Heat exchanger networks (HENs) are widely used in industry. This paper extends the entransy theory to heat-work conversion optimization in one-stream HENs. The expression for entransy loss is set up for the open system with work output. The entransy loss, as well as entropy generation, is used to analyze the one-stream HENs with the Carnot engines. The fluid friction is ignored in the analyses. For the cases discussed in this paper, the dimensional and non-dimensional parameters analyses show that the applicability of the minimum entropy generation principle is conditional. The minimum entropy generation does not always correspond to the maximum output power, while the minimum entropy generation number and the minimum revised entropy generation number do not always correspond to the maximum heat-work conversion efficiency. On the other hand, greater power output always corresponds to larger entransy loss and larger entransy loss coefficient always corresponds to larger heat-work conversion efficiency for all the cases discussed in this paper. (C) 2012 Elsevier Ltd. All rights reserved.