Re: [TRNSYS-users] TYPE 938 - defrosting cycle

[David BRADLEY <d.bradley@tess-inc.com>]

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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