Question-and-Answer Resource for the Building Energy Modeling Community
Get s tarted with the Help page
Ask Your Question
2

Sizing error of Coil:Cooling:DX:SingleSpeed unit in DOAS ystem

asked 2016-03-09 11:12:44 -0600

updated 2016-03-09 13:46:49 -0600

I am simulating DOAS system with an air-cooled DX unit using OpenStudio, and there is an error when sizing the "Coil:Cooling:DX:SingleSpeed".

Based on the "input output reference" of E+, the rated volumetric air flow to total cooling capacity of "Coil:Cooling:DX:SingleSpeed" should be 300 to 450 cfm/ton; for DOAS application, it should be 125 to 250 cfm/ton. My DOAS system is 168 cfm/ton, which locates in the range of DOAS application. However, E+ seems to use the range of 300 to 450 cfm/ton, and it comes out the error:

* Severe * Sizing: Coil:Cooling:DX:SingleSpeed "1 SPD DX CLG COIL": Rated air volume flow rate per watt of rated total cooling capacity is out of range. * ~~~ * ...Air Volume Flow Rate used in calculation = 1.179869 m3/s * ~~~ * ...Air Volume Flow Rate per Watt of Rated Cooling Capacity is also out of bounds at = 2.2566585E-005 m3/s/W * ~~~ * During Warmup, Environment=NEWARK INTERNATIONAL ARPT ANN CLG .4% CONDNS DB=>MWB, at Simulation time=07/21 00:00 - 00:10

How should I let the program know that it is DOAS application?

Here is my setup:

The "Type of Load to Size On" was set as "VentilationRequirement", and both "100% Outdoor Air in Cooling" and "100% Outdoor Air in Heating" as "Yes". As for the "Coil:Cooling:DX:SingleSpeed", cooling capacity is 178400 BTU/h and air flow rate is 2500 cfm

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted
2

answered 2016-03-09 11:56:57 -0600

Depending on the system type and where and how this coil is configured and used in the simulation, you can tell the program that the coil is a 100% outdoor air coil. This is typically accomplished in a parent wrapper around the coil object.

CoilSystem:Cooling:DX,
 A11,  \field Use Outdoor Air DX Cooling Coil
    \type choice
    \key Yes
    \key No

AirLoopHVAC:UnitarySystem,
 A16, \field Use DOAS DX Cooling Coil
   \type choice
   \key Yes
   \key No
edit flag offensive delete link more

Comments

I didn't find the field of "Use DOAS DX Cooling Coil" in OpenStudio, but I do set both "100% Outdoor Air in Cooling" and "100% Outdoor Air in Heating" to "Yes". I didn't use "AirLoopHVAC:UnitarySystem", instead, I created an empty air loop and add coils, fans. In this case, is there any place I could setup DOAS?

Yan gravatar image Yan  ( 2016-03-09 13:14:13 -0600 )edit

Place your DX coil inside the CoilSystem:Cooling:DX object and select Yes in the "Use Outdoor Air DX Cooling Coil" field.

rraustad gravatar image rraustad  ( 2016-03-09 14:37:44 -0600 )edit

@rraustad, does OpenStudio include "CoilSystem:Cooling:DX" object?

Yan gravatar image Yan  ( 2016-03-09 14:59:47 -0600 )edit

@macumber could answer that question.

rraustad gravatar image rraustad  ( 2016-03-09 15:20:08 -0600 )edit

I believe that the answer is yes but @Kyle Benne and @aparker are the best to field OpenStudio questions about HVAC

macumber gravatar image macumber  ( 2016-03-09 15:39:43 -0600 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

 

Question Tools

1 follower

Stats

Asked: 2016-03-09 11:12:44 -0600

Seen: 440 times

Last updated: Mar 09 '16