Experimental Investigation on Heat Transfer Instability of Kerosene at Supercritical Pressure

The flow and heat transfer instabilities of kerosene flowing in a vertical upward circular tube were experimentally investigated. The tube is 1mm in diameter and 300 mm in length. Pressure ranges from 2.5~4MPa, mass flow rate ranges from 0.7~1.7g/s and inlet temperature ranges from 300~520K. Results indicate that heat transfer instability appears when the applied heating power exceeds a threshold value. It is found that the instability threshold power increases with the increasing of pressure and mass flow rate while it decreases with the increasing of inlet temperature. Heat transfer instability will not happen when inlet temperature reaches a certain value. At the initial state of the instability, the outlet temperature rises rapidly while the temperature of the section wall drops rapidly. Heat transfer coefficient increases during the instability. Increasing of the local flow velocity leads to the pressure pulsation and causes sounds. After the instability, the outlet temperature keeps almost constant while the wall temperature keeps rising until the next instability happens.