Thus, a large potential avenue for utilization of hydrogen in transportation applications is through blending with natural gas, since there is an existing market for natural-gas vehicles of various classes, and since hydrogen can provide a means of achieving even stricter emissions standards. Instead, fuel blending and ''hydrogen-assisted'' combustion are more realizable pathways for wide-scale hydrogen utilization within the next ten years. While the hydrogen-fueled fuel-cell vehicle that is the focus of the 'Freedom Car' program would rely on electrochemical energy conversion, and despite the large amount of resources being devoted to its objectives, near-term implementation of hydrogen in the transportation sector is not likely to arise from fuel cell cars. In simpler way we can say, 89MN fuel can be compressed more and handled safely than 85MN fuel and there will be less chance of pre-ignition or self ignition.The 'Freedom Car' Initiative announced by the Bush Administration has placed a significant emphasis on development of a hydrogen economy in the United States. If a gas fuel has methane number 85, it has more sustainable combustion property of a fuel with MN 80 and lower sustainability than a fuel of 89MN. Methane number is a measure of this characteristic. This characteristic should be consistent. Resistance of self-igniting at higher pressure and temperature is a desired characteristic of the fuel. It should be burnt only with controlled spark, otherwise the combustion will be random and cause failures to the combustion chamber. The gas should not ignite automatically at this pressure and temperature level. Temperature and Pressure increase to a good level while the mixture is compressed.
So, air and gas should be mixed well, then compressed. Spark plug first ignites that mixture, then a comparatively strong flame front started and spreads around the whole combustion chamber.
Pre-chamber is a small volume space where richer mixture of fuel presents. This primary ignition state is called pre-chamber ignition. If the amount of the mixture is much bigger, it may need a preliminary combustion to set in first. In spark ignition gas engine, gas and air mixture is compressed and then ignited by the spark from the spark plug. Spark ignited gas engine is different than the compression ignition diesel engine. How important the Methane Number for Gas Engine Operation So if a gaseous mixture having 80MN, it simply says, it is equivalent to a fuel with mixture of 80% methane and 20% Hydrogen.īiogas has higher methane number, >100. Hydrogen is easy-burning fuel, and its knock resistance property is chosen as 0MN. The scale is arbitrarily chosen, pure methane has a good knock resistance. This scale is used normally for gaseous hydrocarbon based fuel, example- Natural gas, Bio Gas etc. Knock resistance of a fuel is measured by Methane number.
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