Fire Tube Boiler: Spiral Retarders in tube analysis

[Cool SH]

Dear All,

I am having trouble to finding the heat transfer coefficient of spiral retarders. The sketch of the tube is shown in the link.

[highlight #FCE94F]My objective is the find the heat transfer coefficient for the spiral retarders[/highlight]. With retarders, a turbulent flow will be created inside the tube. With greater turbulence, the overall heat transfer coefficient will increase.

I am looking at [highlight #FCE94F]Chilton, Drew and Jebens correlation[/highlight], but I am having doubt.[highlight #FCE94F][/highlight]

 

[chicopee]

Interestingly, I have never seen these devices used on fire tube power boilers and I have inspected a ton of these as a former N.B. boiler and Pressure Vessels in the NE regions of the USA. I have seen these devices used on hot water storage tanks constructed with vertical fire tubes and well before I was born, I suspect that vertical fire tube power boilers may have been fitted with these spiral retarders. My advice do your research on Vertical fire tube boilers in libraries. You could also research old NB bulletins. Just remember that the steaming capacity of fire tube boilers is based on 5 to 7.5 lbm of steam per hr-ft^2 of heat surfaces if that may help working for the heat transfer coefficient backward.

 

[EdStainless]

Often these are not used to raise the heat transfer as much as create a more uniform condition.
We use then in radiant tube heat treat furnaces to help prevent localized overheating of tubes when we are firing hard.

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P.E. Metallurgy, Plymouth Tube

 

[chicopee]

To EdStainless "... as much as create a more uniform condition" would you explain that portion of your statement.