超声波共振与驻波相控运动强化除霜技术及大功率空气源热泵应用

Frosting influences the normal operation of aircraft, wind power generation equipment and heat exchanger equipment and leads to additional energy consumption. In severe cases frosting may lead to machine accidents even disasters. To solve the problems of high energy consumption, low efficiency and heat transfer process affection in heat defrosting method, we propose an ultrasonic vibration defrosting technology. Based on our previous study, which has proved that the ultrasonic defrost technology is feasible, the ultrasonic vibration strengthening defrosting technology will be further explored including the phenomenon that the intermittent ultrasonic vibration defrosting effect is superior than continuous ultrasonic vibration and the standing wave effect of ultrasonic vibration..The study will be focused on high-powered air source heat pumps. From the point of mechanical effect, the relationship between the frost crystal resonance and the ultrasonic intermittent operation high-efficiency defrosting will be examined through theoretical analysis, finite element simulation and experimental test to study the enhanced mechanism of ultrasonic resonance defrosting..In addition, the ultrasonic transmission characteristics in the finned-tube evaporator will be investigated based on the wave theory to reveal the guided wave type and the regularities of wave mode conversion. Based on this, the ultrasonic standing wave phased movement method will be established and the ultrasonic strengthen defrosting by standing wave resonance peak＂moving＂will be realized by using standing wave effect..This study can produce breakthroughs for the theories and applications of ultrasonic defrosting technology. The proposed method in this project can provide theoretical support and technology accumulations for developing high efficient, reliable ASHPs. Furthermore, it can be extended to other defrosting/de-icing fields such as blades of air-planes and blades of wind driven generators.

结霜影响航空、风电、热交换等装备的正常运行，轻则增加能耗，重则引发事故。针对热除霜方法能耗高、效率低、影响换热过程等问题，本课题以超声振动除霜技术为目标展开研究，在前期研究验证了超声除霜的技术可行基础上，根据超声除霜中存在的间歇运行优于连续运行、超声振动呈现驻波效应等现象，探索超声振动强化除霜技术。以大功率空气源热泵作为验证对象，首先通过理论分析、有限元仿真与试验测试，从超声振动的力学作用角度研究霜晶共振与超声间歇运行高效除霜的关系，探索超声波共振强化除霜机理；其次，基于波动理论研究超声在翅管式蒸发器中的传播特性，揭示超声导波类型及导波模态转换规律；在此基础上，利用驻波效应，提出超声驻波相控运动技术，实现驻波振峰行走强化除霜。通过研究，实现超声高效节能除霜理论和应用技术方面的突破，为创建高效节能的空气源热泵等产品提供理论支持和技术储备，同时对飞机、风电等运行过程除霜具有良好的借鉴意义。

结霜影响热泵、冷链等热交换装备的正常运行，轻则增加能耗，重则引发事故。针对热除霜方法能耗高、效率低、影响换热过程等问题，本项目以超声振动除霜技术为目标展开研究，基于前期研究基础，采用理论分析、仿真与试验相结合的方法，主要研究了超声波共振强化除霜机理、超声波在翅管式蒸发器中的传播特性及超声波驻波相控运动强化除霜技术。研究结果：1）超声机械振动产生的高频振动与剪切应力是超声波除霜的主要机理，而共振效应可强化除霜效果。2）翅管式蒸发器结构中传播的超声波以导波为主。在厚度小于波长的板状结构中传播的超声以Lamb波和SH波为主。蒸发器铜管中主要存在导波弯曲模态。具有除霜效应的是板状结构中的Lamb波S0、A0模态及铜管中的前三阶弯曲模态F(1,1)、F(1,2)和F(1,3)。当超声激励频率小于250kHz时，翅管式结构中导波传播的模态转换规律为：传振板Lamb波S0、A0模态→铜管F(1,1)，F(1,2)，F(1,3)模态→结霜翅片S0、A0模态。低频段，Lamb波S0、A0模态面内位移激发的XZ平面剪切应力和SH波激发的YZ平面剪切应力对翅表基础霜层具有剥离作用，而Lamb波A0模态离面位移激发ZZ方向主应力对基础霜层具有破碎作用，是超声除去基础霜层的主要机理。3）为解决大型翅管蒸发器多超声除霜需求和阵列式超声除霜“驻波”效应的问题，项目提出基于阵列式超声间歇错相控制的优化除霜方法。通过间歇错相实现驻波在蒸发器表面的可控运动，可消除蒸发器表面除霜死角，仿真与实验验证了该方法解决除霜“驻波”效应的有效性。4）针对超声除霜效率缺乏准确、有效评价指标的问题，基于蒸发器等效霜厚与机组性能系数（COP）间的热力学关系，提出基于机组COP的超声除霜效率评价方法，实现了超声除霜效率的定量评价，通过翅表霜厚检测验证了该评价方法的有效性和正确性，为超声除霜技术的工程化应用提供了依据。项目的研究成果，为创建高效节能的具有超声波除霜功能的空气源热泵、冷链等产品提供了理论支持和技术储备，同时对风电设备等运行过程除霜具有良好的借鉴意义。