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Re: type 60
Gilles,
using type 60 (TRNSYS 15) for solar domestic hot water system with
variable flow rate , I have some problems with the internal heat
exchanger. The HX model equations lead to error as "sqrt : domain error"
, "UA has not converged" " UA is negative" . I think it is due to the
temperature difference between inlet and water temperatures inside the
tank (node temperatures) as this difference is sometime (rarely)
negative . Moreover , when I change from 10 internal nodes to 5 nodes
the "sqrt : domain error" doesn't occurs. Perhaps it is preferable that
I don't use several nodes for water temperature around the heat exchanger.
Does anybody already have this kind of problem ?
There is a bug in Type 60 that causes the calculated heat exchanger
U-values to be negative in some circumstances. This may explain the
error you are getting. We are working on a solution but in the meantime,
I would recommend that you use one of the following workarounds (as you
found out yourself, sometimes the errors are very sensitive to some
modeling choices):
- Reduce the time step
- Reduce the number of nodes, especially in the heat exchanger region
- Change the fluid in the heat exchanger (sometimes problems occur at
some concentrations of glycol)
If you have a simplified deck file (preferable Type 60 only and
equations) that allows to reproduce the problem, I would appreciate if
you can send it to me directly.
Kind regards,
Michaël Kummert
--
_________________________________________________________
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@xxxxxxxxxxxxx
SEL Web Site: http://sel.me.wisc.edu
TRNSYS Web Site: http://sel.me.wisc.edu/trnsys