engine specs

At the 1999 United States Department of Energy Hydrogen Program Review Conference, Peter Van Blarigan presented HCCI research data from Sandia National Laboratories, Livermore, California. The reader is encouraged to review this data in its entirety (35 pages), but specific data as it relates to the Bourke Engine is referenced in summary form in this table. Sandia National Laboratories was investigating the use of a free piston linear alternator (one moving part – Figure 1, page 5 of the presentation document) utilizing HCCI operation. The presentation document outlined the advantages of this free piston linear alternator as: 

The linear alternator is a free piston engine design with one (1) moving part. The Bourke Engine is a free piston engine design with two (2) moving parts (piston/rod/yoke plate assembly and the crankshaft). The proposed linear alternator would extract work in the form of electricity while the Bourke Engine extracts work by converting reciprocating motion (piston/rod/yoke plate assembly) to rotary motion (crankshaft) and using that rotary motion to do work. The advantages of the free piston linear alternator outlined in the presentation document are applicable to the free piston Bourke Engine plus the Bourke Engine overcomes some of the shortcomings of the free piston linear alternator: 

For the linear alternator, all of the output power is converted to electrical energy, there is a narrow speed/power output range, it would cycle on and off as needed and engine operation would be controlled automatically so that throttle response is unimportant. For the Bourke Engine, it would be coupled with a permanent magnet alternating current (PMAC) motor/generator and all of the output power is converted to electrical energy, there is a wide speed/power output range (6,000 to 12,000 rpm for the 10.842 cid unit), it would cycle on and off as needed and engine operation would be controlled automatically including a gentle throttle response (Full Authority Digital Engine Control – FADEC). 

Generally, higher temperatures and higher compression ratios are required to burn more of the fuel to completion. Thermal efficiency improvements of near 40% can be realized. Nitrogen oxide emissions can be sufficiently controlled by decreasing the equivalence ratio. An interesting possibility for emissions control would be to utilize 50% exhaust gas recirculation (EGR). Restricting the exhaust in a Bourke Engine raises the effective compression ratio in order to initiate detonation/HCCI at the appropriate time and this in turn results in varying percentages of EGR.

The 10.842 cid Bourke Engine has a bore of 52 mm (2.047”) and a stroke of 1.542”. To achieve a piston speed of 1,500 feet per minute, the rpm would have to be 5,906 rpm (round off to 6,000 rpm). Maximum speed for the permanent magnet alternating current (PMAC) motor/generator is 12,000 rpm. The only fuel that fully completed the first and second stages of combustion was n-Pentane (C₅ H₁₂) with a combustion duration of 600 microseconds. The first stage of the two (2) stages of the combustion process (carbon trigger) started at a compression ratio of 18:1. The fixed mechanical compression ratio for the 10.842 cid engine shown in the animation is 12.28:1. The Full Authority Digital Engine Control System (FADEC) would restrict the exhaust to the point where the 18:1 compression ratio starts the combustion process (carbon trigger) at 22.5° degrees before top dead center. The combustion duration time is 600 microseconds (detonation/HCCI), the combustion process is completed at 22.5° after top dead center. There is no flame left, only heat and pressure (2,100 psi) and the timed shock imparts kinetic energy to the piston/rod/yoke plate assembly. The FADEC system controls the above process for all engine speeds between 6,000 and 12,000 rpm with the use of all the heavier algae Bio fuels or any heavier fossil fuel. 

In this 1999 presentation, it was indicated that future papers would detail further developments of the linear alternator concept. That report was released in March of 2015. The reader is welcome to read the entire document, “Experimental Evaluation of the Free Piston Engine – Linear Alternator (FPLA)” which is a 119 page read, but a summary is provided below: 

It has been at least sixteen (16) years since the conception of the FPLA and it appears that they are still many years away from perfecting a usable design. In 1922 Russell Bourke started studying the old “masters” findings on hydrocarbon chemistry and every book he could find on mechanical design. On October 29, 1932 the Silver Eagle (free piston four cylinder radial – three moving parts) was completed and run for the first time. It would seem prudent that all of the universities, national labs, automobile manufacturers and other engine manufacturers use a proven design that utilizes detonation/HCCI instead of pouring billions of dollars into designs that do not maximize efficiency and minimize emissions.