Hmm. It's certainly not impossible to do this, but I'd like to know how detailed an experimental setup you're looking for? Or, put another way, how flexible do you want the data to be?
You could run every possible combo of fan, rad, and water flow rate under some standard test conditions to generate thermal resistance values from the water in the rad all the way to ambient temperature. Lotta work, lotta accuracy.
Or you could run a single test series and generate lots of empirical data that will apply to any fan you have a PQ chart for. Bear with me:
Setup the rad in a duct with a blower ahead of it. Run warm water through the rad at some constant inlet temperature. Measure incoming air temp, inlet and outlet water temp, and the temperature of the radiator metal in some corner (so the probe can be insulated from air and not affect airflow much). Measure pressure on either side of the rad in the duct and measure airflow with a pitot tube or something similar. Measure water flow rate.
By measuring the difference in water temp and using its specific enthalpy and flowrate, you can determine the heat load.
By adjusting the blower speed you can generate an air PQ curve with the pitot tube and pressure differential data.
By adjusting the flowrate of the water you can generate a water PQ curve.
By adjusting the flowrate of the air and measuring the temp diff between the air and the rad surface (and dividing by heat load) you can generate an airside thermal resistance/Q curve.
By adjusting the flowrate of the water and measuring the temp diff between the water and the rad surface (and dividing by heat load) you can generate a waterside thermal resistance/Q curve.
So there you go. Do this for every rad and you'll have water PQ, air PQ, water thermal resistance/Q, and air thermal resistance/Q curves.
It's pretty ambitious, I admit, but from what I hear of BillA's work, it seems he's done this sort of thing before.
I can work out a fairly detailed experimental method if needed, but I figure I'm just popping in with ideas here and there right now.
Good, you think?
Alchemy
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