[TRNSYS-users] Power Coefficients for Dry Fluid Cooler Type 511

David BRADLEY d.bradley at tess-inc.com
Thu Oct 2 05:45:10 PDT 2014

   The fan power is computed from an equation of the form:

pFan = pFan_rtd*(a0 + a1*yFan + a2*yFan^2 + a3*yFan^3 + ... + aN*yFan^N)

   where yFan is the fan control signal. If your fan is a simple on/off 
(single speed) device then you want to define a0=0 and a1=1. If your fan 
is a variable speed device and can have a control signal anywhere 
between 0 and 1 then you should set the power coefficients as a0=a1=a2=0 
and a3=1. This relationship comes from the fan affinity laws.
Kind regards,

On 10/2/2014 05:27, metkell yebiyo wrote:
> Dear TRNSYS users,
> I am simulating a GSHP system connected to a 300kW Dry air cooler Type 
> 511.
> The Dry air Cooler is controlled when the return temperature from the 
> ground reaches 30degC,
> then the Dry air cooler comes on, to maintain the fluid temperature 
> going to the ground to 22degC.
> My question is, I am trying to obtain the amount of power drawn by the 
> fan when the Dry air Cooler is operating. But in order for TRNSYS, to 
> calculate the power drawn, you need to put the power coefficients a1, 
> a2 and a3, how would I obtain this values? Is it a matter of calling 
> the Dry air cooler manufacturer and ask them for this power 
> coefficients or what do I need to do please?
> Thank you
> Metkel Yebiyo BEng (Hons), MSc
> CEREB PhD Researcher - Ground Source Heat Pumps
> Room T615
> Department of Urban Engineering
> Faculty of Engineering, Science and the Built Environment
> London South Bank University,
> 103 Borough Road,
> London SE1 0AA
> Tel: +44 (0)20 7815 7639
> E: yebiyom at lsbu.ac.uk <mailto:yebiyom at lsbu.ac.uk>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at lists.onebuilding.org
> http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org

Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

d.bradley at tess-inc.com


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