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It is not really possible to diagnose the cause of the problem from the screen captures. However, if I had to make a guess based on the non convergent timestep and then the psychrometrics routine getting called with an unrealistically cold temperature I would first take a look at the simulation timestep and the capacity of the heat pump. Your thermostat models can only make one control decision per time step so if you have a small load, a long timestep and a heat pump with a large heating/cooling capacity then temperatures can really out of hand and cause the kind of error that you are getting. Your time step should probably be no more than 5 minutes.
As a side note, I think the heat pump model you are using is a constant speed compressor device that has one indoor unit and one outdoor unit. VRF heat pumps are a lot more complicated devices in that they typically have a single outdoor unit that contains a variable speed compressor (allowing the unit to adjust the amount of heating/cooling that it is delivering) and multiple indoor units. The standard TRNSYS library does not contain such a model but there is one available as an individual TESS component. As with a lot of VRF models the TESS component can only operate in heating or cooling mode at a given time. It is not able to operate in a mixed mode in which some of the indoor units are heating while others are cooling (which I realize is basically the whole point of VRF systems).
kind regards,
david
Dear David,
I truly appreciate your assistance.
If we were to create a VRF system, could you kindly advise us on the exact types we should use?
Additionally, I have another suggestion regarding a VAV system. I noticed that Types 151 and 152 are available. Could you please guide us on how to properly connect and configure them to establish a fully functional VAV system? Is there anything specific we should consider to ensure it operates correctly?
Thank you very much for your time and support.
Best regards,
