Heat exchangers are the typical products of the process equipment, which have been playing an important role in process engineering. With the increase of awareness of energy shortage, saving energy and reducing waste have become the major principle of industrial production. The key to develop the energy saving technology has been the design of the optimal heat exchangers with the best comprehensive performance adapted to the different working conditions. It is thus of urgent need to develop the related design methodology and evaluation system. Because of the difficulties met in conception design of compact heat exchangers, a multi-level, multi-factor and non-structural fuzzy optimum decision model is used in the optimal selection of compact heat exchangers. A three-level fuzzy optimum decision is introduced with success to cover most of the effective factors and determine the optimal design projects, which includes six design projects and eight influencing factors. (C) 2013 Elsevier Ltd. All rights reserved.