Question

# Engineers in a process plant suspect that there is an error in the air flow direction shown on one of theirprocess flow diagrams. They have measured data at two points

on a straight run of piping as follows: At point 1: a. Pressure = 95 bar b. Temperature= 67 C C. Velocity = 75 m/s At point 2: a. Pressure= ,8 bar b. Temperature = 22 C C. Velocity = 310 m/s One engineer suggests that the pressure drop tells them that the air is flowing from point 1 to point 2,but another engineer cautions that the temperature difference is pretty large and suggests that theyhad better use a second law analysis to determine which way the air is flowing. Part 1: What is the second law concept that will tell you which way the air if flowing? Part 2: Write the appropriate form of the 2d law. Show all assumptions and simplifications. Part 3: Use the air tables to solve the second law for the appropriate term and prove which directionthe air is flowing.

Fig: 1

Fig: 2

Fig: 3

Fig: 4

Fig: 5

Fig: 6

Fig: 7

Fig: 8

Fig: 9

Fig: 10

Fig: 11

Fig: 12

Fig: 13