**Bohong Wang 1,\*, Jiˇrí Jaromír Klemeš 1, Petar Sabev Varbanov <sup>1</sup> and Min Zeng <sup>2</sup>**


Received: 26 April 2020; Accepted: 22 May 2020; Published: 24 May 2020

**Abstract:** Heat exchanger network (HEN) retrofit is a vital task in the process design to improve energy savings. Various types of heat exchangers such as shell and tube, double-pipe, compact plate, and spiral tube have their working temperature ranges and costs. Selecting suitable types of heat exchangers according to their temperature ranges and costs is a crucial aspect of industrial implementation. However, considering the type of heat exchangers in the HEN retrofit process is rarely seen in previous publications. This issue can be solved by the proposed Shifted Retrofit Thermodynamic Grid Diagram with the Shifted Temperature Range of Heat Exchangers (SRTGD-STR). The temperature ranges of six widely used heat exchanger types are coupled in the grid diagram. This diagram enables the visualisation of identifying the potential retrofit plan of HEN with heat-exchanger type selection. The retrofit design aims to minimise utility cost and capital cost. An illustrative example and a case study are presented to show the effectiveness of the method.

**Keywords:** heat exchanger network (HEN); retrofit; Shifted Retrofit Thermodynamic Grid Diagram (SRTGD); Pinch Analysis; type selection
