Advanced Heat Transfer Devices for Aerospace Applications

Abstract

Aerospace system efficiency improvement and capacity growth has fueled demand for innovative, affordable and scalable thermal management technologies. Recent advancements in additive manufacturing (AM) and materials has extended the thermal design space for heat exchangers, cold plates, heat sinks, and heat pipes. Novel heat transfer enhancement techniques, along with design and system interface innovations, offer attractive cooling solutions for use in numerous aircraft systems. These advances are becoming increasingly relevant in aircraft systems as customers are demanding the use of air-cooling instead of liquid-cooling with minimal impact on overall energy conversion efficiency, installed volume and weight. This paper provides an overview of Boeing-led advances in analysis, design, fabrication and testing of next generation heat transfer devices. A case study is presented to provide insight into a methodology for selection of heat transfer surfaces and design optimization for an air-to-air heat exchanger. Design considerations are presented for additive manufacturing of the thermal management devices using a range of high performance materials including aluminum, titanium, stainless steel, and conductive polymer composites.

Aircraft thermal management: Practices, technology, system architectures, future challenges, and opportunities

“…In this case, the fan air is also bled from the engine and the pre-cooler heat exchanger is situated external to the engine (often in the pylon) [109]. However, in some engines, there are 'annular' heat exchangers for pre-cooling in the fan bypass stream [110].…”

“…Despite their maturity and ubiquity in engineering systems, there is still much research ongoing to improve heat exchanger performance. This is especially true in aerospace, where the focus is particularly on reducing weight, increasing compactness and effectiveness, and improving manufacturing techniques [41], [110]. There is also much work being undertaken to enable the production of heat exchangers with special shapes that enable them to fit better into tight and irregularly shaped spaces.…”

“…Other examples of irregularly shaped heat exchangers include the developments in annular fan duct air-air heat exchangers for pre-coolers of bleed air systems. According to Kasim et al [110], by using traditional fins in such an unconventional volume space, Boeing Research and Technology achieved a heat exchanger weight reduction of 2% and a volume reduction of 6%, compared with conventional designs.…”

“…[175]. Kasim et al [110] describe possible enhanced heat transfer and lower pressure drops for compact heat exchangers with novel heat transfer surfaces geometries. These include offset-strip fins with new geometry variations, such as longer offset lengths, as well as novel combinations of wavy fin wave amplitudes and wavelengths [110].…”

“…Kasim et al [110] describe possible enhanced heat transfer and lower pressure drops for compact heat exchangers with novel heat transfer surfaces geometries. These include offset-strip fins with new geometry variations, such as longer offset lengths, as well as novel combinations of wavy fin wave amplitudes and wavelengths [110]. It is vital that the fluid dynamics and heat transfer behaviour of such new geometries be characterised by researchers, to enable the design space to be expanded, which will ensure that these could be exploited [110].…”