[TRNSYS-users] Creating the data file for the Air Source Heat Pump (Type 119)

Thu Dec 19 00:47:48 PST 2019

Thanks for the reply, David!

I shared my question and your answer with two other researchers, who gave me these suggestions:

  1.
Use the output values of Type 119c without any changes in its .dat files. The rated COP of our heat pump in cooling mode is 4.17 (Rated cooling power / Rated cooling input power) and the rated COP of the model in Heating.dat seams to me to be 3.12 (The largest cooling power 18173 divided by the input power 5823). The ratio equals 1.34. Then the input power for cooling at each time step can be found as the “Total Cooling Rate”/(”Output COP”*1.34), where “Total Cooling Rate” and ”Output COP” are output from Type 119c. The above calculation method is based on the assumption that the COP variation due to operating condition changes is equally propotional for different air-conditioners.
  2.
Use Type 401<https://trnsys.de/download/en/ts_type_401_en.pdf> (license can be bought from TRANSSOLAR). I think the model is relatively transparent.

I share the answers, in case they might help someone who has the same question. I am not sure about the accuracy of the first approach, but I assume that it is more accurate than to use the .dat files without any modification.

Audun

From: David BRADLEY<mailto:d.bradley at tess-inc.com>
Sent: ‎Wednesday‎, ‎December‎ ‎18‎, ‎2019 ‎12‎:‎55‎ ‎AM
To: trnsys-users at lists.onebuilding.org<mailto:trnsys-users at lists.onebuilding.org>
Cc: Audun Bull Kristiansen<mailto:audun.bull at hotmail.com>

Audun,

  It is sometimes possible to make a plot of the normalized data in the *.dat files that are provided and then to normalize and overlay the data points that you have from the manufacturer. Patterns in the data files and in the manufacturer data may become evident and you can fill in the remainder of the points in the data file and also intelligently extrapolate beyond the data that is given in those *.dat files.

  My larger concern is that it looks to me as though the heat pump you are working with is a variable capacity (perhaps a variable speed compressor) machine while Type119 is a single capacity device that is either on or off and whose performance (cooling capacity, heating capacity, and COP) are a function primarily of the ambient temperatures but not of part load. I have written a variable speed compressor heat pump model but like Type119 it still requires a performance map data file.

kind regards,

 David

On 12/16/2019 01:55, Audun Bull Kristiansen via TRNSYS-users wrote:
I use the Air Source Heat Pump (ASHP) unit Type 119c in a simulation of a container building in TRNSYS 18, since this seems to be the only ASHP type available. I need to add the two external .dat- files that contains the heating and cooling performance data, respectively. I read in “09-Tutorials” page 163-164 that:

“The ASHP component model requires a data file that includes the performance map for the piece of equipment. This performance map is unique to the exact piece of equipment that is being modeled and you will need to produce this file from the manufacturer’s performance data for the specific equipment being modeled.”

The component does not extrapolate beyond the data range provided, so we need to include data for outdoor temperatures between -5 °C and 40 °C (Shanghai climate). The indoor temperature is expected to be between -5 °C and 50 °C (due to that the heat pump is turned off when no one is at home).

I read “10.2.3.4 Resizing the PTHP Units” that says that the recommended method is to find a manufacturer of PTHP units online and to search through the available product literature to find a PTHP that has a capacity as close as possible without being less than the peak total cooling or heating load required by the zone that will be conditioned by the PTHP. Do someone know any such online source that contain adequate information where I can search for a similar product?

Or do you recommend me to go for the second approach, to renormalize the example files ASHP_Cooling.dat and ASHP_Heating.dat that comes with TRNSYS to a different rated capacity? But my highest “return air dry bulb temperature” and “Outdoor dry bulb temperature” are far higher than in these example files, so then I need to extrapolate the data. And how do I locate the performance point in ASHP_Cooling.dat that corresponds to the rated point, as described in 10.2.3.4?

I have also tried to model with ideal heater and cooler and divide the electric energy use for heating and cooling by their respective seasonal COP, but that is not accurate enough since I need to take into account the variation in COP over the year.

The heat pump that we have installed and want to model is GREE KFR-35W/FNhD02-A1 outdoor unit (corresponding to indoor unit model KFR-35GW/(35592)FNhAa-A1) which has the following performance data:

  *   Cooling power (rated/min./max.): 3500/200/4200 W
  *   Heating power (rated/min./max.): 4900/500/5600 W +1000 W (Additional electrical heating)
  *   Cooling input power (rated/min./max.): 840/90/1300 W
  *   Heating input power (rated/min./max.): 1450/120/1700 W
  *   Additional electrical heating input power: 1000 W
  *   Cooling seasonal COP: 5.33
  *   Heating seasonal COP: 3.53
  *   Yearly COP: 4.53

I tried to contact the manufacturer to get input data for the files and sent them the instructions from “4 Mathematical Reference” page 174-175 “Data Files” and the two  example files ASHP_Cooling.dat and ASHP_Heating.dat that comes with TRNSYS 18. The data they sent me, however, was not for constant air flow rates. For instance, for heating mode they sent me similar information as in the table below for various temperatures. The problem is that these data does not keep a set of fixed temperatures and air flow rates, like in the example files.

indoor air temperature  outdoor air temperature Total capacity (kJ/h)    Power consumption(kJ/h)        Air Flow Rate(l/s)      Return air dry bulb(℃)
30℃     28℃/RH50％       762     127     163     44.5
24℃/RH55％       706     128     163     43.3
20℃/RH59％       785     169     163     44.9
15℃/RH65％       992     284     161     49.2
11℃/RH75％       1078    362     160     51.2
7℃/RH85％        1085    418     160     51.3
2℃/RH85％        1063    485     159     51

Audun

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