[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: [EnergyPlus_Support] Re: fan problem
You are using plain text mode, that is why all the formatting are lost.
In the IDF I received from the group, nine out of ten of them do not have a proper schedule for DesignDays in one way or another.
The schedule for design days are lumped in the allOtherDays. If allOtherDays are for the holidays and weekends which has the plants and system turned off, the DesignDay sizing run would be for holiday settings, with many zero output values..
====================
The set point manager mixedAir require two monitoring points for cooling. One is at the mixed air node and the other at the cooling coil node. The use of economizer is not compulsory. but it will save energy by not retuning the hot zone air when the OA temperature is in the cooler range. When the mixed air node is high, the cooling coil takes over.
I do not know what is causing your problem. I do not know which set point is changed to 50°C. The cooling coil temperature sets the cooling supply capacity at the rated fan flowrate. It must be set below the required zone temperature. The reference node in the example is the output node of the fan.
Without using reheat and using extra cooling by the panel, I am not sure how the system will work. What is condition for the panel to turn on?
One possibility is for the panel to come on at the maximum fan flow rate, and set point temperature not met. I am not sure whether priority 1 and 2 will cover these operation.
If the panel is in the heating mode, then it is necessary to set the ref node temperature below the required zone temperature. The panel would come on when the damper is at the minimum position.
This is one reason why I said special VAV system is not easy to design and requires more sensors and a computor program to decide on what to do.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeannieboef@xxxxxxxxx
Date: Thu, 29 Sep 2011 19:57:03 +0000
Subject: [EnergyPlus_Support] Re: fan problem
Thank you Dr Li,
You have verified my understanding of the fan types.
My setpoint manager sets a constant temperature setpoint after my cooling coil which is far below 50 deg C. Do you suggest I investigate using the econimiser as a work around to the problem?
Could you explain your first sentance a bit more, please.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
>
>
> The Summer or WinterDesignDay may be in the wrong place of your schedule, and shut off the system regardless. Turn on the Daytype Index variable to see the actual day used in the simulation. Because the AHU is setpoint based on a reference node, the VAV damper position does not control the fan velocity diretly. When the zone temperature is not met, the damper will move towards the maximum or minimum position and lock. If the ref. set point is at 50°C for the AHU in the cooling mode, and the zone temperature is below this, the AHU fan would not be turned on. To use the OA in take, the economizer must be on, and the ref set point is ignored. This may also depends on what set point manager is used.===============================Continuous fan is on all the time. Constant speed fan has a fixed volume. VAV fan would change it speed to maintain the reference set point temperature, by change the air flow through the coils. In the cooling mode, the reference set point temperature must not be higher than the desired zone temperature.
> Dr. Li
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: jeannieboef@...
> Date: Thu, 29 Sep 2011 17:37:25 +0000
> Subject: [EnergyPlus_Support] fan problem
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Dear group,
>
>
>
> I am doing a summer design day analysis.
>
>
>
> I am using AHU fan:variablevolume with zone vav:noreheat and notice that the AHU fan will not run regarless of damper positions or outdoor air requirements if there are no space loads to meet (because I set the cooling setpoint to 50 deg C.)
>
>
>
> This is unwanted behaviour.
>
>
>
> My cooling loads are combated with a seperate radiant cooling system which has a setpoint of 22 deg C.
>
>
>
> The objective is to de-couple the cooling function of the AHU to a pure ODA functionality.
>
>
>
> As I understand the io ref, the only fan type that doesn't operate to meet loads is continuous.
>
>
>
> Comments please.
