Objectives  The air-conditioning chilled water system of ship is usually designed according to the experience of designer, resulting in the designed capacity is much higher than expected. There is no assessment method that can examine equipment operation matching degree to assess whether the system design is rational.

  Methods  In order to evaluate the design and type selection of air-conditioning chilled water system, this paper proposes an evaluation index-operation matching degree based on exergy analysis, i.e. analyzing the difference between exergy efficiency of the equipment in actual operation state and that in optimal operation state. An air-conditioning chilled water system of ship is used as the study object. Based on Matlab software, the simulation model of the chilled water system is built, and whole year operation conditions are simulated. Eight alternative designed chillers and three alternative designed chilled water pumps are introduced to compare with the original design, to calculate the matching degrees of chilled water system in different designs.

  Results  the results show that the optimal design of chilled water system is "CH3-CHP1", whose operation matching degree is 90.0%, which is 2.5 percentage points higher than the matching degree in the original design.

  Conclusions  The study shows that the design matching degree can be used as the evaluation criterion to guide the design and type selection of air-conditioning chilled water system of ship.