Evidence Supporting Advanced Rankine Cycle Engine Technology

John A. Cozby, Oct. 2008

Many historical evidences corroborate the fact that advanced Rankine cycle systems are sound engineering and good science. The Rankine cycle was named for William John Macquorn Rankine (ran^/-ken, 1820 – 1872). Rankine was a Scottish engineer and physicist and chair of mechanics at Glasgow University. He defined the closed loop steam power cycle. The Rankine cycle is the accepted thermodynamic standard for comparing the performance of steam prime movers (engines and turbines).

The contention that good advanced Rankine cycle engines cannot be built for automobiles is absurd, prima facie, and flies in the face of the evidence and all logic. This widely accepted claim that good advanced Rankine cycle engines cannot be built for automobiles is contradicted by the U. S. Department of Energy itself. It is logical to assume that with modern materials, technology, and innovation steam engines can be built much better through the extension and application of steam theory and concepts to a higher degree. We will consider six evidences which support the premise that advanced Rankine is a sound choice.

1. Frank Duncan Graham, BS, MS, ME, Princeton University

Frank D. Graham was a distinguished engineer, steam expert, and mechanic of the early part of the twentieth century. His books show the good efficiency of multi-stage, reheat, high expansion engines. Graham’s books (1921, 8 vol.) came to us from my grandfather, Alvin P. Gibson, and composed our introduction to the science of advanced Rankine cycle engines.

2. Lionel S. Marks was professor of mechanical engineering, Harvard University. He edited Marks’ Mechanical Engineers’ Handbook, Fourth Edition, 1941. Of all the engineering books that we have used, I found this to be the best on steam engines. The section on “The Steam Engine” by W. D. Ennis and revised by W. Turnwald should be required reading for anyone serious about steam engine technology. I studied through this section carefully. I read it six times over a six month period. I have read it about fourteen times by now. It is very instructive, and enlightening. In this section a reference is made to an earlier efficient multi-stage reheat engine. Note the following quotation:

“Tests by Schmidt of a 150 hp quadruple-expansion engine using steam at 794 lb per sq in abs at 815 F, with 28.6 in. Vacuum (Z.V.d.I., June 25, 1921), and with superheating in the receivers to 568, 536, and 436 F respectively, show a total steam consumption of 5.12 lb per ihp-hr, a thermal efficiency of 31.1 percent . . .”

This was an important revelation to me. The steam engine of 1921 got over 31% thermal efficiency. Today’s best gasoline engines get around 20%! Using much higher pressures, temperatures, and expansion ratios even greater efficiency can be realized. I found that steam pressure of 3,400 lb. per square inch was employed in 1896, and that steam pressures of 5,000 lb. per square inch and 1,200° F temperature were in use in the 1950's. Using much higher pressures, temperatures, and expansion ratios even greater efficiency can be realized than was demonstrated in 1921.

3. The Encyclopaedia Britannica, 1973 edition, volume 21, steam article is particularly informative as well as many other articles. Britannica shows that in the 1950's and 60's high pressure (5,000 lb.), and high temperature (1,200° F) multi-stage, two reheat systems were in use and were very efficient.

4. Power Magazine, July 2002, Special Report by Robert Swanekamp, PE, Editor-in-chief reports that:

“Nearly 200 supercritical boilers are operating worldwide . . . well into the supercritical range — up to 4500 psig — . . . More advanced designs introduced in the 1990s have raised steam temperature as high as 1150F . . . and main steam conditions above 1200F are forseen which should yield an efficiency approaching 50% . . . The increase in efficiency not only reduces fuel costs, but also specific emissions of NOx . . . as well as overall emissions of CO2 . . . . . . Note also that the efficiency of a supercritical boiler does not fall off significantly at part load . . .”

It is clear that higher pressure, higher temperature results in better efficiency and performance.

5. Roger Demler was the head engineer for Scientific Energy Systems Corp. (SES).

Scientific Energy Systems was the selected contractor to the U. S. Department of Energy for research and development on Rankine engines for automobiles. Roger Demler presented a paper to the Society of Automotive Engineers in February 23 – 27, 1976 / 760342. The paper was titled, “The Application of the Positive Displacement Reciprocating Steam Expander (engine) to the Passenger Car”. The main point of Roger’s paper was that a design based on advanced Rankine cycle principles would be much more efficient than the internal combustion gasoline engine. The Department of Energy acknowledged Roger Demler’s work and stated:

“Superior fuel economy will be a firm requirement for any future automotive engine . . . SES has published design concepts and calculations for possible future steam engines of greatly improved efficiency . . . This design . . . the “Mark II” design is conceivable after a major program of expander research and development, . . .” (DOE/CS-0125, 1977, page 53).

Roger was basically right. He was the shining exception among steam engine innovators of the 1960's – 70's. Roger made some important discoveries and realized that the proper path lay in the principles employed in the large steam power plants. He admitted that he did not have all of the problems resolved. He also did not realize that an additional expansion stage and vacuum exhaust were needed, but if given the opportunity to pursue his basic design criteria he probably would have gotten there shortly. He properly identified the valving to be a significant area of needed study.

What the Department of Energy affirmed was that “IT CAN BE DONE!!”, and that a major program of expander research and development is needed. The need is even greater now than it was then. The Department of Energy also affirmed that efficient Rankine engines can produce less emissions and cleaner exhaust, while using a broad cut of alternative fuels.

So what happened to the “major program of expander research and development”? It was killed by the Departments of Energy, Commerce, and Transportation – that’s what happened. Because Roger Demler was right and the Department of Energy affirmed that it can be done, the major program of expander research and development should be revived, adequately funded, and initiated expeditiously.

6. Ken Cozby and John Cozby are principals of Cozby Enterprises, Inc., and U. S. Engine, Inc. which are corporations of the State of Montana. Cozby Enterprises holds title to the patented “Unitary Steam Engine” (Aug. 2, 1983) Ken and John have worked together for forty-two years in the discipline of steam engine technology. Cozby’s findings are basically the same as those of Roger Demler and those other cited authorities. The primary difference between Roger Demler and the Cozbys is that the Cozby design extends the range of efficiency and performance, and offers solutions to several mechanical problems that Roger identified. The Cozbys have continued their research and design beyond their original patent and have design solutions to other problem areas which they have identified. They have other appealing design arrangements as well as design for higher performance and power out-put. These need to be put into practice in order to greatly advance the state of the art.

The great need for a major program of expander (engine) research and development was identified in the 1970's. Such a program is needed even more now and better results can be realized. Roger presented a superb and sophisticated paper to the Society of Automotive Engineers. Ken and John’s work is comparatively dry, boring, old hat, unspectacular, unimpressive, steam table based sort of stuff, but the result is the same. The evidence demonstrates that advanced Rankine cycle engine development is the right thing to do. A solid commitment to a major program of research and development by both government and industry is required. Such a program should not be attempted “on the cheap”, but it will be one of the best investments that our country has ever made to a better future for the world.

John A. Cozby

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