Flow Behavior and Heat Transfer Characteristics of Ice Slurry along a Heated Cylinder

• Published in: Thermal Science and Engineering Vol. 21; no. 1; pp. 21 - 29
• Main Authors: TOGASHI, Kenichi, KAWANAMI, Tsuyoshi, FUMOTO, Koji, HIRASAWA, Shigeki
• Format: Journal Article
• Language: English; Japanese
• Published: The Heat Transfer Society of Japan 2013
• Subjects: Cylinder in cross flow; Cylinders; Forced convection; Heat flux; Heat transfer; Heat transfer coefficients; Ice slurry; Mathematical analysis; Melting heat transfer; Slurries; Surface chemistry; Thermophysical properties; Two-phase flow
• ISSN: 0918-9963; 1882-2592
• DOI: 10.11368/tse.21.21

An experimental study on melting and forced-convectional heat transfer characteristics of an ice slurry around a horizontal heated cylinder has been conducted. A mixture of fine ice particles and a trehalose aqueous solution is used as the ice slurry under test. While the ice slurry forms a sub-steady flow around a heated cylinder, a constant heat flux is electrically imposed on the surface of the cylinder. Under a sub-steady state, temperatures on the heated surface are measured at different angular locations in order to evaluate the heat transfer coefficient distribution. Simultaneously, the flow behavior of the ice slurry is carefully observed to discuss the mechanism of the heat transfer. Experiments are carried out under two parameters: velocity of the ice slurry and heat flux through the surface of the cylinder. Heat transfer coefficients obtained with the ice slurry are compared to those with a single-phase solution. Based on this comparison, specific heat transfer characteristics of the ice slurry relative to those of single-phase liquids are discussed. Furthermore, the average heat transfer coefficient on the entire heat transfer area is also evaluated. The results reveal that heat transfer coefficient increases together with an increased heat flux. This tendency can be attributed to an increase in an inhibitive effect on the temperature rise at the surface due to increased latent heat absorption. In addition, it is found that the effect of ice particles on the heat transfer is greatly affected by velocity conditions, particularly in the front region of the cylinder. This fact can be explained in connection with a transition of the contact state between ice particles and the heated surface, which is brought by the action of velocity-dependent body forces on ice particles. Moreover, thermophysical properties of the testing ice slurry are estimated for a dimensional analysis to organize the effects of each factor. Finally, an experimental correlation equation is proposed.