duct designe

[zarohliburd]

i recently received a job as the head of maintenance for the local univercity. my first task is to designe a a duckt system for several class romes what are the factors that should be considered when designing a duct system interms of duct sizing and duct reuction for effecient air distribution

[nicolacozma]

Hi zarohliburd,

Obviously with a short answer at your question is not possible to solve the problem.
First of all, you have to know very well what you want to do (a pure ventilation system, an AC/AHU ductware supply system,..)
Generally you have to take into account the number of occupants, the number of hour changes, the airflow of the fan or AC/AHU units, and many other parameters.
Otherwise you can use an software program that help you to save time. On the net you can find many ductsize software. Try this one, www,p3italy,it there is also english version.

Hope be useful for you.
Nicola

[lraja]

i recently received a job as the head of maintenance for the local univercity. my first task is to designe a a duckt system for several class romes what are the factors that should be considered when designing a duct system interms of duct sizing and duct reuction for effecient air distribution

Hi

this sounds like a small air conditioning/ventilation job. However, it is advisable that you use a standard approach like what you get in ASHRAE. Since the application is a classroom, provision of sufficient ventilation with good quality air, while maintaining required temperature and humidity inside the classroom, is one of the main concerns of the designer.

Sizing of the duct needs to primarily consider the air volume flow rate, allowable noise level, air temperature and moisture condensation issues (depending on air temperature if the application is for cooling)

Raja

[vijay_study]

Hi,

In order to start basic working of duct sizing, most important thing required is airflow rate i.e. cfm.

Ducts can be sized based on equal friction method, static regain method & constant velocity method.

Based on equal friction method, constant friction rate is selected across supply and return air ducts and ducts are sized accordingly.

In constant velocity method, ducts are selected in order to have constant velocity across the duct crossection.

In static regain method, ducts are sized in order to have static regain by converting velocity energy into pressure energy.

For details examples on calculations, refer ASHRAE handbook chapter on duct design.

Regards

[wineman]

spelling should be a factor