Abstract
This paper describes experimental investigations of single-phase and two-phase gas–liquid flow through channels with a diameter of 20 mm and length of 2690 mm, filled with metal foams. Three types of aluminium foams with pore densities of 20, 30 and 40 PPI and porosities ranging from 29.9% to 94.3% were used. Air, water and oil were pumped through the foams. The tests covered laminar, transitional and turbulent flow. We demonstrated that the Reynolds number, in which the hydraulic dimension should be defined based on foam porosity and pore diameter de = ϕdp/(1 − ϕ), can be used as a flow regime assessment criterion. It has been found that fluid pressure drops when flowing through metal foams significantly depends on the cell size and porosity of the foam, as well as the shape of the foam skeleton. The flow patterns had a significant influence on the pressure drop. Among other things, we observed a smaller pressure drop when plug flow changed to stratified flow. We developed a model to describe pressure drop in flow through metal foams. As per the proposed methodology, pressure drop in single-phase flow should be determined based on the friction factor, taking into account the geometrical parameters of the foams. We propose to calculate pressure drop in gas–liquid flow as the sum of pressure drops in gas and liquid pressure drop corrected by the drop amplification factor.
Highlights
The literature review suggests that studies of pressure drop in gas–liquid flow through channels filled with metal foams mostly concern the flow of boiling agents in evaporators of refrigerating appliances and solar collectors
The necessity to develop a new model for predicting the value of pressure drop in gas–liquid flow through the open-cell metal foam, which would correctly describe this value for various flow patterns and could be applied in flow conditions where literature models are not applicable, was deemed a useful objective of the works we engaged in
The energy lost to form the interfacial surface varies across the individual flow patterns, which in combination with the different degree of foam wetting by the fluid manifests itself in a non-uniform course of changes in pressure drop in the gas–liquid flow
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Due to small pressure drop after flowing through foams, their large specific surface area and the high thermal conductivity of the skeleton, the foams are increasingly being considered as an alternative to other structured packings. Noted the great importance of thermal conductivity These authors have shown that when boiling in a channel filled with highly conductive copper foam, heat transport increases by 130 to 300%, with an average increase in pressure drop by 42%. In a study of subcooled flow boiling in a duct filled with copper foam [12], the authors recorded a 22% increase in the energy efficiency of the process. Studies of gas–liquid co-current flow through metal foams in processes other than boiling or condensation are mainly related to the use of foams in catalytic reactors fuel cells and packed columns. The papers devoted inter alia hydrodynamics phenomena, but pressure drop was not their subject
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