ALUPOR™ is an innovative material based on cast aluminum with open pores that reveals new possibilities in the field of thermal management. Now it is possible to create compact, efficient and task-adapted heat exchange devices thanks to ALUPOR™ high specific surface area, controlled porous structure, and good thermal conductivity of the metal matrix.
How it works
Heat from the heated surface penetrates deep into the coolant flowing through the pores via the metal matrix. Next heat is efficiently distributed into fluid due to the high specific internal surface by contact thermal conductivity. In the case of cooling, this process occurs in the reverse order.
Advantages
High heat transfer surface area per unit volume
100% permeable structure
Fully controlled and stable structural parameters
Intense convection in pores themselves
Components combining solid and porous sections in a single product
Parts are manufactured by casting: we are able to produce complex shapes
Parts with integrated tubes in a single product
Superior strength compared to other porous aluminum technologies
Environmentally friendly – material recyclable as aluminum scrap
Limitations
Pressure losses will be higher compared to traditional solutions
Not suitable for media contaminated by dust and other solid particles that will clog the pores: preliminary filtration is required
For incompressible fluids cavitation in pores is possible
Aggressive fluids will interact more actively with porous metal due to the developed reaction surface area. That will happen even if we consider solid aluminum to be resistive at the same conditions
Repair complexity: if the porous structure is damaged, repair and restoration of original characteristics becomes difficult
The porous structure reduces thermal conductivity relative to solid metal (20–25% of solid metal)
Despite these drawbacks, modern technologies make it possible to minimize many of them, making porous metal heat exchangers competitive in certain application areas. However, when choosing this type of heat exchanger, it is necessary to take into account these limitations and operational characteristics.
properties
Property
Material type (graded by main pore size range), μm
Maximum dimensions of the final part: 850 × 650 × 150 mm
Minimum plate thickness:
3 mm for parts up to 300 mm
5 mm for parts up to 500 mm
8 mm for parts over 500 mm
Final product weight: up to 150 kg
Manufacturing method: casting with vacuum impregnation of NaCl (see here...)
Threading available for both solid and porous sections
Parts with Solid Metal Sections (SMS) are a significant advantage of our technology because we eliminate thermal resistance at the interface between the solid and porous sections. Possible options for manufacturing parts with solid metal sections are presented below.
Parts with embedded elements: our technology allows to embed tubes, plates, and profiles made of aluminum, copper, and stainless steel during casting. As a result, we obtain a complex product in a single part.
case study
Standard design encemhanent
Tube-in-tube.
Increase of heat transfer surface
Spiral-in-tube cooler.
Enhancement of heat transfer from pipe to environment
Plate heat sink.
The cold and hot circuits are both made of ALUPOR™ with solid metal divider plates.
Phase change coolers
Standard heat pipes contain liquid and its gas phase. The liquid vaporizes and goes to condenser. After cooling in condenser liquid goes back for evaporation.
Porous aluminium ALUPOR™ of fine pore size possess capillary effect.
Porous structure can lift the liquids up. We believe it can be used as wick structure in heat pipes.
Contour heat exchanger with phase change and natural coolant circulation made of ALUPOR™
Contour phase change heat sink with wick coolant supply made of ALUPOR™ with fine pores
Capillary lifting demonstration
Electric heaters
Flow-type air heater.
Heat distribution from heating elements (HEs) through ALUPOR™
Contour phase change heat sink with wick coolant supply made of ALUPOR™ with fine pores
Flow-type air heater. Resistive heating element is ALUPOR™ itself
Inappropriate application case
Let's consider a typical case: a finned heat exchanger made of ALUPOR™. This option may be viable, but it is highly unlikely to produce the desired effect for the following reasons:
To achieve maximum efficiency, it is necessary to ensure uniform supply of the coolant into the material volume
Thermal conductivity is significantly lower compared to solid metal
Only the surface layer of pores will be ventilated by the fan
The majority of airflow will follow the path of least resistance – between the fins
Conclusion: fine-pore structure is not suitable for that case. Regarding coarser pores there remains a question of efficiency: the increase in heat transfer surface area must sufficiently compensate for the reduced thermal conductivity of ALUPOR™ compared to solid metal.
