One of the biggest problems we have had through the years is a source of boilers. Without a boiler, a steam engine simply doesn't work. Ergo, we decided to manufacture our own.
On October 13, 2007, Mike Brown, McGregor Manufacturing, and Peter Bouley met, agreed upon, and began The Steam Car Project.
Mike Brown and McGregor Manufacturing manufacture a 20-horsepower piston valve steam engine, which is quite adequate for passenger cars. The Stanley Steamers used a D-valve steam engine in 10 and 20 horsepower configurations.
Our stumbling block was the boilers.
Enter Peter Bouley.
Peter Bouley has done extensive boiler repair, design, and instruction. Some of what he has to say follows this introduction. At one point he was involved in the Lear Steam Car Project in California. In that project 26 steam cars were built for the California Highway Patrol. Rumor has it the cars are stored in a warehouse in San Francisco.
At our October 13th meeting the first thing Peter did was disabuse us of the idea of a water tube boiler. Water tube boilers require clean water and chemical treatment, whereas, fire tube boilers can operate without chemical treatment provided that a routine blow down is done prior to operation and shut down daily to purge the boiler of impurities which come out of the water during steam production.
Here is what Peter Bouley has to say about fire tube vs. water tube boilers.
Water tube boilers require forced circulation using a feed-water pump and if you are not watchful, they will "load up" with too much water during slow operation and no steam demand while in traffic. When you open the throttle, slugs of water will go with the steam. This is called "carry-over" and can destroy a steam engine or turbine in a heartbeat. Fire tube boilers do not have this surge problem and can be operated at 50% sight glass, which will help to eliminate or reduce the potential of "carry-over."
Water tube boilers, because they are a continuous loop of tubing, are susceptible to clogging due to elements in the water, which fall out and stick to the tube walls during the steaming process. Anything greater than 1/64" is unacceptable.
In a fire tube boiler the water surrounds the tubes and the boiling action tends to scrub the tube walls and causes the heavier materials to fall to the mud ring where they are evacuated during the blow down (cleaning) process at the beginning and end of the day's operation. There isn't a collection point in a water tube boiler for this material to fall out to and therefore, even if you blow down a water tube (monotube) steam car boiler, you merely clean that point only and in no way clean the water space in the boiler.
The causes of a water tube boiler failure are two fold. I.e., built up sludge which causes the metal covered with sludge to overheat and fail causing the water in that area to evacuate out the hole causing you to call a tow truck or you run the boiler too low and the tube overheats as there isn't enough water or steam to cool the tube.
The only water tube boilers that are better are those used in power plants making electricity as they strip the water of all elements therefore eliminating these types of problems. They also have very sophisticated equipment to help maintain proper pump pressure in relation to steam consumption and fuel consumption. During World War II boiler designers in Germany and the USA experimented with water tube boilers in locomotives and quickly abandoned the idea as not being practical for that application.
In a steam car if a tube collapses in a fire tube boiler, you can just put a drift pin in each end of the tube, fire the boiler back up, and drive off down the road. If a water tube boiler collapses in any part of it, you have to call a tow truck.
Our first prototype steam car will be designed to look like a 1920s steam car but will be able to "keep up" with traffic on the modern highways. The California Highway Patrol steam cars would do 140 to 150 mph and-apparently-scared the members of the CHP.
Demand. Check the price of an original steam car. Fuel economy. A steam car may only go half as far on a gallon of fuel but if the fuel costs only 25 cents a gallon (such as glycerin), it is more economical. Durability. Steam engines generally last a lot longer than gas or diesel engines. There is a steam locomotive in India that has been in constant daily service since 1855 and another steam engine in Brazil in a sugar mill that has been in constant service since 1877. Novelty. How many people do you know have a steam car capable of coast-to-coast travel? Environmentally friendly. A steam car pollutes far less than a gasoline or diesel vehicle.
For some time we have been unable to properly figure the usable exhaust heat from one of our 3 horsepower steam engines. Peter Bouley figured it out for us.
Question to Peter Bouley: Using the Mike Brown 3 horsepower twin steam engine operating at 150 psi and exhausting at approximately 20 psi, how many BTUs are available to provide heat for my house?
Peter Bouley: The answer is found in the standard Steam Tables for Saturated Steam (wet steam not super heated). These steam tables have been around for years and are readily available at your local library in a good steam textbook.
Before I get to the answer I need to explain some curious characteristics about steam. Contrary to what many think is that regardless of how many BTUs you have available, you cannot ever get 100% use out of them as there are two terms you will need to understand: (1) enthalphy . . . the amount of potential BTUs available; (2) entropy . . . the amount of BTUs unavailable due to initial BTUs required to change water at inlet temperature to water at 212 degrees F. to steam at 212 degrees F. at zero psi.
This item also includes line losses + BTUs lost to heat up the steam engine + BTUs lost to friction, leaks, or trying to boil muddy water, etc.
Let's look at what it took to bring the water to steam:At zero psi .......................... 1150 BTUs per pound.
Change zero psi to 150 psi .......................... 1195 BTUs per pound.
Exhaust steam is around 264 degrees F. which is approximately 22 psi .......................... 1168 BTUs per pound.
The difference between inlet and exhaust is .......................... 27 BTUs per pound.
Where did the number 1150 BTUs per pound come from?
Engineering bases this number as follows:
32 degrees F. water + 180 BTUs [Sensible Heat] = 212 degrees F. water + 897 BTUs [internal latent heat] = 212 degrees F. steam + 73 BTUs [external latent heat] required to do work in atmosphere = 1150 BTUs
Now how many BTUs can we actually use for heating home, etc?
1168 BTUs minus 180 BTUs minus 73 BTUs = 915 BTUs per pound. Also there will be a % of this number that will be lost due to Entropy, therefore, I would venture to say that the available BTUs/pound should be around 820 BTUs per pound available to do work.
22 psi = 1168 BTUs/pound total heat less Entropy [figured using above calculation] leaves 820 BTUs/pound enthalphy (available) for a loss of approximately 348 BTUs/pound. This is theoretical as there are other factors unknown to me. Therefore using the 3 horsepower twin under ideal conditions the exhaust steam has approximately 18,040 BTUs of heat energy available or 264 degrees F.
You may question why we use water. Water is the best substance as it has a specific gravity of 1 (one) and every other material is based upon less than 1 (one). In the 1960s a man in Florida converted a Volkswagen bus into a steam car using Freon. The car ran great . . . for a while . . . until the change of state in the Freon turned into an acid and ate up the piping and steam engine! Water is still the best substance and the cleaner it is the better it steams and the less fuel it requires to bring it to steam and sustain the operation.
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This page was updated on 5 November 2011