Aerogel Drying via Reduced Pressure to Prevent Pore Collapse
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Solution Overview
Problem
The industrial-scale production of aerogel is limited by the complex and expensive supercritical drying process, which can cause pore collapse and cracking due to capillary forces during conventional drying methods, resulting in products with poor thermal insulation and high density.
Innovation Solution
A method and apparatus for preparing aerogel by drying under reduced pressure, using gradient depressurization or slow temperature-raising to balance capillary forces and prevent pore collapse, allowing for the controlled removal of solvents and water while maintaining the aerogel's three-dimensional structure and high porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If supercritical drying method is used, then pore collapse is prevented, but equipment cost and operational complexity increase significantly
Solution Approach 1:
The patent changes the pressure parameter from atmospheric pressure to reduced pressure during drying. This parameter change allows the drying process to proceed without generating capillary forces that cause pore collapse, eliminating the need for complex supercritical drying equipment while maintaining pore structure integrity.
Solution Approach 2:
The patent replaces expensive, complex supercritical drying apparatus with simple reduced pressure drying equipment. The simple drying device used in this invention is much cheaper and easier to operate, making aerogel production more accessible despite being a simpler, more transient process setup.
2Productivity
If conventional heating drying is used, then drying speed increases, but temperature control difficulty causes pore cracking and collapse
Solution Approach 1:
The patent replaces thermal heating with mechanical vacuum pumping to achieve drying. Instead of using heat to evaporate solvents (which causes temperature gradients and pore damage), the system uses reduced pressure to lower the boiling point and enable solvent removal at low temperatures, maintaining pore structure while achieving efficient drying.
3Manufacturing precision
If supercritical drying is used, then high porosity aerogel is obtained, but production cost increases
Solution Approach 1:
The patent replaces expensive supercritical drying equipment with inexpensive reduced pressure drying equipment. The simple vacuum drying system used here is much cheaper to purchase and operate, significantly reducing production costs while achieving the same high porosity results through pressure-based rather than temperature-based drying.
4Productivity
If microwave heating is used, then drying efficiency improves, but uneven temperature distribution causes pore collapse
Solution Approach 1:
The patent replaces electromagnetic microwave heating with mechanical vacuum drying. By using reduced pressure instead of microwave energy, the system avoids the uneven temperature distribution that causes pore collapse, while maintaining high drying efficiency through the enhanced evaporation rate at low pressure.
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 enables the production of aerogel with high porosity, low density, and excellent thermal insulation properties, overcoming the limitations of expensive supercritical drying and temperature control issues in conventional methods.
Implementation Method 1
The method of reducing pressure by air extraction...is employed for acting upon the water and solvents within the aerogel to be dried, and an outward force is thus generated for the water and solvents to be volatilized outwards
Implementation Method 2
The collapse of the aerogel during drying is due to a capillary effect generated by its own structure during drying. The pores within the gel are similar to the capillaries. During drying, when a part of water and solvents within the gel are discharged out of the gel, a three-phase interface will appear, and the surface tension of the interface encourages the liquid in the interior to generate a concave surface in the capillary
Implementation Method 3
The gel to be dried is placed into a sealed drying apparatus which can be depressurized by air extraction...A drying apparatus for preparing aerogel by drying under reduced pressure comprises: a sealed apparatus with a door, a support frame provided in the sealed apparatus for placing a tray for placing the aerogel...a pipeline for vacuum pumping connected to the sealed apparatus, and a vacuum pump provided inside or outside
Data Source
Figure 1
AI summary
A method and an apparatus for preparing aerogel by drying under reduced pressure. The gel to be dried is placed into a sealed drying apparatus which can be depressurized by air extraction or/and can be heated to raise the temperature. The methods of reducing pressure by air extraction or/and raising temperature are acted upon the water and solvents within the aerogel to be dried, and an outward force is thus generated for the water and solvents to be volatilized outwards. By controlling the rates of reducing pressure by air extraction or/and raising temperature, the outward force is allowed to be equal to or close to the inward capillary force, such that the pores of the gel may not be collapsed or cracked. At the same time, drying is carried out continuously, and finally the interior water and solvents are removed completely.