**8. Acknowledgements**

This work has been supported by a PRIST 2008 grant by the Seconda Universitá degli studi di Napoli, together with a 2011 research grant funded by the Seconda Universitá degli studi di Napoli.

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#### **9. Nomenclature**


#### **10. References**

18 Will-be-set-by-IN-TECH

AFR Air-fuel ratio [kg*air*/kg*f uel*]

MAP Manifold absolute pressure MBT Maximum brake torque

NEDC New European driving cycle

THC Total unburned hydrocarbon

*α* Mole number of NG [mol] *β* Mole number of hydrogen [mol] Δh*<sup>r</sup>* Enthalpy of reaction [kJ/mol]

u*<sup>l</sup>* Unstretched laminar burning velocity [m/s]

R Flame front position [m] rpm Revolutions per minute S Flame speed [m/s]

PAH Polycyclic aromatic hydrocarbons

imep Indicated mean effective pressure [Pa] LHV Lower heating value [MJ/kg or MJ/Nm3]

avg Average CA Crank angle [◦] COV Coefficient of variation BTDC Before top dead center EGR Exhaust gas recirculation HCNG Hydrogen-natural gas blend

NG Natural gas

t Time [s] T Torque [N m]

**Greek symbols**

**Subscripts**

a Air b Burned d Displacement

f Fuel l Laminar mix Mixture n Stretched s Unstretched stoich Stoichiometric tr Turbolent u Unburned vol Volumetric

V Volume [m3] WOT Wide open throttle

*κ* Stretch rate [1/s] *λ* Relative air-fuel ratio [-] *φ* Equivalence ratio [-] *σ* Standard deviation

NOx Nitrogen oxides

**9. Nomenclature**


URL: *http://www.dft.gov.uk/pgr/roads/environment/emissions/ppr-354.pdf*

	- URL: *www.iangv.org*

**3** 

Stanisław Gil

*Poland* 

*Silesian University of Technology* 

**Fuel-N Conversion to NO, N2O and** 

Pressurised combustion is a very attractive clean coal technology due to increased energy efficiency and abated emission of pollutants resulting from application of combined cycles. There is a general agreement that nitric oxide emissions decrease with enhanced combustion pressure. However, for nitrous oxide, the reported results show a contradictory

The mode of NO and N2O formation during coal combustion is far from being understood. The most difficult problem is the pathway of fuel-N conversion for primary nitrogenous species. The issue becomes simpler in case of char combustion, but even here fundamental questions remain. The uncertainty of NO modelling is emphasized by there being two quite different models to explain NO emission during char combustion: char-N is converted to NO with subsequent reduction of NO through a reaction with the char inner pores; alternatively, char-N is converted to HCN with negligible conversion to NO within the

Fuel-nitrogen is found in plants, animal proteins and nitrogen-rich bacteria. Reactions of amines with carboxylic groups or aldehyde groups resulted in nitrogenous species present in coal. Coal is a heterogeneous, complex mineral where nitrogen is typically bound to organic matter. During a coalification cycle, nitrogen content in coal substance only slightly changes so the nitrogen fraction (in per cent) in the substance increases as peat loses oxygen (Stańczyk, 1991). Nitrogen content in coal is 0.5% to 2% (Tingey & Morrey, 1973), reaching maximum for elemental carbon Cwaf = 85% (Rybak, 1996). Coal typically contains 1% to 2% of nitrogen with bituminous coals usually containing 1.5–1.75% and anthracites mostly

The presence of nitrogen in coal has not been fully understood and described yet. There is far better knowledge of the structures of sulphur and oxygen than those of fuel-nitrogen. Due to difficulties encountered in investigations of nitrogen content in solid fuels, indirect methods of analysis are used and structures present in coal extracts or high-temperature coal tars are determined. There are few methods of direct analysis of nitrogen-containing groups in coal.

pores and subsequent conversion to NO outside the particle.

**2. Combustion of nitrogen compounds contained in coal** 

**1. Introduction** 

influence of pressure.

**2.1 Nitrogen in hard coal** 

containing less than 1%.

**N2 During Coal Combustion** 

