Effects of solar radiation/heat transfer on water filled steel pipe

[Ecorp]

Could anyone please help me find a source/aid in solving this problem?

I have to meet the CA water quality standard that will not allow treated effluent to exceed 5F of the average stream temp. which will receive treated water.

I will have a 36" o.d. steel duct. pipe that is approx. 3 miles long transport treated water, above the ground surface,assuming water temp. of 68F. The flow will be approx. 9600gpm and the ambient air temp (I will assume worse case scenario) will be 110F. The pipe will be subject to direct solar radiation on top half of pipe and my version of the computer program "qpipe" forces me into a subterrainian condition. How can I figure the heat losses/increases either over the 3 mile pipe length or per mile?

 

[KRSServices]

I have a resource which may help you. I use it to calculate the heat loss of fluid based on velocity, ambient temps of soil/duct and starting temperatures of the fluid (water in this case). I could scan some of the pages, with examples of calculations for you. Email me and we can take it from there. KRS Services

http://www.krs-services.com

 

[Ecorp]

I have more information on this ever challenging problem.

Two Pipe sizes
A.(20" Schedule 40 Steel Pipe); Q20 = 0.38 m3/s
Outside Diameter 0.5080 m
Inside Diameter 0.4778 m
Wall Thickness 0.01509 m

B. (36" Scedule 40 Steel Pipe); Q36 = 0.61 m3/s
Outside Diameter 0.9144 m
Inside Diameter 0.8763 m
Wall Thickness 0.01905 m

Assumptions:
1. Air Temp. will effect water inside the pipe through convective heat transfer. But this would not be the same as heating the pipe with an electric blanket at 43C. I am still trying to compensate for the heat source from the sun transmitted through the air(an insulator)and then being applied around the outside surface of the pipe through the steel and into the water assuming Laminar Flow.

Tmax,air=43C(Summer)
August: Tave,air=34C(high); Tave,air=14C(low); Twater,influent=19.5C
December:Tave,air=12C(high); Tave,air=3C(low); Twater,influent=14.7C
*It can be safely assumed that August will control and I still don't know the stream temps for August or Dec. but I will simply come up with a temp. increase for per meter of pipe.

2. I will have to calculate the effects of solar radiation and the emissivity properties of the outside of the pipe itself as well as the ground located underneath. As you all pointed out this is a difficult one to pin down but I will have to do the best with the charts that are provided online. I will assume new steel pipe that has not been coated or painted. I will also have to assume ground without vegetation and go with the higher values on steel and soil to be conservative.

Solar Radiation
August 296.5 W/m2(612.2ly)
December 78.2 W/m2 (161.6 ly)

3. I will assume no heat input due to friction of the water travelling through the pipe and pressure in equals pressure out (even though it wont) since flow work effects make a small contribution to heating water.

4. I am assuming that all other possible heat sources in this system, that I haven't listed, will be negligable (maybe this is a bad assumption).

I hope this helps and thanks alot.
Nathan

 

[KRSServices]

Nathan,

Did those formulas provide any assistance or at least get you started in the right direction? KRS Services

http://www.krs-services.com