Slam Valve Motor, supplying efficient steam engines for homeowners and professional solar installers
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             Bringing you the very latest in 18th century steam engine technology

Slam valve performance unported

Unported slam valve motors are useful as generators and pumps, usually solar powered.  Unported motors are simple to convert, requiring no machining of the cylinder.  The head simply bolts on to an existing piston and cylinder assembly, from a pump or engine.  The slam valve motor is essentially an ideal adiabatic expander, with an extra 5-20% steam consumption from valve losses. The 5-20% allows for valve leakage and mis tuning. Normally motors are pulsed on and off to allow constant output power required by the generator or pump under varying sunlight incidence angle. Peak output power represents the stall torque. In multi cylinder designs it is important to stay well below this power to allow for the possibility that the two cylinders are not tuned to the same power. In generators, power can be adjusted by monitoring the electric power generated. In pumps, the motor will be set for the worst operating point (pool pumps for example are with all valves open and filter at its cleanest) and allowed to settle where it may for all other conditions. Efficiency is shaft power out divided by heat in to the boiler. The water pump losses are not included but are only a few percent of the total shaft power if a reasonably efficient pump is used. For comparison, automobile engines generally run 20% thermal efficiency or below (25 mpg cars). A cooler radiator with a vacuum pump gives higher efficiency, but lower power density.

efficiency graph
unported power graph