Preheating air by steam for use in a dryer. an air stream at 32.2°c is to be used in a dryer and is first preheated in a steam heater, where it is heated to 65.5°c. the air flow is 1000 kg mol/h. the steam enters the heater saturated at 148.9°c, is condensed and cooled, and leaves as a liquid at 137.8°c. calculate the amount of steam used in kg/h.