Re: [TRNSYS-users] Type1 Number of identical collectors in series has no effect

Thanks again David

It is not exactly what I meant though. Please consider the 2 cases below (all other parameters and inputs being equal) computed with Type1b.

I get the exact same results in the 2 cases: is it physically consistent?

Type	Variable	Case 1	Case 2	Unit
Param	Number in series	1	6	-
Param	Collector area	100	100	m^2
Param	Tested flow rate	70	70	kg/hr.m^2
Input	Inlet flowrate	5000	5000	kg/hr

Best

Antoine Gautier

Solamen

+33 6 58 24 02 60

antoine.gautier@solamen.fr

De : David BRADLEY [mailto:d.bradley@tess-inc.com]
Envoyé : jeudi 20 octobre 2016 23:35
À : Antoine Gautier <antoine.gautier@solamen.fr>; 'TRNSYS users mailing list at OneBuilding.org' <trnsys-users@lists.onebuilding.org>
Objet : Re: [TRNSYS-users] Type1 Number of identical collectors in series has no effect

Antoine,

There is usually some difference in results. The collectors run more efficiently when all of them are in parallel because there is no efficiency penalty for the increasing inlet temperature to each collector in series after the first one. If all of the inputs are set correctly then the flow rate through any given collector in the two scenarios (12 in parallel or 2 sets of 6 in parallel) should be exactly the same (thus there should not be any effect of the flow rate on the efficiency). You will, of course, get some increase in the amount of power drawn by the pump because in the "12 in parallel" case you have to provide a higher flow rate (although with a lower pressure drop)

best,

David

On 10/20/2016 15:09, Antoine Gautier wrote:

Thanks a lot David!

Sorry I had you taking me by the hand like that.
I must say that my insistence pertains to the following observation: only changing "number in series" from 6 to 1 leads to the exact same results.
I find it really strange…
The new system modelled should be an array of Ntotal collectors connected in parallel and thus receiving M/Ntotal flowrate (Nseries=1).
Does this mean that the drop in efficiency due to lower flowrate is exactly balanced by the raise in efficiency due to lower average temperature (each collector now being supplied directly with water at array inlet temperature)?

--
Antoine Gautier
Solamen
+33 6 58 24 02 60
antoine.gautier@solamen.fr

De : David BRADLEY [mailto:d.bradley@tess-inc.com]
Envoyé : jeudi 20 octobre 2016 21:43
À : Antoine Gautier <antoine.gautier@solamen.fr>; 'TRNSYS users mailing list at OneBuilding.org' <trnsys-users@lists.onebuilding.org>
Objet : Re: [TRNSYS-users] Type1 Number of identical collectors in series has no effect

Antoine,
That is correct so long as "A" is the area of the full array (12 times the area of a single module) and so long as "M" is twice the flow rate that you want to go through each collector. Mathematically:
M = X * Ntotal / Nseries
where M is the pump flow rate, X is the flow rate per collector, Ntotal is the total number of collectors (12), and Nseries is the number of collectors in series per parallel path (6).
best,
David

On 10/20/2016 14:20, Antoine Gautier wrote:
Sorry David I still have some doubts…

Here is a schematic.
Within each row, the collectors are connected in series.
The pump flowrate is M. The total array area is A.
I can model this with Type1 considering:

Number in series=6
Collector area=A
Inlet flowrate=M

Is this correct?
Thanks again.

--
Antoine Gautier
Solamen
+33 6 58 24 02 60
antoine.gautier@solamen.fr

De : David BRADLEY [mailto:d.bradley@tess-inc.com]
Envoyé : jeudi 20 octobre 2016 20:44
À : Antoine Gautier <antoine.gautier@solamen.fr>; 'TRNSYS users mailing list at OneBuilding.org' <trnsys-users@lists.onebuilding.org>
Objet : Re: [TRNSYS-users] Type1 Number of identical collectors in series has no effect

Antoine,
I'm not 100% sure that I follow your logic but you can model that array with a single instance of Type1. If your single module has an area of 1m2 and wants a flow rate of 400kg/h then the full array of 50 modules (10 in parallel, 5 in series) would have:
area = 50 m2
number in series = 5
flow rate = 4000kg/h (400kg/h x 10 in parallel)
best,
David

On 10/20/2016 13:30, Antoine Gautier wrote:
Thanks David

Just to be sure…
Considering an array of 50 collectors = 10 parallel-connected rows of 5 series-connected collectors, total inlet flowrate of array = M, total area = A.
I cannot model the whole array with Type1 only: I need to add an equation multiplying the flowrate and energy rate computed by Type1 by the number of rows. Type1 parameters and inputs being the following:
Number in series=5
Collector area=A/10
Inlet flowrate=M/10

Right?
--
Antoine Gautier
Solamen
+33 6 58 24 02 60
antoine.gautier@solamen.fr

De : David BRADLEY [mailto:d.bradley@tess-inc.com]
Envoyé : jeudi 20 octobre 2016 19:24
À : Antoine Gautier <antoine.gautier@solamen.fr>; TRNSYS users mailing list at OneBuilding.org <trnsys-users@lists.onebuilding.org>
Objet : Re: [TRNSYS-users] Type1 Number of identical collectors in series has no effect

Antoine,
This is a common source of confusion. Two points are important to keep in mind. First, the collector array area parameter is the area of the entire array, not just the area of one module in the array. Second, if you add a second collector you have to be careful about what you do with the flow rate. If you are adding a second collector in parallel to the first one you should double the collector array area, leave the "number in series" parameter set to 1, and double the liquid flow rate to the array. If you are adding a second collector in series with the first one, you should double the collector array area, set the number in series to 2, and leave the liquid flow rate unchanged.
kind regards,
David

On 10/20/2016 11:46, Antoine Gautier via TRNSYS-users wrote:
Hi

I cannot figure out why the number of collectors in series has no effect on the collectors array efficiency: see attached project.
Computing equations from source code manually I would state the opposite…

Thanks for your help.
Best regards
--
Antoine Gautier
Solamen
+33 6 58 24 02 60
antoine.gautier@solamen.fr
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***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA
 
P:+1.608.274.2577
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d.bradley@tess-inc.com
 
http://www.tess-inc.com
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA
 
P:+1.608.274.2577
F:+1.608.278.1475
d.bradley@tess-inc.com
 
http://www.tess-inc.com
http://www.trnsys.com
-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA
 
P:+1.608.274.2577
F:+1.608.278.1475
d.bradley@tess-inc.com
 
http://www.tess-inc.com
http://www.trnsys.com

--

***************************

David BRADLEY

Principal

Thermal Energy Systems Specialists, LLC

22 North Carroll Street - suite 370

Madison, WI  53703 USA

P:+1.608.274.2577

F:+1.608.278.1475

d.bradley@tess-inc.com

http://www.tess-inc.com

http://www.trnsys.com