Heat transfer and pressure drop of a Supercritical pressure fluid flowing in a tube of small diameter

In relation to the development of a Supercritical pressure water Cooled Power Reactor (SCPR), experiments were performed on heat transfer and pressure drop of a supercritical pressure fluid flowing upward in a uniformly heated vertical smooth tube of a small diameter 4.4 mm, using HCFC22 as a test fluid. Characteristics of the heat transfer were clarified for the small diameter tube, comparing with the data obtained previously with tubes of large diameter. General characteristics of the heat transfer were found to be similar to those in the tubes of large diameter. The effect of the tube diameter on the heat transfer was seen for a, 'normal' heat transfer, but not for a 'deteriorated' heat transfer. The limit heat flux for the occurrence of deterioration in heat transfer becomes larger with the tube of smaller diameter. For the 'normal' heat transfer, the Watts and Chou correlation showed the best predicting performance. Frictional pressure drop becomes smaller than that for an isothermal flow in the region near the pseudocritical point, and this reduction was more remarkable in the 'deteriorated' heat transfer.