Re: [TRNSYS-users] Question about water-water heat pump

["Mehdi Shahrestani" <mahdishahrestani@yahoo.com>]

Dear Jeff 

It was a comprehensive response. 
It is highly appreciated.

Regards
Mehdi

-----Original Message-----
From: Jeff Thornton [mailto:thornton@tess-inc.com] 
Sent: 21 January 2011 20:17
To: Mehdi Shahrestani; trnsys-users@cae.wisc.edu
Subject: Re: [TRNSYS-users] Question about water-water heat pump

<I have a question about one of the inputs in water to water heat pump
component.  What is the meaning of scale factor?   How can it be
interpreted beside the definitions of "Number of identical heat pumps"
(parameter) and "Number of heat pumps on" (input)?>

The differences between the scale factor and the number of heat pumps is
subtle.  The number of heat pumps and the scaling factor are both used to
scale the capacity and power read from the external data file.  The
difference is that the number of heat pumps is also used in the
calculation of the normalized flow rate into the device (for use in
reading the external data file).  The scaling factor can be thought of as
some external factor affecting performance that isn't accounted for in the
performance map.  An overly simple example shows this best:

Capacity Needed = 25 Tons, 12 gpm rated flow rate, 12 gpm inlet flow rate.

Option 1: Two 20 ton machines with independent compressors, condensers
etc., scale =1, # hps=2.  Normalized flow rate = 12 / 12 / 2 = 0.5 (each
machine gets half the flow)

Option 2: One 20 ton machine with super secret performance boost, scale
=1.25, # hps=1.  Normalized flow rate = 12 / 12 = 1.0

For most cases, simply set the scale factor to 1 and you'll be fine.  In
some circumstances you may need the flexibility allowed by the scale
factor.

Hope this helps.

Jeff


Jeff Thornton
President - TESS, LLC

22 North Carroll Street - Suite 370
Madison WI 53703 USA

Phone: 608-274-2577
Fax: 608-278-1475
E-mail: thornton@tess-inc.com
Web: www.tess-inc.com