We're looking at the possibility of developing a hybrid vehicle. The
primary power is from batteries. We're curious about the possiblity
of using a Stirling for powering a generator for regen on the
batteries which would greatly enhance distance. We're thinking of
using a small propane burner for heat. Any comments????? Any advice
on engine plans????
Stirling to generator for hybrid????
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stan.hornbaker
- Posts: 532
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- First Name: William S.
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Stirling Powered Generator for Hybrid Auto
This would be a "Stirling" idea. (Note spelling and meaning) A Stirling engine-generator if available would require a large, very lange propane burner.
The current system of a relatively small ICE to charge the batteries in conjunction with regenerative braking and IC controllers is probably the best system to be on the market in the near term.
Let me suggest you download the catalog and reference guide from this site for a general familiarization with Stirling engines.
The current system of a relatively small ICE to charge the batteries in conjunction with regenerative braking and IC controllers is probably the best system to be on the market in the near term.
Let me suggest you download the catalog and reference guide from this site for a general familiarization with Stirling engines.
Response to Stirling to generator for hybrid????
This is an idea that has intrigued me for a long time as well.
I've come to the conclusion that the real stumbling block is the heat generator. It needs to burn efficiently, at a high temparature, but retain that heat in the vacintity of the hot end of the engine.
If you let too much of the heat go out the tailpipe, you eliminate any advantage the Stirling's greater thermal efficiency brings you, but for good combustion you need to provide a place for the expanding gasses to go.
Another challenge is designing a burner that can run on a variety of fuels. To lower fossil fuel dependency, it would be great if a tirling powered car could run on something other than petroleum based substences. If you could design a burner that could efficiently and cleanly burn anything from vegitable oil (fresh or waste) to coal slurry, it would give your Stirling powered vehicle a massive advantage over one powered by an ICE.
Realize, that you only need to produce about 25 HP to run a smaller hybrid vehicle (i.e. not SUV sized). It only takes about 15 to keep a car moving at highway speed, on level ground, and another 10 to power any accessories and top off the battery charge. In the city, power will come mostly from the batteries, with the generator only necessary when the charge gets low.
The Stirling technology is out there. Just look at some of the solar companies. All that needs to be developed is an efficeint and versatile burner.
As a starting point, I'd take a look at Ron Steele's design at http://www.stirlingsteele.com/ It's a four cylinder "cross compound" style engine, that produces about 20 watts with a 2CC displacement. (25hp ~= 20Kw) This type of engine can be scaled up to any number of cylinders, and I think that's how many of the solar engines work, more and bigger cylinders based on the same principle.
One final thing, don't listen to the naysayers who'll tell you "you can't put a Stirling in a car". It is possible, and soon someone will, and should do it.
I've come to the conclusion that the real stumbling block is the heat generator. It needs to burn efficiently, at a high temparature, but retain that heat in the vacintity of the hot end of the engine.
If you let too much of the heat go out the tailpipe, you eliminate any advantage the Stirling's greater thermal efficiency brings you, but for good combustion you need to provide a place for the expanding gasses to go.
Another challenge is designing a burner that can run on a variety of fuels. To lower fossil fuel dependency, it would be great if a tirling powered car could run on something other than petroleum based substences. If you could design a burner that could efficiently and cleanly burn anything from vegitable oil (fresh or waste) to coal slurry, it would give your Stirling powered vehicle a massive advantage over one powered by an ICE.
Realize, that you only need to produce about 25 HP to run a smaller hybrid vehicle (i.e. not SUV sized). It only takes about 15 to keep a car moving at highway speed, on level ground, and another 10 to power any accessories and top off the battery charge. In the city, power will come mostly from the batteries, with the generator only necessary when the charge gets low.
The Stirling technology is out there. Just look at some of the solar companies. All that needs to be developed is an efficeint and versatile burner.
As a starting point, I'd take a look at Ron Steele's design at http://www.stirlingsteele.com/ It's a four cylinder "cross compound" style engine, that produces about 20 watts with a 2CC displacement. (25hp ~= 20Kw) This type of engine can be scaled up to any number of cylinders, and I think that's how many of the solar engines work, more and bigger cylinders based on the same principle.
