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Waste Heat Recovery of Rocket Motors for Reduction of Battery Weight


OBJECTIVE: The Missile Defense Agency (MDA) is seeking innovative solutions for recovering waste heat left in the insulation surrounding a solid rocket motor (SRM) or liquid rocket motor combustion chamber and converting it into electricity to recharge batteries for long flight missions resulting in a reduction in the total battery weight needed. This may result in a net reduction in mass of the overall missile system. DESCRIPTION: The third stage generally follows a ballistic trajectory after burnout and remains relatively close to the kill vehicle that performs the intercept of the target warhead. It may be possible to place communications relay equipment or target tracking equipment on this third stage to reduce the weight of the kill vehicle. Based upon initial estimates, there may be as much as 11-30 MJ of waste heat left over in an average third stage rocket motor after burnout. If a small fraction of this waste heat were to be converted to electricity to recharge a battery, it may be possible to reduce 4-10 kg of battery weight in the overall missile by converting from thermal batteries to rechargeable batteries with this recovery system. The method of heat recovery and conversion should be very light weight (<5kg) and capable of supplying approximately 300W of electricity to the power management system while removing heat from the insulation around a rocket motor case of approximately 0.6 meters in diameter and 1 meters long for at least 5 minutes. At burnout, it is estimated that the average temperature of the fist centimeter of insulation around the motor lining is approximately 2000 K. The system must be capable of operating in a micro-gravity environment and survive the high-g environment of launch. Thermoelectric, thermocouple, and fluid/vapor based systems are all potential candidates but will require extensive modification to operate under the desired conditions and performance requirements. PHASE I: During the Phase I contract, the proposer will conduct an initial design evaluation of their proposed method of recovering the waste heat and perform any laboratory/breadboard experimentation or numerical modeling needed to verify the proposed method. The deliverable will be an initial design for a prototype system with accompanying theoretical/numerical performance estimates. PHASE II: If selected for a Phase II, the proposer will complete a detailed prototype design to government performance requirements. The prototype will then be fabricated and tested in a simulated environment to verify theoretical/design assumptions. The final deliverable will be a detailed performance analysis of the experiment and an initial design of an engineering development model of the resulting system. PHASE III: Phase III selections will have adequate support from a MDA Prime or Propulsion vendor. The proposer shall continue testing and development with a MDA Prime or Propulsion vendor to refine performance and reliability characteristics. COMMERCIALIZATION: Satellite launch systems or small commercial power generation systems.
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