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# High density load in datacenter

Dear Unmet team,

Running a simulation for a datacenter project, in a 200 M2 IT room with 160 Kw IT load, something funny happens:

Description, 200 m2 area, 3m height, DX air system air-cooled, roof and walls exposed, floor ground. Supply temperature 20C, return temperature 32C.

1- If the IT load is low (10 Kw) the simulation runs well

2- If the IT loads is high (160 Kw) the simulation fails, warnings and severe errors are presented.

Warning ** Inside surface heat balance did not converge with Max Temp Difference"


and

Severe "the surface temperature is out of bounds"


Does somebody know how to solve it?

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@HJOJOA Did you ever get rid of the surface temperature errors by the way? I'm having the same problem in my model, and no matter how big I make the equipment, the surfaces are getting to 200C and greater.

( 2021-01-21 14:15:53 -0600 )edit

@HJOJOA Did your find the solution for using high density load in datacenter?

( 2021-05-06 09:59:54 -0600 )edit

@mldichter Did you find the answer to solve these problems above?

( 2021-05-06 10:08:28 -0600 )edit

@tri.ton99 I wouldn't save solved, but I got the simulation working. I used an IdealLoadsAirSystem object. My best guess is the iterative algorithm to solve for the cooling equipment was unstable with too high a load. If you want to calculate the timestep energy used by the data center cooling equipment, you could output the data center and outdoor air conditions variables, then apply the curves to get the energy used. You could also use EMS to modify an ElectricEquipment object, but that's only useful if you're doing many simulations and excel would be too cumbersome.

( 2021-05-06 10:52:01 -0600 )edit

@mldichter I am using the ElectricEquipment:ITE:AirCooled to simulate the server rack load in the data center. My problems are here. Can you have a look? I am not using IdealLoadsAirSystem for this situation because ElectricEquipment:ITE:AirCooled had curves define by EnergyPlus in 2ZoneDataCenterHVAC_wEconomizer.idf file and I think this suitable with my model. Where can I do with this or find the solutions?

( 2021-05-06 10:59:10 -0600 )edit

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It is a guess but might work: When you changed the load you changed it in the run period and not in the design days so the DX is sized to the lower load and that is why it can't satisfy the high load. That is if you auto sized your DX. You might want to start with Ideal Air Load System.

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Hi, I tried again, create new file, run first ideal loads with 160 Kw and works good, but then i added a new air loop ant the simulation fail.

( 2018-05-11 14:25:59 -0600 )edit

@HJOJOA forget about ideal load. just make sure to change the load in design day. If you can post a link to your model I will take a look.

( 2018-05-11 15:24:14 -0600 )edit