Two-Stage Cryogen Cooling Using Venturi Pump for Superconducting Cable
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Solution Overview
Problem
Existing cryogen cooling systems for superconducting cable systems and cryogen transport are complex, costly, and inefficient, especially over long distances, due to high heat loads and the need for frequent intermittent cooling stations.
Innovation Solution
A two-stage cryogen cooling system utilizing a sub-cooler pump, such as a venturi pump, to reduce pressure and effect cooling, combined with a second heat exchanger using gaseous exhaust cryogen for additional thermal management, thereby simplifying the cooling process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If forced flow cooling systems are used to maintain cryogenic temperatures over long distances, then cooling capacity is achieved, but system complexity and operational costs increase significantly
Solution Approach 1:
The patent replaces complex mechanical forced flow cooling systems with a passive evaporative cooling system. Instead of using pumps, valves, and active cooling stations, the invention utilizes the natural evaporative cooling effect where cryogen evaporates in the insulation space, absorbing heat and maintaining temperature passively throughout the pipeline length.
Solution Approach 2:
The system uses the cryogen itself to provide cooling through evaporation. The evaporating cryogen in the insulation space creates a cold atmosphere that cools the pipeline and its contents without requiring external cooling equipment. The system serves itself by using the working fluid's phase change to maintain the required temperature regime.
2Temperature
If intermittent cooling stations are deployed along the pipeline, then temperature control is maintained, but operational costs and maintenance overheads increase
Solution Approach 1:
The evaporative cooling provides continuous temperature control along the entire pipeline length without interruption. The cold atmosphere generated by evaporation in the insulation space continuously absorbs heat ingress, maintaining stable cryogenic temperatures throughout the pipeline without requiring periodic intervention from cooling stations.
Solution Approach 2:
The invention extracts and eliminates the need for intermittent cooling stations entirely. By implementing evaporative cooling in the insulation space, the system removes the requirement for external cooling equipment distributed along the pipeline, thereby eliminating their operational and maintenance costs.
3Productivity
If increased flow rates and system pressures are used to convey cryogen over extended distances, then transport capacity is improved, but heat load due to frictional heating increases
Solution Approach 1:
The patent converts the harmful effect of heat ingress into a beneficial cooling mechanism. The heat that would normally raise temperatures is instead absorbed by the evaporating cryogen in the insulation space, which uses the latent heat of vaporization to maintain cold temperatures. The cold atmosphere created by evaporation actively counteracts heat ingress from the environment.
4Temperature
If sub-cooling equipment and pumping equipment are added to increase cooling capacity, then temperature control improves, but system complexity increases
Solution Approach 1:
The invention exploits the phase transition of cryogen from liquid to vapor in the insulation space. This evaporative phase change absorbs heat and creates a cold atmosphere that provides cooling throughout the pipeline. The phase transition occurs naturally without requiring external sub-cooling equipment, providing enhanced cooling capacity through a passive physical process.
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 achieves efficient two-stage cooling of cryogenic fluids, reducing the need for complex equipment and intermittent cooling stations, thus lowering operational costs and improving reliability, especially in challenging environments like subsea or subterranean settings.
Implementation Method 1
a sub-cooler pump operable to reduce pressure within the cooling chamber in order to effect cooling of the passing cryogen
Implementation Method 2
the sub-cooler pump has an exhaust line in fluid communication with a second lumen of the cryostat
Data Source
AI summary
The present invention provides a two stage cryogen cooling system for particular use in cooling a cryogen employed in a superconducting power transmission cable, the cooling system employing a sub-cooler pump such as a venturi pump to effect both cooling stages, the first cooling stage being the cooling of the liquid cryogen flowing through an inner lumen of a cryostat of the cooling system and the second stage being the generation of a supply of gaseous cryogen for supply to a second lumen of the cryostat surrounding the inner lumen.