[TRNSYS-users] Type 4

[Michaël Kummert]

Leen,

> reading the general description in the manual, I find for Type 4 to set 
> the parameter 6 on a negative number which is in absolute value equal to 
> the height of the thank.This would result in equal size nodes in the 
> stratified storage tank.
> Doing this seems impossible as parameter 6 needs to be greater than 0.
> It would have been a nice tool, if it worked. Did someone encounter the 
> same problem and was there someone who solved it in an elegant way?

Type 4 and Type 60 provide a level of flexibility (and a complexity) 
that is beyond what IISiBat proformas can take, unless you think that 30 
proformas for those two types is not enough...
If you want to use the mode you mention, a workaround is to define 2 
equations:

HTank = 1.5     ! the real height of your tank
HNode = HTank/5 ! Assuming you need 5 nodes

And then use a proforma such as Type4c (for variable inlets, uniform 
losses) where you declare 5 nodes and enter "HNode" for the height of 
each node (after changing the variable type to String).
This can be adapted to any number of nodes. Changing the tank height 
will then be as easy as changing the first equation. Of course, you will 
need to adapt the projects if you change the number of nodes but you 
would have to do that anyway (change the number of derivatives and 
outputs in Type 4, etc.).

Another option is to create your own proforma for the particular mode 
you want to use.

Kind regards,

Michaël Kummert

PS on a side note, changing the height of a tank in a simulation without 
changing the number of nodes and the position of inlets, auxiliary 
heaters etc. will not change the results very much (besides the 
increased/decreased volume) since the model's assumption is that one 
node is one volume of fluid at a given temperature, no matter what its 
physical height is.


-- 
_________________________________________________________

Michaël Kummert

Solar Energy Laboratory - University of Wisconsin-Madison
1303 Engr Res Bldg, 1500 Engineering Drive
Madison, WI 53706

Tel: +1 (608) 263-1589
Fax: +1 (608) 262-8464
E-mail: kummert at engr.wisc.edu

SEL Web Site: http://sel.me.wisc.edu
TRNSYS Web Site: http://sel.me.wisc.edu/trnsys