Cryogenic Temperature Controller Using Liquid Nitrogen Heat Sink
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Solution Overview
Problem
Current methods for controlling temperatures for Argon analysis are inefficient and costly, particularly due to the limited availability and high cost of liquid Argon, as well as the limitations of existing cryostats and compression cryocoolers.
Innovation Solution
A cryogenic temperature controller using a thermostatic block with high thermal conductivity, surrounded by insulation, and a heat sink partially immersed in a cryogenic fluid like liquid Nitrogen, allowing for precise temperature control and extended analysis duration with minimal cost impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid Argon is used for analysis, then the analysis can be performed at 87K temperature, but the cost and availability become problematic
Solution Approach 1:
The patent introduces an intermediary substance (liquid nitrogen) and a thermal conduction medium (metal block) to transfer the cooling effect. Instead of directly using liquid argon on the sample, the system uses liquid nitrogen to cool a metal heat sink, which then conducts the cold to the sample holder, enabling argon analysis at 87K without requiring liquid argon
Solution Approach 2:
The patent replaces expensive liquid argon with cheap liquid nitrogen as the cooling medium. Liquid nitrogen is significantly more abundant and less costly than liquid argon, while still achieving the required 87K temperature through proper thermal conduction design with high-conductivity metal blocks and direct contact heat transfer
2Temperature
If a cryostat is used to control Argon temperature, then the target temperature can be maintained, but the duration is limited and cost is high
Solution Approach 1:
The patent extracts the temperature control function from a complex, expensive cryostat system and implements it using simple, passive thermal conduction principles. By removing the sample holder directly into liquid nitrogen and using a metal block for heat conduction, the system eliminates the need for active cryostat control mechanisms while maintaining temperature stability for extended periods
Solution Approach 2:
The system uses passive thermal conduction through high-conductivity metal blocks and direct immersion in liquid nitrogen to automatically maintain temperature without requiring active control systems. The thermal equilibrium is self-regulating, allowing prolonged analysis duration without external intervention or expensive cryostat equipment
3Temperature
If a compression cryocooler is used, then temperature control is achieved, but the system cost becomes very high
Solution Approach 1:
The patent replaces complex mechanical compression cryocooler systems with a simple thermal conduction-based cooling system. Instead of using moving parts, compressors, and active refrigeration cycles, the system uses static high-conductivity metal blocks in direct contact with liquid nitrogen to achieve and maintain the required temperature, dramatically reducing system complexity and cost
4Loss of energy
If the heat sink is completely covered by insulation, then heat loss is reduced, but the cooling capacity decreases
Solution Approach 1:
The patent applies insulation selectively rather than uniformly. The sample holder and surrounding areas are insulated to reduce heat loss, while the heat sink surfaces that need to contact liquid nitrogen remain exposed. This localized insulation approach maintains cooling capacity at the critical interface while reducing parasitic heat losses elsewhere in the system
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 maintains stable sub-ambient temperatures for prolonged periods, enabling flexible and cost-effective analysis by regulating the temperature locally and reducing the need for expensive cryogenic fluids.
Implementation Method 1
a heat sink made with a material having a high thermal conductivity (thermal conductivity greater than 35 W/m*K)... The heat sink is, in turn, partially immersed in a cooling fluid
Implementation Method 2
surrounded by a thermal insulation material (preferably an insulation foam or a vacuum chamber or a combination of both with a thermal conductivity less than 1.1 W/ m*K)
Implementation Method 3
A heater is provided in the apparatus and is positioned between the thermostatic block and the portion of the heat sink in contact with the cooling fluid
Data Source
AI summary
A cryogenic temperature controller assembly includes a controller and a thermostatic block that has a chamber for receiving a sample holder therein. The thermostatic block has a heat sink with an exposed surface for exposure to a cryogenic fluid. A heater is disposed intermediate the exposed surface and the chamber. The heater is connected to the controller. A temperature probe is disposed in the thermostatic block. The probe is connected to the controller. The controller regulates the heater based on an actual temperature from the probe to maintain a predetermined set point temperature in the thermostatic block.