Coiled Cryogen Tube Phase Separation
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Solution Overview
Problem
Cryosurgical instruments face inefficiencies in heat exchange due to minimal temperature differential between inlet and outlet cryogen fluids when cryogen is supplied in liquid or two-phase form, leading to reduced heat exchange effectiveness.
Innovation Solution
A cryosurgical instrument design that utilizes a coiled tube as both a cryogen delivery and phase separator, leveraging centrifugal force to separate cryogen into liquid and gaseous phases, enhancing heat exchange by forcing the heavier liquid phase against the outer wall, and incorporating a return tube that spirals around the core to promote phase separation and efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cryogen is supplied as liquid or two-phase form, then cooling capacity is increased, but heat exchange effectiveness is reduced due to minimal temperature differential
Solution Approach 1:
The patent segments the cryogen flow into distinct liquid and gaseous phases using a phase separator. The liquid phase is directed to contact the outer surface for maximum cooling, while the gaseous phase flows through the interior. This segmentation resolves the contradiction by ensuring the liquid phase (which provides cooling capacity) is optimally positioned without compromising heat exchange effectiveness through proper phase separation and flow management.
Solution Approach 2:
The patent applies local quality by creating different flow conditions in different regions of the delivery tube. The liquid phase is concentrated at the outer surface where cooling is needed, while the gaseous phase occupies the interior region. This localized differentiation allows the system to maintain both high cooling capacity at the surface and effective heat exchange through the temperature differential in the gaseous phase.
2Stability of the object's composition
If coiled tube is used as phase separator, then phase separation is enhanced by centrifugal force, but device complexity increases
Solution Approach 1:
The coiled delivery tube serves multiple functions simultaneously: it delivers the cryogen mixture, acts as a phase separator using centrifugal force generated by its coil geometry, and provides thermal exchange pathways. This multi-functionality resolves the contradiction by achieving effective phase separation without requiring additional separate components, thereby maintaining device simplicity while enhancing phase separation capability.
Solution Approach 2:
The patent utilizes the curved/coiled geometry of the delivery tube to generate centrifugal force that separates phases. The curvature of the coil creates the necessary radial acceleration to push the heavier liquid phase outward while the gaseous phase remains toward the center. This geometric solution achieves phase separation without complex mechanical separators.
3Temperature
If liquid phase contacts outer surface, then cooling effectiveness is increased, but heat exchange between inlet and outlet fluids is minimized
Solution Approach 1:
The patent segments the two-phase cryogen flow into distinct liquid and gaseous phases, with the liquid phase directed to the outer surface for cooling and the gaseous phase flowing through the interior. This segmentation allows the system to maximize cooling effectiveness through liquid contact while the gaseous phase maintains temperature differential for heat exchange, resolving the apparent contradiction between these two functions.
Solution Approach 2:
The patent utilizes the different physical properties of liquid and gaseous phases (hydraulic behavior of liquid, pneumatic behavior of gas) to achieve functional separation. The liquid phase, being denser, is forced to the outer surface where it provides cooling, while the gaseous phase flows through the interior maintaining thermal exchange. This exploitation of phase differences resolves the contradiction between cooling effectiveness and heat exchange efficiency.
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 design significantly enhances heat exchange efficiency by ensuring the liquid phase is in contact with the outer surface, increasing the cooling capacity and effectiveness of the cryosurgical procedure.
Implementation Method 1
A cryosurgical instrument design that utilizes a coiled tube as both a cryogen delivery and phase separator, leveraging centrifugal force to separate cryogen into liquid and gaseous phases, enhancing heat exchange by forcing the heavier liquid phase against the outer wall
Implementation Method 2
In such heat exchangers, the expansion of the gas causes it to change its temperature. As explained in U.S. Pat. No. 6,706,037, for example, this phenomenon is referred to as the 'Joule-Thomson effect' and is thermodynamically known as adiabatic expansion.
Implementation Method 3
a coiled tube that serves as both a cryogen delivery tube and a phase separator that separates cryogen into liquid and gaseous phases... in energy exchange contact with the outer wall of a portion of a cryosurgical instrument
Data Source
AI summary
A cryosurgical instrument including: a core, a cryogen delivery tube, a cryogen return tube, and a shaft surrounding the core and the tubes. The shaft has a pointed distal end and a proximal end adapted and configured to receive an inflow of cryogen and to exhaust a flow of expanded cryogen. The cryogen delivery tube and the cryogen return tube both have respective helical portions that spiral around the core. The helical portions of the tubes are in fluid tight contact with the core and an inner surface of the shaft. The helical portions of the tubes spiral about the core in an alternating arrangement such that they alternate along a length of the core. The core and the helical portions of the delivery tube and the return tube comprise centrifugal phase separators.