蒸发器动态参数数学模型的建立与理论计算

用分布参数的方法，建立了蒸发器动态参数模型。提出了使模型方程封闭可解的界面关系方程及求解该动态参数数学模型所用偏微分方程的离散方法。用此数学模型对空调器中的蒸发器的空调工况下，进行了稳工况模型计算，得出了冷剂侧（包括两相流各主要参数，空隙率，滑动比等）、管壁温度及空气侧各参数沿管长及蒸发器空间结构的变化关系。为系统的动态参数模型的建立和计算，产品质量验证，优化产品结构以及充灌量的准确计算打下基础。     

冷凝器动态参数数学模型的建立与理论计算

用分布参数的方法，建立了冷凝器动态参数数学。建模时，考虑到当冷剂流还 同时冷剂侧可能出现不同的流型，建立了针对不同流型的动态方程时，提出了使模型方程封闭可解 面关系议程。用此数学模型对空调器中的冷凝器在空调工况下，进行了稳态工况下的模型计算。计算得出了冷剂侧（包括两相流各主要参数，空隙率、滑动比等），管壁及空气温度等参数沿管长的变化关系。为系统的动态参数模型的建立和计算、优化产品结构，充注量的准确     

汽车空调系统蒸发器冷凝器优化计算

运用制冷系统热动力学的观点和系统参数动态分布相互关联的方法建立汽车空调系统动态仿真，利用优化计算方法结合系统动态仿真技术，对汽车空调系统蒸发器和冷凝器分别进行了单目标和多目标优化计算。     

岩石爆破孔壁动态参数的理论探讨

岩石爆破工程中,孔壁近区动态参数是研究岩石与炸药能量关系的重要内容.孔壁爆炸载荷作用下的动态参数分析是爆破模拟实验方案设计和仪器选择的依据.本文通过岩石爆炸冲击波力学模型的建立与计算,分析了孔壁动态参量.     

分群结构对IHNI-1堆动态参数计算结果的影响研究

基于WIMS和CITATION程序的计算结果,编制了动态参数计算程序CKPWC(calculating kinetic parameters based on WIMS and CITATION),对医院中子照射器Ⅰ型堆(in-hospital neutron irradiator mark 1 reactor,IHNI-1)的动态参数计算进行了研究.首先使用WIMS计算出均匀化栅元截面以及69群通量,再使用CITATION进行四群扩散计算,最后编制动态参数计算程序,计算了IHNI-1动态参数(缓发中子有效份βeff和中子代时间Λ).经过比较研究发现,分群结构对动态参数的计算结果有很大的影响.给出了计算IHNI-1缓发中子份额和中子代时间的最佳四群分群结构.使用文章中的最佳分群结构思想对西安脉冲堆动态参数进行了验证计算,计算结果与设计值符合一致,说明给出的IHNI-1动态参数计算结果具有一定的可信性.     

小振幅谐波位移激励下橡胶减振元件动态特性计算方法的研究

对基于超弹性-粘弹性模型计算橡胶隔振器动态特性的方法进行了研究.阐述了频域粘弹性理论及材料粘弹性参数的获取方法.使用简单剪切动态实验获得了材料的粘弹性参数,结合原有的超弹性模型参数,建立橡胶的超弹性-粘弹性模型,并将该模型应用于简单剪切试件的动态特性计算,计算与实验的对比结果表明:经过静态误差系数修正后的简单剪切试件动态特性与实验值误差较小,且不受超弹性模型的影响.以一悬架橡胶衬套为例,针对不同衬套的缩径量,对橡胶衬套的静、动态特性进行了计算和比较.文中所述的方法将有助于橡胶减振产品的动态特性预测.     

基于Novozhilov理论薄壁弯箱位移参数的动态Bayes估计

基于Novozhilov理论推导了薄壁弯箱结构的有限曲条控制方程,并首次建立了薄壁弯箱位移参数的动态Bayes误差函数,推导了参数的动态Bayes均值和方差表达式,提出步长的一维自动搜索方案后,并结合共轭梯度法推导了薄壁弯箱位移参数的动态Bayes估计公式,同时给出了具体计算步骤。通过算例分析,总结了薄壁弯箱位移参数先验信息准确性判定方法及位移参数动态Bayes估计的其它重要结论。     

磁感应式磁力传动器及其性能实验研究

对真空机器人用磁感应式磁力传动器进行了建模,对其磁路和机械本体部分进行了设计.根据结构尺寸要求和已有各参数间的影响关系,确定磁路的关键参数.利用集总参数法建立转矩计算模型,将得到的关键参数代入其中进行计算.搭建动态性能测试平台,对其动态转矩特性进行测试,将结果与理论设计值比较,得到本磁力传动器的动态性能特点:低频涡流损...     

