numerically with boundary conditions by using a code developed by one of the authors.The numerical results with the separated wick structures were compared with those with the centered,which confirmed the effectiveness of the separation of the wick structure.However,the effectiveness of the separation was affected by the position of the separated wick structure.A simple equation was presented to determine the optimum position of the separated wick structures.Numerical analyses were also conducted when the width of the heat pipe was increased with the cooled section,which clarified that the increase in the cooled-section width with the addition of wick structures wasmore effective than the increase in the cooled-section length.A 44%reduction in the total temperature difference of the heat pipe was obtained under the present numerical conditions.Furthermore,a comparison wasmade between experimental results and numerical results.

Equations of two-phase flow in spray chamber

The downstream water-air heat and moisture transfer system in a moving coordinate was studied. The relationship between the diameter of the misted droplets and the spray pressure was determined. Based on the theory of the relative velocity,the two-phase flow mode of the spray chamber and the efficiency equation for heat and moisture exchange were established. Corrections were carried out for the efficiency equation with spray pressure of 157 kPa. The results show that the pressure plays an important part in determining the efficiency of heat and moisture exchange. When the spray pressure is less than 157 kPa,better coincidence is noticed between the theoretical analysis and the test results with the error less than 6%. Greater error will be resulted in the case when the spray pressure is beyond 157 kPa. After the correction treatment,the coincidence between the theoretical and the experimental results is greatly improved.

Laws of Heat Radiation from Surfaces and Gas Volumes

It is proven that the law of radiation from solid bodies, Stefan-Boltzmann law shall not be used to calculate heat radiation from gas volumes which are formed in fuel flaring. The determining influence on heat fluxes density of the torch to the heating surfaces has not only a temperature, but power, dimensions, geometrical position of radiative gas volumes. The laws of radiation from gas volumes disclosed in 2001 and the method for calculating heating fluxes from gas volumes, developed on its basis, which takes into account the radiation from full set of particles in gas volume are stated. The torch model in the form of radiative gas volume is used to calculate heat transfer in torch heating furnaces, steam boiler boxes, turbogas unit combustors. The disclosure has enabled us to create new furnaces, fire boxes, combustion chambers, enhance unit performance, and decrease fuel rate, pollutant emissions.

The use of milk Fourier transform midinfrared spectra and milk yield to estimate heat production as a measure of efficiency of dairy cows

Background:Transformation of feed energy ingested by ruminants into milk is accompanied by energy losses via fecal and urine excretions,fermentation gases and heat.Heat production may differ among dairy cows despite comparable milk yield and body weight.Therefore,heat production can be considered an indicator of metabolic efficiency and directly measured in respiration chambers.The latter is an accurate but time-consuming technique.In contrast,milk Fourier transform mid-infrared(FTIR)spectroscopy is an inexpensive high-throughput method and used to estimate different physiological traits in cows.Thus,this study aimed to develop a heat production prediction model using heat production measurements in respiration chambers,milk FTIR spectra and milk yield measurements from dairy cows.Methods:Heat production was computed based on the animal’s consumed oxygen,and produced carbon dioxide and methane in respiration chambers.Heat production data included 16824-h-observations from 64 German Holstein and 20 dual-purpose Simmental cows.Animals were milked twice daily at 07:00 and 16:30 h in the respiration chambers.Milk yield was determined to predict heat production using a linear regression.Milk samples were collected from each milking and FTIR spectra were obtained with MilkoScan FT 6000.The average or milk yield-weighted average of the absorption spectra from the morning and afternoon milking were calculated to obtain a computed spectrum.A total of 288 wavenumbers per spectrum and the corresponding milk yield were used to develop the heat production model using partial least squares(PLS)regression.Results:Measured heat production of studied animals ranged between 712 and 1470 kJ/kg BW0.75.The coefficient of determination for the linear regression between milk yield and heat production was 0.46,whereas it was 0.23 for the FTIR spectra-based PLS model.The PLS prediction model using weighted average spectra and milk yield resulted in a cross-validation variance of 57%and a root mean square error of prediction of 86.5 kJ/kg BW0.75.The ratio of performance to deviation(RPD)was 1.56.Conclusion:The PLS model using weighted average FTIR spectra and milk yield has higher potential to predict heat production of dairy cows than models applying FTIR spectra or milk yield only.

