Fixed bed heat transfer parameter estimation –a new look at an old problem

The pseudo homogeneous 2D $k_r-h_w$ fixed bed heat transfer model is used for fixed bed reactor simulation and design. The two parameters are estimated by one of two main approaches. Method 2 uses the bed centerline temperature and the exit mixing-cup temperature. Method 4 uses radial temperature profile measurements at the exits of progressively longer beds. Particle-resolved computational fluid dynamics (PRCFD) is used to simulate heat transfer in a bed of spheres with tube-to-particle diameter ratio $N=6$ to determine whether the methods give the same parameter values. Method 2 and variations gave underestimated values of $h_w$ if the mixing-cup temperature was low by 1 K. For Method 4 fitted to long enough bed depths, good estimates of the parameters were obtained. A new version of Method 2 is proposed, which retains the advantages of measuring only axial profiles, while avoiding the sensitivity problems of estimation from single temperature measurements.