Experimental investigation on subcooled boiling heat transfer of emulsified kerosene

Abstract

To investigate heat transfer characteristics of emulsified kerosene in a mini tube, experiments were conducted at the pressure of 3.0–5.0 MPa, mass flow rate of 0.8–2.4 g·s−1, and water mass fraction of 10%–50%. Water in oil type emulsion was prepared using the surfactant of span-80. The basic heat transfer characteristics of emulsified kerosene covering a wide temperature range were revealed. More attention was focused on subcooled boiling of emulsified kerosene. Depending mainly on low-boiling temperature dispersed phase of water, the heat transfer of emulsified kerosene could be divided into 6 regions: single liquid-phase convection, subcooled boiling, saturated nucleate boiling, film boiling, steam-kerosene convection, and single gas-phase convection. Heat transfer deterioration characterized by a significant soar in wall temperature could be observed in the film boiling region. In the fully developed subcooled boiling region, higher heat transfer coefficient could be achieved at lower pressure. With an increase in mass flow rate, subcooled boiling was postponed to higher heat flux. At the same heat flux, the fluid temperature was negatively correlated with the water mass fraction. However, the effect of water mass fraction on inner wall temperature could be ignored. The subcooled boiling heat transfer was enhanced at lower water mass fraction. Most of the existing enhancement-factor type correlations underestimated the subcooled boiling heat transfer of emulsified kerosene. According to the experimental data, a new enhancement-factor type correlation was proposed for subcooled boiling heat transfer of emulsified kerosene. The mean absolute deviation of the new correlation was 9.9%.