Cold Trap Temperature Control for Vacuum Evacuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cold traps face challenges in maintaining uniform temperature across the cold panel due to varying thermal conductivity in connection structures and increased heat input from vacuum vessels, leading to undesirable temperature differences.
Innovation Solution
A cold trap system incorporating a single-stage cryocooler with a stage temperature control unit, input heat estimation, and target temperature adjustment to manage the cooling process, ensuring the cold panel reaches and maintains a target temperature by adjusting the cryocooler's operating frequency based on estimated heat input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage cryocooler is used to cool the cold panel, then the device complexity is reduced, but the temperature uniformity across the cold panel deteriorates due to varying thermal conductivity in connection structures
Solution Approach 1:
The patent divides the cold panel into multiple temperature zones (first cold panel with first target temperature, second cold panel with second target temperature) and applies different cooling targets to different regions. This local quality approach compensates for the varying thermal conductivity in connection structures by adjusting the target temperature of each zone according to its specific thermal characteristics, thereby maintaining overall temperature uniformity despite using a simple single-stage cryocooler.
Solution Approach 2:
The patent dynamically adjusts the target temperature of the cold panel based on the operational state. The target temperature is determined by subtracting a temperature difference (calculated from heat input and thermal conductivity) from the set temperature. This dynamic adjustment allows the system to adapt to changing heat input conditions and maintain optimal temperature distribution across the cold panel.
2Reliability
If the target temperature is lowered to compensate for increased heat input from the vacuum vessel, then the condensation efficiency is improved, but the energy consumption of the cryocooler increases
Solution Approach 1:
The patent applies partial cooling adjustment by selectively lowering the target temperature only in specific zones where heat input is excessive, rather than uniformly lowering the temperature across the entire cold panel. The temperature difference is calculated based on the specific heat input and thermal conductivity of each zone, applying just enough additional cooling to maintain condensation efficiency while minimizing overall energy consumption.
Solution Approach 2:
The patent changes the target temperature parameter dynamically based on operational conditions. The target temperature is adjusted by subtracting a calculated temperature difference from the set temperature, where the temperature difference depends on the heat input and thermal conductivity. This parameter change allows the system to respond to varying heat input conditions while optimizing energy consumption.
3Reliability
If the target temperature is frequently adjusted to maintain optimal condensation, then the condensation efficiency is improved, but the control system complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the target temperature is continuously adjusted based on the calculated temperature difference. The control unit determines the target temperature by subtracting the temperature difference (derived from heat input and thermal conductivity measurements) from the set temperature. This feedback loop maintains optimal condensation efficiency while using a relatively simple control algorithm.
Solution Approach 2:
The patent performs preliminary calculation of the temperature difference based on known heat input and thermal conductivity parameters before adjusting the target temperature. By pre-calculating the required temperature adjustment, the control system avoids complex real-time adjustments and maintains simplicity while ensuring optimal condensation 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
The system effectively maintains the cold panel at a lower temperature than the cold panel upper limit, ensuring efficient condensation of high-boiling gases like water vapor, even with varying heat inputs, thereby enhancing the vacuum vessel's evacuation efficiency.
Implementation Method 1
a cryocooler which cools the cold panel
Implementation Method 2
A gas having a high boiling point such as water vapor is condensed on a surface of the cold panel
Implementation Method 3
The cold panel is cooled so as to reach a temperature at which a vapor pressure of the discharged gas sufficiently decreases
Data Source
AI summary
A cold trap includes a cold panel, a cryocooler which cools the cold panel, a stage temperature control unit which determines a control input to the cryocooler to cool a cooling stage of the cryocooler to a target temperature, an input heat estimation unit which estimates an increase of input heat into the cold panel based on the control input to the cryocooler determined by the stage temperature control unit, and a target temperature adjustment unit which adjusts a target temperature based on the increase of the input heat estimated by the input heat estimation unit.