Wednesday, 3 April 2019

Evaporative cooling in Offices

One of the hidden challenges of Evaporative cooling is dealing with a phenomenon called overcooling during very dry days.

In summer we try to typically introduce air at 18 deg C into a building. This is normally achievable using Two Stage evaporative cooling, but some days, when the air is very dry, you can get excessive cooling when you switch the wetpacks on.

This sudden drop in air temperature can produce supply air temperatures as low as 12 deg C.

The figure above shows that whenever the evaporative cooler goes through a state change, that you risk over cooling.

In offices, this is problematic because the building is typically designed for a constant supply air temperature.

We now have a bypass damper that allows us to smooth overcooling so that after transition, we can mix filtered outside air with over cooled air in order to achieve a constant supply air temperature.