[TRNSYS-users] Type743’s power coefficients parameter setting

[Alastair McDowell]

Dear Weiwei,


power coefficient-1 = a0

power coefficient-2 = a1

power coefficient-3 = a2

...and so on.


You can verify this yourself by going into the Fortran code (available in C:\TRNSYS17\Tess Models\SourceCode\Type743.f90), you will find this code snippet:


! Calculate the power multiplier
    If (frac_rated_flow > 0.) Then
       y_power = 0.
       Do j = 1,n_coeffs
          y_power = y_power+y(j)*(frac_rated_flow**DBLE(j-1))
       EndDo
    Else
       y_power = 0.
    EndIf


This shows that the first power coefficient (y(1)) has an exponent of zero (shown by DBLE(j-1)).


To your second question, the example where a0=a1=0, a2=1, this refers to a power equation: P/P_rated = (m/mrated)^2.


I hope this solves your questions.

Kind regards,

Alastair McDowell
Engineering Consultant
Energy Analysis & Engineering – Enabling innovation for a sustainable future
T: +61 450 600 842
E: alastair.mcdowell at energyae.com
608 Harris St Sydney NSW 2007 Australia | http://www.energyae.com<http://www.energyae.com/>


________________________________
From: TRNSYS-users <trnsys-users-bounces at lists.onebuilding.org> on behalf of ???v v <xiaoweiweiwu at hotmail.com>
Sent: Monday, 16 November 2015 4:49 PM
To: trnsys-users at lists.onebuilding.org
Subject: [TRNSYS-users] Type743’s power coefficients parameter setting

Dear all,
In the type743’s document, there is an equation743.1 about P, which is power drawn the pump, as following:
P=a0+a1(m/mrated)+ a2(m/mrated)2+ a3(m/mrated)3+………..
In the type743’s parameter setting, parameter number 5 is set to“number of power coefficients”,if I input “3”then the parameter number6?7 ?8 is as following:
power coefficient-1
power coefficient-2
power coefficient-3
And the explanation about the coefficient is “The value of the polynomial multiplier for the relationship between normalized pump power and normalized pump flow rate”.
My question is:
1)whether a1?a2 a3 is correspond to power coefficient-1?power coefficient-2 and power coefficient-3 respectively? if yes, how to set the value a0? or i just need fitting an equation that a0 is zero?
2)If not ,what is the right relationship between them?
In addition, I referred to an example named “pumps with flow rate known” in Tess models of TRNSYS software, the type743’s parameter 5 is set to 3, and the parameter6 and 7 (power coefficient-1?power coefficient-2) are  both  0, while parameter 8 is set to 1. The similar situation setting could be found in other types such as TYPE510’s power coefficient.
Thank you very much help me out of this issue.

With best regards

Yours sinscerely
Weiwei

Chongqing university




Thank you very much help me out of this issue.
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