Microporous insulation systems offer better thermal performance, reduced thermal conductivity, resistance to compression, and minimal shrinkage.
FREMONT, CA: Developing efficient thermal insulation systems has been a critical focus for the aerospace industry, driving researchers to explore innovative solutions. As a result, microporous-based insulating systems have emerged as a highly effective choice in aerospace and industrial applications. These systems utilize microporous materials, ranging from metal foils to various textiles, to achieve exceptional thermal performance. This article explores the design considerations, characteristics, and applications of microporous insulation systems in the aerospace and industrial sectors.
Efforts to create highly efficient thermal insulation systems for aerospace applications necessitated the establishment of an optimum theoretical thermal insulation. This involved minimizing the primary modes of heat transfer, including solid conduction, gas conduction, radiation, and convection currents. Researchers aimed to develop a product model meeting specific criteria, such as optimizing thermal performance without needing a vacuum, lightweight construction, high compressive strength, and minimal out-gassing during service.
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Microporous insulation offers several advantages over conventional insulation products. One notable benefit is its significantly reduced thermal conductivity for a given thickness. This results in enhanced thermal insulation properties. Moreover, microporous insulation exhibits resistance to excessive compression and has minimal shrinkage. These materials maintain their thermal conductivity characteristics even under heavy loads without significant degradation. Slight deformation due to compression can improve uniformity and thermal performance. Unlike rigid insulation systems, microporous insulation products do not reach a critical load/deformation point. Additionally, they exhibit minimal shrinkage when used as backup insulation at high temperatures up to 1800F (982C). Installation is typically straightforward, employing fiber cement or sodium silicate to secure the insulation.
The aerospace industry demands high-performance thermal management systems that maintain consistent operating temperatures and provide fire barriers, all within the constraints of high-vibration environments, limited space, and weight limitations. Microporous insulation, in both flexible and molded forms, meets these requirements.
Flexible microporous insulation consists of a microporous core sandwiched between high-temperature textile facings. The system is quilted with high-temperature thread to create a flexible blanket that can be cut and fabricated into unique shapes. It is a superior alternative to traditional fibrous insulators, often reducing the required thickness by 50 to 75 percent. This flexibility makes it ideal for insulating engine nacelles, enhancing temperature consistency, optimizing operating efficiency, and protecting the outer casing. It is also a fire barrier on auxiliary power unit enclosures, passing stringent performance tests. Additionally, flexible microporous insulation is utilized to insulate landing gear struts.
Molded microporous insulation finds extensive use in aerospace applications, particularly as a fire protection for flight data recorders (FDRs), commonly known as black boxes. It can be pressed into metallic casings, machined into shape, or directly machined from standard molded boards to create freestanding enclosures. The exceptionally low thermal conductivity of molded microporous insulation ensures that the internal contents of the FDR remain at low temperatures during simulated fires, allowing for the retrieval of critical data.
