Comparative Assessment of Property Correlations for LiNO3/NH3 Solution in Absorption Chiller Modeling

Accurate thermodynamic property correlations are crucial for the modeling and performance analysis of absorption refrigeration systems. For the ammonia/lithium nitrate (LiNO3/NH3) working pair (a promising fluid for sustainable cooling) several correlations have been proposed in the literature. This study presents a comparative assessment of existing correlations for LiNO3/NH3 across five key thermodynamic properties (vapor-liquid equilibrium, density, dynamic viscosity, specific heat capacity and enthalpy) and, for enthalpy specifically, by quantifying through a dedicated case study and sensitivity analysis how the resulting discrepancies propagate to the performance predictions of a single-effect absorption cycle. For equilibrium pressure, significant discrepancies are identified at low ammonia mass fractions (x ≈ 0.3), where predictions can vary by 20–50%. Density and specific heat capacity correlations show good agreement with experimental data (<6% deviation), whereas a significant divergence (>90% in some cases) is found for dynamic viscosity, raising concerns about the reliability of available models. The impact of selecting different solution enthalpy correlations on cycle performance was evaluated through a case study, revealing excellent agreement between all these correlations, with overall robust Coefficient of Performance (COP) and main heat exchanger duties (deviations < 2%). Furthermore, sensitivity analysis shows that the thermal power in the absorber and desorber is driven primarily by the refrigerant’s enthalpy flow (79–97%), with the solution’s enthalpy flow playing a significantly smaller role. This work underscores the importance of carefully selecting property correlations and provides practical guidance to improve the accuracy and reliability of simulations for LiNO3/NH3 absorption systems. To prevent implementation errors, we recommend that future correlation studies include brief validation tables with sample calculations to verify unit consistency and sign conventions.