Lyophilization Tray Insulation for Uniform Freezing
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Solution Overview
Problem
The formation of solute layers on the surface of frozen solutions during lyophilization can inhibit solvent sublimation, requiring higher temperatures and longer drying times due to rapid bottom-up freezing, which leads to the formation of impermeable amorphous solids.
Innovation Solution
A lyophilization device and method that uses thermally insulated trays to separate the sample container from direct contact with the heat sink, allowing the solution to freeze uniformly from top and bottom, preventing solute concentration and promoting efficient sublimation by maintaining a fixed distance between the heat sink and tray surfaces, and using a thermal insulator with low conductivity to control heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the solution is frozen using direct contact with heat sink, then freezing speed is improved, but solute layers form on the surface causing impermeable amorphous solids that inhibit sublimation
Solution Approach 1:
A thermally insulating tray is introduced as an intermediary between the heat sink and the solution container. The tray separates the solution from direct heat sink contact while still allowing controlled heat transfer, preventing solute layer formation at the interface while maintaining efficient freezing.
Solution Approach 2:
The harmful thermal contact between the heat sink and the solution is extracted/removed by placing the thermally insulating tray between them. This eliminates the direct path for solute concentration at the heat sink interface while preserving the necessary cooling function.
2Productivity
If higher drying temperatures are used to overcome solute layer inhibition, then sublimation is improved, but energy consumption and drying time increase
Solution Approach 1:
The invention applies preliminary anti-action by preventing solute layer formation during the freezing stage through the thermally insulating tray. This preventive measure avoids the need for higher drying temperatures later, as the uniform freezing structure allows efficient sublimation without requiring energy-intensive corrections.
3Power
If the heat sink is placed in direct contact with the tray, then heat transfer efficiency is improved, but uniform freezing from top and bottom is prevented causing solute concentration
Solution Approach 1:
The thermally insulating tray provides different thermal characteristics to different regions: it allows heat transfer from the heat sink to the tray while blocking direct heat transfer to the solution at the interface. This creates localized thermal zones that enable uniform freezing from both top and bottom surfaces simultaneously.
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 approach prevents the formation of impermeable solute layers, enabling efficient solvent sublimation and resulting in lyophilized cakes with larger, consistent pore sizes, reducing drying time and energy requirements.
Implementation Method 1
using a thermal insulator with low conductivity to control heat transfer
Implementation Method 2
a refrigerant conduit in thermal communication with the heat sink surface
Implementation Method 3
the frozen solvent is removed by sublimation under reduced pressure
Data Source
AI summary
This application discloses devices, articles, and methods useful for producing lyophilized cakes of solutes. The devices and articles provide for a method of freezing liquid solutions of the solute by the top and the bottom of the solution simultaneously. The as frozen solution then provides a lyophilized cake of the solutes with large and uniform pores.