Re: [EnergyPlus_Support] problems about people latent load and "SOLUTION ALGORITHM"

["Michael J. Witte" <mjwitte@xxxxxxxx>]

The MTF algorithm is an advanced feature which should be used with great 
caution.  The moisture properties are non-linear and can give incorrect results 
when used outside the range of applicability.  Please see the "Moisture 
Transfer Material Properties" in the Engineering Reference, p. 24.

In answer to both of your questions, remember that "Zone/Sys Moisture Load Rate 
Predicted" is affected by the zone conditions in the previous time step.  Are 
you comparing a single time step or a whole day or month?  There are many 
variables interacting here.  Turn on extra report variables so that you can see 
the different mechanisms occuring in the zone.  Report both relative humidity 
and humidity ratio, and be sure that the zone dry bulb temperatures are the 
same in both cases.

Mike


On 10 Aug 2004, at 18:09, Zheng Li wrote:

> Dear:
> 
> I am calculating a case about the cooling load, especially the latent one. The
> basic case only inculdes the envelope, no people, light, electric equipment,etc.
> and the "SOLUTION ALGORITHM" is MTF, and then I get the result of "Zone/Sys
> Moisture Load Rate Predicted". I know that the value is  not the real latent
> load, but I think the difference between this basic case and others may be
> meaningful. Now, I have two questions:
> 
> 1. When the "SOLUTION ALGORITHM" is changed into CTF and all the other inputs
> remain the original values. What is the differece between the two "Zone/Sys
> Moisture Load Rate Predicted" under the CTF and MTF conditions? Is it the latent
> load of the envelope permeance? If yes, why the result is about 1500W, I think
> it is unreasonable.
> 
> 2. Base on the basic case, when 4 people is added, the value of "Zone/Sys
> Moisture Load Rate Predicted" is smaller than the basic case, that means, the
> latent load that should be removed is lower than that has no people. How about
> the people latent load? 
> 
> Thanks a lot!
> 
> Best Regards
> 
> LI
> 
> 
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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