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Hi TRNSYS community,
I am currently working on a research project on building flexibility, which requires to use VRF heat pumps. The models we are using are LG Muli V5 (Air source heat pump) and Multi V Water 5 (Water source heat pump). Just wondering is there any VRF heat pump model available in TRNSYS 18? If so, can you please provide a quote?
Kind regards,
LIU Jingjing
Liu and László,
There has been a good bit of interest in this topic lately. Some years ago I developed a VRF model of an air-to-air device in the context of a project that we were doing at the time. Like most of the heat pump models in Trnsys it relies on performance maps and manufacturer's catalog data. I decided at the time that it was too clumsy to be of much use; it requires one data file for each indoor unit as well as some data files for the outdoor unit. Trnsys component proformas are not really set up to allow for there to be a variable number of external data files. There is a workaround but it isn't the most straightforward thing to implement.
Given the interest of late, I am working on dusting the model off and making it ready for public consumption. I hope that it will be ready some time in mid July. I will certainly let everyone on this forum know when the model gets near completion.
I would be interested in knowing how the water source VRF is configured. It may be that my air-to-air model would not be so hard to adapt to a water-to-air version. Please feel free to message me directly!
kind regards,
David
JJLiu 01/06/2023 12:16 am
@davidbradley
Hi David,
Thanks for your reply.
I saw a post discussing the VRF heat pump in the old email list. The researcher pointed out that the Type Multi-Dimensional Data Interpolation (Type 581) could generate an interactive interpolation of the parameters studied, such as Compressor Frequency, outlet water temperature, etc. However, I could only find Conditioning Equipment (Type 42) and Part Load Performance (Type 43) in the TRNSYS 18 library.
I am wondering if it is possible to use Type 42 or Type 43 and connect it with a single-speed heat pump (Type 919 or Type 954) to realize the VRF heat pump operation? If so, can you please explain how to realize this function in TRNSYS? I'm using Type 56 to generate the building load.
Thanks for your time.
Kind regards,
Jingjing
Jingjing,
Type581 is in the TESS Utility library. Types42 and 43 are basically the same concept but are a little more limited in the number of dependent and independent variables that they can handle.
The existing heat pumps and the VRF model that I wrote all use the same idea; there are external data files that contain information about how the device's capacity and COP change as a function of the inlet conditions. The trouble with 581, 42, and 43 is that they are very generic. They read and interpolate the performance data but they don't know if they're acting on air or liquid and so using them you're a bit stuck computing the air and liquid outlet conditions. In a way the heat pumps and the VRF model are all special cases of those basic Types.
kind regards,
David
