Abstract
In the present study, natural circulation model of heat recovery system using supercritical CO_2 is examined and its thermal flow behaviors were experimentally investigated. The system provides a possibility to circulate CO_2 without any mechanical pumps and the high heat recovery efficiency can be achieved. In order to understand optimum conditions for the high heat recovery efficiency of the system, thermal flow behaviors, which are dependent on the heat input and mass flow rate, are studied in detail. From the experimental results, there were two peaks of the local heat transfer occurred in the heating section. This is due to the local heat transfer of the heating section, which is remarkably enhanced by large variation of Reynolds number and Prandtl number in a region of the pseudocritical boundary. The outcome of this study shows the feasibility of the high efficient heat recovery system using supercritical CO_2 as a working fluid.
