1 Steam Cars : Phorum
General Steam Car topics
thermal storage mediums
Posted by: tom ward (IP Logged)
Date: May 29, 2002 09:00PM
<HTML>In my posting of 5-10-02 I suggested the use of lead filled beads as a heat storage medium. Upon fur ther review I have learned that pound for pound zinc holds 7.2 times the energy of lead as it cools from 1000 degrees F to 500 F. A ton of lead would release only twelve horsepower/hours of heat while a ton of zinc would release 89.5 HP/hr of heat. At roughly 30% efficiency zinc would give about two hours of travel while the lead would allow about 20 minutes.
Does anyone know how many HP/hr a ton of thermal oil would release over the same temperature drop?</HTML>
Does anyone know how many HP/hr a ton of thermal oil would release over the same temperature drop?</HTML>
Re: thermal storage mediums
Posted by: David K. Nergaard (IP Logged)
Date: May 29, 2002 10:48PM
<HTML>The specific heat of mineral oil is about 0.4/ (square root of specific gravity) BTU/lb. In other words, water is twice as good a heat storage medium as oil, except that it must be pressurized. I don't know about synthetic oils.</HTML>
Re: thermal storage mediums
Posted by: Tom Ward (IP Logged)
Date: June 01, 2002 07:47PM
<HTML>thanx to dave for the info. on specific heat alone the oil would hold over 150 hp/hr per ton. At twelve hp and 30% eff. that's 12.5 hours per ton without using latent heat. Back to the drawing board.</HTML>
Re: thermal storage mediums
Posted by: Peter Brow (IP Logged)
Date: June 02, 2002 09:07AM
<HTML>Hi Tom,
About the best (non-phase-change) heat-storage material I found was pure carbon. I don't have the specific heat figure handy, but it beats oil and everything else I could find figures on. One possibility is to mix graphite into oil to up the heat storage (assuming you can keep it in suspension). A lot of these materials have different specific heats in different heat ranges, which adds to the mathematical fun! I found some of those figures in an old Machinery's Handbook.
One thing I like about a liquid heat storage system is that the low-pressure liquid can be run thru a compact heat exchanger from a hot tank to a cold tank. This minimizes the whole thermal storage mass dropping in temp via heat migration as the heat runs out, so the steam stays closer to a target temperature for more consistent performance.
Recently somebody wrote me about SynCoal, a commercially available processed/powdered coal fuel of 1/3 to 1/4 the cost of gasoline. Kept dry, it flows like a liquid. I am looking into it as a possible future alternative automotive fuel, but a similar hot carbon dust might make a good thermal storage medium? But, charge system with inert gas and keep air the heck away from 1000°F carbon dust! After a couple broken tanks, the military explosives guys will classify that high-yield system PDQ.
And speaking of fuel-air bombs, there are other renewable/ZEV steamcar fuel options. Aluminum or iron wire or wool will burn in a proper refractory/forced air combustion chamber, and the oxide can be collected and reduced back into fuel. Iron oxide can be easily reduced back to iron fuel with (solar-heated?) carbon monoxide. Turn the CO2 back into CO for a zero-emissions system. Also, metal wire can be oxidized in water with electric spark initiators, releasing hydrogen fuel, then the oxide sludge can be reduced with solar heat and CO. A metal-fueled steam car may be a possibility; reportedly experimental IC cars have already been run on this system.
Or, maybe steel-jacketed carbon pellets to store heat directly?
There are all sorts of intriguing possibilities.
Peter</HTML>
About the best (non-phase-change) heat-storage material I found was pure carbon. I don't have the specific heat figure handy, but it beats oil and everything else I could find figures on. One possibility is to mix graphite into oil to up the heat storage (assuming you can keep it in suspension). A lot of these materials have different specific heats in different heat ranges, which adds to the mathematical fun! I found some of those figures in an old Machinery's Handbook.
One thing I like about a liquid heat storage system is that the low-pressure liquid can be run thru a compact heat exchanger from a hot tank to a cold tank. This minimizes the whole thermal storage mass dropping in temp via heat migration as the heat runs out, so the steam stays closer to a target temperature for more consistent performance.
Recently somebody wrote me about SynCoal, a commercially available processed/powdered coal fuel of 1/3 to 1/4 the cost of gasoline. Kept dry, it flows like a liquid. I am looking into it as a possible future alternative automotive fuel, but a similar hot carbon dust might make a good thermal storage medium? But, charge system with inert gas and keep air the heck away from 1000°F carbon dust! After a couple broken tanks, the military explosives guys will classify that high-yield system PDQ.
And speaking of fuel-air bombs, there are other renewable/ZEV steamcar fuel options. Aluminum or iron wire or wool will burn in a proper refractory/forced air combustion chamber, and the oxide can be collected and reduced back into fuel. Iron oxide can be easily reduced back to iron fuel with (solar-heated?) carbon monoxide. Turn the CO2 back into CO for a zero-emissions system. Also, metal wire can be oxidized in water with electric spark initiators, releasing hydrogen fuel, then the oxide sludge can be reduced with solar heat and CO. A metal-fueled steam car may be a possibility; reportedly experimental IC cars have already been run on this system.
Or, maybe steel-jacketed carbon pellets to store heat directly?
There are all sorts of intriguing possibilities.
Peter</HTML>
Re: thermal storage mediums
Posted by: Mike Bennett (IP Logged)
Date: June 21, 2002 01:15PM
<HTML>What about soapstone? S.H. = .22
MB</HTML>
MB</HTML>
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