Mathematical Modelling & Optimisation of Heat Exchanger Design

Discretization of a two-pass shell-and-tube heat exchanger
Discretization of a two-pass shell-and-tube heat exchanger.

Saif Kazi, PhD, Carnegie Mellon University, USA

Heat Exchangers are an important part/equipment in not only industrial processes but also in residential and commercial utility systems. Traditional methods for heat exchanger design were developed in the 1950s and 80s and are not suitable for current applications. My PhD project looked into an improved way of modelling and designing heat exchangers using advanced numerical and optimisation methods.

The strategy is to discretise the heat exchanger geometry into a discrete element structure. The idea is similar to CFD where the conservation laws are solved inside each of these elements. Our approach combined the heat transfer PDE and mass balance to the design parameters/variables of the exchanger such as number of tubes, tube length, shell diameter etc. The methodology was applied and integrated in process optimization problems such as heat exchanger network synthesis (HENS), natural gas liquefaction (NGL) process and refrigeration cycle.