Multi-objective optimization of a residential air source heat pump with small-diameter tubes using genetic algorithms

• A comprehensive design optimization of an ASHP using multi-objective genetic algorithms.
• Focus on using small diameter (3–5 mm) tubes in the heat exchangers.
• Results are presented for R-410A and R-32.
• Optimum HX designs show a potential of cost and charge reduction of 44% and 33%, respectively.

Heat exchangers are key components in refrigeration and air conditioning systems. Significant research is being devoted to reduce the size, weight and cost of the heat exchangers while maintaining the same, if not better, system performance. This helps reduce the system refrigerant charge and negative environmental impacts. This work presents an optimization of an air source heat pump (ASHP) using multi-objective genetic algorithms, specifically focusing on the use of small diameter tubes in the heat exchangers. The objective is to minimize the heat exchangers' cost while maximizing the system performance. The goal is to find the potential material savings and cost reduction when using tube diameters between 3 mm and 5 mm in the heat exchangers. We show and discuss the results for R-410A, and the lower GWP R-32. The system utilizing the improved heat exchanger designs showed a cost reduction of 44%, and 47% in comparison to the baseline R-410A, and R-32 systems, respectively. Improvements in the system's COP are around 17%, and 15% for R-410A, and R-32, respectively. The system charge can be decreased to 33% for both refrigerants.