1 Steam Cars : Phorum
General Steam Car topics
Doble evaporation rate
Posted by: R Ulsky (IP Logged)
Date: May 24, 2005 04:49PM
<HTML>On page 155 of Walton's book "Doble steam cars", there is a graph that shows an evaporation rate of 20 lbs/hr/sq-ft for a Doble monotube boiler with 75% efficiency. I seem to be only able to get this rate if I have a very low efficiency--like 20%. Does anyone know if the numbers indicated by Walton have indeed been achieved?
Thanks, Roger</HTML>
Thanks, Roger</HTML>
Re: Doble evaporation rate
Posted by: Jim Crank (IP Logged)
Date: May 25, 2005 03:14PM
<HTML>Rodger,
Exceeded. Several lab test runs produced 27 lbs/sq/ft.
With Walton's book, you must know which boiler was being tested and when.
Dobles ran numerous tests on all the D,E, F, and experimental steam generators.
JC</HTML>
Exceeded. Several lab test runs produced 27 lbs/sq/ft.
With Walton's book, you must know which boiler was being tested and when.
Dobles ran numerous tests on all the D,E, F, and experimental steam generators.
JC</HTML>
Re: Doble evaporation rate
Posted by: George Nutz (IP Logged)
Date: May 27, 2005 07:40PM
<HTML>Roger,
Look at pages 80 (and 78 that is "F" data labeled "E") and you will see the run#16 evaporating 1532# with 80 sqft=19#/sqft/hr) with a boiler efficiency of 76.96% really quite good as most of the heating surface is economiser and water heating surface. I don't understand your number of 20% efficiency. A more modern approach could possibly yield 25#/hr/sqft. Think of the poor 20HP Stanley boiler evaporating about 320#/hr with about 100 square feet of heating surface!.
Best, George</HTML>
Look at pages 80 (and 78 that is "F" data labeled "E") and you will see the run#16 evaporating 1532# with 80 sqft=19#/sqft/hr) with a boiler efficiency of 76.96% really quite good as most of the heating surface is economiser and water heating surface. I don't understand your number of 20% efficiency. A more modern approach could possibly yield 25#/hr/sqft. Think of the poor 20HP Stanley boiler evaporating about 320#/hr with about 100 square feet of heating surface!.
Best, George</HTML>
Re: Doble evaporation rate
Posted by: R Ulsky (IP Logged)
Date: May 28, 2005 02:25PM
<HTML>Thanks Jim, I am encouraged that it can in fact be done.
Roger</HTML>
Roger</HTML>
Re: Doble evaporation rate
Posted by: R Ulsky (IP Logged)
Date: May 28, 2005 02:35PM
<HTML>George,
My thought was that if one was to run a boiler at very low efficiency, then one should be able to get way more specific output from it. I am building a go-kart steam-thingie for use at the Berrien Springs meet and therefore want a small, very high output boiler and am not worried about fuel usage. Here is what I have set up:
One pancake constructed of 30' of 3/16" cu tubing. It is 10" in diameter, with 1/32" spacing between adjacent tubes and has 1.5 sq-ft of heating surface. This gives me a 4" equivalent diameter flue space which seemed to me to be enough. I am firing it with a "turkey deep-fryer" type propane burner and feeding it maybe 200 KB/hr. The gas temp just below the pancake is 1800 F and it is 1000 F above it. I am feeding it with a constant flow pump (by restricting the pump input) on the engine and have a thermocouple that turns the fire off if the temp gets above 800 F. I only get 30 lbs/hr of 600 F steam out of the thing and I thought I should be getting at least 2-3 times this much.
Can you see where I am going wrong? Obviously, some huge mis-thinking as I am so far off.
Thanks, Roger</HTML>
My thought was that if one was to run a boiler at very low efficiency, then one should be able to get way more specific output from it. I am building a go-kart steam-thingie for use at the Berrien Springs meet and therefore want a small, very high output boiler and am not worried about fuel usage. Here is what I have set up:
One pancake constructed of 30' of 3/16" cu tubing. It is 10" in diameter, with 1/32" spacing between adjacent tubes and has 1.5 sq-ft of heating surface. This gives me a 4" equivalent diameter flue space which seemed to me to be enough. I am firing it with a "turkey deep-fryer" type propane burner and feeding it maybe 200 KB/hr. The gas temp just below the pancake is 1800 F and it is 1000 F above it. I am feeding it with a constant flow pump (by restricting the pump input) on the engine and have a thermocouple that turns the fire off if the temp gets above 800 F. I only get 30 lbs/hr of 600 F steam out of the thing and I thought I should be getting at least 2-3 times this much.
Can you see where I am going wrong? Obviously, some huge mis-thinking as I am so far off.
Thanks, Roger</HTML>
Re: Doble evaporation rate
Posted by: Graeme Vagg (IP Logged)
Date: May 28, 2005 10:30PM
<HTML>Roger,
Your logic is OK but you need more than one coil layer to get reasonable output. It is a law of diminishing returns. The amount of tube you have is less than what many put into a model hydroplane and most of your heat is going up the stack.
All the best.
Graeme</HTML>
Your logic is OK but you need more than one coil layer to get reasonable output. It is a law of diminishing returns. The amount of tube you have is less than what many put into a model hydroplane and most of your heat is going up the stack.
All the best.
Graeme</HTML>
Re: Doble evaporation rate
Posted by: Arnold walker (IP Logged)
Date: May 29, 2005 07:02PM
<HTML>I agree with Vagg....
30-45ft would be your superheat coil.3/8" tube,coming off your original size.
About 100ft of evaporator coil should get you in the ballpark.Using the size you started with.
Trail and error should get you tuned out the rest of the way.
Used a Lamonte circuit in addition to all that on my garden tractor....
so you will need to tune some more ,if you are running with just superheat and evaporator.</HTML>
30-45ft would be your superheat coil.3/8" tube,coming off your original size.
About 100ft of evaporator coil should get you in the ballpark.Using the size you started with.
Trail and error should get you tuned out the rest of the way.
Used a Lamonte circuit in addition to all that on my garden tractor....
so you will need to tune some more ,if you are running with just superheat and evaporator.</HTML>
Re: Doble evaporation rate
Posted by: Arnold walker (IP Logged)
Date: May 29, 2005 07:11PM
<HTML>Stick a cooking thermmeter in the flue and check for 350deg F coming out the stack.Between that and a pressure gauge and steam temp.The boiler will actually tell you how to go on feedwater and coil length.</HTML>
Re: Doble evaporation rate
Posted by: Arnold walker (IP Logged)
Date: May 29, 2005 08:37PM
<HTML>For what you are talkiing on boiler rating for your little go-cart .
Probably get the whole thing to fit in a container about the size of a 15gallon trashcan. Zinc would stop you from actually using a trashcan(metal fever).</HTML>
Probably get the whole thing to fit in a container about the size of a 15gallon trashcan. Zinc would stop you from actually using a trashcan(metal fever).</HTML>
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