Particle deposition in a tray dryer model was studied with special emphasis on the particle size dependent thermodiffusiophoretic force. The drying material was simulated by crumpled glass fiber tissues. The aerosol to be measured was produced by atomizing various solutions of sodium fluorescein in water. The deposition velocities to the tissues of ‘large’ particles (dae ≳ 0.24 μm) decreased when using wet instead of dry tissues, whereas the deposition velocity of ‘small’ particles (dae ≲ 0.24 μm) increased when using wet tissues. Thus, the repulsion of large particles and the attraction of small particles due to thermodiffusiophoresis, as predicted by Yalamov et al. (1977) and Slinn and Hales (1971), was confirmed. In addition, the size dependence of the deposition velocity for dry tissues was found to follow single-fiber deposition theory much better than Sehmel's (1980) and Wood's (1981) theory for turbulent deposition to rough surfaces.