An adaptive funnel control method is considered for the regulation of the output for a class of nonlinear infinitedimensional systems on real Hilbert spaces. After a decomposition of the state space and some change of variables related to the Byrnes-Isidori form, it is shown that the funnel controller presented in (Berger et al., 2020b) achieves the control objective under that some assumptions on the system dynamics are considered, like well-posedness and BIBO stability assumptions of the nonlinear system. The theory is applied to the regulation of the temperature in a chemical plug-flow tubular reactor whose reaction kinetics are modeled by the Arrhenius nonlinearity. Furthermore a damped sine-Gordon model is shown to fit the required assumptions as well. The theoretical results are illustrated by means of numerical simulations.