  The steady state behavior of thermodynamically supercritical natural
circulation loops (NCLs) is investigated in this work. Experimental steady
state results with supercritical carbon dioxide are presented for reduced
pressures in the range of 1.1-1.5, and temperatures in the range of 20-65
{\deg}C. Distinct thermodynamic states are reached by traversing a set of
isochors. A generalized equation for the prediction of the steady state is
presented, and its performance is assessed using empirical data. Changes of
mass flow rate as a result of changes of thermodynamic state, heating- and
driving height are shown to be accurately captured by the proposed predictive
equation. However, the enhanced viscous losses in the instrumentation of the
loop and in the proximity of heat transfer equipment are shown to significantly
limit the steady state flow rate. Subsequently, the findings are put forward in
aid of the development of safe, novel supercritical natural circulation
facilities.
