多尘环境下液压系统用冷凝器及螺旋旋风分离器特性研究

发布时间：2018-06-23 07:04

本文选题：冷凝器 + 螺旋旋风分离器　；参考：《武汉理工大学》2012年硕士论文

【摘要】：冷却器作为一种重要的液压辅件,在液压系统正常工作过程中具有重要作用。由于风冷式冷却器与冷媒式冷却器相比,其冷却效果差,无法彻底解决液压系统油温过高的问题。因此,有必要对适应于工程机械的冷媒式冷却器及其相关组成部件进行研究。本文所研究的冷凝器及螺旋旋风分离器是为在多尘环境下工作的工程机械液压系统所用冷媒式冷却器的研发打下基础。因此,分析粉尘在冷凝器换热表面的沉积机理,采用合理的除尘方式降低气流中的含尘量对冷媒式冷却器的正常工作具有重要意义。本文以某一应用对象的液压系统为例,根据计算所得散热功率对翅片管冷凝器的结构进行了设计计算。结合港口的大气环境,分析了港口环境对冷凝器换热效果所产生的影响。通过分析对比,本文选择螺旋旋风分离器作为多尘环境下冷媒式冷却器的除尘装置,并利用计算流体力学(CFD)分析方法,对分离器进行了数值模拟仿真。选择基于各向异性的RSM模型对螺旋旋风分离器内的三维强旋流动进行了模拟,通过仿真得出了分离器内的速度特性、压力特性及湍流特性,从而揭示了螺旋旋风分离器内的流动状态和能量损失。采用DPM模型对分离器内的气固两相流动进行了模拟,得出了分离器的分级效率,并利用相间耦合的随机轨道模型对颗粒的轨迹进行了跟踪。在改变操作参数及结构参数的基础上,分析了不同风速、螺旋圈数及锥体高度时的分离特性。为分离器的结构优化提供了依据。利用计算得出的翅片管冷凝器结构参数,建立了翅片管的传热模型。通过数值模拟分析了翅片的对流耦合换热,并得出了翅片换热性能与风速的对应关系。本文对污垢的类别进行了阐述,建立了颗粒污垢的沉积模型,揭示了粉尘颗粒在换热表面的沉积机理,并综合分析了影响粉尘沉积的主要因素。此外,通过数值模拟得出了在不同污垢厚度下翅片管冷凝器的换热特性。结果表明,污垢的增加将导致迎面风速降低,流动阻力增加。与洁净换热表面相比,当污垢厚度达到0.25mm时,翅片管的换热量下降了16%。
[Abstract]:As an important hydraulic accessory, cooler plays an important role in the normal working process of hydraulic system. Because the cooling effect of air-cooled cooler is worse than that of refrigerant cooler, the problem of excessive oil temperature in hydraulic system can not be solved thoroughly. Therefore, it is necessary to study the refrigerant cooler and its components suitable for construction machinery. The condenser and spiral cyclone separator studied in this paper are the foundation for the research and development of refrigerant cooler used in hydraulic system of construction machinery working in multi-dust environment. Therefore, it is of great significance to analyze the deposition mechanism of dust on the heat transfer surface of condenser and to reduce the dust content in air flow by using reasonable dust removal method. In this paper, the structure of finned tube condenser is designed and calculated according to the calculated heat dissipation power, taking the hydraulic system of a certain application object as an example. Combined with the atmospheric environment of the port, the effect of port environment on the heat transfer effect of condenser is analyzed. Through the analysis and comparison, the spiral cyclone separator is selected as the dust removing device of the coolant cooler in multi-dust environment, and the numerical simulation of the separator is carried out by using the computational fluid dynamics (CFD) analysis method. The anisotropic RSM model is selected to simulate the three-dimensional strong swirl flow in the spiral cyclone separator. The velocity characteristics, pressure characteristics and turbulence characteristics in the cyclone separator are obtained by simulation. Thus, the flow state and energy loss in the spiral cyclone separator are revealed. A DPM model is used to simulate the gas-solid two-phase flow in the separator, and the classification efficiency of the separator is obtained. On the basis of changing the operating parameters and structural parameters, the separation characteristics of different wind speeds, the number of spiral cycles and the height of the cone are analyzed. It provides the basis for the structure optimization of the separator. The heat transfer model of finned tube was established by using the calculated structural parameters of finned tube condenser. The convection coupling heat transfer of the fin is analyzed by numerical simulation, and the corresponding relationship between the heat transfer performance and the wind speed of the fin is obtained. In this paper, the types of fouling are described, the deposition model of particulate fouling is established, the deposition mechanism of dust particles on heat transfer surface is revealed, and the main factors affecting dust deposition are comprehensively analyzed. In addition, the heat transfer characteristics of finned tube condenser with different fouling thickness are obtained by numerical simulation. The results show that the increase of fouling will result in the decrease of wind speed and the increase of flow resistance. Compared with the clean heat transfer surface, when the fouling thickness reaches 0.25mm, the heat transfer of the finned tube decreases by 16.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH137.8

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