Structural optimization of a coupled liquid storage gas-liquid separator for enhanced heating performance in air source heat pumps

The integration of a liquid storage chamber with a gas-liquid separator in air source heat pumps (ASHPs) enables continuous autonomous heating from the liquid storage chamber to the gas-liquid separator, effectively elevating evaporator temperature and enhancing system performance. To further improve the low-temperature applicability and heating efficiency of ASHPs, this study conducts a structural optimization of the coupled liquid storage gas-liquid separator (LSGLS). A heat transfer model of the LSGLS and a system-level ASHP model are developed, with a genetic algorithm-based optimization framework proposed to maximize system Coefficient of Performance (COP). Key geometric adjustments include enlarging the liquid storage chamber diameter while reducing its height to strengthen thermal energy retention, combined with decreasing the gas-liquid separation chamber (GLSC) diameter and increasing its height to intensify turbulence-driven phase separation. Based on an experimentally validated model, simulations predict that the optimized design achieves a 3.0 W/(m²·°C) improvement in the liquid chamber's heat transfer coefficient (8.39 % heat exchange capacity increase), with system-wide enhancements including 11.3 % higher heating capacity (41.5 kW–46.2 kW) and 14.2 % improved COP (2.95–3.37). These results establish a novel design paradigm for high-efficiency ASHPs, offering a robust solution to enhance heating performance in cold climates and advance sustainable energy transitions.