>
.ExternalClass #ecxygrp-mkp {border:1px solid #d8d8d8;font-family:Arial;padding:0 10px;} .ExternalClass #ecxygrp-mkp hr {border:1px solid #d8d8d8;} .ExternalClass #ecxygrp-mkp #ecxhd {color:#628c2a;font-size:85%;font-weight:700;line-height:122%;} .ExternalClass #ecxygrp-mkp #ecxads {margin-bottom:10px;} .ExternalClass #ecxygrp-mkp .ecxad {padding:0 0;} .ExternalClass #ecxygrp-mkp .ecxad p {;} .ExternalClass #ecxygrp-mkp .ecxad a {color:#0000ff;text-decoration:none;} .ExternalClass #ecxygrp-sponsor #ecxygrp-lc {font-family:Arial;} .ExternalClass #ecxygrp-sponsor #ecxygrp-lc #ecxhd {font-weight:700;font-size:78%;line-height:122%;} .ExternalClass #ecxygrp-sponsor #ecxygrp-lc .ecxad {margin-bottom:10px;padding:0 0;} .ExternalClass a {color:#1e66ae;} .ExternalClass #ecxactions {font-family:Verdana;font-size:11px;padding:10px 0;} .ExternalClass #ecxactivity {background-color:#e0ecee;float:left;font-family:Verdana;font-size:10px;padding:10px;} .ExternalClass #ecxactivity span {font-weight:700;} .ExternalClass #ecxactivity span a {color:#5085b6;text-decoration:none;} .ExternalClass #ecxactivity span span {color:#ff7900;} .ExternalClass #ecxactivity span .ecxunderline {text-decoration:underline;} .ExternalClass .ecxattach {clear:both;display:table;font-family:Arial;font-size:12px;padding:10px 0;width:400px;} .ExternalClass .ecxattach div a {text-decoration:none;} .ExternalClass .ecxattach img {border:none;padding-right:5px;} .ExternalClass .ecxattach label {display:block;margin-bottom:5px;} .ExternalClass .ecxattach label a {text-decoration:none;} .ExternalClass blockquote {;} .ExternalClass .ecxbold {font-family:Arial;font-size:13px;font-weight:700;} .ExternalClass .ecxbold a {text-decoration:none;} .ExternalClass dd.ecxlast p a {font-family:Verdana;font-weight:700;} .ExternalClass dd.ecxlast p span {margin-right:10px;font-family:Verdana;font-weight:700;} .ExternalClass dd.ecxlast p span.ecxyshortcuts {margin-right:0;} .ExternalClass div.ecxattach-table div div a {text-decoration:none;} .ExternalClass div.ecxattach-table {width:400px;} .ExternalClass div.ecxfile-title a, .ExternalClass div.ecxfile-title a:active, .ExternalClass div.ecxfile-title a:hover, .ExternalClass div.ecxfile-title a:visited {text-decoration:none;} .ExternalClass div.ecxphoto-title a, .ExternalClass div.ecxphoto-title a:active, .ExternalClass div.ecxphoto-title a:hover, .ExternalClass div.ecxphoto-title a:visited {text-decoration:none;} .ExternalClass ecxdiv#ygrp-mlmsg #ecxygrp-msg p a span.ecxyshortcuts {font-family:Verdana;font-size:10px;font-weight:normal;} .ExternalClass .ecxgreen {color:#628c2a;} .ExternalClass .ecxMsoNormal {;} .ExternalClass ecxo {font-size:0;} .ExternalClass #ecxphotos div {float:left;width:72px;} .ExternalClass #ecxphotos div div {border:1px solid #666666;height:62px;overflow:hidden;width:62px;} .ExternalClass #ecxphotos div label {color:#666666;font-size:10px;overflow:hidden;text-align:center;white-space:nowrap;width:64px;} .ExternalClass #ecxreco-category {font-size:77%;} .ExternalClass #ecxreco-desc {font-size:77%;} .ExternalClass .ecxreplbq {;} .ExternalClass #ecxygrp-mlmsg {font-size:13px;font-family:Arial, helvetica,clean, sans-serif;} .ExternalClass #ecxygrp-mlmsg table {font-size:inherit;font:100%;} .ExternalClass #ecxygrp-mlmsg select, .ExternalClass input, .ExternalClass textarea {font:99% Arial, Helvetica, clean, sans-serif;} .ExternalClass #ecxygrp-mlmsg pre, .ExternalClass code {font:115% monospace;} .ExternalClass #ecxygrp-mlmsg ecx* {line-height:1.22em;} .ExternalClass #ecxygrp-mlmsg #ecxlogo {padding-bottom:10px;} .ExternalClass #ecxygrp-mlmsg a {color:#1E66AE;} .ExternalClass #ecxygrp-msg p a {font-family:Verdana;} .ExternalClass #ecxygrp-msg ecxp#attach-count span {color:#1E66AE;font-weight:700;} .ExternalClass #ecxygrp-reco #ecxreco-head {color:#ff7900;font-weight:700;} .ExternalClass #ecxygrp-reco {margin-bottom:20px;padding:0px;} .ExternalClass #ecxygrp-sponsor #ecxov li a {font-size:130%;text-decoration:none;} .ExternalClass #ecxygrp-sponsor #ecxov li {font-size:77%;list-style-type:square;padding:6px 0;} .ExternalClass #ecxygrp-sponsor #ecxov ul {padding:0 0 0 8px;} .ExternalClass #ecxygrp-text {font-family:Georgia;} .ExternalClass #ecxygrp-text p {;} .ExternalClass #ecxygrp-text tt {font-size:120%;}
------------------------------------
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
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 currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
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:
EnergyPlus_Support-digest@xxxxxxxxxxxxxxx
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/