Computationally Efficient Numerical Modelling of LiBr-H2O and H2O-NH3 in Single Effect, Double Effect and Double Lift Absorption Refrigeration Configurations Using Open-Source Tools

Absorption chillers offer an alternative to the electricity intense compression chillers and can play an important part in the transition to renewable energy systems by allowing for a sector coupling of heating and cooling. This work aims at providing a detailed description of the numerically efficient modelling of the fundamental cycle configurations single effect, double effect and double lift with the two most prominent working fluids LiBr-H2O and H2O-NH3. The modelling approach bases on energy and mass balances for all heat exchangers and simplifying assumptions for the solution and refrigerant states. With the detailed description of the solution procedure for the development of such models this work offers a reproducible, Open-Source platform for the discussion of modelling aspects and details for absorption chiller modelling. The models calculate all relevant internal solution and refrigerant state points and can be used with state of the art optimization methods for absorption chiller design, control and cost calculation. A detailed description of the model structure as well as the solution procedure is given. The modelling approach is validated with simulative and experimental data from the literature. For the investigated boundary conditions and model input parameters the single effect model achieves a maximal theoretical COP of 0.91 and 0.84, the double lift model generally has a lower efficiency with maximal COP values of 0.47 and 0.44 while the double effect model shows maximal COPs of 1.49 and 1.39 for LiBr-H2O and H2O-NH3 respectively. All models and the formulations for the calculation of refrigerant and solution state properties are published via the GitHub platform and available as MATLAB and Python Code.     «

Absorption chillers offer an alternative to the electricity intense compression chillers and can play an important part in the transition to renewable energy systems by allowing for a sector coupling of heating and cooling. This work aims at providing a detailed description of the numerically efficient modelling of the fundamental cycle configurations single effect, double effect and double lift with the two most prominent working fluids LiBr-H2O and H2O-NH3. The modelling approach bases on ener...     »