Effect of Heat Flux on Bubble Coalescence Phenomena and Sound Signatures During Pool Boiling
| Autor: | Akshat Negi, Aniket M. Rishi, Satish G. Kandlikar |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
geography
Materials science geography.geographical_feature_category Critical heat flux Mechanical Engineering 02 engineering and technology Mechanics 010501 environmental sciences 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Heat flux Mechanics of Materials Boiling Heat transfer General Materials Science Bubble coalescence 0210 nano-technology Sound wave Sound (geography) Nucleate boiling 0105 earth and related environmental sciences |
| Zdroj: | ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels. |
| Popis: | Boiling heat transfer is extensively used in various industrial applications to efficiently dissipate a large amount of heat by maintaining low surface to fluid temperature differences. The maximum heat flux dissipated during boiling is limited by the critical heat flux (CHF). Difficulties in visualizing the boiling process and monitoring surface temperature make it difficult to identify the impending CHF condition. As a result, larger factors of safety are employed, and the equipment is operated at considerably lower heat fluxes. This study focuses on identifying acoustic signatures of different nucleate boiling regimes. The bubble nucleation and coalescence along with bubble collapse lead to variation in acoustic emission patterns during boiling. In this work, acoustic signatures representative of the impending CHF condition are identified during pool boiling of water over plain and enhanced copper substrates. It was observed that sound was dominant in two frequency regions (400–500 Hz dominant throughout the nucleate boiling, and 100–200 Hz dominant at heat fluxes > 100 W/cm2). However, just before CHF, a sudden drop in amplitude was observed in the high frequency region (400–500 Hz), while the amplitude in low frequency region (100–200 Hz) continued to rise. This combination of the amplitude trend has potential to predict the approaching CHF condition. This is the first study that correlates high-speed images with the acoustic trends at different stages of nucleate boiling and compares experimental frequency with Minnaert frequency for coalescing bubbles. |
| Databáze: | OpenAIRE |
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