Heat transfer behavior of an immersed tube with sCO2 working fluid in a hot fluidized bed at high pressure

Abstract

In this work, a pilot-scale pressurized fluidized bed test rig was built to test the heat transfer performance between the supercritical CO2 (sCO2) loaded immersed tube with the dense bed. Results showed that the bed-to-tube heat transfer coefficient (HTC) in CO2 atmosphere was slightly larger than that in air atmosphere. The HTC increased with the increase of pressure and bed temperature, respectively. The increase of pressure did not change the circumferential distribution of HTC, but the increase of fluidization number improved it. A bed-to-tube heat transfer model was proposed on the basis of the partial heat penetration theory with the accuracy in ±25 %. For the heat transfer of sCO2 within the immersed tube deteriorated due to the buoyancy effect.