Cryopreservation Cooling Chamber Control With Multi-Point Nitrogen Feedback
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Solution Overview
Problem
Existing cooling equipment for cryopreservation of biological samples experiences unsatisfactory temperature control behavior, leading to deviations from the desired temperature course during freezing and thawing, which can result in damage to the samples.
Innovation Solution
Implementing a multiple controller system that monitors multiple temperatures within the cooling chamber and adjusts the heating performances of both the evaporator and the heater in the supply line, using a combination of temperature sensors to maintain precise temperature control and minimize nitrogen consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single heater in the cooling agent supply line is used to control temperature, then the device complexity is low, but the temperature control behavior is unsatisfactory with overswinging and deviations from target temperature
Solution Approach 1:
The control system is segmented into multiple independent control loops: one controlling the evaporator heating power based on cooling chamber temperature, and another controlling the supply line heater power based on cooling agent temperature. This segmentation allows each loop to independently optimize its control parameters, eliminating the overswinging problem while maintaining manageable system complexity through modular design.
Solution Approach 2:
The evaporator heating power is adjusted in advance based on the cooling chamber temperature to prevent temperature deviations before they occur. By proactively controlling the evaporator rather than reactively responding to temperature errors, the system avoids overswinging and maintains stable temperature control.
2Speed
If the evaporator heating performance is increased to cool the chamber faster, then the cooling speed increases, but the nitrogen consumption increases unnecessarily
Solution Approach 1:
The evaporator heating power is dynamically adjusted based on real-time cooling chamber temperature measurements. The control system continuously monitors temperature and modulates heating power to match the actual cooling demand, enabling fast cooling when needed while minimizing nitrogen consumption during stable temperature periods through adaptive control.
Solution Approach 2:
A feedback control mechanism continuously measures the cooling chamber temperature and adjusts the evaporator heating power accordingly. This closed-loop control ensures that heating is applied only to the extent necessary to maintain target temperature, preventing both overswinging and unnecessary nitrogen consumption while maintaining optimal cooling speed.
3Measurement precision
If only the cooling chamber temperature is monitored, then the measurement system is simple, but the control accuracy deteriorates due to lack of intermediate temperature data
Solution Approach 1:
The temperature measurement system is segmented into multiple sensing points: one in the cooling chamber and another in the cooling agent supply line. Each sensor provides localized temperature data that feeds into its respective control loop, enabling precise control at each stage of the cooling process while maintaining simple individual sensor designs.
Solution Approach 2:
The control system transitions from monitoring only the final cooling chamber temperature to also monitoring the intermediate cooling agent temperature. This additional dimensional measurement of the cooling agent state enables proactive adjustment of heating power before the cooling agent enters the chamber, improving overall control accuracy without requiring complex sensor 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
The solution enhances temperature control behavior, reducing temperature fluctuations and ensuring more accurate and efficient preservation of biological samples by dynamically adjusting heating performances based on real-time temperature readings, thereby minimizing damage and optimizing nitrogen usage.
Implementation Method 1
an evaporator (4), in particular a electrically operated evaporator, for heating the liquid nitrogen (3)
Implementation Method 2
a heater (6), in particular a electrically operated heater, for heating the gaseous nitrogen (3)
Implementation Method 3
the outgassing nitrogen being conducted via a cooling agent supply line into a cooling chamber and correspondingly cools its inner space so that material to be cooled located in the cooling chamber is frozen
Data Source
AI summary
The invention relates to a cooling apparatus, especially for cryogenically preserving biological samples, comprising a duct (5) for delivering a coolant (3) to a cooling chamber (1), a heater (6) that has an adjustable first heating performance (P2) for heating the coolant (3) delivered to the cooling chamber (1), a first temperature sensor (8-10) for measuring the temperature (T2-T4) in the cooling chamber (1), a second temperature sensor (7) for measuring the temperature (T1) of the coolant (3) delivered to the cooling chamber (1), and a regulator (11) for regulating the temperature. Said regulator (11) is embodied as a multiple regulator which detects several temperatures (T1-T4) as control variables and/or adjusts several heating performances (P1, P2) as manipulated variables. The invention further relates to a corresponding operating method.