Welcome to the TRNSYS Users Forum.
The forum is a place where people can interact and have discussions about different topics involving the use of the TRNSYS software package. Here you can post topics for discussion or questions on using TRNSYS and get advice from other users or TRNSYS experts. This forum is not intended for detailed technical support. Users should contact their distributor’s hotline for such assistance.
Some tips for success on using the forum:
- Follow the Forum Rules posted in Forum Administration.
- There are categories for different types of topics and questions. Post your topic or question into the proper category.
- Before posting a topic or question search the existing topics (and the TRNSYS Users listserv archive or Post archive) to see if a similar topic or question has already been answered.
- Use a descriptive topic name. Don’t use attention getting subjects, they don’t get attention and only annoy people.
- State the version of TRNSYS and which add-ons your are using.
- Include enough specific details for your topic of question to be answered. Just posting “Why am I getting an error?” without describing the specific error and what you are trying to do when you get the error will not receive a response that fixes your issue.
- Remember when people help you, they are doing you a favor. Be patient, help people out by posting good descriptions of what you need help with, and be polite even if a response does not solve your issue.
- Moderators may edit your post for clarity or move your topic to a more appropriate category.
Hi TRNSYS users,
I want to generate a data file for a heat pump as the available HP models are not capable of using very low temperature entering liquids. I tried to generate the correction data file; however, I could not generate the file as some cells in the table are blank for sensible cooling which causes inconsistency in the data file. You can see the table in the attachment.
@shamsoddinghiami Unfortunately Trnsys is not able to deal with partially complete data files so there are two options.
One option is that you can set the machine's capacity and power consumption to zero in the blank cells. What will happen in that case is that the controls in your simulation will still ask for cooling but the heat pump will not be able to provide any so the temperature in your space temperature will until the heat pump has come capacity again.
The other option is to plot the manufacturer's data and then extrapolate it so that you enter some values of capacity for those lower temperatures.
The first option is probably the more correct approach but it can give you some frustrating simulation results. I suppose one other question I might pose is that if the ambient temperature is low and the building still needs cooling, is there some way that the cooling could be provided without resorting to mechanical cooling (such as with an economizer)
kind regards,
David
ShamsoddinGhiami Topic starter
28/05/2024 3:50 pm
@davidbradley That is a good idea if the fluid side heat was not needed; however, the heat generated from the cooling heat pump would be needed for further use.
Regarding the first part, I went for the first option and as you mentioned, the results are incredibly different from what I expected. I also tried to skip the columns with blank sensible cooling capacity multipliers which again resulted in many warnings. I thought that it might be possible to use a heat pumps with lower sensible cooling capacities; however, I could not find any heat pumps with lower dry bulb temperatures.
I could not find any heat pumps with lower dry bulb temperatures.
That is not uncommon. I am working on a project at present and we are seeing the system initiating cooling when the ambient temperature is as low as 10-12C. The rooftop unit performance data doesn't extend down that far so I have extrapolated the data file while at the same time trying to convince the building operators that they should lock out the rooftop unit and bring in more ambient air if they need cooling at such low ambient temperatures.
