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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@energyae.com
608 Harris St Sydney NSW 2007 Australia | http://www.energyae.com
From: TRNSYS-users <trnsys-users-bounces@lists.onebuilding.org> on behalf of 吴伟伟v v <xiaoweiweiwu@hotmail.com>
Sent: Monday, 16 November 2015 4:49 PM To: trnsys-users@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-1power coefficient-2power coefficient-3And 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
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