THEORETICAL, EXPERIMENTAL, AND ANALYTICAL EXAMINATION OF SUBCOOLED AND SOLID HYDROGEN

Abstract : Methods were investigated, both theoretically and experimentally, for production of liquid-solid mixtures of hydrogen ('hydrogen slush'). Small scale experiments were conducted to determine the feasibility of a number of techniques; the practicability and costs for these methods were determined theoretically. The theoretical analyses showed that techniques for producing hydrogen slush by vacuum pumping appeared most practical in view of capital investment and operating costs. Injection of cold helium gas was determined to be the most promising method for upgrading the solid content of slush mixtures after transfer to flight vehicle tankage. The theoretical analyses were verified within expectable error by large scale experiments in a low heat leak apparatus that permitted visual observation of experiments through a periscopic device. Liquid-solid hydrogen mixtures were produced having solid contents ranging from 20 percent to 55 percent. A number of characteristics were noted which varied with the production techniques used and with attempts to upgrade the quality of the slush produced. Some mixtures were flowable, and others were not.