• Energy Research

Abstract The goal for performing heat exchanger network (HEN) retrofit is not only to reduce utility consumption but to ensure that the retrofit is economically viable. The problem of using heat transfer enhancement for retrofit lies with the uncertainty of the best location in which to apply enhancement, the augmentation level and dealing with downstream effects after enhancement is conducted. To solve these problems, a systematic methodology is proposed. The first step in this methodology is the identification of candidate heat exchangers. In the second step, two methods, sensitivity analysis and an area ratio approach are compared for the identification of the best candidate heat exchangers to enhance. Heat transfer enhancement is then performed on the best candidate heat exchanger and, a non-linear optimisation based model is used to deal with the downstream effects after enhancement, subject to meeting set constraints on the HEN, such as the stream target temperatures and heat transfer area. Following this approach, the problems posed by the use of enhancement for retrofit can be addressed in a simple and computationally inexpensive manner. Heat transfer enhancement is an attractive option for HEN retrofit as it can provide energy saving without the need for topology modifications and additional heat transfer area with an added benefit of reduced implementation time, as modifications can be carried out during normal shutdown periods.