THE CALCULATING EQUATIONS OF THE THERMOPHYSICAL PARAMETERS OF THE MOIST AIR AT HIGH TEMPERATURE

By using compression factors of real gas and the Vilia equations and considering the variation of the thermophysical parameters of the mois air with its temperature, this paper develops the calculating equations of the thermophysical para leters of the moist air at high temperature ranging from 100℃- 200℃. It is convenient to calculate the thermophysical parameters and the thermophysical processes of the moist air at high temperature.

Energy and Exergy Analysis of Moist Air for Application in Power Plants

In this study an energy and exergy analysis is made of moist air, it is used the psychometrics charts. A Visual Basic program is used to generate psychometrics charts. These charts are used to analyze the air thermodynamic behavior, considering the environmental variations, pressure, temperature and relative humidity. Also, the available energy in the cooling processes at constant enthalpy, humidification at constant temperature and heating with constant relative humidity is analyzed. For example, we obtained that the enthalpy and exergy in a thermodynamic state, with conditions, Patm = 1.013 bar, Tatm = 25oC and Φatm=50%, are h = 50.56 kJ/kga and ε =11.5 kJ/kga;and for Patm= 0.77 bar to the same conditions of Tatm and Φatm, the enthalpy and exergy increases in a 14% and 20%, respectively.

Liquid Phase Evaporation on the Normal Shock Wave in Moist Air Transonic Flows in Nozzles

This paper presents a numerical analysis of the atmospheric air transonic flow through de Laval nozzles. By nature, atmospheric air always contains a certain amount of water vapor. The calculations were made using a Laval nozzle with a high expansion rate and a convergent-divergent(CD) "half-nozzle", referred to as a transonic diffuser, with a much slower expansion rate. The calculations were performed using an in-house CFD code. The computational model made it possible to simulate the formation of the liquid phase due to spontaneous condensation of water vapor contained in moist air. The transonic flow calculations also take account of the presence of a normal shock wave in the nozzle supersonic part to analyze the effect of the liquid phase evaporation.

Effect of Nonequilibrium Condensation of Moist Air on the Boundary Layer in a Supersonic Nozzle

When condensation occurs in supersonic flow fields, the flow is thected by the latent heat released. In the present study, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finitedifference scheme with a second-order fractionabetep for time integration. Baldwin-Lomax model, that is the algebraic model, called the zero equation model was used in the computations. The effects of initial conditions (initial degree of supersaturation and total temperature in the reservoir) on condensing fiow of moist air in a supersonic circular half nozzle were investigated. In this case, the effect of condensation on the boundary layer was also discussed in detail. As a result, the simulated flow fields were compared with experimental data in good agreement, and the velocity and temperature profiles were largely changed by condensation.

Transonic Moist Air Flow around a Circular Arc Blade with Bump

The unsteady phenomena in the transonic flow around airfoils are observed in the flow field of fan, compressorblades and butterfly valves, and this causes often serious problems such as aeroacoustic noise and the vibration.In recent years, the effect of bump wall on the flow field around an airfoil has been investigated experimentallyand as a result, it was observed that the bump wall is effective for the control of shock wave on the airfoil. In thetransonic or supersonic flow field, a rapid expansion of moist air or steam gives rise to non-equilibrium condensation.In the present study, the effect of non-equilibrium condensation of moist air on the self-excited shock waveoscillation around a circular arc blade with or without a bump on the blade was investigated numerically. The resuitsshowed that the non-equilibrium condensation significantly reduced the flow field unsteadiness such as rootmean of pressure oscillation and frequency compared to the case without the non-equilibrium condensation.

Effect of Nonequilibrium condensation of Moist Air on Transonic Flow Fields

When condensation occurs in a supersonic flow field, the flow is affected by the latent heat released. In the present study, a condensing flow was produced by an expansion of moist air in nozzle with circular bump models and shock waves occurred in the supersonic parts of the flow fields. The experimental investigations were carried out to show the effects of initial conditions in the reservoir and nozzle geometries on the shock wave characteristics and the turbulences in the flow fields. Furthermore, in order to clarify the effect of condensation on the flow fields with shock waves, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finitedifference scheme with a second order fractional step for time integration. As a result the effect of condensation on the aspect of flow field has been clarified.