Theory and Practice of Heat Transfer in Electric Arc and Flare Furnaces and Power Plants

The author describes the fundamental laws of physics, the laws of thermal radiation of ionized and non-ionized gas volumes. Based on open laws, a modern theory of heat transfer and methods for calculating heat transfer in electric arc and flare metallurgical furnaces, furnaces of steam boilers, and combustion chambers of gas turbine plants of power plants have been developed. The use of scientific discovery makes it possible to create innovative electric arc steel-smelting furnaces, flare heating furnaces, and combustion chambers in which the consumption of electricity and fuel is reduced, productivity and service life are increased, and the amount of harmful emissions into the environment is reduced.

Biophysical warming patterns of an open-top chamber and its short-term influence on a Phragmites wetland ecosystem in China

Passive-warming, open-top chambers(OTCs) are widely applied for studying the effects of future climate warming on coastal wetlands. In this study, a set of six OTCs were established at a Phragmites wetland located in the Yellow River Delta of Dongying City, China. With data collected through online transmission and in-situ sensors, the attributes and patterns of realized OTCs warming are demonstrated.The authors also quantified the preliminary influence of experimental chamber warming on plant traits.OTCs produced an elevated average air temperature of 0.8°C(relative to controls) during the growing season(June to October) of 2018, and soil temperatures actually decreased by 0.54°C at a depth of 5 cm and 0.46°C at a depth of 30 cm in the OTCs. Variations in diel patterns of warming depend greatly on the heat sources of incoming radiation in the daytime versus soil heat flux at night. Warming effects were often larger during instantaneous analyses and influenced OTCs air temperatures from-2.5°C to 8.3°C dependent on various meteorological conditions at any given time, ranging from cooling influences from vertical heat exchange and vegetation to radiation-associated warming. Night-time temperature depressions in the OTCs were due to the low turbulence inside OTCs and changes in surface soilatmosphere heat transfer. Plant shoot density, basal diameter, and biomass of Phragmites decreased by23.2%, 6.3%, and 34.0%, respectively, under experimental warming versus controls, and plant height increased by 4.3%, reflecting less carbon allocation to stem structures as plants in the OTCs experienced simultaneous wind buffering. While these passive-warming OTCs created the desired warming effects both to the atmosphere and soils, pest damages on the plant leaves and lodging within the OTCs were extensive and serious, creating the need to consider control options for these chambers and the replicated OTCs studies underway in other Chinese Phragmites marshes(Panjin and Yancheng).

归黄方治疗Ⅲ型前列腺炎精室湿热瘀滞证的临床研究

目的:观察归黄方治疗Ⅲ型前列腺炎精室湿热瘀滞证的有效性与安全性。方法:纳入Ⅲ型前列腺炎精室湿热瘀滞证患者120例,随机分为试验组(归黄方)60例,对照组(盐酸坦索罗辛缓释胶囊)60例。连续服药6周,随访4周。观察治疗前后美国国立卫生研究院慢性前列腺炎临床症状积分指数(NIH-CPSI)、中医症状评分、前列腺按摩液常规,以及血尿常规、肝肾功能、心电图。结果:两组治疗后均可显著降低NIH-CPSI总评分、疼痛评分、排尿评分、生活质量影响评分、中医症状评分、WBC数量(P<0.05),增加卵磷脂小体数量(P<0.05)。试验组在治疗6周结束后,NIH-CPSI评分由(28.34±9.23)分降低为(6.78±3.53)分;对照组在治疗结束后,NIH-CPSI评分由(27.81±8.28)分降低为(14.48±4.27)分。试验组与对照组比较,除治疗第2周时排尿评分与对照组无明显差别以外(P>0.05),第4、6、10周时试验组在降低NIH-CPSI总评分、疼痛评分、排尿评分、生活质量影响评分及中医症状评分方面,均优于对照组(P<0.05)。试验组在减少WBC数目、增加卵磷脂小体数量方面优于对照组(P<0.05)。安全性检查两组治疗后均未见明显异常,治疗过程未见明显不良反应。结论:归黄方治疗Ⅲ型前列腺炎精室湿热瘀滞证安全、有效。

