2022 Volume 39 Issue 3 Pages 223-
This research presents an assessment technique based on the evolutionary optimization of heat exchanger circuitries for the performance evaluation of next-generation refrigerants. To this aim, a finned-tube heat exchanger simulator is structured around a bijective mathematical representation of the refrigerant circuitry (Tube-Tube Adjacency Matrix) and the formulation of the related constraints for ensuring coherence and feasibility of the circuitry during the evolutionary search. The “thermal path generator”, a novel evolutionary algorithm for refrigerant circuitry optimization, is developed. This novel technique was able to handle the implementation of genetic operators to complex circuitries with unrestrained number and location of splitting and merging nodes, hence, expanding the search space of previous optimization studies. The performance of three refrigerants representative of air conditioning applications, namely R32, R410A, and R454C is assessed for optimized circuitries of a 36- tube evaporator. Larger COP improvements (up to 7.26%) are achieved for zeotropic refrigerant mixtures, such as R454C, where the proper matching of the temperature glide with the temperature variation of the air yields the possibility of further reducing the required compression ratio at corresponding operative conditions. It is thus demonstrated that low-GWP zeotropic mixtures with temperature glide may achieve higher performance than R410A and comparable to R32, while previous drop-in performance analyses yielded the opposite conclusion.
