Modeling of a stand-alone liquid air energy storage

Sammanfattning: The aim of this project was to create a model of the stand-alone LAES for use in future work at Siemens Industrial Turbomachinery (SIT). The model was created in IPSEpro with components developed from the software's standard library of power plant components. Required fluid properties were obtained from the Refprop DLL. This was accessed through the development of a DLL, functioning as a link between IPSEpro and the Refprop DLL. The model of the LAES was created from the plant layout proposed by Guizzi et al. (2015), along with presented stream data. Simulations with the final model showed relatively small deviations in stream data and round-trip efficiency when compared to the reference. A test case was conducted to evaluate the model's capability of handling an off-design scenario with boil-off in the liquid air tank. The result showed that to compensate for the lost mass of liquid air the round-trip efficiency would be reduced from 53,23% to 50% over a stand-by duration of approximately ten days. The way the system compensated for the limited amount of cold energy by increasing the total compression ratio to maintain the rated capacity was considered reasonable. It could be concluded that the model could be useful for further evaluation of the energy storage system, but depending on the scenarios of interest, more development of the model may be necessary.