EvaporativeCooler:Direct:ResearchSpecial not working below certain outdoor air temperature

asked 2019-05-01 17:08:03 -0500

elco8141 gravatar image

updated 2019-05-03 07:42:22 -0500

I am trying to model an airloop in OpenStudio 2.7 (energyplus 9.0) with a direct evaporative cooler on it. image description

The above airloop has a setpoint manager after the direct evap object. I have tried both a "setpoint manager single zone cooling" set for a range of 0 degrees F to 210 degrees F and a "setpoint manager schedule" set for a constant temperature of 70 degrees F. The setpoint manager on the supply air node is a "setpoint manager single zone reheat" set with a very wide range. The inputs for my direct evap object are below: image description

The model results in over 500 cooling hours in this zone. I have set an output variable to generate in a csv for the dry bulb temperature of the node before the direct evap cooler and after the direct evaporative cooler. Looking at the temperatures for each hour of the year it is clear that the direct evap cooler is not doing anything to change the dry bulb temperature of the air loop except when the outdoor air is above 90 degrees F (i.e. on the summer design day). I have looked up and down through the energyplus input output reference guide and through my .osm file and I cannot figure out what is preventing the direct evap cooler from working turning on below 90 degrees.

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Have you tried removing the SetpointManager on the node downstream of the evap object?

MatthewSteen gravatar imageMatthewSteen ( 2019-05-01 17:14:20 -0500 )edit

Yes, that is how I was modeling it initially. Then I was looking through the input/output reference and realized that the EnergyPlus idf object calls for a Sensor Node Name (which it auto-defines as the node after the object). The input/output reference definition for this sensor node name is: "This field specifies the name of a node that will provide system air temperature setpoint information. A separate SetpointManager object should be setup to update this node."

elco8141 gravatar imageelco8141 ( 2019-05-01 17:27:24 -0500 )edit

I would check the in.idf generated from OS and make sure the inputs are translating correctly. I found in a test that OS 2.7 does not convert the EvaporativeCooler:Direct:ResearchSpecial object fields to SI units in the IDF. Also, the field for primary design airflow does not seem to translate anything to the IDF.

kramerica gravatar imagekramerica ( 2019-05-02 11:52:07 -0500 )edit