增材制造技术在散热器件研制中的应用与最新进展

5G技术的普及以及高性能算力系统的快速发展,导致电子器件的功率不断增加,因此对散热器件的性能提出更高要求。优化散热器件的结构是提高散热性能的重要途径之一。然而,传统制造工艺在处理复杂结构时存在一定的局限性,限制了对更高性能散热器件的探索。增材制造技术采用逐层累加的方式,可制备出具有复杂内部几何形状的结构,从而制造出更高性能的散热器件。本文对增材制造技术在散热器件领域的研究进展进行了综述。首先,介绍了增材制造技术的常用方法和基础材料;其次,综述了利用增材制造技术研发微流道散热器、热管/均热板、热沉以及其他散热器的最新进展;最后,归纳了散热结构的优化设计方法。本文着眼于利用增材制造技术制备具有优化结构的散热器件,为应对电子器件、航空航天、 5G通讯、移动设备、汽车、相控雷达、柔性穿戴等领域日益增长的散热需求提供了有益的参考。

复合蒸汽通道柔性均热板设计及其传热性能研究

近年来,随着科技的发展与进步,各种柔性电子设备得到普及。成倍增长的功耗导致电子芯片在狭小空间内产生过高的热流密度和工作温度,引发了严重的散热问题。然而,传统的均热板因较大的刚性不适用于柔性电子设备。为解决上述问题,文中基于铝塑膜壳体制造了一种具有复合蒸汽通道结构的厚2.2 mm的柔性均热板,并对其在不同灌液量、不同重力方向、不同弯折角度和弯折次数的稳态传热性能进行了测试。结果表明:该柔性均热板的最佳灌液量为700μL;在7 W的加热功率下,其热导率最高可达1264.9 W/(m·℃),为壳体材料(铝塑膜)本身热导率的4517.6倍,其传热性能良好。

双支点对转轴承腔两相流动及换热特性的数值研究

为探究双支点对转轴承腔两相流动及换热特性,利用耦合的CLSVOF两相流方法开展数值研究,对比高低压轴同转、对转形式下的轴承腔流动及换热特征,重点探讨对转条件下,高低压轴转速及双侧供油流量对轴承腔壁面油气分布特征与换热特性的影响。结果表明:不同转向下轴承腔壁面油膜形成过程类似,滑油在壁面以油滴、油矢、油带形式分布;同转形式下壁面流线旋向相同,对转形式下壁面流线旋向则相反,对转提高了轴承腔壁面剪切力及湍流强度,平均换热系数相对提升了16.47%;对转转速越大或转速比越高时,壁面滑油体积分数增大而油膜厚度降低,油膜流速平均增加72.95%,双侧供油量或供油流量比越大时,壁面滑油体积分数与油膜厚度均上升,油膜流速平均增加31.02%;增加转速与供油流量均可提高壁面热流密度,增大换热系数,采用双支点对转形式布局能够一定程度提高轴承腔换热性能,有利于保障发动机的安全可靠运转。

