[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: [EnergyPlus_Support] validation of extensive coefficients use
John,
Keep in mind that there are at least two possible "policies" for curve-fits. One option is to use curves that are normalized with respect to capacity (or efficiency) at a single operating point. The other is to use curves that directly fit the capacity/efficiency data without normalization. It is not unreasonable practice to use normalized curves for components that have a different nominal capacity or efficiency than the one used to produce the curves. Clearly it is better to use performance curves that apply to the unit being modeled, but this isn't always practical. On the other hand, direct performance curves (that aren't normalized) are basically limited to the original unit and cannot be used to model components with a different size or nominal performance.
Developers have different opinions on which is the best way to go. The normalized-curve group want curves to be more general so that one can easily adjust equipment capacities when doing a simulation study. The direct-curve group are more leary of the pitfalls of abusing curves and want to force the user to use curves that match the component. I am not sure if it is true across the board, but curves tend to be of the normalized type in EnergyPlus. So it is not blatently wrong to reuse such curves for different capacities. However, do not assume that the example files that ship with EnergyPlus represent best modeling practice. It is better to think of them as test and demonstration files.
Brent
-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]On Behalf Of deserteagle_zhou
Sent: Tuesday, October 11, 2005 4:13 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] validation of extensive coefficients use
Hi,there,
Components, i.e., chiller, fan, etc, are defined according to a
performance curve-fit policy. Curves, however, often have something to
do with the real working conditions and an equipment capacity. I think
users are not supposed to use directly the same coefficients as before
after the equipment capacity has been changed. That means we 'd better
not use directly the curves and parameters in E+ example files directly
unless we cannot get the data from the equipment producer.
Is this understanding right or not?
Another question is whether the object SINGLE DUCT:VAV REHEAT can deal
with heating condition alone in a zone without a company heating device
(such as a baseboard heater), especially in a cold area?
Thank you.
John
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.idf and press the "search" button.
_____
YAHOO! GROUPS LINKS
* Visit your group " EnergyPlus_Support <http://groups.yahoo.com/group/EnergyPlus_Support> " on the web.
* To unsubscribe from this group, send an email to:
EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx <mailto:EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx?subject=Unsubscribe>
* Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> .
_____
[Non-text portions of this message have been removed]
------------------------ Yahoo! Groups Sponsor --------------------~-->
Most low income households are not online. Help bridge the digital divide today!
http://us.click.yahoo.com/cd_AJB/QnQLAA/TtwFAA/dkFolB/TM
--------------------------------------------------------------------~->
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.idf and press the "search" button.
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/EnergyPlus_Support/
<*> To unsubscribe from this group, send an email to:
EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/