|
Description:
|
The heat transfer behavior of phase change material fluid under laminar flow conditions in circular tubes and internally longitudinal finned tubes are presented in this study . Two types of boundary conditions , including uniform axial heat flux with constant peripheral temperature and uniform axial and peripheral temperature , were considered in the case of circular tubes . An effective specific heat technique was used to model the phase change process assuming a hydrodynamically fully -developed flow at the entrance of the tube . Results were also obtained for the phase change process under hydro dynamically and thermally fully developed conditions . In case of a smooth circular tube with phase change material (PCM ) fluid , results of Nusselt number were obtained by varying the bulk Stefan number . The Nusselt number results were found to be strongly dependent on the Stefan number . In the case of a finned tube two types of boundary conditions were studied . The first boundary condition had a uniform axial heat flux along the axis of the tube with a variable temperature on the peripheral surface of the tube . The second boundary condition had a constant temperature on the outer surface of the tube . The effective specific heat technique was again implemented to analyze the phase change process under both the boundary conditions . The Nusselt number was determined for a tube with two fins with different fin height ratios and fin thermal conductivity values . It was determined that the Nusselt number was strongly dependent on the Stefan number , fin thermal conductivity value , and height of the fins . It was also observed that for a constant heat axial flux boundary condition with peripherally varying temperature , the phase change slurry with the internally finned tube performed better than the one without fins . A similar trend was observed during the phase change process with internal fins under the constant wall temperature boundary condition . |