[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: [EnergyPlus_Support] Water film on a building wall
One can theoretically calculate an effective heat transfer temperature
for evaporative processes, much like one can calculate a sol-air
temperature to account for radiant effects on a roof. If you are able to
input a separate outside temperature for just the surface that is
evaporatively cooled then you could pick up the heat transfer benefits
in that manner without having to try and calculate the exact surface
temperature - i.e. you could process the weather data externally.
I have no idea if this is feasible with E+ but I have modeled roof spray
and roof pond systems successfully using this concept in a "hand-built"
analysis tool. It might have also involved re-calculation of custom
transfer functions for the walls under evaporative conditions. I'd have
to dig out my paper - it was a while ago...
If, as you state, you want to simply remove a known load based on your
experiments then you could put in a negative heat load in the space that
equals the cooling effect you have measured. I believe there have been
discussions of this strategy on this forum before.
Peter
________________________________
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of HSIEH Chun-Ming
Sent: Thursday, September 14, 2006 4:08 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Water film on a building wall
Hello,
I want to simply have a idea about how the building energy use decreases
when a thin water film system is installed on a specified wall of a
building.
Heat is removed by water evaporation from the wall so that the
temperature of outside wall reduces.
Therefore, we can also save the electric power of air conditioners
due to the temperature decrease of wall.
>From the experiment results, we know how much water evaporated during
the daytime.
Is there any good way to simulate this kind of situation?
I am thinking of using the Other side Coefficients, but I am not sure
how to do it.
Actually, two ways are available for us.
One is to set the temperature of outside wall directly.
The other way is to set both the film coefficient and the outside air
temperature.
Under the assumption of how much heat was removed (the amount of water
evapoated) from the experiment,
I want to use the later one instead of setting the wall temperature
directly if it is a possibile way.
>From the Input-Output Reference, there is a equation in the part of
Other Side Coefficients.
However, C1, the combined convective film coefficient was not shown in
the equation.
I wonder how this coefficient works in the calculation?
Does it simply act as a coefficient for the temperature difference
between the outside temperature and air temperature.
It seems that a higher C1 gives a higher temperature of wall.
Do you have ideas to simulate the water film system by using another
method?
Is there any simple way to remove 50 W/m2, for example, from the outside
wall in the simulation?
Thank you very much.
Chunming
[Non-text portions of this message have been removed]
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses
[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.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/
<*> 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/