Tenders Are Invited For Secondary Heat Exchanger

Tenders are invited for Secondary Heat Exchanger for Combustion Chamber Cooling of Rocket Engines - Expro+ The objective of this activity is to develop a cooling approach for steady state rocket engines to enable the use of more cost-effective materials. This should be achieved with the use of secondary heat exchange.Currently only two cooling approaches are used forrocket motor chamber design. Direct regenerative cooling with the propellants or much simpler radiative cooling. Regenerative cooling recovers energy lost in the radiative approach and offers both higher performance and, wider material options which is possible due to the lower operating temperature. Regenerative cooling is almost never limited by the sensible enthalpy, the temperature rise of the cooling propellants. It is typically limited by local effects in the cooling channel design. These effects come down to two factors the local geometry and the local vapor pressure of the coolant. The geometry is naturally constrained by the need for a rocketchamber shape.In the absence of local geometric options then the local vapor pressure can only be improved for a given propellant by driving up the local static pressure. This rules out many in-space applications where gas pressurized feed systems are the norm, the static pressure is too low. The power for high pressure pumps to regeneratively cool current spacecraft engines would require pumps more than 1.5 kWs. An alternative approach is to design a heat exchanger to transfer the heat from the wall of the combustion chamber to propellant indirectly. This has the advantage of allowing the design of specified cooling rates independent of the geometryor propellant feed conditions. Either end of the exchanger can be designed to operate at specified temperatures. This simplifies the material selection of the chamber and the transfer of energy to the propellant.A fixed temperature exchanger would have none of the limiting factors of a classical regeneratively cooled chamber. It could also simplify start up transient for many larger engine cycles. The more benign operating conditions would also allow for greater reusability; thermal gradients could be more tightly managed and more robust materials could be used, eliminating issues such as plasticity and deformations of the cooling channels. As statedearlier local conditions drive the failure in regenerative engines these are compounded when the engine flow conditions are dynamicwhen throttling. Lander engines tend to require deep throttle rates. Secondary heat exchangers operate outside these constraints and would maintain thermal integrity of deeper throttling designs. Similarly higher performance engine architectures such as aerospikes are inhibited from adoption due to the thermal complexity ofimplementing them compared to classical designs. Various ideas have been considered; however liquid metals are only one potential solution. Active pumping of a secondary coolant would also be feasible.This activity shall focus on the concept of secondary heat exchange design for high performance engine design and demonstrate a secondary heat exchanger unit by firing a representative breadboard. This would allow a greater exploitation of the propellant sensibleenthalpy than current regenerative approaches. In addition, secondary heat exchange would allow low pressure drop designs and enable actively cooled design applications where currently radiative cooling is mandated. Finally secondary heat exchange would allow theenergy to be exploited in other systems if required: repressurization, power recovery, etc. The activity encompasses the following tasks: Analysis of the state of the art of secondary heat exchanger options for combustion chamber applications. Develop and manufacture a breadboard of a secondary heat exchanger for combustion chamber. Demonstrate a secondary heat exchanger for combustion chamber design by firing a representative breadboard with heat exchanger or an appropriatesimulator. Validate the design tools toimplement such a chamber.NOTE: This activity is currently in the GSTP Work Plan but will only be implemented after confirmation offinancial support from Delegations. The final list of participating states will be known at tender issue.Read more Tender Link : https://esastar-publication-ext.sso.esa.int/ESATenderActions/filter/open