Final test results for the ground operations demonstration unit for liquid hydrogen

摘要

Highlights?The GODU LH2 system has completed the initial round of functional tests using an Integrated Refrigeration and Storage method to remove heat from a cryogenic storage system.?The system behavior depends on the capacity of the refrigerator compared to the heat leak of the tank. These tests have successfully demonstrated the three primary objectives, zero loss storage and transfer, propellant densification, and hydrogen liquefaction.?A zero loss chilldown and three zero loss tanker offloads successfully proved the capability to perform zero loss cryogenic transfers. Three different zero boil off storage methods were tested at various fill levels to show the system capability for indefinite zero boil off storage.?Most promising is the ZBO method using tank pressure as the control variable, as the system demonstrated the ability to control the liquid to essentially any point along the saturation line.?This testing also demonstrated the ability to reliably produce large quantities of densified hydrogen down to the triple point.AbstractDescribed herein is a comprehensive project—a large-scale test of an integrated refrigeration and storage system called the Ground Operations and Demonstration Unit for Liquid Hydrogen (GODU LH2), sponsored by the Advanced Exploration Systems Program and constructed at Kennedy Space Center. A commercial cryogenic refrigerator interfaced with a 125,000?l liquid hydrogen tank and auxiliary systems in a manner that enabled control of the propellant state by extracting heat via a closed loop Brayton cycle refrigerator coupled to a novel internal heat exchanger. Three primary objectives were demonstrating zero-loss storage and transfer, gaseous liquefaction, and propellant densification. Testing was performed at three different liquid hydrogen fill-levels. Data were collected on tank pressure, internal tank temperature profiles, mass flow in and out of the system, and refrigeration system performance. All test objectives were successfully achieved during approximately two years of testing. A summary of the final results is presented in this paper.]]>