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 RESEARCHING THE 21st CENTURY FIRELESS  STEAM RAILWAY LOCOMOTIVE

             The traditional wood, coal and oil burning Stephenson type steam railway locomotive had a fireless derivative which graced the shunting yards, the "fireless cooker". This engine was essential a giant thermos bottle laying on its side and was
dependent on a remote firebox as its heat source. Maintenance and operating costs of a fireless cooker were low, due to the absence of the firebox and smokebox, two of the high maintenance items on a traditional steamer. Energy recharging of the cooker engine was done by passing steam through a heat exchanger line, which ran in coiled fashion through this type of locomotive combination "boiler"/water tank.

             Prior to recharge, the combination boiler/water tank would be 80% filled with water. It would then be connected to an external steam line, which would heat the water in the tank to temperatures of  400-degrees fahrenheit (200-centigrade), with internal tank pressures rising up to 400-psi (pounds per square inch). The cylinders would operate at pressures of  150-psi. After a recharge, the steam heater line was disconnected and the driver would open the throttle, resulting in the sudden generation of "flash steam" inside the boiler/water tank, as a slight pressure drop occurred. Like its counterpart which carried an on-board firebox, the cooker too required the occasional boiler washdown to remove scale.

           In countries like Spain and Austria, fireless cookers still see commercial service in shunting yards and hauling passenger cars at low speed over short distances. Traditionally, a source of waste steam has been the energy source of fireless cookers, though in more modern times other alternatives are available. A small on-board natural gas burner could
circulate superheated gas through the cooker's on-board heat-exchanger line, while at the same time avoiding the soot buildup problem incurred when using wood, coal or oil in more conventional steamers. Solar thermal panel technology can also be applied to heating the traditional cooker engine, though hot oil would need to be circulated through the engine's heat exchanger line.

Modernizing the Fireless Cooker:
          Modernizing the traditional fireless cooker to deliver higher power and greater operating range is possible. Modern metallurgy and manufacturing techniques can allow for larger, better insulated boiler/water tanks capable of pressures of 1,500-psi and water temperatures of 600-degrees F (400-deg.C). Thermal storage tanks containing a molten compound, storing thermal energy in its latent heat of fusion phenomena, could be included in the loco's boiler/water tank.  In Southern Africa, lithium nitrate which melts at 260-deg C, occurs quite naturally and could be used as a thermal storage medium, as its energy of fusion is 159 Btu/lb. Unlike electric storage batteries, some thermal storage compounds have virtually infinite life expectancy.

             The use of a thermal storage tank allows for several other options. A separate reserve water tank could be  incorporated into the system, along with a water pump to add water to the heater tank. The thermal tank allows for the superheating of steam prior to entering the cylinders, as well as for reheating lower pressure steam if a double expansion
cylinder system is used. Heating the thermal tank via solar thermal technology, using fibre optic lines of Al2O3 (processed bauxite) to transmit the concentrated infrared spectrum to the locomotive, also becomes an option.

          While the cooker bypasses the labour-intensive maintenance requirements of a the firebox and smokebox, water and boiler system washdowns will still be required. This cost can be reduced and efficiency can be improved by switching from an open system of exhausting waste steam and refilling the water storage tank, to a closed system which recycles the water. While the South African condensing steamers were troublesome, some research undertaken by ACE (American Coal Enterprises) showed that the condensor problems can be resolved by passing exhaust steam through a cooled expansion valve system, which would transform the exhaust steam into hot water. The South African engines were designed to cool the exhaust steam directly in the radiators, while the ACE system cools high temperature water, after it has pre-heated cool water being pumped into the main thermal storage/heater system.

          A contemporary cooker engine could dispense with the frequent boiler washdowns as well as firebox and smokebox maintenance requirements. While a small thermal storage tank could be incorporated into the boiler/water tanks of traditional cookers, a modern cooker could separate the two. A large, high temperature thermal storage system with pipes running through it, may exist separately from the water storage system. Thermal recharging would focus exclusively on the thermal tank, not on a high pressure combined "boiler"/water tank. Operating steam pressures could be in the 350-500-psi range, instead of 1,500-2,000 - psi range. The thermal storage mediums could be changed from lithium nitrate to other compounds and mixtures, to raise energy storage levels, locomotive output as well as operating duration. The intention would be to transform the shunting yard workhorse into an engine with mainline capabilities.

