performance input for DOAS DX coil

asked 2015-11-07 05:18:28 -0500

ngkhanh
2156 ●1 ●3 ●12

updated 2015-11-07 19:34:43 -0500

Hello, I am trying to get DOAS DX coil working while i get low flow rate /W cooling. However, it frequently fault because of auto sizing process so i am thinking about hardsizing but i have never done it before. Please someone had done it show me a typical way to pass this step. Every time i try DOAS option in coilsystem:dx cooling get fatal error. Note: i checked TRANE TRACE Library and saw similar curve in their library. Are they can use as input for E+ ? Have any people tried to do like this before ?

Here is my link : https://www.dropbox.com/s/h18xs3y7fht... It gets fault with sizing period.If you enable DOAS option it will get fatal error, it was mentioned in Energyplus mailing list. if i keep like this, the DOAS coil wil be kept at normal rate limit which is less than 12 kW gross rate and not able to suply dry enough air - the main advantage of DOAS. Thanks

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Can you add the error you are getting to your question?

Neal Kruis ( 2015-11-07 10:06:18 -0500 )edit

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answered 2015-12-18 16:51:16 -0500

rraustad

13599 ●72 ●12 http://www.fsec.ucf.edu/

Whether the DX coil is hard-sized or autosized, the coil model can sometimes fail to find a valid SHR or bypass factor during sizing. This is due to inputs that cause the model to miss the air properties saturation curve when attempting to find the coil apparatus dew point (ADP) temperature. If the coil outlet air temperature and/or humidity ratio are adjusted such that the model can find a valid ADP, the warnings should disappear. This is an iterative process that can take several attempts before the warnings are eliminated.

A recent improvement was added to the interim release of the V8.4 debug version to overcome this shortfall.

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Thanks for your answer. Most of time this error was solved by change dehumid operation from multi mode to cool reheat then disable the enhanced dehumid. mode in DX coil 2 stage humidity control. But im not sure about the effect on result

ngkhanh ( 2015-12-20 03:23:20 -0500 )edit

Multimode and Coolreheat provide significantly different performance. I suggest taking an example file and switch between these 2 modes to see the impact on cooling and heating energy. Then decide if this difference is significant enough to warrant the time needed to correct your original inputs (or upgrade to the latest release).

rraustad ( 2015-12-20 09:14:55 -0500 )edit

In fact, i have never been getting simulation run for DOAS DX coil with multimode.without DOAS coil seting, the capacity of DX coil will be limited due to min flow rate per dx coil capacity . i used psychometric chart to check ADP. It comes from sizing design day when the humidity and temp. so high that ADP can not meet the dewpoint line of design supply air. i use 15-16oC dewpoint for my sizing data due to high cool. setpoint in hot humid climate. What exact interim release of V8.4 has this debug? Autosize for DOAS temp. in sizing:zone is also prone to get error.

ngkhanh ( 2015-12-20 15:41:00 -0500 )edit

See if the latest is available here https://energyplus.net/

rraustad ( 2015-12-20 20:23:55 -0500 )edit

@Edwin is this the right link?

rraustad ( 2015-12-20 20:29:18 -0500 )edit

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