[TRNSYS-users] TYPE 938 - defrosting cycle

[David BRADLEY]

Michał,
   Type938 does not take a defrosting cycle into account because the 
sequence of controls used to run a defrost cycle change from one 
manufacturer to another. You can create your own defrost cycle, however 
by using a thermostat model to watch the outdoor unit outlet temperature 
and turn the heat pump on in cooling mode for a period if the outlet air 
temperature falls too far. Depenging on how the defrost cycle works in 
your case you can also use some other components if an electric heater 
runs to keep the supply air warm during that cycle.

   As a side note, please remember that Type938 (and all the components 
that read performance data from an external data file) can interpolate 
performance data within the range given in the file but cannot 
extrapolate beyond the range. If you expect to run your heat pump in a 
climate where defrost will be needed please also make sure that both the 
heating and cooling data files contain capacity and input power 
information for temperatures that low.
kind regards,
  David


On 5/20/2015 8:30 AM, Michał Klimas wrote:
>
> Dear All,
>
> I’m trying to simulate the behavior of air source heat pump during a 
> year.
>
> Does anyone know how to take into account *defrosting cycle* (reverse 
> mode of heat pump) during winter time ?
>
> kind regards
>
> Michal Klimas
>
> Poznan University of Technology
>
>
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at lists.onebuilding.org
> http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org

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

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/attachments/20150521/8667d4a7/attachment-0003.htm>