[TRNSYS-users] COP Type 941 Ait to water Heat Pump

[miriam di matteo]

Dear all users,

About the Type 941 (Trnsys v.17):

   - First: can you confirm if I understand its functioning? I use it only
   for heating, at the moment.
   - Second: I believe that the values of the COP it isn’t correct, or I
   don’t understand it. The COP trend depends on the external files with the
   heating performance data, is it? In this file I have:
   Capacity increases when the entered water temperature decreases and the
   air temperature increases ( <Tin,w and >Tin,a → >Capacity)
   Power increases when the entered water temperature increases and the air
   temperature decreases ( >Tin,w and <Tin,a → >Power)
   So the COP increases when the entered water temperature decreases and
   the air temperature increases ( <Tin,w and >Tin,a → >COP). But the
   simulation gives opposites results. The external files are wrong? or I
   misunderstand the Type functioning?
   I tried to calculate the COP with excel and the results come out as per
   the provision, therefore different from TRNSYS' results.

About the first question:

I know as *Parameters:*

   - Specific Heat of Liquid Stream
   - Blower Power (pb)
   - Total Air Flowrate (Fa,d)
   - Rated Heating Capacity (qh,d)
   - Rated Heating Power (ph,d)

*and as Input:*

   - Inlet Liquid Temperature (Tin,w)
   - Inlet Liquid Flowrate (Fin,w)
   - Inlet Air Temperature (Tin,a)
   - Inlet Air Humidity Ratio
   - Inlet Air % Relative Humidity
   - Heating Control Signal

and as *external files*

   - Heating and cooling catalog data for the capacity and power as a
   function of entering the water and air temperature (fc=f(Tin,a;Tin,w) and
   fp=f(Tin,a;Tin,w))

So when the simulation running:

   1. The Type 941 reads the air and water entering temperature (Tin,w and
   Tin,a)
   2. Interpolates the heating performance file and multiplies this
   “performance factor” by HP Rated capacity and power. (fc(Tin,a;Tin,w) and
   fp(Tin,a;Tin,w))
   3. So obtain Capacity and Power as a function of entering the water and
   air temperature by each time step. (qh(t)=fc*qh,d and ph(t)=fp*ph,d)
   4. Calculates the COPh as a ratio between qh(t)/(ph(t)+pblower) , i put
   paux=0

Is it correct??

Thank you in advance,
Regards,
Miriam Di Matteo
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