Cryogenic Probe Vacuum Exhaust for Faster Cooling
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Solution Overview
Problem
Current cryosurgery systems, particularly liquid cryogenic systems, face challenges such as inefficient cooling due to phasing issues, high costs, and the need for single-use probes, as well as limited cooling capacity and long setup times.
Innovation Solution
The implementation of a cryogenic system that utilizes a vacuum source to draw liquid cryogen to the probe, eliminating the need for high-pressure gases and incorporating a dispersive medium within the probe to enhance cooling efficiency, along with a concentric insulating and exhaust conduit design to manage boil-off gas effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If liquid nitrogen is pressurised to encourage faster cooling of the feed lines, then cooling speed is improved, but system complexity increases and phasing issues worsen
Solution Approach 1:
Instead of pressurizing the liquid nitrogen feed to accelerate cooling, the patent applies vacuum to the exhaust line to draw cryogen through the system. This inverted approach (using suction rather than pressure) achieves faster cooling without the complexity of pressure control systems and eliminates phasing issues by maintaining atmospheric or sub-atmospheric pressure throughout the feed line.
Solution Approach 2:
The patent extracts the problematic pressurization step from the system and replaces it with vacuum application at the exhaust end. By removing the need for pressurized feed, the system eliminates the associated complexity and phasing problems while maintaining effective cooling performance.
2Temperature
If Joule-Thompson devices are used to achieve low temperatures, then temperature is improved, but cooling capacity is limited
Solution Approach 1:
The patent utilizes the phase transition of liquid nitrogen to gas (evaporation) as the primary cooling mechanism. When liquid nitrogen evaporates, it absorbs latent heat of vaporization, providing vastly superior cooling capacity compared to the Joule-Thompson effect. This phase change process occurs naturally in the probe tip where the liquid nitrogen is delivered, creating effective cooling without requiring high-pressure gas expansion devices.
3Temperature
If high pressure gas is used in Joule-Thompson devices, then cooling is achieved, but safety risks increase
Solution Approach 1:
The patent replaces the mechanical high-pressure gas expansion system with a vacuum-based liquid evaporation system. Instead of using high-pressure nitrogen oxide gas that requires containment and poses safety risks, the system uses atmospheric or vacuum conditions with liquid nitrogen that evaporates to provide cooling. This substitution eliminates the safety hazards associated with high-pressure gas while maintaining effective cooling performance.
4Productivity
If liquid cryogenic systems are used to achieve superior heat absorption, then cooling capacity is improved, but setup time increases due to phasing
Solution Approach 1:
The patent inverts the traditional approach by applying vacuum at the exhaust end rather than pressurizing the feed end. This causes the liquid nitrogen to be drawn through the system by suction, which accelerates the cooling of feed lines and eliminates phasing delays. The vacuum application creates a pressure gradient that promotes continuous, smooth flow of liquid nitrogen without the phasing problems that cause delays in traditional pressurized 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
This approach enables faster and more efficient cooling, reduces the need for multiple probes, allows for reusable components, and shortens treatment times, improving safety and reducing costs.
Implementation Method 1
a vacuum source configured such that it can suck or draw the liquid cryogen to the probe
Implementation Method 2
Liquid cryogenic devices rely on evaporation of a liquid, such as liquid nitrogen or helium, to produce cooling by boiling and/or evaporation
Implementation Method 3
the cryogenic liquid boils and/or evaporates. When liquid nitrogen boils and/or evaporates the phase change results in an approximately 700 fold increase in volume
Implementation Method 4
the latent heat of vaporisation for most cryogenic fluids commonly used in liquid cryogenic systems is significantly greater than the heat absorbed by the expanding gas(es) commonly used within Joule-Thompson systems
Implementation Method 5
a dispersive medium configured such that, in use, cryogen delivered to the probe disperses within the probe through the dispersive medium
Implementation Method 6
concentric insulating and exhaust conduit design to manage boil-off gas effectively
Data Source
AI summary
An apparatus, probe and method for a cryogenic system are described. According to certain embodiments of the invention there is provided an apparatus for cryosurgery comprising: an exhaust line configured to receive cryogen from a probe; and a vacuum source configured to be in fluid communication with the exhaust line.