In-Cylinder Heat Retention Technology Enhances the Combustion Process in Natural-Gas-Fueled Internal Combustion Engines
This Technical Paper presents results from simulation, modeling and scale-up engine tests of a proven, in-cylinder, heat-retention technology derived from liquid-fueled, two-stroke engines powering unmanned aerial vehicles (UAVs) currently in operation. This extant, UAV engine technology is being transferred to natural-gas-fueled, two-stroke, internal combustion engines. This Paper covers the process being taken to advance the Technology Readiness Level (TRL) of the passive, in-cylinder, Regenerative Heat-Retaining Element (RHRE) for large-bore engines. Proof-of-Concept Validation, including the journey from small-bore, liquid-fueled, two-stroke, air-cooled, internal combustion engines to gaseous-fueled, two-stroke, liquid-cooled, engines is provided. Scale-up test results with timing sweeps from 18 to 6 degrees BTDC on an 8.5-inch bore AJAX engine are presented. Statistical analysis of some 5000 emissions data recordings per spark timing is also addressed conveying virtually zero probability these data occurred solely by chance. Preliminary computer simulation and modeling results are included in this paper. We intend to use simulation as a tool to help develop an optimized RHRE design that will enable rapid scaling to Legacy-size, slow-speed engines. This paper provides a summary of testing with improved instrumentation and conveys the key benefits to deploying RHRE. Included is an Introductory Primer for those not familiar with the RHRE concept of operation. RHRE test results on an 8.5-inch bore AJAX engine with supporting statistics in this paper lead to these conclusions:
• Engine with RHRE runs to higher torque than Baseline engine and higher Lambda for same fuel/rpm/timing.
• Lower NO at stock timing can be duplicated at all timings during a Lambda sweep.
• Appreciably lower CO and HC with all spark timings indicate the probability of reduced formaldehyde.
• COV’s of IMEP and PFP are consistently lower, thus demonstrating better engine
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