Considerable research effort has been reported in both Pinch Technology and MINLP techniques for the synthesis of heat exchanger networks. However, most of the design procedures assume constant stream heat transfer coefficients. A problem arises because there is no guarantee that the values of the coefficients assumed during network synthesis are the same as those actually achieved in detailed equipment design (Trans. IChemE 69 (1991) 445). It has been shown that network synthesis and detailed exchanger design can be made consistent if network synthesis is based on allowable pressure drops rather than on assumed film coefficients. Motivated by earlier applications in pinch technology, in this work we extend the simultaneous MINLP model for the design of heat exchanger networks (Comput. Chem. Eng. 14 (1990) 1165) by removing the assumption of constant film heat transfer coefficients and incorporating instead the effect of allowable pressure drop. Numerical results in two illustrative examples are shown to demonstrate the potential benefits and scope of the proposed approach. (C) 2003 Elsevier Science Ltd. All rights reserved.