An experimental study on heat transfer of CO2 solid-gas two phase flow with dry ice sublimation

Knowledge on heat transfer characteristics of CO2 solid-gas two phase flow is important to design of some new refrigeration systems. Continuously obtaining CO2 solid gas fluid flow in a closed loop is necessary to measure its heat transfer. In this paper, an experiment set-up is designed, constructed and tested in order to measure the temperatures, pressures of the CO2 solid gas two phase flow, and also further its heat transfer characteristics. As the first step of the investigation, the measurement work is conducted in a horizontal circular tube. Based on the obtained results, it is verified the present experiment set-up can continuously obtain CO2 solid gas fluid flow in the closed loop and also heat transfer measurement is possible. The results show an average value 310 W/(m(2) K) of heat convective coefficient is experimentally obtained in the present range, which is higher than that of gas flow. The Nusselt number is found to increase along the tube length in the sublimation area. In addition, some knowledge on the heat transfer characteristic of the CO2 solid gas flow is learned from the present study. (C) 2011 Elsevier Masson SAS. All rights reserved.