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Conventional automotive ignition systems are known for their ability to ignite fuel-air mixtures with a spark, which is an example of thermal plasma. In recent times it has been demonstrated that compared to thermal plasma, non-thermal plasma is an effective means of enhancing combustion. To establish this point, an experimental setup was built, and experiments were carried out in a Constant Volume Combustion Chamber (CVCC) with a conventional J type spark plug. Under atmospheric conditions, the combustion tests were carried out with methane-air mixtures. A nano-second, high voltage repetitive pulse discharge generator was used as a non-thermal plasma ignition source. To generate thermal plasma, an induction-based automobile ignition system was used. Flame propagation inside the CVCC was captured using a high-speed camera by employing shadowgraph imaging.

A large quantity of fuel is injected into the cold manifold of the engine to enable a quick start. A substantial part of this fuel gets deposited on the manifold walls leading to the formation of a fuel pool. Improper fuel vaporization during the engine cold start leads to the formation of a large amount of HC emissions. In the present investigation, a small flexible polyamide strip heater was placed at a specific location where the fuel impingement happens to enhance fuel vaporization in a 4-stroke motorcycle engine. The heater was turned on 20 seconds before the engine started. A temperature controller was used to maintain the heater at 323 K. The emission data for 180 seconds from the engine start was measured. Initial tests were carried out without the heater to establish the baseline emissions. Later, tests were carried out with the heater switched on and compared. The results showed a 32 % reduction in cumulative HC emissions with the use of the heater.