Hi all, I am trying to model 2 air-cooled chillers that have a free cooling component to disable the chiller when applicable. I have tried a couple of approaches listed below and haven't been able to figure out the right solution.
Approach #1- Heat Exchanger in parallel with chillers. Then,attaching the HeatExchanger:FluidToFluid to a condenser loop with cooling tower on the supply end. Since the control needs to make sure the chillers are off when the free cooling is available- make this control to component override. 2 problems with this approach 1a-Heat exchanger always get pushed to the end in the sequence making this last priority with sequential distribution on the loop. 1b-component override option needs a demand side component inlet node, which I believe based on this post https://unmethours.com/question/14606/waterside-economizer-integrated-with-more-than-one-chiller/ is chiller's condenser inlet node. Since this is air-cooled chiller I don't have a node to refer to!
Approach #2-attaching the HX in series with each chiller. The sequencing problem is addressed from Approach#1 but the Component override node problem still remains
Approach#3- attaching HX right after pump. The nodes required for this to work is still 1 set of chiller nodes, I have 2!
Approach #4- Set the HX in parallel and change the control to Cooling setpointOnOff. This seems to avoid the node references but the HX seems to work only for the first half of January!
Can anyone shed light on a working approach for this?
Thanks, Sri
