Abstract
Abstract This study aims to investigate heat transfer and flow characteristics of ethylene glycol/water (EGW) and CuO–EGW nanofluids in circular tubes with and without trapezoid ribs. Nusselt number and friction factor in tubes with trapezoid ribs are analysed under a constant heat flux by changing rib bottom angles. This study compares the convective heat transfer coefficients of 6 vol.% CuO–EGW nanofluid and base fluid. It is found that under a constant Reynolds number, the Nusselt number and friction factor for CuO–EGW nanofluid and base fluid increase with an increase in the inclination angle. The Nusselt number for the CuO–EGW nanofluid in the tube with 75° rib bottom angle averagely increases by 135.8% compared to that in the smooth tube, and the performance evaluation criterion is 1.64.
Highlights
Heat exchangers have numerously been applied to the industrial field, such as air conditioning, power station, This work is licensed under the Creative Commons Attribution 4.0Nanofluids in circular tube with trapezoid ribs 225 chemical industry and so on
This part will discuss the effects of structure parameters using ethylene glycol/water (EGW) fluid and CuO–EGW nanofluid
In order to validate the numerical model, Nu and friction factors for CuO–EGW nanofluid from the present study work, the average error of f is 0.8%
Summary
Nanofluids in circular tube with trapezoid ribs 225 chemical industry and so on. Rib structures have been studied to enhance the heat transfer performance of heat exchangers in recent years. In six-start spirally corrugated pipes, Jin et al [3] carried out a numerical study on flow resistance characteristics of the tubes with various geometric parameters (such as pitch and depth) Results showed that they had 1.28–3.45 times the resistance coefficient of the circular tube when Reynolds number ranged from 100 to 1,000. Results revealed that the heat transfer performance for the tube with spherical corrugation was enhanced 1.05–1.7 times compared with the smooth tube. Kristiawan et al [11] investigated the heat transfer characteristics of TiO2/water with the volume concentration of 1.18% flowing inside a circular tube by using innovative numerical method. For TiO2–H2O nanofluids in tubes with different corrugation pitches, Wang et al [14] experimentally investigated heat transfer performance and resistance coefficient. Three-dimensional models with various trapezoid ribs are designed to study heat transfer characteristics of the CuO–EGW nanofluid
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