During an experiment conducted in the laboratory, air-ammonia mixture is blown downward parallel to a falling water film on the inside of a pipe. Required:
a. Determine the effective thickness x in cm. Compare the result in (a) with the following:

b. The value obtained from the Gilliland equation.
c. The effective film thickness for heat transfer to gas flowing in a dry pipe with the same Reynolds number.
d. The value obtained from friction data using the Colburn theoretical equation.
e. The value estimated using Arnold theory based on the