基于数值-解析方法测量静压条件下阻尼材料动态力学参数

建立了一种测量静压条件下阻尼材料动态力学参数的数值-解析方法。首先,分别制作两种空腔半径不同的圆柱空腔覆盖层样品,测量两种样品在静压力下的复反射系数。其次,采用有限元法仿真静压力下的空腔结构变形,在此基础上同样采用有限元法计算复反射系数。以实测复反射系数和计算复反射系数建立二元非线性方程组,利用牛顿迭代法求解方程组可获得复弹性模量和复泊松比等黏弹性动态力学参数。对聚氨酯材料制作的样品进行了复反射系数测量,分析了静压力对聚氨酯材料动态力学参数的影响规律。最后,测量了某不同结构吸声覆盖层静压下的反射系数,并与采用实测材料参数计算的反射系数进行了比较,验证了该方法的正确性。     

一种闪光动态参数校准方法

建立了闪光测量理论模型,提出了一种利用亮度阶跃信号校准闪光动态参数的方法,分析了闪光持续时间、动态亮度和闪光强度测量误差的来源,阐述了通过静态亮度和时间参数实现闪光动态参数量值溯源的方法。利用LED光源发出的亮度阶跃信号测定了闪光测量系统的阶跃响应,分别计算了闪光参数的各误差分量,推导了测量不确定度计算公式,测量了氙灯闪光参数并给出了测量不确定度。结果表明该方法可实现闪光动态参数的计量校准和量值溯源。     

Effect of refrigerant flow direction and throttle opening in RAC unit using micro-channel evaporator

Experimental comparisons are made on the performance of a room air conditioner using micro-channel evaporator with the refrigerant flowing in the Upward Flow mode (UF mode, meaning refrigerant flowing upward from the bottom) and Downward Flow mode (DF mode, meaning refrigerant flowing downward from the top). Test results show that UF mode develops a superior refrigerant distribution in the micro-channels to what DF mode does. This is then illustrated by the infrared thermographs at the nominal operating condition. Subsequently, the effect of the width of throttle opening on the sample unit performance is investigated experimentally in the micro-channel evaporator adopting the UF mode. Measurement and calculation results of pressure difference between evaporator inlet and outlet, mean temperature of the evaporator surface, cooling capacity, input power and EER show that the tested unit operates with the best performance with the refrigerant pressure of 993.61 kPa at the inlet of micro-channel evaporator. Infrared thermographs of the working evaporator verify this conclusion.     

Heat transfer and pressure drop in a plate-type evaporator

A plate-type evaporator, working with natural refrigerant circulation, has been investigated both experimentally and theoretically. Motivated by the phase-out of ozone-depleting substances, HCFC22 was compared to HFC134a and two zeotropic refrigerant mixtures. The effect of different separator liquid levels, i.e. refrigerant flows, and its influence on heat transfer was also studied. The investigated plate-type evaporator consists of thirteen vertical flow channels and its size is 3.0 m × 0.5 m. The heat source for the evaporator is a falling water film on the outside of the plate. Experimental studies have been carried out using a test facility that enabled detailed measurements of heat transfer and pressure drop. Experiments were compared to results from a calculation method that simultaneously calculates heat transfer and pressure drop in a variable number of steps along the evaporator. The calculation method is based on a pressure drop correlation proposed by the VDI-Wärmeatlas and a heat transfer correlation for vertical tubes proposed by Steiner and Taborek. For different evaporator duties, heat transfer was over predicted by 12% for pure fluids by 15% for mixtures. Calculated pressure drops were well within ±5% of the measured values. Changes in heat transfer due to different flows were closely predicted by the proposed calculation method.     

家用热泵空调的系统模拟和实验研究

本文通过对家用热泵型空调的运行分析,针对热泵型空调自身特点,主要考虑制冷剂充灌量和蒸发器结霜对系统性能的影响,并建立系统模型。进行了模拟计算,并对蒸发器结霜做了动态计算,分析了蒸发器结霜和制冷制充灌量对系统性能的影响。计算结果与实验结果较吻合。     

Impact of refrigerant–oil solubility on an evaporator performances working with R-407C

We propose in this study a simplified model of enthalpy calculation for a refrigerant–oil mixture, as well as a new presentation of the pressure–enthalpy–vapour quality diagram which is applied to refrigerant–oil mixtures with different oil circulating mass fractions. This presentation allows the calculation of the enthalpy change through an evaporator, with and without taking into account the effect of oil, and the prediction of the non evaporated quantity of refrigerant at the compressor suction. The results of the model for two pairs of R407C/POE oil of different solubilities show that under the same working conditions, the solubility of the refrigerant in oil can have a considerable effect on the evaporator performances. Indeed, for two oils presenting the same viscosity grade, the evaporator performances decrease when the refrigerant–oil solubility increases.     

