Comments on the letter to the editor and some notes

We have conducted our experimental research on the critical heat flux (CHF) of subcooled flow boiling with water for many years in order to make clear the coolability limit of high heat flux components of fusion reactors. The research concerned the CHF of smooth and twisted tape tubes both under circumferentially uniform and circumferentially non-uniform heat flux conditions. All experiments were conducted under axially uniform heat flux conditions. We proposed empirical correlations for smooth tube (modified Tong correlation) and for twisted tape tube (Nariai-Inasake correlation), and then conducted the evaluation of various correlations proposed to date by many researchers, including ourselves. Our evaluation results, however sometimes differed from other researchers' evaluations; we proposed that the reason for the differences might be the evaluation methods used. We called the two methods used direct substitution method (DSM) and heat balance method (HBM), and adopted HBM for the evaluation of correlations (Inasaka and Nariai, 1996). This is a comment on Todreas, N.E. and Hejzlar, P. ibid vol. 163(1-2) p. 25 (1996). (orig.)