Radiation heat transfer in a glass Lehr

In partnership with Ford/Visteon, Sandia National Laboratories investigated an intelligent control for the annealing lehr in float glass production, both for optimum usage of sensors and for the ability to report digitally the state of the lehr to an end-to-end control system, under DOE Office of Industrial Technology sponsorship. The heat transfer simulation of the lehr enclosure for that purpose is described here. This includes a closed-form solution for the infinitely wide glass ribbon, which allows robust computations of the thermal profile and inverses of this function for controls use. This also allows useful initial temperature estimates for the case with counterflow in the lehr ducts, which should greatly simplify and speed the convergence of more detailed models in which the glass participates in the radiative exchanges.