重力供液蒸发器的实验研究

采用R404A作为制冷剂对重力供液蒸发器在低温工况下的特性进行实验研究,建立重力供液蒸发器的传热模型,搭建重力供液蒸发器的实验装置,用热平衡法测试重力供液蒸发器在不同蒸发器供液高度下的运行特性.研究表明:供液压头在h1=1200mm时比供液压头在h1=800mm、h1=1000mm时的传热温差明显下降,且随着室内温度的下降,传热温差随之变小;在同一供液高度下,重力供液蒸发器的循环倍率n随蒸发温度的降低而增大,而在不同供液高度下,循环倍率n随供液高度的升高而增大;重力供液蒸发器在供液高度h_1=1000mm时的制冷量明显高于h_1=800mm时的制冷量,其最大增幅为16.9%;而h_1=1200mm时其制冷量与h_1=1000mm很接近,甚至会有所下降;与h1=800mm相比,h_1=1000mm时重力供液制冷系统COP大幅度增加,最大增幅为17%,h_1=1200mm时系统COP介于前两者之间,重力供液制冷系统存在最佳的蒸发器供液高度.     

Quick and empirical correlations for refrigerant pressure drop in mobile air conditioning system evaporators

In heat exchanger design and simulation, a precise refrigerant pressure drop prediction is difficult because of limited correlation's accuracy. In the present paper, several quick and accurate empirical correlations for refrigerant pressure drop of the typical evaporators (laminated plate evaporator and minichannel parallel flow (MCPF) evaporator) used in mobile air conditioning (MAC) system were proposed. A factor which was related with the refrigerant mass flow rate, thermodynamic properties and refrigerant status was introduced. The types of evaporator and refrigerant were considered in the correlations which were available under typical MAC evaporator application conditions. The analysis results showed the refrigerant pressure drops were implied in a linear relationship with the proposed factor. The predicted data agreed with the experimental data very well. For laminated palate evaporators, the average deviations were 1.8% and 0.7% for R134a and R1234yf, respectively. For MCPF evaporator, the average deviations were 4.5% and 0.6% for R134a and R1234yf, respectively.     

Effects of synthetic oil in a compression refrigeration system using R410A. Part II: quality of heat transfer and pressure losses within the heat exchangers

The consequences of the oil rejected by the compressor of a vapour-compression refrigeration system on the operation of the evaporator and condenser are analysed. The modelled prototype uses the mixture of HFC R410A and a synthetic polyolester (POE) oil. The rise of the amount of lubricant circulating in the system leads to a progressive change in the behaviour of the mixture of refrigerant and oil that, for the higher oil mass fraction, evolves like a zeotropic mixture. One also observes that the presence of lubricant is generally associated with a fall of the performances of the heat exchangers, except however in the evaporator where an optimum is observed when the quantity of oil is equal to 0.1% of the total mass of the mixture. Some conclusions are drawn about the choice of correlations for the calculation of the refrigerant side heat transfer coefficient in a plate evaporator.     

干式蒸发器制冷剂分配模拟分析与优化

换热管制冷剂分配不均是制约干式蒸发器性能的主要因素。为改善这一问题,本文提出了增设分液管和孔板两种优化方案,并利用CFD模拟和传热计算分析优化后各换热管分液均匀性、压降水平以及蒸发器换热性能的变化规律。结果表明：最优分液管方案及最优孔板方案混合相的均匀性相比样本分别提高了56.60%和60.80%,虽然带来了更大的压力损失,蒸发器换热量仍然可以提高19.69%和23.83%。     

客车空调平行流蒸发器研制

对用于客车的顶部安装的空调中使用的平行流蒸发器进行了研究设计和实验验证。通过建立仿真模型模拟平行流蒸发器的换热能力,调整翅片参数优化结果,并制作了两组样件,对冷凝水、分液等问题进行实验验证和对比。实验结果表明,优化参数的百叶窗翅片在实验中几乎未见冷凝水沉积,同时分液的流路数为4分路的分液均匀性优于8分路,换热效果比8分路高11.2%。新设计的百叶窗翅片平行流蒸发器基本解决了冷凝水排除和两相流分液两大研究难点,体积较原来减少了57.6%,重量减轻了38%,充注量降低了10.5%,换热能力达到行业要求,从而达到取代旧式翅片管式蒸发器的目的。     

以R407C为工质的翅片式蒸发器结霜过程模拟

翅片式蒸发器的结霜特性对于空气热源热泵的冬季运行十分关键。随着 对HCFCs替代的展开,一些非共沸制冷剂被建议为替代品。同现在使用的纯工质相比,这些非共沸制冷剂的温度滑移使和沿流动方向制冷剂的温度分布更加不均匀。在本文中,作者建立了翅片式蒸发器的分布参数模型,用以模拟结霜过程。传热与流动被认为是准稳态的。文中探讨了数值算法,并以某蒸发器为例进行了模拟。计算表明,结霜过程中空气量的改变明显,整个结霜过程存在一转折点,经过这点后流量急剧下降。R407C在蒸发过程中的温度滑移对霜层在蒸发器上的分布有重要影响。