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Hi,
I need to generate a performance map for a water to water heat pump and I need to know the rated condition for the heat pump attached (TMW036 (60 Hz I-P) - Heating).
I used a TMW036 water loop heat pump with heating capacity of 43100 Btuh. According to AHRI/ASHRAE/ISO 13256-2, the load and source flow rate is 9 GPM. How can I understand the entering load and source water temperature for the rating condition? I considered 70F of entering source water temperature and 100 F of entering load water temperature.
Would you please check the attachment and guide me if the rating condition is correct or not. If not, how can we determine the rating condition.
Besides that, in almost no catalogue file, I could not find the PLR data. Where can I get these data from.
Finally, for type 1323 variable speed compressor water to water heat pump, in case lower demand is required, should we control the flow rate in the source and load file?
Thanks
ShamsoddinGhiami Topic starter
09/12/2024 11:35 pm
The last question is modified:
Finally, for type 1323 variable speed compressor water to water heat pump, in case lower demand is required, should we control the flow rate in the source and load side?
You're running into something that is very frustrating in our industry. It is very hard to get performance data for newer (particularly for variable speed compressor) heat pumps. Part of the problem is that the way these devices are controlled (and thus how they operate and perform) is increasingly built in to the machine itself and manufacturers are (understandably) not willing to make their controls public. There is a committee at ASHARE (and within other groups) to come up with a standard for how manufacturers will report such things but it is a slow moving process.
What we typically do in variable speed compressor models is to assume that the compressor speed modulates to maintain a user specified outlet temperature. Full load performance is reasonably easy to find. The part that is hard to find is the part load; basically we assume that the compressor speed varies linearly with its thermal output. For instance if the machine has a 5kW thermal output at full compressor speed given the present inlet conditions but only 3kW are needed in order to get the inlet load temperature to the desired outlet load temperature then the compressor would run at a plr of 3/5. The hard thing to find is the relationship between PLR and compressor power. If you have measured data sometimes you can work out how the two are related. Some manufacturers are willing to provide a few points along that curve.
As far as the rating point is concerned, usually somewhere in manufacturer's literature they will say something about "standard ARHI conditions" or something similar. That in turn can lead you to a Standard where can get what those conditions are. The flow rates are a bit harder; typically when I can't find any information I look in the performance tables for a combination of power and capacity that are close to the stated rated conditions and can sometimes back out what the rated flow rate is from that. If I am totally stuck, I'll choose the middle flow rate. As long as you are very careful to be consistent between the conditions at the point to which you normalize the data file, the performance at that point, and then the flow rates that you give the model when it is in place in your simulation then everything should work out okay.
I know the above is not a very good answer to your question but I hope it gives you a little more direction (or at least some comfort in knowing that you are not alone in this struggle!)
david