Turbine Cooker Locomotive;
              While the traditional Stephenson derived steam locomotive, especially in double expansion superheated form, has merit, a turbine alternative is possible. Traditionally, turbine propulsion only delivers its maximum efficiency at maximum output, with drastic reductions in efficiency as throttle settings are reduced. This shortcoming, unfortunately, marred earlier steam turbine locomotives.

             The system proposed for the contemporary steam turbine electric locomotive would take advantage of this characteristic of turbines, as well as the fact that turbines are sold on the basis of  power output. A 4-turbine system in a  1-2-4-8 power ratio would be able to offer 15-power settings, all at maximum output and maximum efficiency at each
power setting. Example, a 4-turbine system using a 250-hp, 500-hp, 1,000-hp and 2,000-hp system would yield a maximum of 3,750-horsepower, yet offer 15-increments at jumps of 250-hp, from a low of 250-hp right up to maximum. This system could recover its extra turbine costs within a year of service, resulting from savings in energy costs.

              The 4-turbine system could operate in either a stored thermal energy locomotive or in a design which boils water and raises steam by on-board combustion of a fuel, like coal slurry, an oil unsuitable for a piston engine, or a solvent fuel which would destroy the lubrication in a piston engine. A modern steamer using the multi-turbine system could become a multi-fuel locomotive, operating on fuels which a present day diesel locomotive's engine could not be adapted to. World oil projections indicate a worldwide decline in oil production after 2010, meaning that other energy sources will have to be considered. A
study undertaken by the London School of Economics during the late 1980's, revealed that a modern steam locomotive could be more cost effective than diesel or electric traction.

A Fuel Cell Cooker Locomotive:
             A considerable amount of research effort and funding is being directed toward developing fuel cell technology geared toward the transportation industry. The automotive industry is betting on the proton exchange membrane (PEM) fuel cell as a possible alternative to the piston engine. This type of fuel cell typically operates on hydrogen gas, which it combined with oxygen to produce water and electricity which powers the electric motor. PEM fuel cells typically operate below 40% efficiency, which electrolysis of water to produce hydrogen has an efficiency of 70%. If the electricity to produce the hydrogen comes from a thermal electric power station (nuclear/coal/natural gas/hydrogen fusion), it would be less costly and more efficient charging up a fireless cooker locomotive directly from the waste heat of the thermal power station.

            There are, however, two types of fuel cell which could be used in locomotives, in tandem with fireless cooker technology. The molten carbonate fuel cell (MCFC) and solid oxide fuel cell (SOFC) operate at high temperatures (600-deg C - 750-deg C) and can use natural gas as their fuel source. The reject heat from the fuel cell could add to the thermal energy being converted to traction in the multi-turbine system. Several types of fuel cells incur greatly reduced life expectancies if operated continuously at maximum efficiency. In starting a heavy train, fuel cells (which cost some $2,000 US per Kilowatt) would have to operate at maximum output and efficiency, reducing its useful life expectancy. Alternatively the fuel cells could be operated to assist the thermal propulsion side of the fuel cell cooker locomotive (fccl), which could reliably operate at maximum output for  prolonged periods, repeatedly.

            After 2010, greater use of electricity in transportation is a distinct possibility. The increased demand for power could result in accompanying price increases. In city transit services, fuel cell buses and electric trolleybuses and trams could become more numerous, as could electrified railway lines. This will be combined with increase use of electric cars and vans, which would try to connect to major power producers. Opposition to building new mega-power stations is high in many countries, as demand for power increases. More home users may opt to generate their own power using solar panels and wind turbines, both of which are dropping in price, while using new generation high efficiency lighting technology. While such initiatives will ease the demand for electric power, the economics of operating a new generation steam locomotive could make it extremely competitive against straight electric and modified diesel traction.

Energy Storage in the Cooker;
             Energy storage for the cooker engine comes directly from the fundamentals of thermochemistry as well as metallurgy. The research challenges are to develop a high density compound which melts between 300-deg C and 500-deg C, with a very high level of  latent heat of fusion. Some compounds already exist in this range, such as lithium hydroxide, which results from steam coming into contact with the naturally occurring lithium nitrate. However, this may not be the optimal compound, as the area of thermal energy storage using latent heat of fusion is wide open for new research. At present, there remains
much more to research and discover, than what is already known in this field.

