**6. References**

64 Fuel Injection in Automotive Engineering

between the UMH nozzle and the original nozzle. NOx and soot emissions of the UMH nozzle are reduced by 68.2% and 20% respectively than that of the original nozzle in case A, but BSFC increases by 10.4%. For case B, NOx and soot emissions of the UMH nozzle are reduced by 78.1% and 76.2% respectively than that of the original nozzle, but BSFC only increases by 8.7%. This is because the excess air ratio of case B is higher than that of case A. Therefore case B can use higher EGR rate than case A, which leads to the achievement of

Fig. 10. NOx—soot emissions comparison between UMH and original nozzle

EGR rate 0% EGR rate 25% EGR rate 35% EGR rate 50% EGR rate 80%

original engine

Injection pressure Injection

0 0.2 0.4 0.6 0.8 1 1.2 1.4

soot(g/kW.h)

nozzle 0 2.25 75 -2 7.35 0.54 1.38 0.05 235 -2

nozzle 28 1.49 110 2 2.34 0.73 10.33 0.04 259.4 0.1

nozzle 0 3.5 50 0 6.73 1.52 7.69 0.005 252.6 -4.6

nozzle 80 1.68 110 -2 1.47 5.08 21.15 0.001 274.8 4.1

1. The UMH nozzle has a large flow area of holes, which is beneficial to homogeneous mixture preparation prior to ignition. The better premixed combustion can be achieved combing the UMH nozzle with EGR, suitable injection pressure and injection timing to obtain simultaneous reduction of NOx and soot emissions in a

2. For case A, NOx and soot emissions of the UMH nozzle compared with the original nozzle are simultaneously reduced by 68.2% and 20% respectively when the EGR rate is

Table 6. Combustion characteristics comparison between UMH and original nozzle

% MPa °ATDC g/kW.h °CA

start NOx HC CO soot BSFC τpmix

0 2 4 6 8 10 NOx(g/kW.h)

case A

EGR rate 0% EGR rate 22% EGR rate 28% EGR rate 33%

original engine

much more lean-homogeneous charge combustion.

case B

case

A

B

Nozzle type

0 0.01 0.02 0.03 0.04 0.05

soot(g/kW.h)

Original

UMH

Original

UMH

**4. Conclusions** 

diesel engine.

EGR rate

excess air ratio λ

0 2 4 6 8 10 12 14 NOx(g/kW.h)


**Simulation of Combustion Process** 

**on Fuel Injection Characteristics** 

Kazimierz Lejda and Paweł Woś *Rzeszów University of Technology* 

*Poland* 

**in Direct Injection Diesel Engine Based** 

Combustion engines are still the major propulsion devices for many mechanical equipment including mostly all automotive vehicles. Unfortunately, they negatively affects natural environment due to exhaust gas emission consisting of harmful compounds, like the carbon monoxide CO, unburned hydrocarbons HC, nitric oxides NO and NO2 (altogether marked as NOX), solid particles PM, and finally the carbon dioxide CO2, that is to blame for the global warming phenomenon. All of them may cause human health deterioration or unwanted changes in the atmosphere in a large scale. As the examples, formation of the photochemical smog where hydrocarbons and oxides of nitrogen play the main role, or destruction of the ozone protective layer with participation of nitric oxide can be pointed here. There are also many other compounds in the exhaust gases which, besides their ecotoxicity, show also a serious carcinogenic action against people and animals, e.g. some

The prevention-natured, legislative limitations of vehicle exhaust emission stemmed from these threats, together with the current and prospective growth of road transportation intensity, calls for continuous effort to develop vehicle powertrains that must be done both in design and technology domains. Hence the combustion engine improvement works have been spreading out within the space of last decades, and now they consider more and more factors. They pursue a simultaneous decreasing of harmful exhaust emission (CO, HC, NOX, PM) and fuel consumption. Particularly, the thing is to cut down on CO2 emission by increasing engine total efficiency. Fulfilling all above tasks encounters many problems. They contradict each other, what originates from complex physical and chemical interactions during the working cycle of piston engines, especially at combustion stage, where many phenomena combine together in the same time and area. For example, in direct injection engines simultaneously occurs: injection, fuel atomization and vaporization, induction of ignition or autoignition, fuel burning and many other chemical processes. All it takes only a few milliseconds. That is why improving exhaust emission parameters usually claims resignation from good fuel efficiency, and vice versa, fuel consumption decreasing escalates harmful emission. Hence, it is necessary to perform a lot experimental research in order to find an optimal solution. Unfortunately, they are generally complicated and expensive, but they could be successfully supported by numerical simulation. By the way, computational

**1. Introduction** 

hydrocarbons and particulate matter fractions.

Xuelong,Miao; Xinqi,Qiao& Xianyong,Wang(2009). *Study on Ultramultihole Nozzle Fuel Injection and Diesel Combustion,Energy and Fuels*, vol.23,no.2, pp.740-743. **4** 
