Airside Economizer Demonstration

This demonstration answers a common question: how to model an airside economizer in CoolSim. The example uses the room editor and a small in-row unit as the outside air inlet.

What the video shows

1. Setting the room to a non-raised floor with a ceiling plenum, so ceiling grilles can return air to the inlet side.
2. Building a partition wall from a block that is 6 in thick and spans the 30 ft room. A column block is slab to slab by default, so it is changed to sit in the room, which leaves the plenum open above it for air to pass.
3. Making the inlets from the default in-row cooling unit, resized to 2 ft by 2 ft by 2 ft with 2 ft inlets and outlets, raised a couple of feet off the floor. The inlet side passes through the wall by about an inch, so no manual hole is needed. Copies are made and set the same way, and several editors can be open at once.
4. Setting each unit to a constant supply temperature, 70 degrees F in the demo. The presenter notes a unit can also run fan only, or use a temperature difference, which makes it useful for fan walls or plain flow.
5. Adding a rack as the load and ceiling grilles so air can exhaust up and return through the plenum to the units.
6. Submitting the model and reviewing results: computer room air conditioner (CRAC) performance, flow through the ceiling grilles, rack conformance to the ASHRAE recommended range, and the temperature range. Only one corner is slightly warm and the spread is a few degrees.

Tips

• Do not trap air. Too much pressure can make the solver fail.
• The units deliver the set temperature regardless of load, so the cooling capacity of real units can be exceeded. The presenter says the aim of the computational fluid dynamics (CFD) run is to test extreme conditions, for example to find when to switch to another form of cooling.
• Blocks, cable trays and most other objects may overlap, but avoid blocking inlets and outlets.