Adding a reversing valve and cooling or heating loads on heat pump

[NicholasFry]

Hi all, Are there any plans to develop a reversing valve with a desuperheater in the heat pump configuration as an option? This might help for energy assessments at the building or district substation level (domestic hot water preparation and cooling). If this feature already exists, please point me to it in the documentation. Best, Nick

[fwitte]

Hi Nick, very interesting topic, thanks for asking. There is no inbuilt component for this task. Just to make sure, that I understood correctly: You want to have a typical cycle inversion with a 4-way-valve like in the picture below.

EDIT: My coffee was not strong enough this morning, of course you meant this... :D

If so, I would just go a different approach with the current architecture available:

• Build two networks, one for heating one for cooling. (Do not use the Condenser component but HeatExchanger or HeatExchangerSimple for both sides and in case of condensation add saturated liquid state condition at the outlet to the respective Connection)
• Run the design simulations on either of both networks.
• Transfer the component parameters to the other network and run the simulation based on the respective component parameters. E.g. heat transfer coefficient of the heat exchangers must be similar in both networks. Actually, the heat transfer area is equal, the heat transfer coefficient might change due to flow regime, but we can not model that very precisely in TESPy. (I need to think about the data transfer, not sure if this is currently possible.)

I will add an example code here later. If we find something nice, we might also add it to the documentation, I think this is a highly appreciated feature.

One more question: Do you have any measurement data to very a modelling approach? Even just the COP of an application in heating and cooling mode would be helpful to see, if the model generates similar results.

Best regards, Francesco

[NicholasFry]

Hi @fwitte, Sorry I dropped off the Earth for a bit. I am here. I will look into the documentation on some commercial scale heat pumps and residential scale heat pumps to see what I can find. If it is worthwhile, I will pass it onto you. Thank you as always for being so attentive. Nick

[NicholasFry]

@fwitte There are a few papers on refrigerant performances with reversing valves in the loop. It is important to know that the refrigerant standards for residential heat pumps are changing right now. The building codes are being rewritten to take only fluids with lower global warming potentials (GWPs). I am not an expert at that by any means, but this will change the expected COPs. For now, here is an older document on R134a and R407C. It has performance charts for both directions of the cycle. https://www.sciencedirect.com/science/article/pii/S1359431102001369?via%3Dihub

In cooling mode R134a: In cooling mode R407C:

In heating mode:

System parameters:

If I find more appropriate examples, I will continue to add them here. If you have come up with an early working example, I would love to take a look.

Best wishes, Nick