Cryogenic Fuel Sub-Cooler Design for Density Control During Refueling
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Solution Overview
Problem
Existing refueling systems for cryogenic fuel tanks fail to control the temperature and density of cryogenic fuels, leading to potential catastrophic damage and inefficient use of tank volume due to high saturated pressures during refueling.
Innovation Solution
A sub-cooler system that includes a first valve to separate the cryogenic fuel into primary and auxiliary flowlines, a second valve to reduce saturated pressure, a cryogenic heat exchanger to transfer heat, and a controller to regulate the temperature and flow rates, thereby reducing the temperature and increasing the density of the fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cryogenic fuel is supplied at high temperature, then the tank volume can be larger, but the density decreases leading to catastrophic damage risk
Solution Approach 1:
The sub-cooler performs preliminary cooling of the cryogenic fuel before it enters the onboard tank. By pre-cooling the fuel to a lower temperature (e.g., from 20K to 10K), the system ensures the fuel is at the optimal temperature for dense packing before refueling begins, preventing temperature-related safety issues during the refueling process
Solution Approach 2:
The system changes the temperature parameter of the cryogenic fuel by introducing a sub-cooler that actively reduces the fuel temperature below its normal storage temperature. This parameter change from ambient cryogenic temperature to sub-cooled temperature increases density and reduces saturated pressure, resolving the safety contradiction
2Volume of stationary object
If cryogenic fuel density is increased through sub-cooling, then the onboard tank volume can be reduced, but the system complexity increases
Solution Approach 1:
The sub-cooler utilizes phase transition principles by causing partial vaporization of the cryogenic fuel during the cooling process. The vapor-liquid equilibrium state allows for efficient heat transfer and temperature reduction, achieving density increase while managing the added system complexity through controlled phase change
Solution Approach 2:
The sub-cooler acts as an intermediary device between the fuel supply and the onboard tank. It mediates the temperature and density characteristics of the fuel, providing a buffer that allows the main refueling system to operate without direct exposure to the extreme conditions required for high-density fuel storage
3Device complexity
If the cryogenic fuel temperature is not controlled, then the refueling system is simpler, but the mass control precision decreases
Solution Approach 1:
The sub-cooler system incorporates feedback control mechanisms that monitor the temperature and density of the cryogenic fuel during refueling. By continuously measuring these parameters and adjusting the cooling rate accordingly, the system achieves precise mass control while managing the complexity through automated feedback loops
Solution Approach 2:
The system replaces manual or mechanical temperature control methods with thermodynamic-based sub-cooling mechanisms. By utilizing the inherent thermal properties of cryogenic fluids and controlled heat exchange processes, the system achieves precise mass control through physical laws rather than complex mechanical control systems
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
The system effectively reduces the temperature and increases the density of cryogenic fuels, allowing for smaller onboard tanks and precise mass control, enhancing safety and efficiency in vehicles like hydrogen aircraft.
Implementation Method 1
a cryogenic heat exchanger to reduce the first temperature of the cryogenic fuel in the primary flowline by transferring heat from the primary flowline to the auxiliary flowline
Implementation Method 2
a second valve to reduce the saturated pressure of the cryogenic fuel in the auxiliary flowline by reducing a saturated pressure in the auxiliary flowline
Implementation Method 3
a flexible vacuum jacketed flowline between the supply tank and the onboard cryogenic fuel tank
Data Source
AI summary
A sub-cooler for a sub-cooling cryogenic refueling system is disclosed herein. The sub-cooler includes a first valve to separate flowing cryogenic fuel into a primary flowline and an auxiliary flowline, a second valve to reduce the saturated pressure and temperature of the cryogenic fuel in the auxiliary flowline, a cryogenic heat exchanger to transfer heat from the primary flowline to the auxiliary flowline, a temperature sensor to measure the temperature of the sub-cooled cryogenic fuel in the primary flowline, and a sub-cooler controller to control the effective areas of the primary flowline inlet and the auxiliary flowline inlet at the first valve.