New models for conventional and heat exchangers enhanced with tube inserts for heat exchanger network retrofit

The retrofit of heat exchanger networks requires detailed models of the heat exchangers for the detailed assessment of network performance. Network retrofit options include heat transfer enhancement. There is thus a requirement for detailed models of heat exchanger performance, including heat transfer enhancement, suitable for inclusion in network retrofit optimization algorithms. Such models must be robust, computationally efficient and accurate enough to reflect the heat transfer and pressure drop performance of actual equipment. This paper presents a simple but reliable method to model the performance of shell-and-tube heat exchangers, including heat transfer enhancement with tube inserts. Two commonly used tube inserts, twisted tapes and coiled wires, are investigated for tube-side heat transfer augmentation. A new set of consistent performance correlations covering all flow regions for twisted-tape and wired-coil inserts is introduced. The models can be conveniently used for existing exchanger simulation, rating and assessment of heat transfer enhancement. They can also be used for sizing new exchangers to be introduced in a network. A case study illustrates the application of these performance models.