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Hello. I am trying to model a thermosiphon flat-plate solar thermal collector with a horizontal storage tank at the top. I have selected Type 45a for this purpose. The system that I am modelling contain a heat exchanger: the DHW circulates inside the heat exchanger. Now, it seems that Type 45a has no heat exchanger in the tank. Do you have any hint for me to fix the issue?
@ken, I think that you would have to modify the source code in order to do that. Does the collector you are modeling have a load side heat exchanger? Or is the heat exchanger between the collector fluid and the liquid that is stored in the tank?
kind regards,
David
Ken Topic starter
28/11/2023 1:54 am
@davidbradley I wonder if there is any TESS component doing the same job...
@davidbradley, Thank you for your feedback. The system looks like what is in the enclosed email. I guess, it is what you call load side heat echanger. Indeed, the heat exchanger is in the tank. The water in the tank is the same circulating in the collector. The water of the user is circulating in the heat exchanger: whenever there is a demander, water flows through (inside) the heat exchanger, so, it is a kind of instantaneous heating.
A_Weiss 28/11/2023 4:24 pm
@ken We've modeled these systems in the past using a flat-plate collector from the TESS library (Type 1346 or similar, depending on the parameters provided), a TESS horizontal tank model with immersed heat exchanger (Type 1537 or similar), and a thermosiphon "pump" model that sets the flow rate in the loop between the two components based on the height and temperature difference over the loop. We've found that works better than trying to write an all-in-one model of a thermosiphon system. Unfortunately the thermosiphon pump model isn't currently distributed as part of any of the TESS libraries, and I don't know enough about its development story to say whether it may be available for individual purchase or as part of a library in the future. You could certainly write your own, if you have a formula you'd like to use relating the flow rate in the loop to the average temperature difference between the tank and the collector or other inputs.
Ken Topic starter
29/11/2023 5:58 am
@A_Weiss, thank you for that suggestion. I have had a look on Type 1346 and Type 1537 and I see that I could imagine a model to connect them. But to avoid starting from scratch, maybe you do have more info on that "thermosiphon pump" model, for instance the exact name, a description in an old version of General Description TESS Libs -or the version of TESS Libs, anything that could help further, if available. Thanks.
