【作者】 苏秀平；

【导师】 陈芝久； 陈江平；

【作者基本信息】 上海交通大学 ， 制冷与低温工程， 2006， 博士

【摘要】 节能降噪是家用制冷器具(冰箱,房间空调器等)永久的追求目标。间冷式冰箱以其自动除霜、大容量、多功能等诸多优点受到了能源发达国家和地区的普遍青睐,但相对于同规格直冷室冰箱来说,能耗高、噪声大的问题始终是制约间冷式冰箱发展的主要原因。因此,有必要对间冷式冰箱不同于直冷式冰箱的节能和降噪问题进行深入的研究。现有间冷式冰箱的开发模式基本以“经验+试验”为主。经验规律的可靠性受多方面因素的影响,有效适用范围常受较大限制。试验研究的结果可靠性好,能真实地反映实际,因而是人们深入了解装置性能不可缺少的手段。但单纯的试验研究投资量大,研究周期长,具有很大的局限性,而且希望通过试验研究获得优化的结果也相当困难。采用建模分析、计算机仿真和数值计算的方法,可克服单纯试验的不足,弥补试验研究的缺陷。间冷式制冷装置中现在存在的许多问题,如能耗过高,噪声过大等问题,均可用计算机仿真和数值计算的方法加以研究。计算机仿真、数值计算和适当的试验研究相结合,可为装置的设计和改进提供迅速而可靠的依据,是提高间冷式装置各项性能,增强其市场竞争力的最有效途径。本文采用理论分析和试验相结合的方法,研究了间冷式冰箱节能降噪的下列几个重要课题:建立了翅片管蒸发器结霜及换热特性试验台,以对翅片管蒸发器进行实验研究。对间冷式冰箱进行了性能试验研究,以验证本文所建理论模型,并对冰箱进行了结构及性能方面的优化试验研究。从质量和能量守恒方程出发,建立了蒸发器管外侧空气换热及流动模型、蒸发器管壁模型、蒸发器管内侧工质的换热及流动模型和蒸发器外侧的霜生长模型,丛而建立了翅片管蒸发器结霜及换热的动态分布参数仿真模型,并对仿真结果进行了针对性的试验验证。基于传热学和热力学基本理论,建立了间冷式冰箱的化霜模型,以寻求间冷式冰箱运行过程中的最优化霜周期,为间冷式冰箱化霜控制提供理论依据。建立了包含箱体及送风风道、风扇和蒸发器在内的间冷式冰箱流场温度场分析模型。以风扇的转动作为整个流场的动力源,蒸发器制冷量以源项的形式引入能量方程,因而不再需要通过大量试验来确定冰箱内部流动及温度边界条件。结合一台间冷式冰箱的具体结构,研究了冰箱的动态运行过程。通过CFD分析,对该冰箱的性能进行了评估,并提供结构优化方案,以提高冰箱制冷性能,降低能耗。通过对辐射换热的研究发现:间冷式冰箱内部的辐射换热不可忽略。建立了间冷式冰箱系统动态仿真模型,该模型包含蒸发器结霜模块,风道-风机模块等。采用CFD方法求解风道阻力曲线,使得理论模型更为实用。对一台间冷式冰箱进行了动态仿真,计算结果与整机性功能试验结果吻合的较好。针对该冰箱,讨论了系统仿真在冰箱性能分析方面的应用。采用声类比模拟的方法,建立了针对间冷式冰箱中由于风扇叶片旋转所引起的气流噪声的CFD模型。对轴流风扇系统的气动噪声进行了预估计算并与噪声测量值进行比较,为寻求间冷式冰箱降噪方案提供依据。最后,作者简要阐述了本文研究工作存在的不足和进一步的研究设想。更多还原

【Abstract】 Energy efficiency and noise reduction are the main target for domestic refrigeration appliance (refrigerator, room air-conditioner, etc) research. In-direct refrigerator is popular in developed counties since its automatic defrosting, high volume, multi-function. Comparing with direct refrigerator, lower energy efficiency and higher noise are main challenge to in-direct refrigerator. So, it is necessary to research the energy saving and noise reducing for in-direct refrigerator.Meanwhile, main development method for in-direct refrigerator are combined the experiential and the experimental method. To experiential principles, the reliability is affected by many factors, and the validity is limited. To experimental method, the results are reliable and it is necessary to find out the essential principles for refrigeration equipments. But the experiments normally mean high cost, long duration. Also, it is difficult to get an optimized result by pure experiments. Therefore, model based computer simulation is a good compensation for experiments.The main issues in in-direct refrigerator field, i.e. low energy efficiency and high noise, could be studied by numerical simulation method. The combination of simulation and experiment is an efficiency method for product development and improvement. In this paper, based-on theoretical and experimental method, researched some issues regarding to in-direct refrigerator as following:An experimental rig for frosting and heat transfer character of fin-tube evaporator was design to study the fin-tube heat exchanger.Experimental study was applied to in-direct refrigerator to validate the theoretical model built in this paper, as while as to optimize the structure and performance of the refrigerator.Based on mass and energy equation, a dynamic and distribution parameter model for frosting and heat transfer of fin-tube evaporator was set up. The model included air-side flow and heat transfer module, tube-wall module, refrigerant side flow and heat transfer module, and frost growing module. The model was validated by special experiment.From fundamental theory of heat transfer and thermodynamics, the defrosting model of in-direct refrigerator was established to look for an optimized defrosting cycle time of operating period, which provided a theoretical evidence for the defrosting control strategy.The analytical model of the flow and thermal field, including the enclosure structure and air-duct, fan and evaporator, was established, where the fan was treated as source power of the flow fields with the cooling capacity of the evaporator introduced as source item in energy equation. From above treatments, it was unnecessary to identify the flow and temperature boundary conditions by large quantities of experiments. The dynamic operating process was analyzed based on a specific in-direct refrigerator. By CFD simulation, the performance of this refrigerator was evaluated and the constructive optimized design was provided to improve the cooling capacity, and at the same time to reduce the energy consumption. A fact was found through the study of the radiating heat transfer that radiating process should not be omitted in an in-direct refrigerator.A system simulation model for in-direct refrigerator was established, including evaporator frosting module and duct-fan module. CFD method was used to calculate resistance curve of the air-duct, which makes the theoretical model more practical. The model was validated in a specific refrigerator, and simulation results agreed well with the testing results. Meanwhile, the application of system simulation used in analyzing refrigerator performance was discussed.A CFD noise model of in-direct refrigerator fan blades rotation was established. The aerodynamic noise of axial fan system was estimated and compared with testing result, which provided evidence of noise reduction. Finally, summary of the open issues in this research and further study topics related to this field in future was given.更多还原