Re: Enquiry on Type 4, Type60 and Type 66 modules

[Michaël Kummert <kummert@xxxxxxxxxxxxx>]

Dear Howard,

Type 4 is easier to use than Type 60 but it does not allow you to 
simulate internal heat exchangers. If you don't have internal heat 
exchangers or if you can neglect them, I would recommend that you use 
Type 4. On the other hand, Type 60 uses its own internal time step. Type 
4 uses TRNSYS time step, which may lead to numerical instabilities in 
some cases, e.g. if you have high flowrates to/from the tank and a large 
number of nodes (usually, the problem is easily fixed by reducing the 
TRNSYS time step).

Regarding the number of nodes, several studies have shown that using a 
relatively small number of nodes (<=10) gives a satisfactory accuracy 
for yearly simulation of solar systems. The problem is of course 
different if you want to simulate a particular tank design accurately, 
especially if you are interested in short-term/transient behavior. You 
could start using a small number of nodes and then increase it 
progressively. You can then decide how many nodes you need to obtain a 
good accuracy in your particular case. Of course, this assumes that the 
real tank is actually stratified.

The current version of Type66 is restricted to one instance per 
simulation. However, the EES solver can cope with a large number of 
equations so you can group different components in the same EES file.

Regards,

Michaël Kummert




Howard wrote:


> Dear all,
>
> Currently I am trying to model a hot water storage tank for storing 
> water heated by a heat pump. There are two similar models, the Type 4 
> and Type
>
> 60 in the TRNSYS and I would like to know:
>
>  
> - Any general guidelines to decide which Type of storage tank should 
> be used?
>
> - How do we define the number of stratification? Aren't the 
> stratification is a natural phenomena?
>
>  
> On the other hand, I tried to write my own component in EES (such as 
> the compressors, condensers) and would like to add them into the 
> Trnsys project by Type66 module.
>
> However, plenty of error popped up when I started the simulation if 
> two or more Type66 module is used. I sorted out there may be some 
> problem with the data transfer through CLIPBOARD but I cannot resolve 
> it indeed. Does anyone have similar experience before which can share?
>
>  
> Regrads,
>
>  
> Howard But
>
> The University of Hong Kong
--
_________________________________________________

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@engr.wisc.edu

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