Conduct a lab experiment to test and plot the air flow distribution in a rectangular duct, as well as establishing a relationship between flow rate and fan speed. BLDG 371
Conduct a lab experiment to test and plot the air flow distribution in a rectangular duct, as well as establishing a relationship between flow rate and fan speed.
BLDG 371
LAB 3
performed on Feb 25, 2014
submitted on Mar 11, 2014
Objective
This experiment is designed to test and plot the air flow distribution in a rectangular duct, as well as establishing a relationship between flow rate and fan speed.
Introduction
Determining the airflow of a system is very important, especially when evaluating a new HVAC system. knowing the airflow in a system will help:
Modifying of a new system
Troubleshooting problems in an already installed system
evaluation of flow changes produced by a retrofit.
– determining the compliance of the system to regulations/building codes
This experiment gives insight into how air behaves inside the duct and how at different locations there are different velocities. It also provides a better understanding of how to measure the velocity in a cross section of the duct at a specific time, and by obtain the velocity the airflow can be obtained. The calculations are done by obtaining the area averaged velocity “V avg” at different points in the cross section area; then from the V avg we can obtain the flow rate “Q” by multiplying V avg with the cross sectional area, defined by the equation:
Q = Vavg A
Procedure:
1- Set the fan speed (ω) at its maximum value.
2- Using the TSI Velocicalc, measure the velocity at locations specified in the cross section.
3- Measurements are done on ly in one quarter of the area of the duct, since it can be assumed that the flow is symmetrical.
4- After each measurement, the fan speed will be lowered by an increment of 200 RPM.
Data:
The table below shows the data obtained from measuring the different speeds at different locations across the duct cross sectional area. It also, shows the calculated flowrate as well as V avg and the correction factor.
Below is a graph showing fan speed versus flow rate. (graph 1)
Sample Calculations
The post Conduct a lab experiment to test and plot the air flow distribution in a rectangular duct, as well as establishing a relationship between flow rate and fan speed. BLDG 371 appeared first on My Nursing Writer.
