Steady and transient CHF (critical heat flux) were measured in a platinum vertical samll tube with exponentially increasing heat inputs. A platinum test tube with an inner diameter of 1.0 mm and a length of 40.9 mm was used as test tube. The flow velocities (u=1.0～7.5 m/s),inlet liquid temperatures (Tin=300.04～357.28K), and inlet pressures (Pin=738.54～805.00kPa) were systematically measured by a forced convection test loop comprised of a multistage canned-type circulation pump with high pump head. The heat generation rate was raised with an exponential function, Q0exp(t/τ),where Q0(W/m3) denotes the initial heat generation rate, t(s) represents time, and τ(s) indicates the e-folding time,respectively. The e-folding time ranged from 33 ms to 20 s. It was understood that the CHF can be divided to three groups depending on the e-folding time. The CHF at a small e-folding time showed a higher value compared to that a large e-folding time.
