EXPERIMENTAL EVALUATION OF DEWAR VOLUME AND COLD FINGER SIZE IN A STIRLING CRYOCOOLER LIQUID AIR ENERGY STORAGE (LAES) SYSTEM

Abstract

This paper uses an experimental approach to evaluate two design characteristics for a liquid air energy storage (LAES) and generation system as part of the verification and validation of system component design for a microgrid power system. The LAES subsystem evaluated utilized a Stirling engine–based cryocooler that employs a cold finger placed into Dewar, which allows the pumping of heat out of a Dewar. As the heat is pumped out, the air temperature in the Dewar cools to below the condensation point and the air in the Dewar liquifies and is stored in the Dewar. Using a design of experiments, the cold finger surface area and Dewar volume were evaluated to determine the criticality and significance of changing their dimensions on the total liquid air production mass and average liquid air production rate during the experiments. This analysis found that changing the surface area of the cryocooler cold finger was a statistically significant design characteristic that affected total liquid air production and average production rate while changing the volume of the Dewar was not statistically significant. Additional responses relative to the time when the first gram of liquid air was produced and the minimum cold tip temperature that the cryocooler was able to achieve provided additional insight into design characteristics that can be used to inform the engineer when making design tradeoffs for specific microgrid operational environments.