梯度渗透率金属泡沫管内的流动与传热特性分析

To solve the problem that the pressure drop of the system is greatly increased by the traditional fully filled metal foam enhanced tube, a new gradient filling method is simulated. The heat exchanger pipe is filled with two layers of metal foam with different permeabilities in the radial direction. Numerical simulation is conducted to study the flow and heat transfer characteristics of the metal foam filled tubes with gradient permeability. The results show that the heat transfer and flow performances are directly related to the permeability gradient. When the dimensionless permeability gradient is greater than 10, the comprehensive heat transfer performance of the metal foam filled tube with gradient permeability can be improved by 2 times compared with that of the pipe with uniform permeability. However, when the dimensionless permeability gradient is less than 0.1, the comprehensive heat transfer performance is decreased by 27%. In order to achieve better heat transfer performance, the permeability of the metal foam near the tube wall needs to be at least 10 times that in the central area of the tube. This study may provide theoretical guidance for design and development of new type of high efficiency, low resistance and compact heat exchangers.