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

Tue Nov 17 01:51:12 PST 2015

```Dear Alastair,

Thank you for your patient reply. Now I can understand the relationship
between the coefficients and the parameters. And, I tried to understood the
Fortran code although my poor knowledge about it.

But it sees that the pump’s power drawn result is not right according to
the setting as the following, Which is much lower than the equation curve I have
attached the simple project(.tpf and.txt file) and the fitting equation(.xls)
data file.

For example, I has fitted a pump power curve equation as followings

p = 56877 + 49714(m/m rated)
+ 1094.3(m/m rated) ^2  (R² =
0.9959), So the setting is :

power coefficient-1 = a0=56877 (Parameter 6 for TYPE 743)

power coefficient-2 = a1=49714
(Parameter 7 for TYPE 743)

power coefficient-3 = a2=1094.3(Parameter 8 for TYPE 743)

May you tell me the
reason? Thank you very much for your time!with best regards
yours sincerelyWeiweiChongqing University
From: xiaoweiweiwu at hotmail.com
To: trnsys-users at lists.onebuilding.org
Subject: Type743’s power coefficients parameter setting
Date: Mon, 16 Nov 2015 13:49:52 +0800

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 sinscerelyWeiwei
Chongqing university

Thank you very much help me out of this issue.
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