Study on the high-performance evaporator for enhanced gasification via microbubble clusters

Enhancing the vaporization efficiency of evaporators is crucial for improved energy management and heat transfer enhancement. To explore efficient evaporation methods, this study proposes a novel technique that actively introduces microbubble clusters to intensify the vaporization of the working fluid. Experiments were conducted using a microbubble generator fabricated from microporous titanium foam mesh. The effects of key parameters, including operation mode (continuous heating/no heating), average pore size of the titanium foam (2, 5, 10 μm), and gas flow rate (1-15 NL/min), on the evaporation performance (vapor output, liquid temperature drop) were quantitatively investigated. The associated bubble dynamics were analyzed via high-speed visualization. The results indicated that under the no-heating condition, the introduction of microbubble clusters with an average pore size of 10 μm and a flow rate of 15 NL/min led to a temperature drop of 30 ℃, while the corresponding vapor output increased by 38 times compared to the case without bubbles. Under the continuous heating mode, microbubbles with the same parameters caused a temperature decrease of approximately 15 ℃ and enhanced the vapor output by a factor of 1.7. Mechanistic studies reveal that the microbubble clusters substantially increase the vapor-liquid phase change interface area. The agitation caused by the rising bubbles and the alteration of vapor partial pressure due to the presence of non-condensable gas collectively accelerate the vaporization process at the interface, thereby enhancing the evaporation efficiency. This method requires no external fields or surface modifications, offering a simple and effective new approach for enhanced evaporation.