Review of Heat Exchanger Network Retrofitting Methodologies and Their Applications

Heat exchanger network (HEN) retrofitting improves heat recovery and thus reduces energy required in existing plants. This can be achieved by either increasing the heat transfer area and/or using heat transfer enhancements to increase heat transfer coefficients. There is an increasing interest in HEN retrofitting as can be seen from 20 journal papers since 2009 (about 5 years) compared to 15 in the 10-year period 1999–2008. In total, there are about 60 journal papers on HEN retrofitting since the year 1985; however, in the past 20 years, there has been no review paper summarizing HEN retrofitting methodologies and their applications. This provides the motivation for this review paper. HEN retrofitting methods can be classified into three broad categories, namely, mathematical programming based methods, pinch analysis based methods, and hybrid methods according to their underlying approach. Further, some HEN retrofitting methods include pressure drop considerations, and HEN retrofitting can be using heat transfer enhancements. This paper reviews all these methods and their applications in each of these categories. Finally, it discusses alternate solutions of five application problems solved by several methods/researchers and/or for different objectives. Review of HEN retrofitting methods and their applications presented in this paper will be useful to both researchers and practitioners.