Modelling of an electric IR heater at transient and steady state conditions Part II: modelling a paper dryer

A model for an electric infrared (IR) paper dryer has been developed. The m odel includes non-grey radiative heat transfer between the different parts of the IR heater, as well as conduction in reflector material and convectiv e cooling of surfaces. Such heat transfer calculations are combined with en ergy balances to provide a system of equations that simulates the behaviour of an electric III dryer. Using IR module voltage as the only input, the m odel predicts the temperature of dryer components and cooling air, as well as the net radiation heat transfer to the paper sheet at steady state and t ransient conditions. The model has been used to investigate trends in effic iency and component temperature with changing voltage and paper grade. Emph asis has been on back reflector temperature and dryer efficiency. Also, the transients during start-up of an IR paper dryer have been investigated. Th e study indicates that the transients of the back reflector is important fo r the time needed to reach steady state heat flux at the paper sheet. (C) 2 000 Elsevier Science Ltd. All rights reserved.