Energy transfer

[2807]

Hello list

I recall reading a post on this forum detailing how much energy can be pushed down various diameter tubes.

Having used the search engine, I have been unable to locate it.

Can anyone point me in the right direction?

Best

2807

[Alan]

http://tierling.home.texas.net/PipeHeatLossShell.htm

http://www.engineeringtoolbox.com/copper-pipes-insulation-heat-loss-d_52.html

Above is an online calculator for pipe and insulation.

Regards

alan

[2807]

Hello Alan

Many thanks, but that isnt really what I am after, what I want to know is how much energy I can push down either a 10mm or 15mm copper tube.

I have an underground pipe run of 12 meters each way from an array of 100 47mm evac tubes together with 60 58mm tubes that I want to use during the winter & want to know whether I can get away with 10mm copper or whether I need to use 15mm.

In the summer, the collectors simply heat a hot tub & then dump into a swimming pool, next to the roof they are sited on, so no problems there.  However, in the winter I use them for my central heating, this worked fine last winter.

Foolishly, I originally installed 15mm plastic pipework on the underground section, this burst when the system overheated during an exceptionally sunny spell when I was away from home in March.

If I had been here, I would have manually dumped the heat into the Hot Tub, but when the radiators in the house got to 120 deg c the underground pipework melted somewhere.......

2807

[Alan]

http://www.engineeringtoolbox.com/hazen-williams-water-d_797.html

http://www.freecalc.com/fricfram.htm

You need to know the gallons per minute that you want to transfer.
Is it a variable speed pump. You need to be able to take the maximum amout of heat away from the panels.
Information provided on the data sheet provided from your pump manufacture
You also need to know the pump head capacity.

Below is two examples for

first ( pipe inside diameter ) 0.622 inch. At 10 gallons per minute gives a loss of 30.62 P.S.I. Across 100 ft of pipe

second ( pipe inside diameter ) 1.049 inch. At 10 gallons per minute gives a loss of 2.5 P.S.I. Across 100 ft of pipe

This is based on clean pipe, when you factor in pipe roughness for calcium deposits it gets far worse.

Its all down to how many gallons per minute you need to transfer to stop the system from over heating.

How mant right angle bends. The losses get silly with bends ?


Pressure Loss (psi):  30.62   Head Loss (ft):  70.7
Line Number:  
Date:  5/3/2011
Nominal Pipe Size:  0.5
Pipe Schedule:  SCH 40
Flow Rate (gpm):  10
Viscosity (cP):  1
Specific Gravity (water=1):  1
Temperature (F):  180
Pipe Roughness (ft):  0.000005
Actual Pipe ID (in.):  0.622
Fluid Velocity (ft/sec):  10.56
Reynolds Number:  50845
Flow Region:  Turbulent
Friction Factor:  0.021
Overall K:  40.82




Pressure Loss (psi):  2.5   Head Loss (ft):  5.8
Line Number:  
Date:  5/3/2011
Nominal Pipe Size:  1
Pipe Schedule:  SCH 40
Flow Rate (gpm):  10
Viscosity (cP):  1
Specific Gravity (water=1):  1
Temperature (F):  180
Pipe Roughness (ft):  0.000005
Actual Pipe ID (in.):  1.049
Fluid Velocity (ft/sec):  3.71
Reynolds Number:  30149
Flow Region:  Turbulent
Friction Factor:  0.024
Overall K:  27.01


Go large and insulate.

Regards

Alan

[wookey]

There's a spreadsheet for this on the underused Navitron wiki:
http://www.navitron.org.uk/pmwiki/pmwiki.php?n=Main.PipeSizingCalculations

[MR GUS]

I have never seen that navi-resource!
 could someone highlight a screenshot as to where that is exceptionally well hidden please!

..gutted


...but not unexpected