Panel pressure drop

[mostyn]

Could someone tell me what is the pressure drop on a 47mm 30 tube panel or is there any location on the web to find this information.

We have a 90 tube installed and was just looking for the pressure drop.

[Ivan]

I can't remember what it is (it's pretty low), but it should be in the Solar Keymark or BS12975 reports which can be downloaded from the Navitron download area (solar thermal/technical information section)

[EccentricAnomaly]

http://www.spf.ch/fileadmin/daten/reportInterface/kollektoren/factsheets/scf782de.pdf gives a graph of pressure lost for different flow rates ("Druckverlust bei Nennvolumenstrom") for a 20 tube Navitron 47 mm panel.

[mostyn]

Thanks for the information, but all of these reports are for a 20 tube panel

[mostyn]

The SPF report is also for a 20 tube system, is there anything on the pressure drop on a 30 tube panel?

Thanks

[EccentricAnomaly]

Just curious, but why is it an issue?

For context, the highest pressure loss on that SPF graph is 400 pascals for 250 litres/hour (which would give a temperature rise across the panel of only a few degrees C even in full sun (290 W/K). Atmospheric pressure, equating to a head of about 10 metres, is around 100 kPa so 400 Pa corresponds to a head of about 40 mm. I'd have thought that:

a) pressure drop in the pipe work will dominate and

b) a disproportionate amount of the drop in the panels would be in the entry and exit parts so it would be pretty conservative to simply multiply the 20 tube figure by 1.5 to get an estimate for the 30 tube panel.

[mostyn]

What I'm looking for is actual test data on a 30 tube panel, I'm looking for either test reports from SPF or other sources with real world data applications. We have 3 x 30 panels connected to a 180L preheat cylinder and a 210L main cylinder, we are using a secondary return pump from main back to the preheat when the preheat reaches 60 degrees and off at 40 degrees. I'm checking the pressure drop against the coil surface area and pump curve to make sure everything is giving us the best results.