One final thing, don't listen to the naysayers who'll tell you "you can't put a Stirling in a car". It is possible, and soon someone will, and should do it.
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stan.hornbaker
- Posts: 532
- Joined: Thu Jun 20, 2002 6:01 pm
- First Name: William S.
- Last Name: Hornbaker
Response to Stirling to generator for hybrid????
I perceive that you are one of the “True Believers”
A major stumbling block in Stirling engines is inefficient heat transfer. Hence one reason for the high temperature at the hot end. This requires exotic, read expensive, alloys for the hot end to eliminate or minimize oxidation, thick walls which cut conduction, film factors on the inside surface(s), and finally the conduction of the working fluid, air, helium, or hydrogen. Pressuring the engine helps but this means a closed crankcase of packing gland(s) with sealing problems.
The heat sink for an Stirling automotive engine is necessarily the atmosphere and approximately 80% if the input heat goes out the “exhaust pipe.” Only some 20% is converted to useful work or power to charge the batteries.
Ability to burn a variety of fuels unnecessarily complicates the design and practicality of the system. Storage and handling of coal slurry would be complicated and power consuming.
The Stirling engine is essentially a fixed speed engine. It does not respond quickly to load demand changes and would work best at supplying a constant charging current. The current hybrid systems use the full power of the electrical and ICE output to accelerate and climb hills, then idle of shut off the ICE and use regenerative braking on the downhill runs to recover some of the charge in the battery.
Scaling up any piece of or system of machinery can be very tricky. A unit which works on the desk top may not work at all when scaled up by as little as a factor of 2. When it is scaled up 3 or 4 x it becomes useless. Linear dimensions increase linearly, areas by the square of the scaling factor and volumes as the cube. A solar heated soft drink can pump works beautifully but when scaled up to use a 1 gallon paint bucket or an oil drum it fails miserably.
Research has been carried on for years, much of it funded at Government (read taxpayers) expense to support a specific program which may produce some useful information and demonstration units. None of this has resulted in large scale applications for production. CHP and the Submarine Stirling powered systems are the exception and even here the costs are prohibitive without Government funding to spread the cost over time or the special nature of the application as in the submarine.
Perhaps you are the one to design an ingenious system to overcome these difficulties.
A major stumbling block in Stirling engines is inefficient heat transfer. Hence one reason for the high temperature at the hot end. This requires exotic, read expensive, alloys for the hot end to eliminate or minimize oxidation, thick walls which cut conduction, film factors on the inside surface(s), and finally the conduction of the working fluid, air, helium, or hydrogen. Pressuring the engine helps but this means a closed crankcase of packing gland(s) with sealing problems.
The heat sink for an Stirling automotive engine is necessarily the atmosphere and approximately 80% if the input heat goes out the “exhaust pipe.” Only some 20% is converted to useful work or power to charge the batteries.
Ability to burn a variety of fuels unnecessarily complicates the design and practicality of the system. Storage and handling of coal slurry would be complicated and power consuming.
The Stirling engine is essentially a fixed speed engine. It does not respond quickly to load demand changes and would work best at supplying a constant charging current. The current hybrid systems use the full power of the electrical and ICE output to accelerate and climb hills, then idle of shut off the ICE and use regenerative braking on the downhill runs to recover some of the charge in the battery.
Scaling up any piece of or system of machinery can be very tricky. A unit which works on the desk top may not work at all when scaled up by as little as a factor of 2. When it is scaled up 3 or 4 x it becomes useless. Linear dimensions increase linearly, areas by the square of the scaling factor and volumes as the cube. A solar heated soft drink can pump works beautifully but when scaled up to use a 1 gallon paint bucket or an oil drum it fails miserably.
Research has been carried on for years, much of it funded at Government (read taxpayers) expense to support a specific program which may produce some useful information and demonstration units. None of this has resulted in large scale applications for production. CHP and the Submarine Stirling powered systems are the exception and even here the costs are prohibitive without Government funding to spread the cost over time or the special nature of the application as in the submarine.
Perhaps you are the one to design an ingenious system to overcome these difficulties.