the answer has to be 10.05 kg/h

4. Air enters a heat exchanger at a rate of 50 SCFM at 75C and leaves at 225C. The air stream is heated using steam. The steam enters the heat exchanger as saturated vapour at 45 bar and exits as a saturated liquid at 45 bar. Determine the required steam flow rate in kg/h, assuming the only significant heat transfer that occurs is between the steam and the air. Answer: 10.05kg/h