Water temperature change per minute

[wimbot XR]

I need to know how much the water temperature will change in a PVC pipe.

I have a 1.2m long PVC pipe filled to 1 meter of water. The inside diameter is 12 inches and the outside diameter is 13 inches. I have a plastic end cap on the bottom and the pipe stands up vertically. I keep it in a 20 degree C room and take it outside for 30 minutes then bring it back in. I lay a thin piece of plastic on top to keep the sun off the water. I want the temperature to stay at 20 degrees. Let's say the temperature outside is 100 F. How do I calculate how fast the temperature will change? Thanks.

 

[Dr_Morbius]

There are a lot of variables to consider. The thermal mass of the water and pipe, the thermal conductivity of the pipe, the amount of sunshine, air temperature, wind speed, the color of the ground the pipe is on, is the pipe near a wall, etc. etc. It would be a lot easier to leave the pipe out for 30 minutes and measure the temperature change and then use that to decide how long to leave the pipe out for.