Multi-objective optimization of a cold-climate two-stage economized heat pump for residential heating applications

Energy consumption and environmental concerns are the two main drivers optimize heat pump systems. However, under extreme weather conditions especially in heating mode, conventional heat pumping systems face challenges when operating in cold-climates such as in Minneapolis, MN, USA. In the current work, a two-stage vapor injected heat pump system was optimized for residential applications at low ambient operating conditions using R-32, R-290, R-410A, R-454A and R–452B as working fluids. The system model was simulated using nondominated sorting genetic algorithm II (NSGA-II) method to obtain the Pareto-Frontier curves. The final solution for decision-making was selected based on a technique for order performance by similarity to ideal solution (TOPSIS) method. The system with R-32 and R-290 had a minimum unit cost of heat (UCH) of 0.19 $ kWh⁻¹ and a maximum heating coefficient of performance (COP) of and 5.2, respectively. From the specific exergy costing (SPECO) analysis of the system, the results showed that the highest and lowest total investment cost were contributed with R-290 by 1.35 $ hr⁻¹ and R-32 by 0.09 $ hr⁻¹, respectively. Whereas, the maximum and minimum total cost rate of destruction were associated with R-290 by 1.73 $ hr⁻¹ and R–452B by 1.33 $ hr⁻¹, respectively.