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
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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 Centre1350 Nobel, Suite 150, Boucherville, Quebec J4B 5H3 (Canada)
Tel.: 450-641-0021
laura.guillon@ctgn.qc.ca
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