Calculating Heat Transfer Between 3 Mediums: Copper, Ground, Water

[James Brady]

I had a quick thermal dynamics question... I'm looking into geothermal systems and I was wondering how to calculate the transfer from the ground, through a copper pipe into water. I know how to calculate the heat transfer from air of different temperatures though a medium, but I do not know how to calculate the heat transfer in watts between three different mediums:

Thermal conductivities (W/m*k):

Copper: 400
Ground: 1
water: 0.58

Just wondering how to do some basic calculations, thanks.

 

[256bits]

You do know that the amount of heat that transfers from the ground is equal to the amount of heat that transfers through the copper pipe and into the water.

 

[James Brady]

Yes, I know that heat out = heat in. I'm wondering how to quantify that though. For instance, if I used an iron pipe, would that heat transfer be slower?

 

[Naty1]

MAYBE some tips you can use here:
http://en.wikipedia.org/wiki/Ground_source_heat_pump#Thermal_efficiency

I'm guessing you will likely need some standard engineering tables for different environmental and mechanical systems. In other words, idealized formulas are probably in the realm of experts in the field and may not match real world situations easily.

NOTE the organizations mentioned in the article...
maybe they have reference material online...

 

[James Brady]

Ok thanks. You know what I was thinking of how long it would take for the water to heat up. That's a function of specific heat, I just couldn't put my finger on it. But I should be able to turn it into a differential equation now.

Just be sure though... A larger pipe wall will result in less watts going into the fluid, correct?

Heat in = thermal conductivity*surface area*deltaT/wall thickness...?