Fwd: Re: Fwd: [EnergyPlus_Support] Radiant Cooling Modeling

[Linda Lawrie <linda@xxxxxxxxxx>]

>Date: Mon, 22 Apr 2002 10:55:38 -0500
>Subject: Re: Fwd: [EnergyPlus_Support] Radiant Cooling Modeling
>
>My cautious answer is that the user has the ability to specify flow rates 
>and temperatures hourly, but not at a 15 minute time step.  As a result, 
>one might be able to come close to what Vinay is trying to 
>simulate.  Naturally, the program is not set-up to verify experimental 
>data and to get the hourly schedules to work for verification purposes is 
>less than obvious.
>
>The user may schedule both the pump flow rate and the plant loop setpoint 
>temperature on an hourly basis.  Thus, if the user knows these quantities, 
>they can be entered as schedules and applied to the appropriate input 
>parameter.  I would recommend using a constant speed pump that is set to 
>"CONTINUOUS" operation.  The schedule will modify the maximum flow rate 
>entered so the schedule values and the maximum flow rate product really 
>defines the current flow rate.  Using a constant, continuous pump will 
>guarantee that the flow rate is set at that value and that the pump always 
>operates.
>
>The plant loop setpoint temperature will also have to be scheduled hourly 
>to approximate the temperature variation that is being measured.  This is 
>tedious, but the flexibility is there if the desire to do this is 
>there.  If the user is only concerned about building response, then I 
>would recommend using an "infinitely large" purchased cooling plant so 
>that the setpoint temperature is always met.
>
>The last thing that will have to be done is some slight of hand with the 
>schedule.  If the user wants to force the system to run all the time based 
>on the given flow rates and temperatures, the control definition 
>(temperatures) will need to be set-up so that the radiant system is always 
>running.  To do this for cooling, the MAT, MRT, or operative setpoint 
>temperature schedule will need to be set to a very low temperature to 
>force the system to run.
>
>In theory, this has the possibility of working, but I have not tried to 
>vary both temperature and flow rate in this way.  I have looked at cases 
>where the fluid temperature was varied hourly and this works.  I would 
>recommend trying this for a single day of data and seeing whether the 
>program interprets the user's intent correctly.
>
>If the user has suggestions on improvements for controls for radiant 
>systems, I would be happy to hear them.  I'll let you handle the issue of 
>hourly schedules vs. something more frequent.

First this forward from the developer of the radiant cooling systems.

We have a suggestion in the making of developing schedules for more 
frequent than "hourly".

Linda


------------------------ Yahoo! Groups Sponsor ---------------------~-->
SALE --> Wireless Video Cameras
for Home Surveillance! VERY TINY! PRICE BREAKTHROUGH - $79.99!
http://us.click.yahoo.com/W0toNC/7o6DAA/yigFAA/dkFolB/TM
---------------------------------------------------------------------~->

To unsubscribe from this group, send an email to:
EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/




 

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/