Calculating Heat Loss 1

[martane]

I am calculating for the heat loss in valves. Is it possible to use the "equivalent lenght" of a valve used in pressure drop calculations to compute for the total heat loss?

Heat loss in un-insulated valve:

Fluid = Steam
Temp = 340F
Pipe Size = 24"
Valve Size = 24"
Pipe and Valve material = Steel
Ambient Temp = 80F
Wind Velocity = 10kph

Thanks.

 

[MintJulep]

No.

 

[DRWeig]

You'll have to deal with the surface area calculations.

Best to you,

Goober Dave

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[ione]

The answer to your question is definitely no. The two phenomena you’ve quoted (heat loss and head loss) are not related.

There is an ASTM standard (specifically C1129) which deals with the estimation of heat losses from valves. As pointed out above by DRWeig it has to do with the surface area of the valve and with the steady-state heat transfer theory as per practice C680.
There should be something useful at the link below:

http://www.pipeinsulation.org/pages_v4/details.html

There you’ll find a downloadable software that allows to compute heat losses from pipes and fittings.

 

[racookpe1978]

If the valve operator is not insulated against heat loss, the extra operator area and exposed amount of metal-to-air heat loss rate need to be added to the valve body losses through the valve insulation.

 

[martane]

Thanks everyone for your replies. I was able to find multiplication factors for estimating heat loss in valves from online resources. I compared the results using surface area calculations, the numbers I got were close. Thanks everyone!