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Increasing
population and demand for fossil fuels is leading to rapid depletion
of fossil fuels. In addition, because of stringent emissions norms,
researchers are trying to develop next generation internal
combustion engines having improved efficiency and reduced emissions.
Hydrogen has shown great promise as an alternative fuel.
CNG also seems to be great alternative to petrol for SI engine.
However, CNG have very low flame velocity. This problem could be
overcome by using hydrogen enriched CNG mixture as fuel for SI
engine. Laser ignition has also
emerged as an efficient ignition technique for delivering superior
engine efficiency with lower emissions. Use of laser ignition to
initiate combustion in an engine fuelled with hydrogen-air mixtures
can greatly help in emission reduction, improving engine performance
and tackling the problem of fossil fuel depletion.
Initially a single cylinder diesel engine was modified and converted
into a prototype hydrogen fuelled engine. Experiments were performed
on this prototype hydrogen fueled engine using laser ignition
system. A Q-switched Nd:YAG laser with pulse duration of 6-9 ns was
used to perform laser ignition experiments. Baseline experiments
were performed in hydrogen-air mixtures using conventional spark
ignition and then experiments were repeated using laser ignition
system to compare combustion, performance and emission parameters of
laser ignition vis-āvis baseline spark ignition. Effect of laser
pulse energy and compression ratio was evaluated comprehensively on
the combustion, performance and emissions characteristics of
hydrogen-air fueled engine. Results show an increase in peak
pressure, rate of pressure rise and heat release rate for laser
ignition of hydrogenair mixture compared to spark ignition. Higher
efficiency and lower NO emissions for laser ignition were also
observed vis-ā-vis spark ignition. Increasing laser pulse energy and
compression ratio also improved combustion and performance of the
engine. CO, CO2 and THC were negligible in both LI and SI for the
hydrogen-air mixtures at all operating conditions. In summary, laser
ignition of this prototype hydrogen fuelled engine did not exhibit
the problem of engine backfire and delivered an excellent engine
performance and emission characteristics. Since, most of the
commercial engine is multi-cylinder. Hence, it is very important to
understand the feasibility study of laser ignition for multicylinder.
Currently, we have modified a two-cylinder Mahindra Engine and
converted into prototype laser ignited HCNG fuelled engine. Now, we
are working on further necessary change for adapting laser ignition
technology. |
