A two-dimensional finite element model describing the performance of parallel-plate regenerators with arbitrary channel width distributions has been developed in order to investigate the effect of non-uniform plate spacing on the performance of regenerators. Results for a series of hypothetical plate spacing distributions are presented in order to understand the impact of spacing non-uniformity. Simulations of more realistic distributions where the plate spacings follow normal distributions are then discussed in order to describe the deviation of the performance of a regenerator relative to one with uniform spacing as a function of the standard deviation of the plate distribution. It has been shown that the most significant reduction in performance occurs when a volume of fluid between 100% and 200% of the regenerator void volume is displaced in a single blow. (C) 2010 Elsevier Ltd. All rights reserved.