A partial oxidation is carried out by passing air through 40-mm tubes packed with 2m of 3-by-3-mm cylindrical catalyst pellets. The air enters at 350C and 2.0 atm with a superficial velocity of 1 m/s. What is the pressure drop through the packed tubes? How much would the pressure drop be reduced by using 4-mm pellets? Assume =0.40. (Use Ergun equation)