受限蒸汽腔内气液两相传热特性研究

蒸汽腔是实现电子元件热管理的高效设备之一。随着电子元件的紧凑化发展,蒸汽腔的尺寸受到限制。为探究受限蒸汽腔内气液两相传热特性,本文设计了由蒸发板、冷凝板和方形石英玻璃组成的可视化实验系统。探究了空间高度和加热功率对蒸汽腔传热特性的影响,揭示了不同高度腔体内的沸腾和冷凝相互作用机制。结果发现:空间高度为50 mm的蒸汽腔内气泡行为与池沸腾相似,而10 mm高度蒸汽腔则存在较大差异。在较低加热功率下,10 mm高度蒸汽腔内气泡成核生长后接触冷凝壁面并反弹回落;而在较高加热功率下有气泡膜产生。当输入加热功率为65 W时,10 mm高度受限蒸汽腔的热阻为50 mm高度受限蒸汽腔的3.74倍。该结果表明,较低高度的受限蒸汽腔传热性能恶化,受限蒸汽腔结构有待进一步设计优化,以实现更高要求的电子热管理应用。

环路热管控温精度影响分析与毛细极限预测

环路热管具备无振动、传热能力强、控温精度高、传输距离远等优点,被广泛应用于航天器平台和载荷的热控制领域。控温精度和传热极限作为环路热管的关键性能参数,是环路热管设计和应用领域的研究重点。分析姿态和控温点位置对环路热管控温精度的影响规律。研究发现,重力条件下环路热管姿态会影响储液器内气液分布。当储液器控温点处于饱和蒸气区时,控温精度达到±0.2℃,优于控温点处于纯液相区(±0.6℃)。同时,通过分析毛细芯内气液分布,对环路热管毛细极限预测模型进行修正。通过实验验证,修正后模型可以较好地预测环路热管的毛细极限。

气库容积对低温环路热管的影响

低温环路热管(CLHP)的气库容积通常为其余部件总容积的30~100倍,重量占比最大.为了实现CLHP的轻量化设计,提高卫星载荷资源的利用率,开展气库容积对CLHP启动与稳态工作特性影响的机理研究.建立CLHP的启动模型和稳态失效模型,开展气库容积对冷凝温度、次蒸发温度和传热热阻等关键参数影响的理论与实验验证研究.结果表明:通过提高次蒸发温度设计值,CLHP实验样机可在气库容积仅为其余部件总容积的11倍的情况下顺利启动;当主热负荷较高时,不同气库容积对CLHP传热热阻影响较小;当主储液器容积一定时,可通过减小气库容积增强主储液器的调节能力,使CLHP稳定运行的热负荷范围增加.

《金匮要略》柔痉的再辨析

由于历史背景的原因,仲景论治柔痉多从外感风寒入手,认为柔痉多由外感风寒过汗误治化热而来,瓜蒌桂枝汤为治疗柔痉一病的专方。而后世医家受温病学启发认为柔痉亦可由津液亏虚外感风热而发,瓜蒌桂枝汤非治疗柔痉之良方。通过分析原文与各家注释,旁参《伤寒论》中相关条文对《金匮要略》中柔痉的相关内容再次进行辨析,认为《金匮要略》中所论述的柔痉既可起于风寒误治,亦可源于津液亏虚直接外感风热,但其基本病机均为热盛津伤。而瓜蒌桂枝汤为治疗柔痉的主方,应当根据临床实际辨证用之。

某高射速自动炮多体瞬态传热及应力研究

为提高拦截概率,提高发射速率是高炮武器系统的重点发展方向之一,以期单位时间内发射较多的弹丸至目标区域。然而,高射速发射造成的热效应反过来又会影响火炮自动机中多体关键件的工作效率,最终影响火炮射击安全性。为提高高射速自动机射击速率和射击安全性,解决影响其关键件寿命的热效应问题,需对高射速自动炮自动机多体关键件瞬态传热及应力变化进行研究。以某转膛型高射速自动炮为研究对象,采用瞬态传热学理论,建立了自动机关键件传热模型,采用有限元分析软件ANSYS Workbench进行了多体瞬态传热及应力变化仿真研究,仿真结果表明:随着射击频次的增加,关键件形变、温度急剧增加,最终会引起多体部件运动干涉影响射击安全性。仿真结果能够为自动机的设计、使用和维护保养提供理论支撑。

