Turbulizers are often mentioned inserted into boiler tubes of boilers fired by propane. They are usually considered essential to the performance of the boiler to the point of the difference between producing enough steam or not. Yet many are unsure as to if they are necessary or actually do anything. I thought what I need is some test data. But, such a test involving boiler output would be rather complicated for a home workshop gear head like me. For my NYC 999 project I'm fitting a five element hair pin type super heater. I have discuss this super heater in a previous thread. It occurred to me that if turbulizers are fitted to boiler tubes why can't they be fitted to a hair pin type super heater AND here is something that I can run a simple test. Here is my raw data:
Oven Temp. Air Out Temp. Ambient Temp. Rise
With Out Turbulizer 573 F 473 F 82 F 391 F
With Turbulizer 578 F 518 F 82 F 436 F
The air out temperature with out turbulizers is 100 F less than oven temperature and 60 F less with turbulizers.
The air out with turbulizer is 45 F hotter than with out, or about a 11% increase when compared to 391 F.
My conclusion is turbulizers do make a significant difference. That is in a pin type super heater element like mine. How that compares to a boiler tube I have no idea. Also, I was measuring air which is a gas. The results with saturated steam which is a water vapor will probably be different. But, the tests did show the turbulizer did something.
There are other variables that would be hard to reconcile against a boiler. In my test the super heater was at the same temperature it's entire length. In a boiler it would likely be 1000 F cooler in the smoke box then in the fire box. Same for a boiler tube. My super heater being the hair pin type is twice as long as the tube it would sit in plus the projection into the fire box so the air inside has a much longer distance to collect heat. Also, the super heater is made of 303 stainless that has a thermo-conductivity of about 1/3 that of copper and 2/3 that of steel.
The attached photos show the turbulizers and my set up. The super heater was simply inserted into my back yard barbecue and supported so that it was central to the air space. I.E.: not touching any thing. The thermocouple was supported next to it. Another thermocouple was inserted 3" into the outlet. A needle valve was used to regulate the air flow that was measured buy the argon flow monometer from my TIG welder. Flow measurements were compensated for the 71% lower density of air to argon. The measurements given were taken at 45 cu. ft. hr. per element for a speed of 5 mph of my 999.
I can hardly wait to read what you all have to say about this, Dave
To Turbulize or not
To Turbulize or not
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Re: To Turbulize or not
Hi Dave,
Yes a turbulator should make a difference, but if you are going to try one, try the zig-zag type instead of the twisted strip style. The zig-zag type is much more efficient. At one time I believe it was patented, but any patents should have run out a long time ago.
The whole idea of a turbulator is to break up the hot center core of the gas that flows in the tube, whether it is in a superheater or a flue. To make the zig-zag style, cut a stainless steel strip that is one third the width of the internal diameter of the tube and put 5 or 6 alternate bends in it so that it forms a zig-zag. The total installed length can be the length of the tube or a bit less. The spring in the bends will hold it in place.
If you try this style in your experiment, you should get an even higher differential between the inlet and outlet temperatures. Put simply, the twisted style isn't terribly efficient and relies mainly on the boundary layer turbulence on the strip for any improvement. There may also be a slight heat transfer to the gas by conduction between the strip and the wall of the tube that its in.
A long time ago I had a vertical fire tube boiler for my house hot water heating system and I installed the zig-zag style in the vertical flues. I had to remove some of them because the boiler stack temperature was so low that the water vapour from the natural gas was condensing into water in the flues (a no-no in the days before the condensing furnace).
Try it and let us know what the results are. It should be interesting.
Richard Trounce.
Yes a turbulator should make a difference, but if you are going to try one, try the zig-zag type instead of the twisted strip style. The zig-zag type is much more efficient. At one time I believe it was patented, but any patents should have run out a long time ago.
The whole idea of a turbulator is to break up the hot center core of the gas that flows in the tube, whether it is in a superheater or a flue. To make the zig-zag style, cut a stainless steel strip that is one third the width of the internal diameter of the tube and put 5 or 6 alternate bends in it so that it forms a zig-zag. The total installed length can be the length of the tube or a bit less. The spring in the bends will hold it in place.
If you try this style in your experiment, you should get an even higher differential between the inlet and outlet temperatures. Put simply, the twisted style isn't terribly efficient and relies mainly on the boundary layer turbulence on the strip for any improvement. There may also be a slight heat transfer to the gas by conduction between the strip and the wall of the tube that its in.
A long time ago I had a vertical fire tube boiler for my house hot water heating system and I installed the zig-zag style in the vertical flues. I had to remove some of them because the boiler stack temperature was so low that the water vapour from the natural gas was condensing into water in the flues (a no-no in the days before the condensing furnace).
Try it and let us know what the results are. It should be interesting.
Richard Trounce.
