Solve Engineering Problem: Air Flow Speed in Duct for 3x4.5x6m Room

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Homework Help Overview

The problem involves calculating the necessary air flow speed in a duct for a room with specified dimensions and air exchange requirements. The context is within the subject area of fluid dynamics, specifically focusing on volumetric flow rates and duct design.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the need to calculate the volumetric flow rate based on the room's volume and the air exchange time. Questions arise about how to derive the flow speed from the given parameters, particularly the relationship between volumetric flow rate and duct area.

Discussion Status

The discussion is active, with participants providing insights into the relationships between volume, area, and velocity. Some guidance has been offered regarding the formulas involved, but there is still uncertainty about how to proceed with the calculations.

Contextual Notes

Participants note that the problem does not provide a direct velocity value, leading to questions about how to derive it from the available information. There is an emphasis on understanding the relationships between the variables involved in the problem.

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Pls help on this problem that I can not solve it.

a room measures 3.0 m by 4.5 m by 6.0 m. The heating and air conditioning ducts to and from the room are circular with diameter 0.30 m, and the air in the room is to be exchanged every 12 minutes. What is the necessary flow speed in the duct? ( Assume that the density of the air is constant)

thanks
 
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Please do not post homework problems in the tutorial section.

Basically, the is a volumetric flow rate problem. One knows the total volume of the room (L * W * H) which has to be replaced in 12 minutes or 720 s.

One knows the diameter of the duct work, so one computes the area.

Q = V * A, where Q = volumetric flowrate, V = mean velocity, and A = cross-sectional area.
 
Thanks

Thank for reply, Astronuc, I have a question, you said Q=V*A, V=velocity, but in the problem, it does not give velocity value, how do I get it. Thanks again.
 
V = Q/A, and one must compute Q and A to get V.
 

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