Heat pumps are today a valuable asset in climate change mitigation and energy decarbonization. To meet the Net Zero Emissions target by 2050, the International Energy Agency forecasts that the global heat pump stocks should increase by over 300% by 2030.
It is widely recognized that the choice of refrigerant used in heat pumps significantly affects their performance. Therefore, accurately ranking available refrigerants is of great importance. However, literature has shown that the compressor behavior strongly depends on the refrigerant selected. As a result, it seems appropriate to perform a new classification that takes into account the effects of refrigerants on the performance of the heat pump and the compressor.
The authors propose an integrated design of the refrigerant and heat pump process with a refrigerant-dependent compressor design model in the form of a nonconvex Mixed Integer Non-Linear Program (MINLP). The MINLP is solved using the Non-Linear Branch and Bound algorithm of Artelys Knitro. To determine the ranking, the optimization is repeatedly executed. Whenever a feasible refrigerant molecular design solution is found, an integer-cut constraint is added to the model to exclude this solution from the design space.
The study conducted with the help of Artelys Knitro shows that when considering the compressor’s refrigerant dependency, the ranking of the top refrigerants changes substantially. This indicates that refrigerant-dependent compressor models are crucial for identifying the optimal combination of refrigerants and heat pump processes. Finally, the authors declare that the complexification brought by integrating a refrigerant-dependent compressor model can only be exploited by using computationally efficient implementations.
Start with a tutorial!
You’re not familiar with nonlinear optimization? This tutorial will present some examples of nonlinear problems for various applications. You will discover nonlinear programming methods using the Artelys Knitro solver in a Python notebook, through different examples.
Get your trial license to test Artelys Knitro’s performances on your own mathematical optimization problem. The trial package includes free support and maintenance. You can have access to Artelys Knitro for free with a 1-month unlimited version or a 6-month limited version.
Artelys Knitro has unmatched performance
Best Nonlinear Solver
Artelys Knitro has been ranked every year by public benchmarks consistently showing Artelys Knitro finds both feasible and proven optimal solutions faster than competing solvers.
The Artelys technical support team comprises Artelys’consultants (PhD-level) who are used to solving the most difficult problems and deploying enterprise-wide optimization solutions. They can advise on algorithmic or software features that may result in enhanced performance in your usage of Artelys Knitro.
Updates and new features
The development team works continuously to provide two releases of Artelys Knitro every year. Based on feedback, we always improve our solver to meet users’ requirements and need to solve larger models faster.