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10 Wheeler Rob
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Re: To Turbulize or not
A question on the test setup, did you set air the flow rate to be equal durring each test, or was the the flow controlled by pressure drop through the tubing? If both test were run at a set inlet pressure then the higher temp might be a result of a lower flow rate caused by the added pressure drop of the turbulators.
I am not trying to say turbulators are not a good thing but just asking about the test procedure used here.
Rob
I am not trying to say turbulators are not a good thing but just asking about the test procedure used here.
Rob
Re: To Turbulize or not
Richard,RET wrote: ↑Tue Sep 17, 2019 7:29 am Hi Dave,
Yes a turbulator should make a difference, but if you are going to try one, try the zig-zag type instead of the twisted strip style. The zig-zag type is much more efficient. At one time I believe it was patented, but any patents should have run out a long time ago.
The whole idea of a turbulator is to break up the hot center core of the gas that flows in the tube, whether it is in a superheater or a flue. To make the zig-zag style, cut a stainless steel strip that is one third the width of the internal diameter of the tube and put 5 or 6 alternate bends in it so that it forms a zig-zag. The total installed length can be the length of the tube or a bit less. The spring in the bends will hold it in place.
If you try this style in your experiment, you should get an even higher differential between the inlet and outlet temperatures. Put simply, the twisted style isn't terribly efficient and relies mainly on the boundary layer turbulence on the strip for any improvement. There may also be a slight heat transfer to the gas by conduction between the strip and the wall of the tube that its in.
A long time ago I had a vertical fire tube boiler for my house hot water heating system and I installed the zig-zag style in the vertical flues. I had to remove some of them because the boiler stack temperature was so low that the water vapour from the natural gas was condensing into water in the flues (a no-no in the days before the condensing furnace).
Try it and let us know what the results are. It should be interesting.
Richard Trounce.
Thank you for the comprehensive reply. I was unaware of the zig-zag type of turbulator. I'm still unsure of what it would look like. A picture or sketch would help. The ".... 5 or 6 alternate bends..." are they per foot or per yard or?
Thanks, Dave
Re: To Turbulize or not
Hello Rob,10 Wheeler Rob wrote: ↑Tue Sep 17, 2019 7:42 am A question on the test setup, did you set air the flow rate to be equal durring each test, or was the the flow controlled by pressure drop through the tubing? If both test were run at a set inlet pressure then the higher temp might be a result of a lower flow rate caused by the added pressure drop of the turbulators.
I am not trying to say turbulators are not a good thing but just asking about the test procedure used here.
Rob
The air flow rate was set equal for each test. Pressure was not considered or set or recorded.
Dave
Re: To Turbulize or not
Hi Dave,
The 5 or 6 bends are over the length of the strip however short or long it may be. The bend locations are not critical, even a sloppily made unit will work. The number of bends is also not critical, but 5 or 6 is a good compromise.
Its a very simple device, but it works very well. In my house boiler, I bent the end of the strip into a hook so I could hook it over the top of the firetube. The material used should be a 300 series stainless because of the temperature and corrosion resistance required.
As the saying goes, "try it, you'll like it."
Richard Trounce.
The 5 or 6 bends are over the length of the strip however short or long it may be. The bend locations are not critical, even a sloppily made unit will work. The number of bends is also not critical, but 5 or 6 is a good compromise.
Its a very simple device, but it works very well. In my house boiler, I bent the end of the strip into a hook so I could hook it over the top of the firetube. The material used should be a 300 series stainless because of the temperature and corrosion resistance required.
As the saying goes, "try it, you'll like it."
Richard Trounce.
Re: To Turbulize or not
I like this idea so much that I went searching the net for a source of suitable material. I found a 21-foot roll of 0.5" wide 304 stainless (no thickness given) on Grainger for under $9. (Item 3A550) Apparently this is the feedstock for a (presumably very heavy-duty) Dymo label maker. Does this sound like material that would work for turbulators?
- Bil F
- Bil F
Re: To Turbulize or not
Hi,
The width of the strip should be about 1/3 of the inside of the tube diameter so there is no possibility of blocking or slowing down the gas flow. 304 is a common 300 series stainless and the thickness isn't critical. Remember there is no mechanical force on these things so strength is not a requirement. When I made mine for the house heating boiler, I used about #22 gauge because that's what I had lying around.
As I said before, its a simple device and its easy to install and remove.
Richard Trounce.
The width of the strip should be about 1/3 of the inside of the tube diameter so there is no possibility of blocking or slowing down the gas flow. 304 is a common 300 series stainless and the thickness isn't critical. Remember there is no mechanical force on these things so strength is not a requirement. When I made mine for the house heating boiler, I used about #22 gauge because that's what I had lying around.
As I said before, its a simple device and its easy to install and remove.
Richard Trounce.
