University of Western Ontario
Department of Chemical and Biochemical Engineering
CBE 2221 – Fluid Flow
Air Through Annubar
Performed: January 20th, 2011
Group members: Ashley Ching, Christopher Chai, Tanuj Dutta
Student no: 250523377
Date of submission: February 3rd, 2011
Table of Contents
Theory and Nomenclature 3
Experimental Setup 3
Experimental Procedure 4
Results and Discussion 5
Conclusion and Recommendations 6
Citations and References 6
Appendix B 10
The objective of this lab is to calculate the mass flow rates across an annubar by ...view middle of the document...
It is important to note that the pipe has an inner diameter of 3.51 cm. Reynold’s number is needed to calculate the theoretical friction factor (f = 0.00114 + 0.125/Re0.32) and it’s equation is where ρ is density (kg/m3), u is the velocity (m/s), d is the internal diameter of the pipe (m), and μ is the viscosity of air at ambient temperature (which has a value of 2 x 10-5 Pa.s). The experimental fanning friction factor is calculated by f = ΔPd/(2 ρLu2) where ΔP is the pressure drop across (Pa), d is the internal diameter of the pipe (m), u is the air velocity (m/s), ρ is density (kg/m3), and L is the length of the straight pipe (m). For other fittings, the following equation can be used to calculate the friction constants K = 2 ΔP/ ρ u2. Lastly, the friction loss in terms of velocity in the straight and various fitting pipes was calculated by the equation ➢where h is the friction loss (m), K is the friction constant, u is the air velocity (m/s), and g is the gravitational acceleration (m/s2).
The apparatus that was used for this experiment consisted of a pressure regulator (Figure 1), an annubar (Figure 2), a long straight pipe, a 90 degree elbow, an elbow meter (corner tap), and finally a gate valve. Magnehelic pressure gages and manometers allowed for the measurement of the pressure drop across the previously listed devices. The apparatus was set up prior to the experiment as seen in Figure 4 below.
Figure 1 – Pressure Regulator
Figure 2 – Annubar with Magnehelic Pressure Gage
Figure 3 – Various Magnehelic Pressure Gages
Figure 4 - Air Flow System Set-Up
Pressure was controlled by using the pressure regulator, while the flow rate of air through the system was controlled by using the gate valve. The first step of this experiment was to set the system air pressure to 2 psig by using the pressure regulator. The pressure drop across the annubar was adjusted to 0.2 inches of water. Both valves were used simultaneously to ensure that the pressure and air flow remained constant at 2 psig and 0.2 inches of water respectfully. The pressure drop across the straight pipe, corner tap, 90° elbow, 45° elbow and globe valve were recorded at 2 psig and 0.2 inches of water. The experiment was repeated at 2 psig with a pressure drop (inches of water) of 0.4, 0.6, 0.8 and 1. The experiment was repeated for various system pressures of 4, 6, 8, and 9 psig. At each of the different system pressures the pressure drop values across the annubar were recorded at 0.2, 0.4, 0.6, 0.8 and 1.
Results and Discussion
In this lab one of the manipulated variables was the overall pressure (gauge) of the system. The gate valve was also used in conjuction with the pressure regulator to change the pressure drop across the Annubar. By using the pressure drop across the Annubar (in cm of water), the mass flow rate was found. Following this the velocity flow rate was calculated, and was used for calculating the fanning...