High-efficiency low-temperature storage device
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Solution Overview
Problem
Current low-temperature storage devices using liquid nitrogen for cryogenic temperatures are energy inefficient due to the need for large amounts of liquid nitrogen and inefficient cooling methods, particularly when storing samples at temperatures below −80°C.
Innovation Solution
A low-temperature storage device with a refrigerated storage chamber divided into zones, where a colder first zone is surrounded by a warmer second zone, utilizing a non-inflammable cryo-liquid refrigerant circuit and an air cycle machine thermally coupled to a refrigerant circuit for efficient cooling, reducing heat flow and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid nitrogen is used for cooling the storage chamber to cryogenic temperatures below -80°C, then the desired storage temperature is achieved, but energy efficiency deteriorates due to large amounts of liquid nitrogen consumption
Solution Approach 1:
The storage chamber is divided into multiple storage zones with different temperature ranges. The first storage zone maintains temperatures below -80°C for cryogenic storage, while the second storage zone maintains temperatures between -20°C and -80°C. This segmentation allows different zones to be optimized for their specific temperature requirements, reducing the overall energy consumption compared to cooling the entire chamber to the lowest temperature.
Solution Approach 2:
Different storage zones are assigned different temperature characteristics based on local storage needs. The first storage zone is designed for ultra-low temperature storage with temperatures below -80°C, while the second storage zone operates at higher temperatures between -20°C and -80°C. This local differentiation of temperature quality reduces the energy required to maintain cryogenic conditions throughout the entire chamber.
2Temperature
If the storage chamber is cooled to cryogenic temperatures below -80°C, then the storage function is achieved, but heat flow into the storage chamber increases energy consumption
Solution Approach 1:
The first storage zone with temperatures below -80°C is nested within the second storage zone that operates at higher temperatures between -20°C and -80°C. This nested configuration allows the warmer second zone to act as a thermal buffer, reducing the temperature gradient and heat flow into the colder first zone, thereby reducing energy consumption for maintaining cryogenic temperatures.
Solution Approach 2:
The second storage zone acts as an intermediary thermal layer between the external environment and the first storage zone requiring cryogenic temperatures. This intermediary zone reduces the direct heat flow into the ultra-low temperature zone, minimizing energy loss.
3Temperature
If liquid nitrogen is used for cooling, then cryogenic temperatures are maintained, but the complexity of liquid nitrogen transport and handling increases
Solution Approach 1:
The patent replaces the mechanical system of liquid nitrogen storage and transport with an absorption cooling system using heat pump liquids. Instead of relying on liquid nitrogen tanks and transfer mechanisms, the system uses absorption chillers that consume thermal energy to produce cooling effects, eliminating the need for liquid nitrogen handling infrastructure.
Solution Approach 2:
The cooling method is changed from direct liquid nitrogen cooling to absorption cooling using heat pump liquids with appropriate boiling points. This parameter change in the cooling mechanism eliminates the need for liquid nitrogen transport and storage, reducing device complexity while maintaining cryogenic temperature capabilities.
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 design enhances energy efficiency and temperature homogeneity within the storage zones, reducing the need for liquid nitrogen transport and minimizing the use of flammable heat pump liquids, while maintaining safe and efficient cooling for laboratory samples.
Implementation Method 1
The refrigerator device comprises a first storage-cooling heat exchanger arranged at said first zone for cooling it. The refrigerant circuit conveys a non-inflammable cryo-liquid through the first storage-cooling heat exchanger.
Implementation Method 2
a first storage-cooling heat exchanger arranged at said first zone for cooling it
Implementation Method 3
an air cycle machine thermally coupled to a refrigerant circuit for efficient cooling
Implementation Method 4
The second storage zone horizontally surrounds the first storage zone from at least partially... The first insulating wall vertically separating the first and said second storage zones
Implementation Method 5
The refrigerator device is adapted and structured to cool the first storage zone to a first temperature T1 and the second storage zone to a second temperature T2. The first temperature is at least 10° C. below the second temperature.
Data Source
AI summary
The storage device is adapted to store a plurality of objects, such as sample tube holders, at several low temperatures, e.g., at −80° C. and at −110° C. The storage device includes a storage chamber with a plurality of storage cassettes arranged in its bottom section. A cassette lift in its top section can be used to lift individual storage cassettes up and to move them to an access opening, where the contents of the storage cassette can be accessed. The bottom section is divided into several, concentric storage zones, with the innermost, first storage zone being colder than the outer, second storage zone. A first insulating wall separates the two storage zones. This design reduces the thermal losses of the storage device. A refrigerant circuit with a non-inflammable cryo-liquid is provided for carrying off heat from the first storage zone.