[Equest-users] Flat part load curve for Chiller

[Nick Caton]

Sambhav and Praveen:

 

Recently I see both of you were asking about "flat" curves or curves
that would always return the same value (1.0) to be multiplied against
the modified input (EIR).

 

Trying to do this in the raw data method might be possible, but it might
not be either... the math involved in those regressions is something I
can only briefly comprehend in short bursts =).

 

What I can offer is - this sounds pretty simple if you define the
coefficients directly instead!  

 

For example:

Bi-Quadratic:  Z = a + bX + cX2 + dY + eY2 + fXY

 

If you want the value returned to always equal 1.0, just choose
coefficients that make the variables X and Y not matter!  

[b = c = d= e = f = 0], and set [a =1].

 

Does that help?

 

~Nick

 

 

 

NICK CATON, P.E.

SENIOR ENGINEER

 

Smith & Boucher Engineers

25501 west valley parkway, suite 200

olathe, ks 66061

direct 913.344.0036

fax 913.345.0617

www.smithboucher.com +

 

 

-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of sambhav
tiwari
Sent: Thursday, July 07, 2011 11:43 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Curve fitting

 

Hi All,

            Each time i create a new curve by putting same values of

raw data i am getting different values of coefficients a,d,c,d for

cubic equation(a+bx+cx2+dx3) the solution (a,b,c,d) should be same

only if raw data values are same in each curve then why

coefficient(a,b,c,d) values are changing?

 

 

Thanks

Sambhav

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From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Praveen
Jain
Sent: Monday, July 04, 2011 11:41 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Flat part load curve for Chiller

 

Dear All

For our district cooling project, we require flat part load curve for
the air cooled screw chiller.

I played  with curve coefficient in two ways 

(1)  A=1, B=0, C=0
With this, Ratio of cooling energy from SS-D and BEPU, is not giving
entered COP.

(2) A=0, B=1 , C=0

With this, Ratio of cooling energy from SS-D and BEPU, is giving approx
entered COP.


What is exact way to create flat part load curve in eQuest.
-- 
With Thanks and Regards,
Praveen K. Jain
Roorkee

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