不同月经时期发病的流感样病例瘥后期表现:一项问卷调查研究

[目的]本研究旨在调查女性流感样病例瘥后期症状与月经周期的相关性。[方法]使用在线问卷调查的方式,针对拥有规律月经并明确病原体的女性流感样病例,采集参与者的基本情况(年龄、身高、体质量)、流感样疾病的发病阶段、病原体以及瘥后期症状,分析瘥后期症状分布及影响瘥后期症状的相关因素。[结果]对514例女性样本分析揭示,流感样疾病瘥后期症状与发病阶段、月经变化以及身体质量指数(BMI)相关。多变量Poisson回归分析表明:相对于非经期及其前后发病的患者,月经期发病的患者中,经期延长的女性不寐易醒、咳嗽咳痰频率增加,而经期不变的女性易疲倦的频率较低。经前期发病时,月经未提前的患者瘥后期更易疲倦咳痰、不寐易醒。相比于正常体质量范围的人群,低体质量患者在瘥后期咳嗽咳痰症状增多。[结论]本研究强调了发病时机以及对应的月经变化与女性流感样病例患者瘥后证的关联,尤其在经期发病时,月经的表现有助于评估流感样病例病情的进展并预测瘥后期特定症状的发生,为个性化医疗干预提供了科学依据。未来研究可进一步探究不同月经周期流感样病例的证型分布、瘥后期各症状的长期转归等,以深化理解,指导临床实践。

地柏益精方治疗男性不育症(肾精亏虚,精室湿热型)的随机平行阳性对照临床研究

目的:评估地柏益精方治疗男性不育症(肾精亏虚,精室湿热型)的有效性和安全性。方法:采用随机、对照的临床研究设计,招募本型男性不育症患者72例。根据随机数字表法将患者分为试验组(36例)和对照组(36例)。对照组口服枸橼酸氯米芬胶囊(每日1次,每次50 mg);试验组口服地柏益精方(每日1剂,早晚饭后30 min口服,每次200 ml)。两组均接受为期12周的治疗。治疗结束后,比较两组患者治疗前后精子浓度、前向运动精子百分率、精子总活率以及精液量。同时,比较治疗前后中医证候总评分、精子DNA碎片指数(DFI)和配偶妊娠情况。结果:试验组脱落3例,对照组脱落4例。两组患者治疗前精液参数比较,无统计学差异(P>0.05),试验组治疗后与治疗前相比,患者精子浓度[(19.42±5.30)×10^(6)/ml vs(10.75±2.41)×10^(6)/ml]、前向运动精子百分率[(27.72±6.62)%vs(20.04±4.10)%]、精子总活率[(49.86±10.68)%vs(33.74±5.58)%]、DFI[(12.33±3.43)%vs(15.06±3.98)%]和中医证候评分[(7.45±1.82)分vs(13.85±1.91)分]均存在明显改善,差异具有统计学意义(P<0.05);精液量[(2.93±1.29)ml vs(3.04±1.31)ml]差异不具有统计学意义(P>0.05)。对照组治疗后与治疗前相比,患者精子浓度[(19.56±5.24)×10^(6)/mlvs(11.31±2.08)×10^(6)/ml]、中医证候评分[(12.81±1.86)分vs(14.06±1.64)分]存在明显差异(P<0.05),而前向运动精子百分率[(21.75±5.93)%vs(20.05±4.67)%]、精子总活率[(34.23±7.15)%vs(32.35±4.09)%]、精液量[(3.19±1.08)ml vs(3.12±1.13)ml]和DFI[(15.11±4.76)%vs(15.51±4.35)%]未见显着性差异(P>0.05)。与对照组相比,试验组治疗后前向运动精子百分率、精子总活率、中医症状评分和DFI的改善情况均优于对照组(P<0.05);试验组精子浓度和精液量和配偶妊娠情况与对照组相比差异不具有统计学意义(P>0.05)。两组患者在治疗期间均未发生严重不良事件。结论:地柏益精方治疗肾精亏虚、精室湿热型男性不育症具有有效性和安全性。