Heat transfer to paper in a hot nip

We used experiments with a fusing nip of a laser printer to verify a simple mathematical model for the heat transfer to paper in a hot nip. After we had adjusted roll parameters to match the measured cooling in the absence of paper, the model reproduced measurements with paper very well. The solution employs perfect thermal contact between paper and hot rolls, thus completely avoiding the phenomenological heat transfer coefficient. We found that the heating of paper in a hot nip depends primarily on its thermal diffusivity. The cooling of the hot rolls, caused by the running paper, depends on the velocity of paper, its heat capacity per unit area, and the initial temperature difference between the rolls and paper.