2021年11月7—9日辽宁省极端雨雪天气分析

选用常规气象观测资料、人工加密观测资料和NCEP/NCAR格点资料,对2021年11月7—9日辽宁省极端雨雪天气进行诊断分析。结果表明:东北冷涡和地面气旋为此次极端雨雪天气的主要影响系统,对流层中低层辐合、高层辐散以及强的冷暖气流交汇,是产生极端雨雪天气的主要原因;高低空急流耦合和高空辐散抽吸作用,配合东北冷涡动力抬升作用,暖湿低空急流沿冷垫爬升,进一步加强了上升运动。暖湿急流为此次极端雨雪天气提供了充沛的水汽条件,暖湿急流的增强对应水汽辐合作用增强,配合低层冷垫和东北冷涡的动力抬升作用,对降雪有明显增幅作用;地面辐合线沿地形分布,触发了此次极端强降雪天气。地形阻挡导致地面冷空气堆积形成冷垫,是极端降雪天气发生的重要原因。温度层结差异是鞍山、岫岩雨雪相态差异的主要原因。具有冻结层特征的低层冷垫,为鞍山极端暴雪提供了有利的温度层结条件;融化层厚度和地面温度是岫岩出现冻雨的关键因素。

Moist Potential Vorticity Vector for Diagnosis of Heavy Rainfall Events in Tanzania

In this paper, we modify the convective vorticity vector (CVV) defined as a cross product of absolute vorticity and gradient of equivalent potential temperature to moist potential vorticity vector (MPVV) defined as a cross product of absolute vorticity () and the gradient of the moist-air entropy potential temperature (). The patterns of (MPVV) are compared with the patterns of heavy rainfall events that occurred over different regions in Tanzania on 20th to 22nd December, 2011 and on 5th to 8th May, 2015. Moreover, the article aimed at assessing the relative contributions of the magnitude, horizontal and vertical components of (MPVV) detecting on the observed patterns of rainfall events. Dynamic and thermodynamic variables: wind speed, temperature, atmospheric pressure and relative humidity from numerical output generated by the Weather Research and Forecasting (WRF) model running at Tanzania Meteorological Agency (TMA) were used to compute MPVV. It is found that MPVV provide accurate tracking of locations received heavy rainfall, suggesting its potential use as a dynamic tracer for heavy rainfall events in Tanzania. Finally it is found that the first and second components of MPVV contribute almost equally in tracing locations received heavy rainfall events. The magnitude of MPVV described the locations received heavy rainfall events better than the components.

波纹板对湿空气冷凝传热特性影响的实验研究

为推进节能减排,进行烟气“消白”,减少水蒸气温室效应,本文基于不同换热板结构的大通道板式换热器,通过搭建回转风洞冷凝换热实验台,研究低温湿空气凝结,测定湿空气的凝结水量和进出口物性参数,获得不同波纹板结构的平均传热系数,并通过改变湿空气的工况参数,研究分析湿空气冷凝换热过程的影响因素。研究结果表明:在85~140℃范围内,湿空气的传热系数随入口温度的增加而减小;在相同入口温度下,湿空气含湿量越低,Re对冷凝传热系数影响越小。随着风速增加,湿空气凝结量逐渐减少;随着Re增加,波纹板和锯齿板的冷凝传热系数均随之提高。在相同Re数下,波纹板的传热系数大于锯齿板。采用波纹板烟气换热器,可更有效凝结回收烟气中饱和水蒸气。

玻纤烘干炉排湿风余热利用应用研究

研究了隧道式烘干炉的工作原理和特点,以及烘干余热回收改进工艺流程,提出使用换热器对高温排湿风的热回收再利用方案,解决了排湿热风直接外排造成的能源浪费,降低成本。结果显示采用换热回收余热排湿风,取得明显的节能和经济效益,为烘干炉节能和提高烘干效率的设计提供一些改进意见,同时减少了有机物、颗粒物等污染直接外排,改善大气质量。

