Properties of Humid Air for Calculating Power Cycles

Accurate calculation algorithms for the thermodynamic and transport properties of humid air are required for modeling compressed air energy-storage power cycles and designing their individual components. The development of such algorithms was part of the Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) project, which had been supported by the European Commission. To obtain the statements of this paper, all available experimental data and new experimental data generated within the AA-CAES project were used as basis for comparisons between the different models for thermodynamic and transport properties. As a result, one model for calculating thermodynamic and one model for transport properties of humid air in AA-CAES cycle design and operation is recommended. Their application is possible for wide ranges of temperature from 243 K up to 2000 K, total pressure from 0.611 kPa up to 100 MPa, and water content up to 10% mass fraction with some restrictions concerning the calculation of viscosity $η$ and thermal conductivity $λ$ (up to 1000 K for both and up to 40 MPa for $λ$⁠). These models have been implemented into a property library, which meets the requirements of programs for calculating compressed air energy-storage cycles. The developed property library can be used for the daily work of an engineer who calculates such cycles. The results summarized in this paper have been used for preparing Section 6, “Real Gas” of the ASME Report No. STP-TS-012, “Thermophysical Properties of Gases used in Working Gas Turbine Applications.”