Stream Temperature

[martin888888]

Does anyone know if there is a way to calculate how much water is needed to be injected to a stream of a certain size to reduce temperature to a set level? If anyone has any ideas on how to approcah this subject it would be interesting too. This is just an idea we are throwing around and a little outside my expertise.

Thanks

 

[gbam]

You may want to post this in the Heat Transfer forum. They may be able to answer that. Sounds very interesting though.

 

[Ryb01]

I'd also agree, very interesting.

Something to keep in mind, when working in a "stream" environment or even using the term "stream", in conjunction with water temperature be cautious of how you combine the two terms. Stream, usually indicates that there is some kind of aquatic habitat present. Reducing water temperatures is generally accepted, however, increasing water temperatures in a stream are usually not.

 

[francesca]

You may want to ask in a power forum too. The Corps of Engineers has to let a certain volume of water flow down the Cumberland River in order to keep the temperature in a safe range downstream of the Cumberland City power plant in Tennessee.

 

[beej67]

This is a fairly easy calculation if you know the temperature of both the stream and the add-water, know the stream flow rate, and assume complete mixing. (also assume no ice) Others can correct me if I'm wrong, but I believe it reduces to a weighted average based on volumetric flow rate:

(Combined T) = [(Stream Q)*(Stream T) + (Add Q)*(Add T)] / [(Stream Q)+(Add Q)]

..then solve for (Add Q)

I don't see why that wouldn't work. As others mentioned, best to ask the folks who do thermo for a living.

If you can't assume complete mixing, it gets horribly complicated. There are a number of other factors I'm neglecting which can also make this horribly complicated, such as sunlight warming, or pesky old hydrology.

I'm not an enviro guy, so I'm not sure what passes for acceptable practice in the field of effluent discharge. I'm just answering from a pure fluid mechs standpoint.



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