The state-of-the-art heat exchanger is the lightest, and most efficient heat exchanger in the world. The heat exchanger is made up of many tightly-wound tubing modules with liquid hydrogen and nano-particle coolant. As hot intake air is drawn through these modules, it is cooled to a temperature that will not damage the engine compressor blades. Consequently, the liquid hydrogen coolant heats up; this gets used as sensible fuel.
By maximizing the heat transfer surface area and using liquid hydrogen as a coolant, it is capable of 2.7 MW of heat transfer. This cools the incoming air from 387°C to 37°C in 10.3 milliseconds. Adding nanoparticles will enhance the heat exchanger capability by up to 40% at no added weight penalties.
The DASS GN1 engine will operate on multiple fuels (hydrogen, hydrocarbons, and metallic fuels) in order to optimize engine performance. Each fuel has characteristics that makes it advantageous. The combination of these fuels is expected to increase the turbojet engine output by up to 10%.
Hydrocarbon fuel, typically used in conventional turbo-jet engines, is a proven technology that provides effective fuel for the engine at subsonic speeds. Proven systems are advantageous because they remove additional complicated design solutions and reduce project costs.
Hydrogen, with a large heat capacity, is an excellent heat sink, has the best energy content per unit mass of any fuel, and is extremely light. As a result, it can provide large thrust levels with a low specific fuel consumption. Therefore, it is an ideal candidate for use in the heat exchanger and combustor.
Metallic fuel has excellent storage qualities, high energy content per unit volume, and can assist in convective heat transfer. It also has good combustion properties at the nano-scale.
Afterburners utilize excess air from turbojet to combust additional fuel downstream of the turbine to provide greater thrust. The Space Engine Systems afterburner is designed to operate at much higher temperatures than the turbine blades; this allows for higher energy extraction from fuel. Higher temperatures are also beneficial in combustion of high density metallic fuels.
At higher supersonic speeds, the incoming air can be compressed using the “ram” effect. The compression takes place without any moving components. Space Engine Systems aims to combine a ramjet/scramjet mode with multi-fuel combustion to generate thrust at supersonic speeds. Space Engine Systems’ PCT patent pending technology of variable geometry inlet and exhaust nozzle allows the ramjet/scramjet mode to be utilized over a range of Mach numbers.
Space Engine Systems has developed expertise in metal additive manufacturing (AM), a method that allows for optimized design features previously unachievable by traditional manufacturing methods. AM is capable of printing production quality parts or prototypes for further part development. This technology has applications in a wide range of industries and is being heavily adopted in the aerospace and biomedical fields.
Space Engine Systems uses a technique called Direct Metal Laser Sintering (DMLS), which builds parts layer by layer, by melting thin layers of metal powder with a high-power laser. This method results in parts that are completely dense, with very similar properties to wrought alloys. By adding material instead of removing it, previously un-manufacturable geometries such as complex internal channels, can be fabricated efficiently. Moreover, the repeatability of the process allows for the production of many identical, high quality pieces, leading to more cost-effective solutions.
Space Engine Systems is currently developing lightweight and highly efficient heat exchangers using AM. The manufacturing method will allow for heat exchangers with complex surface areas for optimized heat transfer while minimizing weight and pressure drop.
Examples of AM heat exchanger applications are: engine pre-coolers, nuclear energy generation, and high contamination environments. Space Engines Systems can help develop these heat exchangers to fit any application's need.