Abstract
Multiple jet impingement is a widely implemented convective process for enhancing heat transfer over target surfaces. Depending on the engineering application, the impinging plate can have different configurations. However, the increased complexity of the surface induces complicated thermal behaviors that must be analyzed. In that sense, this study consisted of the experimental and numerical analysis of multiple jets impinging on a step surface. A particle image velocimetry technique was applied to measure velocity fields, while a heat flux sensor was mounted on the surface to determine the heat transfer. Numerical simulations, for both flat and non-flat plates, were conducted in ANSYS FLUENT applying the SST k-ω model, and experimental results were used to validate the model. Three surface configurations were analyzed, flat, 1 D, and 2 D steps, and the results show an increase in the average Nusselt number compared with the flat plate, 9% and 20%, respectively. This increase was mainly due to the intensification of the flow turbulence induced by the step. Numerical results were in good agreement with the experiments, but the heat transfer was slightly underpredicted for the 2 D step case due to the difficulty of predicting with accuracy the velocity field near the step.
Highlights
The consumption growth of electronic products has increased the demand for printed circuit boards (PCBs) [1]
The averaged velocity field of multiple jets impinging on target plates with different configurations was obtained from particle image velocimetry (PIV) measurements, and the results are presented in
Starting with an overall analysis of the multiple jets’ flow dynamics depicted in Figure 8, it was observed that the air flowed through the circular nozzles at a maximum velocity and started to mix with the surrounding air, entraining mass, momentum, and energy [52]
Summary
The consumption growth of electronic products has increased the demand for printed circuit boards (PCBs) [1]. The expansion of the electronic products market has led to an increase in the complexity of PCBs, which causes a more complex thermal response when a PCB passes through a reflow oven [2] Inside this equipment occurs a process known as reflow soldering, which is achieved by forced convection using multiple air jet impingement technologies [3]. This process is currently the primary manufacturing technology used for the attachment of electronic components to the PCB by melting the solder paste, allowing the connection between the board and the components. To enhance the convective heat transfer and minimize the defects, studies have been conducted to understand the effect of complex surfaces on multiple jet impingement flow dynamics and heat transfer
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