**GWHX -- Single Coil Test -- 050425**

This is the plot for the GWHX with only one coil of half inch PE pipe in the barrel.

There are 28 coils of pipe with an average diameter of 21 inches. Tube ID = 0.61", OD = 0.74 ".

At the start of test, the pipe coil was empty, and it took a while to fill -- so there is a delay from start of flow until the output temp sensor is really seeing a flow of water.

The water started flowing into the tube at around minute 37 (blue curve), and appears to reach the temp sensor on the output side by minute 38 (red curve). Flow was stopped at about minute 47.4 -- from this point on the red and blue curves have no meaning. Not sure why the minute 38 to minute 39 part of the output temp (red) is so irregular?

Flow rate was very close to 1.5 gpm as measured by the Lake flow meter, and confirmed by timing flow into a bucket.

The 5 black lines are the temperature sensors in the barrel, and are at 4, 10, 16, 22, and 28 inches from the bottom of barrel.

Tube length = 28*21*pi = 1847" = 154 ft

Tube surf area (mid wall) = ((0.61 + 0.74)/2)*Pi * 1847 = 3916 sqin = 27.2 sqft

Tube volume = 0.61^2*0.785*1847 = 539.5 in^3 = 2.33 gal