Numerical predictions of jet impingement heat transfer on square pin-fin roughened plates

A comparative numerical study has been conducted on the heat transfer characteristics of an array of jet impingement on a flat plate and plates roughened with inline/staggered square pin-fins with the spent air in one direction. Additional experiments were also conducted using one flat plate and one pin-fin roughened plate to validate the computation models. The comparisons between the experimental and numerical data showed that the numerical computation model can reasonably well predict the heat transfer and pressure loss in the multiple jet impingements on the flat plate and pin-fin roughened plates. The numerical computation results showed that the pin-fins on the plates can have significant effects on the impingement heat transfer. Over the studied Reynolds number from 15,000 to 35,000, the overall averaged and local Nusselt number and the discharge coefficient in the multiple jet impingements on the flat and pin-fin plates were obtained and compared with each other. The overall heat transfer rate of the jet impingement on the inline pin-fin plate can be increased by up to 34.5% with a decrease discharge coefficient by about 3.0% compared with the jet impingement on the flat plate. The impingement on the inline pin-fin plate showed better heat transfer performance than that on the staggered pin-fin plate. Velocity distributions and streamlines, as well as turbulent kinetic energy near the test wall in the impingement system with the flat plate and pin-fin plates were also obtained to explain the heat transfer characteristics. (C) 2015 Elsevier Ltd. All rights reserved.