Subcooled Cryogen Delivery via Baffled Linear Heat Exchanger
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Solution Overview
Problem
Current cryotherapy methods for treating diseases like prostate, kidney, and cardiovascular issues face inefficiencies in delivering and circulating liquid cryogen to cryoprobes, leading to prolonged treatment times, increased hospitalization, and higher costs.
Innovation Solution
A cryogenic medical device with a closed system that includes a vacuum insulated dewar, submersible cryogen pump, baffled linear heat exchanger, and return chamber, allowing for subcooling and efficient circulation of liquid cryogen to cryoprobes, with adjustable pressure vents and control valves for safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid cryogen is circulated through passive heat exchanger coils in a cryogen bath, then subcooling of the cryogen is achieved, but the process is time-consuming and inefficient
Solution Approach 1:
The patent replaces passive thermal diffusion-based heat exchange with an active mechanical pumping system. A pump circulates liquid cryogen through a heat exchanger, enabling controlled and efficient subcooling before delivery to the probe, thereby reducing treatment time while achieving the required temperature reduction.
Solution Approach 2:
The invention utilizes hydraulic principles by implementing a fluid pumping system to actively circulate liquid cryogen through the heat exchanger and delivery lines. This hydraulic approach enables precise control of cryogen flow and enhances heat transfer efficiency, resolving the time-consuming nature of passive subcooling methods.
2Productivity
If moderate to high pressure is applied to the entire system or piston/bellows compression is used to drive fluid movement, then liquid cryogen circulation is achieved, but system complexity and cost increase
Solution Approach 1:
The patent extracts the compression function from the entire system and isolates it to a localized pump mechanism positioned at the heat exchanger inlet. This eliminates the need for system-wide high-pressure components and piston/bellows assemblies, reducing overall device complexity while maintaining effective cryogen circulation.
Solution Approach 2:
The invention introduces a pump as an intermediary device between the cryogen storage and the delivery system. This intermediary component enables controlled fluid movement without requiring complex compression mechanisms throughout the entire system, thereby simplifying the overall design while achieving the desired productivity.
3Temperature
If coil heat exchangers are placed into a bath of cryogen for passive subcooling, then cryogen cooling is achieved, but activation of these devices requires circulating cryogen to create a heat sink, resulting in tissue freezing
Solution Approach 1:
The patent applies preliminary action by pre-cooling the liquid cryogen in a heat exchanger before it reaches the probe. This advance cooling eliminates the need for complex activation sequences where cryogen must be circulated to create a heat sink, thereby simplifying device operation and enabling direct tissue freezing upon activation.
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
Facilitates faster and more effective tissue freezing, reducing treatment time, hospitalization duration, postoperative morbidities, and overall costs, while enabling the treatment of multiple disease states with improved device design and functionality.
Implementation Method 1
The linear heat exchanger comprises a tube-within-a-tube whereby a vacuum is applied to the outer chamber to subcool an isolated reservoir of liquid cryogen
Implementation Method 2
The device comprises a number of parts including a vacuum insulated outer dewar
Implementation Method 3
The outer dewar comprises a submersible rotary pump to drive liquid cryogen through the baffled linear heat exchanger
Implementation Method 4
The inner chamber comprises a series of baffles and a central spiral to increase the flow path of the liquid cryogen while providing for increased contact based surface area with the outer chamber to allow for more effective heat transfer
Data Source
AI summary
A cryogenic medical device for delivery of subcooled liquid cryogen to various configurations of cryoprobes is designed for the treatment of damaged, diseased, cancerous or other unwanted tissues. The device is a closed or semi-closed system in which the liquid cryogen is contained in both the supply and return stages. The device comprises a number of parts including a vacuum insulated outer dewar, submersible cryogen pump, baffled linear heat exchanger, return chamber, and a series of valves to control the flow of the liquid cryogen. The cryogenic medical device promotes the subcooling to any external cryogenic probe.