Consider a design of a hydrazine (N2H4) thruster for a satellite. The thruster produce 350 mN of thrust (at steady state) with a total impulse of 410 kN/s. The thruster is intended to operate with a hydrazine storage tank regulated to 25 atm and held at a constant storage temperature of 290 K using a high pressure (maximum of 65 atm nitrogen) tank and regulator used to maintain the hydrazine tank at the prescribed operating pressure. The products leaving the catalyst bed consist only of NH3, N2, H2, with NH3 making up 30% of the mixture (by mole). For this preliminary design exercise, assume the thruster will use a nozzle having an area ratio of 40 of a conical nozzle with 15 degree half-angle. Assume a constant for all of these.

(a) What is the conversion fraction (in percentage) of the NH3 produced by the N2H4 decomposition?

(b) Using adiabatic steady reactions the maximum temperature is estimated to be 1271 K. Determine the molecular weight and the specific heat ratio of the products exiting the catalyst bed.

(c) Determine the mole fractions of the products

(d) Based on your results from part (b), find the specific impulse of the thruster assuming frozen chemistry in the nozzle

(e) Determine the required throat diameter (f) What are the corresponding run time in seconds and the volume of the storage?

(g) What can you conclude from this design exercise?