广西一次大暴雨过程的不稳定性分析

利用常规地面、高空观测资料和ERA5再分析资料,对2020年7月19—20日广西一次大暴雨的不稳定性进行了诊断分析。结果表明:(1)强降雨第1时段为西南急流中的暖区暴雨,桂北暴雨点分散,具有突发性和局地性;强降雨第2时段为锋面降雨,桂中暴雨落区集中且呈带状分布,强降雨持续时间长且雨强大,其前期有弱冷空气南下,强降雨在锋线上,其后期有冷暖空气对峙,强降雨位于锋后。(2)强降雨第1时段,桂北低层为对流不稳定层结,低空西南急流的暖湿输送和中层干冷空气的卷入使对流不稳定增强并维持。(3)强降雨第2时段前期,桂中低层为强对流不稳定层结,浅薄冷空气侵入,抬升暖湿气流,触发高对流有效能量释放;在后期,对流不稳性减弱,边界层南风急流与降水使垂直风切变与斜压性增强,对称不稳定性显著增大,是锋后带状雨带形成和强降雨持续的主导因素。

MoS_2 基共溅射薄膜摩擦学性能的研究

在球－盘滑动摩擦试验机上考察了法向载荷、盘转速、基体材料和环境气压及潮湿贮存时间对ＭｏＳ２基共溅射薄膜的摩擦因数和耐磨寿命的影响．结果表明：在给定的试验条件下，法向载荷增大时薄膜的稳态摩擦因数有所减小，而耐磨寿命明显缩短；几种不同金属基体对其表面薄膜摩擦因数的影响基本一致，但对耐磨寿命的影响差别较大；盘转速加快使摩擦因数和摩擦因数波动幅值都减小；环境气压降低（特别在真空中）时薄膜的摩擦因数降低，摩擦稳定性提高，耐磨寿命延长；在潮湿大气中贮存后，薄膜的摩擦因数和耐磨寿命均无明显变化．

湿空气热湿转换过程的热学原理

讨论了湿空气处理过程中的传热、传质和相变过程,针对实际工程中的一些困惑,提出了基于(火积)的新的热学分析方法。用这一方法,可以得到空气处理过程中各种(火积)损失的构成,清晰地看到空气等焓喷水加湿过程与沿饱和线加热加湿或冷却除湿过程的巨大差异,找到各种工程条件下最好的湿空气处理途径。介绍了基于(火积)的湿空气热湿转换过程分析方法,对一些典型工程问题进行了深入分析。

二硫化钼溅射膜在潮湿空气中贮存后润滑性能的退化与失效机理

为了探讨ＭｏＳ＿２溅射膜在潮湿空气中贮存期间所发生的化学变化这个长期争议未了的问题，以空间机械常用的９Ｃｒ１８轴承钢为底材，利用ｒｆ溅射法沉积ＭｏＳ＿２薄膜，并且利用Ｘ射线光电子能谱仪、俄歇电子能谱仪和Ｘ射线衍射仪等对这种薄膜在室温（１１－１５℃）下于相对湿度为１００％的潮湿空气中贮存不同时间后的组成、元素价态和晶体结构进行了分析，考察了它在潮湿贮存过程中所发生的化学变化及其润滑性能的退化与失效机理，检测发现，ＭｏＳ＿２溅射膜经潮湿贮存一天就有少量的Ｍｏ￣（４＋）氧化生成了Ｍｏ￣（６＋），在潮湿贮存５天时又发现有少量的ＳＯ生成，随着贮存时间的延长，不仅膜中Ｍｏ￣（６＋）／Ｍｏ￣（４＋）之比在不断地增大，表明有更多的Ｍｏ￣（４＋）发生了深度氧化，而且Ｓ￣（２－）发生氧化生成的ＳＯ之含量也越来越大。由此可见，ＭｏＳ＿２溅射膜在室温下于潮湿空气中贮存期间与氧和水发生了化学反应，生成物是ＭｏＯ＿３和Ｈ＿２ＳＯ＿４．Ｈ＿２ＳＯ＿４的生成致使薄膜表面的凝聚水呈现出ｐＨ值为１．５－２．０的强酸性，从而造成了金属底材的腐蚀。ＭｏＳ＿２的深度氧化和金属底材的腐蚀是导致ＭｏＳ＿２溅射膜在潮湿环境中润滑性能退化与失效的主要原因。

