[TRNSYS-users] Type1 Number of identical collectors in series has no effect
David BRADLEY via TRNSYS-users
trnsys-users at lists.onebuilding.org
Thu Oct 20 14:35:18 PDT 2016
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 at solamen.fr
>
> *De :*David BRADLEY [mailto:d.bradley at tess-inc.com]
> *Envoyé :* jeudi 20 octobre 2016 21:43
> *À :* Antoine Gautier <antoine.gautier at solamen.fr>; 'TRNSYS users
> mailing list at OneBuilding.org' <trnsys-users at 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 at solamen.fr <mailto:antoine.gautier at solamen.fr>
>
> *De :*David BRADLEY [mailto:d.bradley at tess-inc.com]
> *Envoyé :* jeudi 20 octobre 2016 20:44
> *À :* Antoine Gautier <antoine.gautier at solamen.fr>
> <mailto:antoine.gautier at solamen.fr>; 'TRNSYS users mailing list at
> OneBuilding.org' <trnsys-users at lists.onebuilding.org>
> <mailto:trnsys-users at 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 at solamen.fr <mailto:antoine.gautier at solamen.fr>
>
> *De :*David BRADLEY [mailto:d.bradley at tess-inc.com]
> *Envoyé :* jeudi 20 octobre 2016 19:24
> *À :* Antoine Gautier <antoine.gautier at solamen.fr>
> <mailto:antoine.gautier at solamen.fr>; TRNSYS users mailing list
> at OneBuilding.org <trnsys-users at lists.onebuilding.org>
> <mailto:trnsys-users at 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 at solamen.fr <mailto:antoine.gautier at solamen.fr>
>
>
>
>
>
>
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>
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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 at tess-inc.com <mailto:d.bradley at 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 at tess-inc.com <mailto:d.bradley at 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 at tess-inc.com <mailto:d.bradley at 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 at tess-inc.com
http://www.tess-inc.com
http://www.trnsys.com
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