Re: [TRNSYS-users] Type 954b - auxiliary efficiency

[Jeff Thornton via TRNSYS-users <trnsys-users@lists.onebuilding.org>]

Laura - you are correct.  After checking the source code we have discovered the problem.  The auxiliary energy added to the air stream does not include the impact of the auxiliary efficiency (simple typo).  It's an easy fix if you have a FORTRAN compiler and we'd be happy to share it with you.  Please let us know.  Otherwise, we'll make the fix and include it in the next release of the TESS HVAC Library.  If you don't have a compiler, there is still a somewhat easy work-around.  Simply set the capacity to the net capacity (capacity * efficiency) and set the efficiency to one in the model.  Then use an equation to calculate the gross auxiliary input (auxiliary heat output from the model / efficiency).

 

Jeff

 

---
Jeff Thornton
President - TESS LLC
22 N. Carroll Street, Madison WI USA 53703
Office: (608) 274-2577  Fax: (608) 278-1475
www.tess-inc.com
E-Mail: thornton@tess-inc.com

On 09/19/2017 11:36 am, Laura Guillon via TRNSYS-users wrote:

Hello everyone,

 

I have an issue with the Type 954b (air source heat pump with a gas auxiliary system).

 

I don’t understand why the efficiency of the auxiliary heater is not totally taking into account by TRNSYS.

 

Indeed, if I change the efficiency of the auxiliary system, I can see this change by plotting the output “total heat rate”. However, regardless this change, the output temperature of the Type 954b remains the same. In other words, the output air temperature of the Type 954b does not seem influenced by the efficiency of the auxiliary system … 

 

To illustrate my issue, here is an example of data at one specific time (the capacity of the auxiliary system is 22,578 kJ/h) :

 

Efficiency	Total heat rate (output of the Type 954b)	Input air temperature of the Type 954b	Output air temperature of the Type 954b	Airflow
90%	20,320	19.2	23.96	4,752
10%	2,258	19.2	23.96	4,752

 

Is it normal ? Do you have an explanation to this ?

If not, do you have any suggestions ?

 

Thank you,

Laura

 

Laura Guillon, Jr. Eng M.A.Sc

Project Leader

 
Natural Gas Technologies Centre

1350 Nobel, Suite 150, Boucherville, Quebec J4B 5H3 (Canada)
Tel.: 450-641-0021
laura.guillon@ctgn.qc.ca

www.ctgn.qc.ca

 

 

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