Heat transfer in rough tubes to supercritical hydrogen

In this report, the local heat transfer and overall pressure drop characteristics of cryogenic hydrogen flowing vertically upwards through straight circular tubes with different surface roughness are investigated. The experimental results of the heat transfer and pressure drop are compared with previous correlations in both the supercritical and near-critical region. Consequently, the most appropriate correlations are recommended for the following four items: friction factor, heat transfer, entrance- and the roughness-factor effects. 29 refs