Numerical characterization of heat transfer deterioration in supercritical natural circulation loop and role of loop inclination

•Numerical appraisal of heat transfer deterioration in supercritical CO2 based NCL.•Four distinct regimes of operation based on temperature levels in adiabatic arms.•Circulation attains maxima when loop average temperature equals pseudocritical value.•Inclination reduces heat transfer coefficient, prompting friction dominant operation.•Peak of Buoyancy parameter satisfactorily predicts the initiation of deterioration.