Thermochemical cooling for large thermal load applications

The requirement to reject heat within a small envelope has stunted the development and deployment of high heat flux applications. Thermochemical cooling is a new innovative approach, inspired by engine cooling in aircraft. In aircraft, sensible heat is often rejected to the fuel, without altering its chemical composition, and dissipated through the wings. However, sensible heat absorption is limited to 431 kJ/kg for JP8. Using endothermic reactions, JP8 can absorb as much as 11,688 kJ/kg of heat when converted to hydrogen, carbon monoxide, and other gases. A common refrigerant, such as R134A has an enthalpy of vaporization of 209 kJ/kg. However, after evaluating multiple fuels and reforming literature, it was determined that optimum lower temperature performance could be achieved with a methanol water mixture. This endothermic reaction is a strong candidate for heat absorption. Preliminary test data demonstrated heat absorption as low as 300 °C, with peak absorption at 400 °C. At its peak (R = 400 °C), the reactor is capable of absorbing 3411 kJ/kg. Future efforts will evaluate the use of JP8, which has a larger endothermic reaction potential.