The behavior of seven binaryparticledrag closures from the literatures which have been derived based on the kinetic theory of granular flows (KTGF) for the application to fluidizedbeds are investigated using abinary KTGF model. The dynamic size segregation experimental data from the literature is used to validate the simulation results. The validations show that all of the seven binaryparticledrags under-predict the binaryparticle coupling in the densefluidizedbed, satisfactory results could be obtained if an extra semi-empirical frictional binaryparticledrag is included. The semi-empirical frictional binaryparticledrag considering the long term particle–particle contact effects is a correction of the short term collisional frictional binaryparticledrag from Syamlal. Furthermore, a group of comprehensive calculations shows that the model using the semi-empirical frictional binaryparticledrag can fairly well predict the particle segregation rates and the bed heights of the individual particles with a change of gas fluidization velocity, the initial bed height, and the small particle ratio with the same fixed correction coefficient. Therefore, it is proposed that the frictional binaryparticledrag which represents the binaryparticle momentum exchange due to the long term particle contacts (sliding/rolling) must be included in order to model densebinaryfluidizedbeds. Copyright © 2012 Elsevier B.V. All rights reserved.