Diesel combustion processes

Soot dispersion Soot particles formed during the diesel combustion process can cause three-body wear in the engine and must be dispersed to prevent this happening. Soot is suspended in the oil by dispersants, which minimises the effect of soot on wear. 

The sources of particulate matter in the atmosphere can be primary, directly injected into the atmosphere, or secondary, formed in the atmosphere by gas-to-particle conversion processes (13). The primary sources of fine particles are combustion processes, e.g., power plants and diesel... 

Effective with the 1982 model year, particulate matter from diesel vehicles was regulated by the U.S. Environmental Protection Agency for the first time, at a level of 0.37 gm km . Diesel vehicles were allowed to meet an NO level of 0.93 gm km under an Environmental Protection Agency waiver. These standards were met by a combination of control systems, primarily exhaust gas recirculation and improvements in the combustion process. For the 1985 model year, the standards decreased to 0.12 gm of particulate matter per kilometer and 0.62 gm of NO per kilometer. This required the use of much more extensive control systems (1). The Clean Air Act Amendments of 1990 (2) have kept the emission standards at the 1985 model level with one exception diesel-fueled heavy trucks shall be required to meet an NO standard of 4.0 gm per brake horsepower hour. 

Rudolph Diesel s original intent was to produce a low-heat-rejection internal-combustion engine without the need for a cooling system. He believed that this would provide less heat losses from the combustion process and provide him with a superior heat, or thermally efficient (TE), design concept. To his chagrin. 

Conceptual model of conventional Cl combustion characterized by a sequence of processes occurring in a fully developed reacting jet. (From Dec, A Conceptual Model of DI Diesel Combustion Based on Laser Sheet Imaging, SAE, 970873,1997. With permission.)... 

Miles, P. C., In-cylinder Flow and Mixing Processes in Low-Temperature Diesel Combustion Systems, Proceedings of the THIESEL 2006 Conference Thermo- and Fluid-Dynamic Processes in Diesel Engines, Valencia, Spain, September 12-15, 2006. 

Knowing the results of epidemiology studies on the association between diesel exhaust exposure and lung cancer, and animal studies on the toxicity of two types of soot, what can we conclude concerning the toxicity to humans of soot associated with fires Combustion processes produce small, respirable size soot particles. The composition of the soot from fires can vary widely with the condi-... 

An ideal Diesel cycle with a compression ratio of 20 and a cut-off ratio of 2 has a temperature of 105°F and a pressure of ISpsia at the beginning of the compression process. Determine (a) the temperature and pressure of the gas at the end of the compression process, (b) the temperature and pressure of the gas at the end of the combustion process, (c) heat added to the engine in the combustion chamber, (d) heat removed from the engine to the environment, and (e) thermal cycle efficiency. 

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. 

The combustion process in internal combustion engines as an isobaric or isometric heat-addition process is oversimplistic and not realistic. A real cycle p-v diagram of the Otto or Diesel cycle looks like a curve (combination of isobaric and isometric) rather than a linear line. Are the combustion processes in the dual cycle more realistic ... 

The Diesel cycle is a compression-ignition reciprocating engine consisting of an isentropic compression process, a constant-pressure combustion process, an isentropic expansion process, and a constant-volume cooling process. The thermal efficiency of the Otto cycle depends on its compression ratio and cut-off ratio. The compression ratio is defined as f max/ f min- The cut-off ratio is defined as — Toombustion off/f min ... 

A number of environmental applications [3] have been performed in order to size characterize colloids collected in rivers (riverbome particles, SPM, and sediments), clay samples and ground limestone (from soils), coal particles, diesel soot particles (from combustion processes), or airborne particles in urban areas (from waste incinerators, vehicles, household-heating systems, and manufacturing). In many of these cases, not only the size but also the particle size distribution was important and thus, in conjunction with the traditional UV detector, specific detectors such as ETAAS, ICP-MS, ICP-AES were used [40] in order to obtain more detailed, more specific compositional information. 

Since diesel fuel combustion is an autoignition process, the quality and characteristics of the fuel can have a dramatic impact on the efficiency of engine operation. Ignition delay and cetane number go hand in hand to influence the quality of the fuel combustion process. They are the primary engine operability parameters directly related to fuel composition. 

Senatore, A., M. Cardone, V. Rocco, and M.V. Prati. 2000. A Comparative Analysis of Combustion Process in D.I. Diesel Engine Fueled with Biodiesel and Diesel Fuel. Report No. 2001-01-0691. Warrendale, Pa. Society of Automotive Engineers. 

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. 

Certain operating characteristics of the Diesel or compression-ignition engine result from the nature of the combustion process. In particular, the engine operates over a comparatively wide range of over-all fuel/air ratios because fuel and air are not premixed. At a given speed the range is from approximately 0.01 pound per pound (580% excess air) at no load to about 0.055 pound per pound (20% excess air) at full load. Excess air is essential to ensure complete combustion and avoid smoke production. 

---