Exploratory Investigation in Shockwave Generation by Flash Evaporation

闪蒸产生冲击波的探索性研究

• 批准号: 0744160
• 负责人: Norbert Mueller
• 金额: $ 4万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0744160&HistoricalAwards=false
• 关键词: Exploratory; Investigation; Shockwave; Generation; Flash

Exploratory Investigation in Shockwave Generation by Flash EvaporationGeneralThe proposed research is an investigation of the generation of shock waves by flash evaporation. Flash evaporation occurs when a liquid is suddenly exposed to a pressure lower than its saturation pressure. Then some of the sensible heat must be transferred into latent heat of vaporization and a fierce and sudden process of vapor bubble formation occurs within the liquid while the temperature of the fluid decreases significantly. There have already been applications for flash evaporation, including water desalination, the depositing of thin layers of material and in vapor sterilization. Still shock wave processes induced by flash evaporation have not been much documented, hindering the exploitation for new technical applications. Extending this scientific knowledgebase will help to overcome this barrier. Although these phenomena can damage industrial equipment; these shock waves have been hypothesized as useful in creating compression. It has been predicted that condensation can follow the pressure rise, leading to a new phase change compression principle also applicable for thermodynamic cycles. The newly invented condensing wave rotor is an example for a technical application. Such novel technology can yield higher energy efficiency for refrigeration cycles, particularly in combination with the natural and benign refrigerant water (R718). Additionally, this knowledge may be applied to other refrigerant cycles, but also to fuel pumps and to pressure recovery devices for liquefied gases and more.To increase understanding flash-induced shock behavior, basic experimental investigations will be conducted to verify and extend an analytical model. To verify and investigate the generation and behavior of flash-driven shock waves in water vapor under vacuum, particularly the relationship between flash evaporation conditions and shock wave strength will be investigated through a controlled experiment. For this, a single-chamber test rig will be constructed in which pressure and temperature changes will be recorded with transducers and an infrared camera. The experiment shall verify and extend an analytical model previously generated by the PI's team. The Intellectual Merit of the Proposed ActivityThe main objective of the experiment is the verification, recording and investigation of flash evaporation induced shock waves under vacuum in water vapor for which there appears to be no accessible scientific documentation yet. Therefore, the results will extend the fundamental knowledgebase and will help to improve and validate the mathematical models which have been used to describe the dynamics of this compressible phase-change flow. Additionally, this experiment shall confirm that flash induced shock waves can generate pressure rises applicable for the condensation of water vapor at higher pressures. The Broader ImpactsThe understanding of the fluid behavior of flash evaporation induced shock wave processes is important to prevent disastrous effects of flash evaporation and for the development of industrial applications. A first technical application can be in the novel condensing wave rotor that uses the basic principles of flash evaporation and shock waves to increase the efficiency of water refrigeration systems that use only water (no chemicals) as refrigerant. The novel concept of a condensing wave rotor may then replace and combine in one dynamic system three subsystems needed in conventional systems: the compressor, the intercooler, and the condenser. This will compact these systems considerable and reduce the resources used for such systems. Application of the principle for other refrigerants is also envisioned as well as for fuel pumps and for pressure recovery devices for liquefied gases. A female graduate student will work on this exploratory one year project, supported by undergraduate students. The information obtained will be presented in both undergraduate and graduate classes as the PI has a tradition in his classes like Refrigeration, Thermodynamics, Heat Transfer and Turbomachinery. Furthermore, the findings are planed to be published in the International Journal of Heat and Mass Transfer and the Annual Review of Fluid Mechanics, and will be presented at the ASME IMECE and ASHRAE Annual Meeting to inspire further applications. The test rig shall also be used for impressive demonstrations to high-school students at the SET day of the MSU Engineering College, where prospective students are invited to visit the laboratories.

闪蒸产生激波的探索性研究一般提出的研究是对闪蒸产生激波的研究。当液体突然暴露在低于饱和压力的压力下时，就会发生闪蒸。这时，一部分显热必须转化为汽化潜热，在液体内部发生剧烈而突然的汽泡形成过程，同时流体温度显著降低。闪蒸技术已经有了应用，包括海水淡化、薄层材料的沉积和蒸汽灭菌。然而，由闪蒸引起的激波过程还没有很多文献记载，这阻碍了新技术应用的开发。扩大这一科学知识库将有助于克服这一障碍。虽然这些现象会损坏工业设备；据推测，这些冲击波有助于产生压缩。据预测，冷凝会随着压力的上升而发生，从而得出一种新的相变压缩原理，同样适用于热力学循环。新发明的冷凝波转子就是技术应用的一个例子。这种新技术可以为制冷循环提供更高的能源效率，特别是与天然和良性制冷剂水（R718）结合使用时。此外，这些知识可以应用于其他制冷剂循环，也可以应用于燃油泵和液化气体的压力回收装置等。为了增加对闪致冲击行为的理解，将进行基础实验研究以验证和扩展分析模型。为了验证和研究真空条件下水蒸气中闪蒸激波的产生和行为，特别是通过对照实验研究闪蒸条件与激波强度之间的关系。为此，将建造一个单室试验台，其中压力和温度变化将用传感器和红外摄像机记录下来。实验应验证和扩展PI团队先前生成的分析模型。本实验的主要目的是验证、记录和研究真空条件下水蒸气中闪蒸引起的激波，目前尚无科学文献对此进行研究。因此，这些结果将扩展基本知识库，并有助于改进和验证用于描述这种可压缩相变流动力学的数学模型。此外，本实验应证实闪光激波能产生适用于高压下水蒸气冷凝的压力升高。更广泛的影响了解闪蒸引起的激波过程的流体行为对于防止闪蒸的灾难性影响和工业应用的发展是重要的。第一个技术应用可能是新型冷凝波转子，它利用闪蒸和冲击波的基本原理来提高仅用水（不含化学品）作为制冷剂的水制冷系统的效率。冷凝波转子的新概念可以取代传统系统中需要的三个子系统：压缩机、中间冷却器和冷凝器，并将它们组合在一个动力系统中。这将大大压缩这些系统，并减少用于这些系统的资源。还设想将该原理应用于其他制冷剂以及燃油泵和液化气体压力回收装置。一名女研究生将在本科生的支持下进行为期一年的探索性项目。所获得的信息将在本科和研究生课程中呈现，因为PI在制冷，热力学，传热和涡轮机械等课程中都有传统。此外，研究结果计划发表在《国际传热与传质杂志》和《流体力学年度评论》上，并将在ASME IMECE和ASHRAE年会上发表，以激发进一步的应用。该测试台还将在密歇根州立大学工程学院的SET日向高中学生进行令人印象深刻的演示，届时未来的学生将被邀请参观实验室。