Experimental investigation on heat transfer and pressure drop characteristics of supercritical CO2 in circular tube.

Abstract

An experimental investigation on the heat transfer coefficient and the pressure drop characteristics of CO2 during gas cooling process in the horizontal tube is conducted. The experimental data are obtained over a mass flux range of 79.6–358.7 kg/m2.s, inlet pressure range of 7.5–9MPa and mean bulk temperature from 23 to 50°C. The test section is 500 mm long, smooth copper tube with inner diameter of 4.0 mm and outside diameter of 6.0 mm. The effect of mass flux, bulk temperature and inlet pressure on the heat transfer coefficient and pressure drop is investigated. The experimental heat transfer coefficients are also compared with some existing correlations. The predicted results present obvious deviation compared to the experimental results at low mass fluxes. A new heat transfer correlation for the tube is proposed based on the experimental data. The maximum error between the predicted results of the new correlation and the experimental data is 20%.