Experimental and theoretical internal forced convection investigation on air pipe cooling of large-dimension RC walls

Abstract

Air pipe cooling is an emerging technique in dealing with the hydration heat and thermal induced cracking of massive concrete structures. In order to investigate the influence of air pipe cooling on temperature distribution in large-dimension concrete walls, in situ experiments of heat transfer coefficient for internal forced convection were conducted on one experimental wall of 3.6 m × 3.6 m × 0.8 m in dimension with properly embedded corrugated pipes. The relationship between average inlet air velocity and average heat transfer coefficient for internal forced convection was then obtained and fitted to a proposed formula. In addition, air cooling experiments were performed on another three experimental walls to monitor the temperature variations of internal concrete. Meanwhile, finite element (FE) thermal analysis with the proposed formula was carried out and compared with the results of air cooling experiments to verify the accuracy of the proposed FE method. As the comparison results show, the calculated temperature curves are in good agreement with the tested data, with an average deviation of 0.07 °C, 0.13 °C and 0.19 °C under average inlet velocity u¯in of 3.78 m/s, 8.12 m/s and 11.64 m/s, respectively. It indicates that the FE analysis with the proposed heat transfer coefficient formula for internal forced convection is effective in estimating concrete temperature variations, providing a reliable fundamental approach for further thermo-mechanical coupling analysis and ventilation design in practical engineering projects.