Abstract
The application of microchannel heat exchangers is of great significance in industrial fields due to their advantages of miniaturized scale, large surface-area-to-volume ratio, and high heat transfer rate. In this study, microchannel heat exchangers with and without fan-shaped reentrant cavities were designed and manufactured, and experiments were conducted to investigate the flow and heat-transfer characteristics. The impact rising from the radius of reentrant cavities, as well as the Reynolds number on the heat transfer and the pressure drop, is also analyzed. The results indicate that, compared with straight microchannels, microchannels with reentrant cavities could enhance the heat transfer and, more importantly, reduce the pressure drop at the same time. For the ranges of parameters studied, increasing the radius of reentrant cavities could augment the effect of pressure-drop reduction, while the corresponding variation of heat transfer is complicated. It is considered that adding reentrant cavities in microchannel heat exchangers is an ideal approach to improve performance.
Highlights
Heat exchangers are of great significance in chemical, energy, and electronics industries [1,2,3,4,5]
Microchannel heat exchangers have the advantages of larger surface-area-to-volume ratio and provide higher heat and mass transfer rate at smaller size and weight
Microchannel heat exchangers are being applied in cooling electronic systems, chemical machines, and aerospace equipment
Summary
Heat exchangers are of great significance in chemical, energy, and electronics industries [1,2,3,4,5]. As proposed by Truckman et al [6] in their pioneering work, a number of investigations have been conducted to explore the flow and heat-transfer characteristics of single-phase flow in microchannels. Some researchers proposed to enhance the heat transfer via fabricating roughness elements within microchannels, which could disturb the flow. Dharaiva et al [12] conducted a numerical analysis to investigate the flow and heat transfer in microchannels with 2D structured sinusoidal elements. Their work showed that, compared with smooth channels, the structured roughness elements on sidewalls enhanced heat transfer due to a combined effect of increased heat transfer area and modified flow, which resulted in an augment of pressure drop. When maximum wall temperature was set as constraint condition, it was demonstrated that strip-fin could enhance the heat transfer while the pressure drop was augmented simultaneously
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