ChE 502 Spring 2018 HW Assignment 1 Liquid n-pentane is pumped through a 2.55-in
ID: 701037 • Letter: C
Question
ChE 502 Spring 2018 HW Assignment 1 Liquid n-pentane is pumped through a 2.55-in ID pipe at a rate of 22.5 gal/min. 1. Calculate the rate at which kinetic energy is transported by the fluid. Repathe closlatin for a pjpe with daeter f An object initially at rest falls 125 m with no appreciable resistance. 3. Calculate the velocity of the object at the end of the fall. 4. Find the kinetic energy per unit mass of the object at the end of the fall. Air enters a 2.66 cm diameter pipe at a pressure of 2.43 atm, a temperature of 35.6 °C and a velocity of 0.877 m/s. It leaves the pipe at 1.24 atm and 55.6°C. 5. Find the rate at which the gas transports kinetic energy at the inlet and at the outlet of the pipeExplanation / Answer
Answer to Question number 1 and 2
Mass flow rate = 22.5 gal/min = 0.0757 m3/min = 0.00126 m3/s
Diameter = 22.5 inch = 0.5715 m
Area = (Pi/4)*D2 =(Pi/4)*0.57152 = 0.2565 m2
Velocity = 0.00126/0.2565 = 0.00049 m/s
Kinetic energy = (1/2)*V2 = (1/2) * 0.00049 = 0.000012 Joulr/Kg
Density of n-pentane = 626 Kg/m3
mass flow rate = denisty *volumetric flow rate = 626* 0.00126 =0.788 Kg/s
Rate of kinetic energy = 0.000012*0.788 = 9.46512*10-6 Joule/s
Now for 2nd question
Diameter = 5.1 inch = 0.129 m
Area = (Pi/4)*D2 =(Pi/4)*0.1282 =0.0128679 m2
Velocity = 0.00126/0.0128679= 0.0979 m/s
Kinetic energy = (1/2)*V2 = (1/2) * 0.0979= 0.00479 Joule/Kg
Density of n-pentane = 626 Kg/m3
mass flow rate = density *volumetric flow rate = 626* 0.00126 =0.788 Kg/s
Rate of kinetic energy = 0.000479*0.788 = 0.00377 Joule/s