            Compounds of aluminium (aluminum) can form a basis of thermal energy storage. Aluminum mixed with hydrogen peroxide produces aluminum hydroxide (Al(OH)3), which could then be mixed with any of three alkaline metals, lithium, sodium or potassium. The result would be compounds like Al(LiO)3, Al(NaO)3, or Al(KO)3. These are multi-metal oxides which could be mixed in certain proportions to yield a desired melting temperature and a high latent heat of fusion. Metals like vanadium and beryllium do bond to oxygen to yield extremely high melting temperatures and high latent heats of fusion. The oxygen atom can also simultaneously bond to aluminum and beryllium, forming a cyclic molecule comprising a single beryllium atom and multiple aluminum and oxygen atoms. The latent heat of fusion remains extremely high, though the melting temperature is 1,000-deg C lower than for beryllium oxide. Mixing the Beryllium-Oxygen-Aluminum molecule with another similar molecule, could lower its melting temperature to below 500-deg C, where it would become useable.

           Advances in nanotechnology could theoretically enable development of suitable multi-metal oxides for use in a thermal storage locomotive. Such technology could be applied to atoms like uranium and thorium, which will bond to oxygen and possible via oxygen to other atoms which bond to oxygen. The thickness, atomic structure and insulation of the thermal storage tanks could contain radiation, while the thermal energy being stored could enable a locomotive to operate distances of 500-1,000-miles on a charge of energy, delivering some 3,000-hp continuously to the rails. Thermal energy storage technology is a field that is wide open for future research, with the potential for yielding worthwhile and useful results.

Renewable "combustion";
           Latent heat of fusion of a molten compound in an insulated container is one means of thermal energy storage. Another method would borrow concepts used in present and past thermodynamic machinery, where a fuel was burned and the heat of combustion yielded thermal energy to drive pistons and turn wheels. Another way of looking at such systems is to classify them in a broad definition, i.e; their thermal energy resulted from the heat of formation.

          In a wood or coal burning steam locomotive, the compounds being formed were carbon monoxide, carbon dioxide and sometimes sulphur dioxide and sulphur trioxide if the coal had a high sulphur content. In an internal combustion engine, a hydrocarbon fuel is ignited and water vapour, carbon dioxide, carbon monoxide and sometimes nitrous oxides are formed. The burning of the fuel was often regarded as a non-reversible process, as mother nature had to process the carbon dioxide in plant leaves to return oxygen to the atmosphere and incorporate the carbon into the plant.

         The concept of producing heat via processes involving the heat of formation, could be extended to include reversible processes. Example, hydrogen and magnesium will join chemically to form magnesium hydride and release a tremendous amount of heat in the process. The heat can be used to generate steam to drive turbines, which will drive electric alternators which in turn will power up locomotive driving wheels. During a recharge cycle, heat can be infused into the magnesium hydride, resulting in the two dissociating from each other; the hydrogen can be stored on a separate tank until re-use in another repeat cycle of raising thermal energy from heat of formation. Mixing carbon dioxide and sodium oxide will produce sodium carbonate and a measure of heat energy, however, the levels of this energy may not be readily available for locomotive use. However, this chemical process is a reversible one, which can be repeated many times, essentially using the same compounds.

           Using a reversible form of heat of formation is another method of operating a thermal rechargeable locomotive. Again, there is much untapped research potential in this area of thermochemistry, with as yet undiscovered rechargeable energy storage options for the future. Much research funding is presently concentrated into two main areas: fuel cell technology as fusion energy, where two or more hydrogen molecules will fuse to form helium (heat of formation, again) and release a great deal of thermal energy (without the alpha, beta and gamma radiation of a nuclear powerstation). Thermal rechargeable railway engines could, in the future, be re-energised at fusion power stations, on waste heat that could be heat pumped into the thermal storage media.

Conclusions:
-Steam railway traction is a valid option for the future, especially after 2010, after which world oil production is projected to decline, with accompanying price increases.
-Much untapped, unexplored research opportunity exists in the field of thermochemistry and chemistry, that could result in making future steam railway locomotives competitive.
 

Harry Valentine.
Transportation Researcher.
November 2000.
harrycv@hotmail.com

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