The flow distribution features in U-type layers or stacks with certain practical configurations have been investigated analytically. The formulations suggest general designing strategies to improve the flow uniformity, and narrowing some positions of the channels proves effective. The flow uniformity among the layers in a U-type stack is relatively easy to achieve in comparison with that among the channels in a U-type layer, due to the large stack headers and low-pressure loss in them. CFD simulations confirm the formulations, and the discrepancies between the analytical and CFD results have been attributed to the ignored factors during the analytical formulations. (C) 2007 Elsevier B.V. All rights reserved.