Combustion, in compression-ignition

There is a need to seek an environmentally benign, technically feasible and economical alternative fuel because of the limited crude oil reserves and serious pollution all over the world. Recently, dimethyl ether (DME) is proved to be used as an alternative clean fuel in transportation, power generation and household use for its excellent behavior in compression ignition for combustion, cetane number of over 55 and zero sulfur content, and is praised as a super-clean fuel in the 21 century. It has a promising foreground of application. Therefore, the efficient synthesis of DME from syngas derived from natural gas, coal or biomass has drawn much attention. 

Combustion in the Otto cycle is based on a constant-volume process in the Diesel cycle, it is based on a constant-pressure process. However, combustion in actual spark-ignition engine requires a finite amount of time if the process is to be complete. For this reason, combustion in the Otto cycle does not actually occur under the constant-volume condition. Similarly, in compression-ignition engines, combustion in the Diesel cycle does not actually occur under the constant-pressure condition, because of the rapid and uncontrolled combustion process. 

Jacobs, T. J., Bohac, S. V, Assanis, D. N., and Szymkowicz, Lean and Rich Premixed Compression Ignition Combustion in a Light-Duty Diesel Engine, SAE, 2005-01-0166, 2005. 

Compression Ignition A fuel combustion process whereby heat generated by the rapid compression of air is utilized as an autoignition source for fuel. This form of fuel combustion is utilized in the diesel engine. No spark plug is required to ignite the fuel. 

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