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Bill Shields
- Posts: 10551
- Joined: Fri Dec 21, 2007 4:57 am
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Re: To Turbulize or not
these devices have been around a long time in industrial as well as residential boilers...and everyone has the 'best' idea, but the reality is you gotta play with it....or just take an idea and make it fit...you literally have nothing to lose
http://cleanboiler.org/learn-about/boil ... rbulators/
https://www.fuelefficiencyllc.com/turbulator/
think about purchasing some long / small od stainless springs....
http://cleanboiler.org/learn-about/boil ... rbulators/
https://www.fuelefficiencyllc.com/turbulator/
think about purchasing some long / small od stainless springs....
Too many things going on to bother listing them.
Re: To Turbulize or not
As with any turbulator application, the intent is to improve heat exchange efficiency/effectiveness. During my industrial career, have heard of/seen square tubes with zig-zag turbulators and same for rectangular tubes. Came across a pollution control application where the heat exchanger tubes were "corrugated" to improve heat transfer.
The use of turbulators for propane fired steam locos has long been promoted on this board. Use of turbulators in super heaters is something new and there's no reason to believe it would have any less affect in a steam vs exhaust gas application. Dave's numbers prove this out.
Without seeing any numbers, have a hard time understanding why a zig-zag turbulator in a round pipe would be more effective than a spiral? In my mind, that arrangement is akin to a square peg in a round hole. There's open voids on all 4 sides of the square agitator running down the center of the pipe...thereby allowing more or maybe less laminar flow. At least with the spiral "turb"...the entire flow is being twisted and stirred.
Perhaps another way to examine and quantify the different arrangements would be measuring pressure drop. The greater the pressure drop would indicate to me, more turbulence, slower flows and greater heat transfer...with just the opposite for lower pressure drops. In the case of boiler flue turbulators, the more twists increases pressure drop which also needs more blower (and more steam) to pull exhaust gasses thru. Everything is going to have a trade-off...somewhere! The proof is in the temperature readings (heat gained or heat loss depending on application) if thermocouple wiring can be installed at the appropriate locations. Two more cents... Carl B.
The use of turbulators for propane fired steam locos has long been promoted on this board. Use of turbulators in super heaters is something new and there's no reason to believe it would have any less affect in a steam vs exhaust gas application. Dave's numbers prove this out.
Without seeing any numbers, have a hard time understanding why a zig-zag turbulator in a round pipe would be more effective than a spiral? In my mind, that arrangement is akin to a square peg in a round hole. There's open voids on all 4 sides of the square agitator running down the center of the pipe...thereby allowing more or maybe less laminar flow. At least with the spiral "turb"...the entire flow is being twisted and stirred.
Perhaps another way to examine and quantify the different arrangements would be measuring pressure drop. The greater the pressure drop would indicate to me, more turbulence, slower flows and greater heat transfer...with just the opposite for lower pressure drops. In the case of boiler flue turbulators, the more twists increases pressure drop which also needs more blower (and more steam) to pull exhaust gasses thru. Everything is going to have a trade-off...somewhere! The proof is in the temperature readings (heat gained or heat loss depending on application) if thermocouple wiring can be installed at the appropriate locations. Two more cents... Carl B.
Life is like a sewer...what you get out of it depends on what you put into it!
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I don't walk on water...I just learned where some of the stepping stones are!
I love mankind...it's some of the people I can't stand!
Re: To Turbulize or not
I didn't realize, but in retrospect should have that turbulizers we so common in industrial boiler applications. The fact that a company made it their business to make them is significant. I wonder if they have reduced their application down to quantifiable design parameters.Bill Shields wrote: ↑Wed Sep 18, 2019 8:51 pm these devices have been around a long time in industrial as well as residential boilers...and everyone has the 'best' idea, but the reality is you gotta play with it....or just take an idea and make it fit...you literally have nothing to lose
http://cleanboiler.org/learn-about/boil ... rbulators/
https://www.fuelefficiencyllc.com/turbulator/
think about purchasing some long / small od stainless springs....
Dave
Re: To Turbulize or not
It occurred to me that measuring the effect of a turbulizer in a model boiler would actually be rather easy. First with out a turbulizer in a tube place a thermocouple in the inlet and outlet of a tube. Pick a easily repeatable operation mode and location and run the loco and read the inlet and outlet temperatures. Second put the intended turbulizer in the same tube with the same thermocouples and run the same operation mode. Read the inlet and outlet temperature then compare them to the first test. The temperature reduction with turbulizer will be the additional heat that went into the boiler. With the inlet and outlet temperatures the thermos efficiency of both cases can easily be determined.
All of this effort is probably not necessary for most model work. But, I find it interesting and like to have an understanding of what I'm dealing with. I don't look so much for absolute values as better than or less than and % difference. Besides it might help optimize the situation with a boiler that has difficulty making enough steam.
Dave
All of this effort is probably not necessary for most model work. But, I find it interesting and like to have an understanding of what I'm dealing with. I don't look so much for absolute values as better than or less than and % difference. Besides it might help optimize the situation with a boiler that has difficulty making enough steam.
Dave