A micro impinging jet with supercritical carbon dioxide

A micro device with a 206 pm nozzle diameter and a standoff of 7.3 was fabricated and used to study the characteristics of micro jet impinging heat transfer with supercritical CO2. The issuing jet impinged on a 500 mu m thick fused silica substrate measuring 30.5 x 1.9 mm(2), onto which a heater, three temperature sensors (RTDs), and their respective leads were sputtered. The RTDs were arranged in a concentric manner with r/d values of 0.21, 1.44, and 2.89. Four holes were drilled into the device to allow passage of spent fluid, which were collected in a single channel out of the medium. The effects of heat flux, radial positions, mass flux and inlet temperature were studied for a pressure of 7.45 MPa - higher than the supercritical pressure of CO2. The highest local heat transfer coefficient of similar to 40,000 W/m(2)K was recorded at the RTD closest to the stagnation region at a heat flux of 54.5 W/cm(2) and an inlet Reynolds number of approximately 15,500, corresponding to conditions near the pseudocritical temperature. Deviations between experiments and available correlations were noted especially at higher Reynolds number. A Nusselt number correlation for micro jet impingement with sCO(2) was proposed. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the characteristics of microm jet impingement heat transfer with supercritical CO2, revealing that high heat transfer coefficients can be achieved under certain conditions. Additionally, a Nusselt number correlation for micro jet impingement with sCO2 was proposed.