Speaker
Description
Abstract: Liquid-oxygen-liquid-methane reusable rocket technology is currently a hot topic in the field of spaceflight. Storage of liquid methane and liquid oxygen in a single tank but with a common bulkhead partition is the most compact and favorable scheme. Reduced or even zero boil-off loss of the cryogenic bipropellants is one of the key endeavors for prolonging the storage duration and extending the transport capability. Usually, two cryogens with different saturation temperatures are separated by a partition made of some low-conductivity materials or insulation structures, which creates difficulties in the processing and manufacturing of the tank. Instead of keeping the pressure on bilateral chambers close to each other, an idea is proposed to have the partition made of the same metal as the main body of the tank, which turns out a temperature equilibrium result on both sides. To explore the feasibility of the new scheme, a small-scale storage system with a stainless-steel common bulkhead tank is designed and established, and is tested by measuring the transient thermodynamic behavior of the liquid oxygen and liquid methane on both sides during the self-pressurization and venting processes. In addition, the testing rig allows supplying cooling power to a shield surrounding the tank, which enables zero boil-off of the liquid oxygen and liquid methane. Experiments show that zero boil-off storage of both liquid oxygen and liquid methane can be easily realized at a common temperature of 105.8 K, with a 3.17 W cooling power provided. However, the pressures in the liquid oxygen and liquid methane chambers are 399.36 kPa and 67.86 kPa respectively (Scheme 1), which means a large pressure difference between the two sides, and even worse a vacuum state in the methane chamber. Consequently, helium is charged into the liquid methane chamber as a non-condensable gas to increase its pressure (Scheme 2). The thermodynamic behavior of the fluids during the self-pressurization and venting process are recorded again and compared with that in Scheme 1. The results indicate that Scheme 2 significantly prolongs the storage duration, with a 64.91% increase in self-pressurization and venting time on the liquid oxygen side, and a 20.26% increase on the liquid methane side, compared with Scheme 1 with the same filling ratio and boundary conditions.
Keywords: common bulkhead storage, zero boil-off, self-pressurization and venting, helium gas
| Submitters Country | China |
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