System for preparing deeply subcooled liquid oxygen based on mixing of liquid oxygen and liquid nitrogen and then vacuum-pumping

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Solution Overview

Problem

The traditional vacuum-pumping method for deeply subcooling liquid oxygen is energy-intensive due to its low triple point temperature and saturation pressure, limiting its subcooling efficiency and increasing costs, while existing methods like helium bubbling are costly and inefficient.

Innovation Solution

A system that mixes liquid oxygen and liquid nitrogen, leveraging their phase equilibrium to achieve a lower eutectic point temperature and higher saturation pressure, allowing for deeper subcooling of liquid oxygen at lower vacuum-pumping costs, using a secondary and primary subcooler with a vacuum multilayer heat-insulated pipeline and a pumping-out device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the traditional vacuum-pumping method is used to deeply subcool liquid oxygen to its triple point temperature, then the subcooling degree is improved, but the energy consumption and vacuum-pumping cost increase significantly

Engineering Contradiction:
Improvesubcooling degree of liquid oxygenVSAvoidenergy consumption of vacuum-pumping
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The patent introduces liquid nitrogen as an intermediary cooling medium. Instead of directly vacuum-pumping liquid oxygen to achieve subcooling, the system uses liquid nitrogen (cooled to its triple point) as a heat sink to extract heat from liquid oxygen, achieving the desired subcooling effect with much lower vacuum requirements and energy consumption.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical vacuum-pumping process with a thermal heat-exchange process. By substituting the mechanical removal of vapor with a thermal coupling approach using liquid nitrogen, the system achieves subcooling without the high energy costs associated with maintaining deep vacuum conditions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If liquid nitrogen is evacuated to its triple point to subcool liquid oxygen, then the subcooling efficiency is improved, but the saturation pressure remains too high to achieve deep subcooling below 63.2 K

Engineering Contradiction:
Improvesubcooling temperature of liquid oxygenVSAvoidsaturation pressure of liquid nitrogen
Core Design Contradiction:
TemperatureVSStress or pressure

Solution Approach 1:

The patent applies preliminary cooling to liquid nitrogen, evacuating it to its triple point (63.2 K) first. This pre-cooled liquid nitrogen then serves as an ultra-cold heat sink, enabling liquid oxygen to be cooled below its own triple point temperature through heat exchange, overcoming the pressure limitation.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables liquid oxygen to be subcooled to its triple point temperature at a lower cost, maximizing subcooling efficiency by utilizing the cold energy of the gas mixture and reducing the pumping-out device's performance requirements, primarily consuming nitrogen over oxygen.

Implementation Method 1

mixes liquid oxygen and liquid nitrogen, leveraging their phase equilibrium to achieve a lower eutectic point temperature and higher saturation pressure

Methodology Applied
Scientific EffectPhase equilibrium:

Implementation Method 2

vacuum-pumping method can subcool the cryogenic working medium to a temperature near the triple point with a readily-available device and low cost

Methodology Applied
Scientific EffectVacuum-pumping:

Implementation Method 3

utilizing the cold energy of the gas mixture and reducing the pumping-out device's performance requirements

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS11262124B2System for preparing deeply subcooled liquid oxygen based on mixing of liquid oxygen and liquid nitrogen and then vacuum-pumping
Publication Date: 2022.03.01 XI AN JIAOTONG UNIV
  • US11262124B2 patent drawing

AI summary

A system for preparing subcooled liquid oxygen based on mixing of liquid oxygen and liquid nitrogen and then vacuum-pumping, including atmospheric-pressure saturated liquid nitrogen and oxygen tanks. An inlet of the liquid nitrogen tank communicates with pressurized gas, and an outlet is connected to an inlet a of a secondary subcooler. An inlet of the liquid oxygen tank communicates with the pressurized gas, and a first outlet is connected to an inlet b of the secondary subcooler. An outlet c of the secondary subcooler is connected to an inlet d of a primary subcooler. An outlet e of the primary subcooler is connected to a pumping-out device through a rewarming device. A second outlet of the liquid oxygen tank is connected to an inlet n of the primary subcooler. An outlet o of the primary subcooler is connected to an inlet r of the secondary subcooler.