Experimental study of multilayer gradient copper foam effect on pool boiling heat transfer performance and gas-liquid behavior characteristics

The rapid growth of the internet of things has induced the integration of many microelectronic devices in physical objects, yet the generated heat decreases the performance and stability of microelectronic devices. Therefore, new materials such as gradient metal foams (GMFs) have been recently designed to improve heat transfer. In this paper, an experimental visualization setup was built to investigate the effect of the GMFs gradient layers number and the arrangement order on the pool boiling heat transfer performance. Results show that increasing the number of gradient layers enhances the heat transfer when the copper foam pore density is low. By contrast, at high pore density of 50 PPI, increasing layers hardly changes heat transfer. The bubbles dynamic behavior on the metal foams surface of with different gradient structures is also different. When bubbles detach upward, the temperature of the metal foam is lower, and the temperature gradient is higher. When bubbles detach sideward, the bubble escape is much shorter, and the bubble detachment frequency and size increase. Combined with the theoretical research, the metal foam gas-liquid flow heat transfer model were constructed. The advantages and disadvantages of GMFs with different structures and the applicable scenarios are analyzed.