Solar Water Heating - Glycol

Hi Paul,

When glycol is selected in the SWH model, does the model use a 50/50 glycol/water solution, or is it a pure glycol solution?

Thanks, 
Chase P.

Hi Chase,

The working fluid option sets the value of the working fluid specific heat, which you can see in the code here: github.com/NREL/ssc/blob/d349a139d22e15396a6c99dbd7f9153f2d9b3a66/ssc/cmod_swh.cpp#L239 .



Based on this table from engineeringtoolbox.com, if we assume that the Cp values of water and glycol are at 40 degrees Celsius, the value of 3400 J/Kg-K seems to be a mixture of about 50%: www.engineeringtoolbox.com/ethylene-glycol-d_146.html



Best regards,
Paul.

Paul,

I appreciate all the questions you've answered for my team and I. I'm guessing you haven't gotten a lot of questions on the Solar Water Heating model recently, so thanks for taking the time to respond to ours.

Chase P.

Paul,

If I desired to change the cp value for glycol, how would I edit the SWH code and run it in SAM? I've tried looking into the help material about the SDK, but I can't quite figure out how to load, edit, ad run the code from the github link you shared.

Thanks,
Chase

Hi Chase,

I showed the code so you could see where the value it set and what the value is.

In order to make changes to the code, you would need to build your own version of SAM from the four repositories as described in the SAM repository wiki:

github.com/NREL/SAM/wiki

The build process is very involved, so if you want to go that route, be prepared to spend a lot of time getting things working before you can start modifying code.

The SDK allows you to set the values of inputs, run simulations, and read the values of outputs of SAM simulation modules, but it does not provide access to the underlying code.

Best regards,
Paul.