[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [EnergyPlus_Support] Enthalpy reference temperature - PCM
I am currently having some trouble with the PCM model. I was given some data, enthalpy vs temperature, and it resembles a bell curve for the fusion enthalpy. E+ only takes DH/DT as the current specific heat for each node, and on the second half of the bell curve, this is calculated as negative. (enthalpy is going down as temperature increases) Because of this, E+ uses the simple Cpo (specific heat brought in by the material:regular definition) for the second half of the curve. I realize that the overall enthalpy should be increasing, but the data I was given looks is parabolic. Have you had any experience seeing this or overcoming this?
Thanks
----- Original Message ----
From: Michael J. Witte <mjwitte@xxxxxxxx>
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Sent: Tuesday, September 4, 2007 2:22:29 PM
Subject: Re: [EnergyPlus_Support] Enthalpy reference temperature - PCM
My understanding is that the model is computing changes in enthalpy, so the
reference for zero enthalpy should not matter. For example, if you were to add
1000 to every enthalpy value, but keep the same temperatures, you should get
the same result.
I will forward this to the Conduction Finite Different model developer for
clarification.
Mike
On 29 Aug 2007 at 17:19, Renato Sousa wrote:
> Hello all,
>
> I'm using simulating a building to see the effect of phase change materials and
> in order to input the Enthalpy-Temperatur e data, I would like to know which is
> the reference temperature that EnergyPlus uses for a zero enthalpy of the
> material. I couldn't find this on the documentation, and from the example in the
> Input-Output reference (from April 9, 2007 - page 81), it looks like the
> reference temperature for zero enthalpy is -20 ºC. Should I use -20ºC for zero
> enthalpy?
>
> Thanks in advance,
>
> Renato Sousa
>
> Tel: +351 919 316 221 | E-mail: renato.sousa@ fluidinova. pt
>
>
>
> ____________ _________ _________ _________ _________ ___
>
> FluidInova, Engenharia de Fluidos, SA
>
> TECMAIA - Parque de Ciência e Tecnologia da Maia
>
> Rua Engº Frederico Ulrich, nº 2650 | 4470-605 Moreira da Maia | Portugal
>
>
> Tel: +351 229 408 265 | Fax: +351 229 408 266
>
> E-mail: <mailto:geral@fluidinova. pt> geral@fluidinova. pt | Web:
> www.fluidinova. pt/
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> The primary EnergyPlus web site is found at:
> http://www.energypl us.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. pdf under the
> Documentation link and press the "search" button.
>
> Yahoo! Groups Links
>
>
>
>
>
============ ========= ========= ========= ========= ========
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@ gard.com
<!--
#ygrp-mkp{
border:1px solid #d8d8d8;font-family:Arial;margin:14px 0px;padding:0px 14px;}
#ygrp-mkp hr{
border:1px solid #d8d8d8;}
#ygrp-mkp #hd{
color:#628c2a;font-size:85%;font-weight:bold;line-height:122%;margin:10px 0px;}
#ygrp-mkp #ads{
margin-bottom:10px;}
#ygrp-mkp .ad{
padding:0 0;}
#ygrp-mkp .ad a{
color:#0000ff;text-decoration:none;}
-->
<!--
#ygrp-sponsor #ygrp-lc{
font-family:Arial;}
#ygrp-sponsor #ygrp-lc #hd{
margin:10px 0px;font-weight:bold;font-size:78%;line-height:122%;}
#ygrp-sponsor #ygrp-lc .ad{
margin-bottom:10px;padding:0 0;}
-->
<!--
#ygrp-mlmsg {font-size:13px;font-family:arial, helvetica, clean, sans-serif;}
#ygrp-mlmsg table {font-size:inherit;font:100%;}
#ygrp-mlmsg select, input, textarea {font:99% arial, helvetica, clean, sans-serif;}
#ygrp-mlmsg pre, code {font:115% monospace;}
#ygrp-mlmsg * {line-height:1.22em;}
#ygrp-text{
font-family:Georgia;
}
#ygrp-text p{
margin:0 0 1em 0;}
#ygrp-tpmsgs{
font-family:Arial;
clear:both;}
#ygrp-vitnav{
padding-top:10px;font-family:Verdana;font-size:77%;margin:0;}
#ygrp-vitnav a{
padding:0 1px;}
#ygrp-actbar{
clear:both;margin:25px 0;white-space:nowrap;color:#666;text-align:right;}
#ygrp-actbar .left{
float:left;white-space:nowrap;}
.bld{font-weight:bold;}
#ygrp-grft{
font-family:Verdana;font-size:77%;padding:15px 0;}
#ygrp-ft{
font-family:verdana;font-size:77%;border-top:1px solid #666;
padding:5px 0;
}
#ygrp-mlmsg #logo{
padding-bottom:10px;}
#ygrp-vital{
background-color:#e0ecee;margin-bottom:20px;padding:2px 0 8px 8px;}
#ygrp-vital #vithd{
font-size:77%;font-family:Verdana;font-weight:bold;color:#333;text-transform:uppercase;}
#ygrp-vital ul{
padding:0;margin:2px 0;}
#ygrp-vital ul li{
list-style-type:none;clear:both;border:1px solid #e0ecee;
}
#ygrp-vital ul li .ct{
font-weight:bold;color:#ff7900;float:right;width:2em;text-align:right;padding-right:.5em;}
#ygrp-vital ul li .cat{
font-weight:bold;}
#ygrp-vital a{
text-decoration:none;}
#ygrp-vital a:hover{
text-decoration:underline;}
#ygrp-sponsor #hd{
color:#999;font-size:77%;}
#ygrp-sponsor #ov{
padding:6px 13px;background-color:#e0ecee;margin-bottom:20px;}
#ygrp-sponsor #ov ul{
padding:0 0 0 8px;margin:0;}
#ygrp-sponsor #ov li{
list-style-type:square;padding:6px 0;font-size:77%;}
#ygrp-sponsor #ov li a{
text-decoration:none;font-size:130%;}
#ygrp-sponsor #nc{
background-color:#eee;margin-bottom:20px;padding:0 8px;}
#ygrp-sponsor .ad{
padding:8px 0;}
#ygrp-sponsor .ad #hd1{
font-family:Arial;font-weight:bold;color:#628c2a;font-size:100%;line-height:122%;}
#ygrp-sponsor .ad a{
text-decoration:none;}
#ygrp-sponsor .ad a:hover{
text-decoration:underline;}
#ygrp-sponsor .ad p{
margin:0;}
o{font-size:0;}
.MsoNormal{
margin:0 0 0 0;}
#ygrp-text tt{
font-size:120%;}
blockquote{margin:0 0 0 4px;}
.replbq{margin:4;}
-->
____________________________________________________________________________________
Got a little couch potato?
Check out fun summer activities for kids.
http://search.yahoo.com/search?fr=oni_on_mail&p=summer+activities+for+kids&cs=bz
[Non-text portions of this message have been removed]
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.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/EnergyPlus_Support/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/EnergyPlus_Support/join
(Yahoo! ID required)
<*> To change settings via email:
mailto:EnergyPlus_Support-digest@xxxxxxxxxxxxxxx
mailto:EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx
<*> 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/