SpaceX uses the MERLIN rocket engine to power its Falcon 9 and Falcon 9-heavy launch vehicles. In addition to commercial launch services, SpaceX uses the Falcon 9 to launch the dragon capsule to re-supply the International Space Station. The MERLIN rocket engine uses RP-1 (kerosene) fuel and liquid oxygen oxidizer. Kerosene contains a variety of hydrocarbons, but the main constituent is n-dodecane, which has chemical formula C12H26 and enthalpy of formation of -291,010 kJ/kmol. The total mass flow rate for the engine is 140 kg/s. a. Write out the chemical reaction for the combustion process of the MERLIN engine assuming stoichiometric combustion and only CO2 (44 g/mole) and H20 (18 g/mole) product species.
b. What is the molecular weight of the product mixture?
c. What is the enthalpy (or heat) of this reaction?
d. Determine an estimate for the temperature of the combustion products assuming the reactants enter the combustion chamber at 298K and only CO2 and H20 product species.
e. Determine an estimate for the thrust and specific impulse of this rocket motor assuming y=1.3. (SpaceX reports Ispvac = 304 sec, Fvae = 617 kN)