Re: [TRNSYS-users] type 17's question

[David Bradley <bradley@tess-inc.com>]

Dapeng,
  The mathematics of the heat exchangers in Type17 are the same as
the mathematics of the Type5 heat exchanger as far as the energy
transferred across a given heat exchanger. However, Type17 assumes that
there is one primary heat exchanger and at least two secondary heat
exchangers so you would have to include at least three Type5s in your
simulation to model Type17.
Kind regards,
 David


At 20:19 1/22/2008, LiDapeng wrote:

Dear trnsys users,

 

Type 17 models a cascaded waste heat recovery system, e.g. only two heat exchangers in the system, one is as a primary heat exchanger and another is as a secondary heat exchanger. The mode of two heat exchangers are all assumed to counter mode.

 

I think the effect of type 17 is equal to two type 5. So I use two type5b(counter heat exchanger) instead of a type 17 and the connection between two type 5b is given as: the output 3 and 4 of a type 5 as the secondary heat exchanger in type 17 are connected to the input 1 and 2 of another type 5 as the primary heat exchanger in type 17; and the output 3 and 4 of a type 5 as the primary heat exchanger in type 17 are connected to the input 1 and 2 of another type 5 as the secondary heat exchanger in type 17. The other parameters in two type 5 are set the same as the corresponded parameters in type 17.

But the results from two type 5 are quitely different of the one from a typ! e 17. Maybe my thought is wrong, but anyone can tell me the reasons about my question?

 

Kind regards!

 

Dapeng

 

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