Production Area Airflow

[wrench]

I am trying to satisfy my own curiosity with regards to calculating the required airflow for an air handler.

Normally when installing production area jobs we use duadischarge cooler but recently a few clients have been requesting air handlers and the associated duct work.

With the cooler option we obvioulsy do the load calc etc but with the air handler option we are speaking to air handler manufacturers who are looking for airflow detail etc.

I would love to know how to calculate the required airflow for a system based on heat load and supply/return temperatures.

[mad fridgie]

Your heat load will not change, apart from additional heat from AHU fan.
You have decide what your "air on" temp is and what your "air off" temp is.
Your evaporating temperature.
At this point you should be doing this with your existing design. (if indirectly your dual discharge has had it done for your)
When you have worked out your air flow, Duty/TD/SHC = flow.
You then need to design ducting and distribution.
From here you can work out air pressure drops, you give this the AHU manufacture, who will add the internal pressure drops, then size a fan to meet both flow requirement and presure drop. (if you are worried about your sizing ask for an over sized moter and adjustable speed (VSD or Belts and pulleys), with speed set at 80% to meet requirements, so if F***up, you increase or decrease the speed to meet requirements.

[wrench]

Thanks for the reply.

To help me undersatand further I have a duty of 60kW, air on @ 10'C, air off @ 3'C and evaporating @ 1'C, from this point how do I get to a design airflow.

Thanks