Multi-objective optimization of thermodynamic and dynamic performance of free-piston Vuilleumier heat pump using NSGA-II

Free-piston Vuilleumier heat pump (FVHP) is a heat pump driven by thermal energy such as the combustion of natural gas. Thus, it is a more energy-efficient way for heating than boilers. In this work, one dimensional computational fluid dynamic model is developed for FVHP with dwell motion. Structural design parameters of FVHP are optimized for higher COPtotal based on the coupling of developed model and NSGA-II (Non-dominated Sorting Genetic Algorithm-II) under the condition of given heating capacity. 8 structural parameters are optimized for dynamic performance. The results show that free stroke is improved by 78% and COPtotal is improved by 2.61%. Then, based on the obtained optimal 8 structural parameters, 9 structural parameters for thermodynamic performance are further optimized. The results show COPh is increased by 3.04% while the heating output power is only reduced by 3.15%