[TRNSYS-users] TYPE 938 - defrosting cycle

[Michal Klimas]

Thank you David !

Then idea to connect outside air to electric air heater and control it 
by an equation sounds reasonable.

All the best,
Michal


On 2015-05-21 16:02, David BRADLEY wrote:
> 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
>>
>>
>>
>> _______________________________________________
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>> 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

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