湿空气在泡沫金属内析湿过程的换热与压降特性影响因素分析

实验研究了湿空气在泡沫金属内流动析湿过程的换热和压降特性,分析了不同因素的影响规律。研究结果表明:随着入口空气相对湿度的增大,凝结水增多,使泡沫金属的换热量和压降均增大;当入口相对湿度从50%增大到90%时,换热量和压降最大增加了67%和62%;随着入口空气温度的升高,泡沫金属换热量和压降增大;随着冷却水温度的升高,泡沫金属的换热量和压降均下降;随着孔密度的增大,压降增大,但由于受到凝结水影响,总换热量会先减小后略有增大;泡沫金属的迎风高度越大,总换热量和压降越大。

跨音速湿空气非平衡凝结流动的数值研究

跨音速流动条件下湿空气中的水蒸气由于快速膨胀而发生非平衡凝结,凝结潜热对跨音速气流进行加热,会显著改变气流的流动特性。通过对商用计算流体动力学软件FLUENT进行二次开发,建立了湿空气非平衡凝结流动的数值求解方法。该方法可用于二维或三维、粘性或无粘、内流或外流的求解中。采用该方法分别对缩放喷管、透平叶栅以及绕CA-0.1圆弧翼型的湿空气非平衡凝结流动进行了数值分析。计算结果表明:湿空气凝结引起缩放喷管中的凝结激波、导致叶栅流动中总压降低;对于翼型周围的流动,在相对湿度分别为50%、57.1%、64.1%时,依次计算得到了单激波、λ激波、双激波。

非静力平衡条件下的垂直坐标变换及湿空气动力学方程组

为了解决目前湿空气动力学中一些悬而未决的问题，拓宽物理量垂直坐标系的应用范围，本文讨论了非静力平衡条件下的垂直坐标转换，给出了不同坐标系的转换公式和动力学方程组，最后运用它们建立了湿空气动力学方程组。

湿空气相对湿度的一种计算方法

利用工程热力学的基本知识推导了计算式 ,并与传统的计算方法进行了比较。新计算式形式简单 ,物理意义明确 ,计算较准确。

高温高压下湿空气的焓和熵计算

本文以湿空气透平和压缩空气储能系统中的工质-湿空气为研究对象,运用所提出的一个适合计算高温高压湿空气热力学性质的对应态维里方程,对湿空气的偏差焓和偏差熵进行了计算。在湿度0≤W≤1kg/kg(A),温度小于573．15K,压力小于5 MPa时,与ASHRAE用的多项式维里方程计算得到的偏差焓和偏差熵进行了比较,误差很小。用这个对应态维里方程外推计算了温度和压力分别达到600 K和15 MPa的湿空气焓和熵。计算结果表明对湿空气而言压力和湿度越大,偏差焓和偏差熵越大;温度越高,偏差焓和偏差熵越小。

热源塔热泵系统相变潜热的应用研究

空气源热泵冬季制热的热源是室外湿空气,室外湿空气由干空气和水蒸汽两部分组成,因此湿空气流经室外换热器表面的热交换过程可以分为两部分来研究,一部分是干空气的放热降温过程,热交换前后都是气态;另一部分是水蒸汽放热降温过程,随着换热器表面温度的不同,水蒸汽降温放热过程中往往伴随着相变发生。而传统的空气源热泵并没有充分地利用后者的相变潜热,且一般认为凝结水珠或水膜附着在换热器表面,影响换热效果,也减小了肋片间距,增加了空气流通阻力,减小了空气流通量,因此以往的空气源热泵设计一般希望室外侧换热器偏向于干工况运行。但对于长江以南冬季低温高湿地区,想维持这一工况运行有一定的难度。针对此区域冬季这一问题,以及推迟室外侧翅片表面结霜时间为目的,开发出了一套名为热源塔热泵的新型热泵系统。本文选择此区域中的几座典型城市(重庆、长沙、南昌、南京和杭州),根据各自相应的典型气象年数据,在冬季工况,通过对热源塔内管翅式换热器在含湿工况下的热工计算,分析将湿空气中水蒸气的相变潜热用于空调方式采暖的热源是否有意义,以及针对其开发出的热源塔热泵系统,评价其是否有一定的经济效益和环境效益。