A new method using a phase-change-material slurry to enhance convective heat transfer was studied in this research. Hexadecane was used as a phase-change material and was mixed with water, the carrier fluid. An emulsifier was used to generate fine and homogeneous hexadecane particles in water. The hexadecane-water slurry was circulated through a heating test section, where pressure drops and heat transfer coefficients were measured. The heating test section was made of 6.532 m long, 10.14 mm ID stainless steel tubing and heated by a high current DC power supply, resulting in a uniform heat flux boundary condition.
The solid particles used in the present study were small enough to prevent clogging. The local pressure drop was found to decrease when the solid particles melted, a phenomenon which was used to find out the location of the slurry melting. The behavior of local heat transfer coefficient curve was quite distinctive in three region along the heating test section. In the first region, the heat transfer coefficient increased along the test section because the number of the melted particles on the wall increased. In the second region, it decreased because the number of solid particles abruptly decreased. In the third region, it increased because of the temperature-dependent viscosity effect. The maximum local heat transfer coefficient was about twice as high as that without phase-change materials.