The open-cell honeycomb structure exists in nature in different forms. Nowadays, polymer, metal and ceramic porous materials have played a role in industrial production. These structures have excellent performance at high temperatures, stability in harsh environments (acidic, alkaline or oxidizing) and excellent thermomechanical properties (thermal shock resistance). Due to their porous nature, they have a fluid surface with higher surface area and permeability, so they are suitable for applications in catalysis, solar energy collection, heat storage, heat exchange, radiation burners and other fields.
The traditional manufacturing methods of ceramic honeycomb structure include: uneven pore molding, direct foaming and replication of polymer foam. Additive manufacturing-3D printing technology has become a new manufacturing process for ceramic foam materials. By combining CAD, simulation and additive manufacturing, it can meet the needs of end users in different industrial fields.
Random foam is commonly used in the hot zone of porous burners
Due to the manufacturing methods of polymers, the problem with standard foams is their reproducibility and uniformity. This will cause problems when handling, assembling and operating the burner. Using the structured lattice design method in the previous article can solve this problem. Porous burners, the standard conditions for this component are: operating temperature 1350 ° C, combustion ambient air, H2O and volatile organic compounds. The EU ECCO project aims to increase the radiated power of such components by increasing the operating temperature to 1450 ° C and optimizing the architecture topology to improve the radiation.
The manufacturing method can adopt the hybrid manufacturing method of 3D printing polymer covered ceramic paste. First, the 3D printed polymer structure is manufactured by SLA or SLS 3D printing technology, and then the 3D printed object is immersed in the ceramic paste to make the ceramic material cover layer reach a certain thickness. The object is then heat-treated according to the composition of the ceramic slurry. In this way, complex high-performance components can be produced, significantly improving the mechanical strength and thermal shock strength of the ceramic porous structure.
Innovative conical geometry porous burner. The conical burner shows stable and complete combustion under the low pollutant emissions from the low calorific value exhaust gas produced by hydrogen. The Si-SiC flat and conical prototype has 10 PPI Voronoi open cells. The structure is designed using the Voronoi design method. The polymer Voronoi cone-shaped porous structure is 3D printed, then copied using SiC slurry, and then immersed in the melt Of silicon.
Application in heat exchanger
Ceramic materials are widely used in applications in high temperature environments, such as heat exchangers. The engineered ceramic honeycomb architecture can improve heat transfer efficiency and improve the performance of these systems. You can also insert such structures into tubular heat exchangers to take advantage of convection and radiation phenomena caused by internal structures.
The ceramic lattice structure obtained by the structured lattice design method has a 4 mm rotating cubic unit cell. These 3D printed ceramic lattice structures are manufactured using SLA technology. Numerical and experimental studies have shown that the morphology of the lattice greatly affects the performance of the heat exchanger. During the experiment, in order to find the best heat transfer solution, the researchers adopted different morphologies.
If the lattice structure is integrated in the tube, the heat transfer performance of the heat exchanger is improved. Depending on the internal lattice system structure, the performance is increased by 160% -280%. Among them, the design of the outside is a large unit cell and the inside is a small unit cell, so that a higher proportion of heat radiation can reach the central support, thereby improving the heat transfer efficiency.