Practically every field of science and engineering now uses simulations. As a case in point, the Nobel Prize in Physics 2021 was awarded "for groundbreaking contributions to our understanding of complex systems" [1]. One half was awarded jointly to Syukuro Manabe and Klaus Hasselmann "for the physical modelling of Earth's climate, quantifying variability and reliably predicting global warming" and the other half to Giorgio Parisi "for the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales."

The use of simulations has become commonplace in practically every field of engineering design, including heat exchangers. The mathematics has been available for decades or even for centuries and now computing power has caught up with the mathematics, making powerful simulation software widely available to product design engineers. Simulation tools for design engineers have also become relatively easy to use, with menu driven interfaces and 3D visualizations of results.

One does not need to be an expert in the mathematics of complex systems to run a simulation of a heat exchanger design. That is fortunate because there is a need to bring new technologies to bear on new product designs. There is an urgent demand for heat pumps to facilitate electrification. A new generation of refrigeration and AC appliances and systems is needed for F-gas reduction and improved energy efficiency [2]. Refrigerant formulations, heat-exchanger technology and compressor designs are rapidly changing even as the times-to-market are accelerating in a once stodgy industry.

What follows is an overview of several important simulation software tools available to design engineers today. Well-known programs are the Heat Pump Design Model (HPDM) from Oak Ridge National Laboratory (ORNL); CoilDesigner® from Optimized Thermal Systems (OTS) and the University of Maryland; and HXSim from Shanghai Jiao Tong University and the ICA.