Ammonia Plus Hydrogen as Fuel in a S.I. Engine: Experimental Results Universita degli Studi di Pisa

Format:

Conference/Event

Author/Creator:

Frigo, Frigo, author.

Contributor:

Doveri, Nicolò

Gentili, Roberto

Conference Name:

2012 Small Engine Technology Conference & Exhibition (2012-10-16 : Madison, Wisconsin, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2012

Summary:

Storing hydrogen is one of the major problems concerning itsutilization on board vehicles. Today hydrogen can be compressed andstored at 200 or 350 bar (it is foreseen that in a near futurestorage pressure will reach 700 bar, according to new expectedregulations and using tanks in composite materials) orcryogenically liquefied.An alternative solution is storing hydrogen in the form ofammonia that is liquid at roughly 9 bar at environmentaltemperature and therefore involves relatively small masses andvolumes and requires light and low-cost tanks. Moreover, ammoniacontains almost 18% hydrogen by mass and, by volume, liquid ammoniacontains 1.7 times as much hydrogen as liquid hydrogen.It is well known that ammonia can be burned directly in I.C.engines, however a combustion promoter is necessary to supportcombustion especially in the case of high-speed Place of publication not identified engines. Amongthe potential promoters, hydrogen is worthy of note, since it iscarbon free and counteracts ammonia combustion characteristics. Asa matter of fact, hydrogen has high combustion velocity and wideflammability range, whereas ammonia combustion is characterized bylow flame speed, low flame temperature, narrow flammability range,high ignition energy and high self-ignition temperature.The experimental activity shown in this paper is correlated witha project that is focused on a range-extended electric vehicleinvolving an ammonia-plus-hydrogen I.C. engine and where hydrogenis obtained from ammonia by means of on-board catalytic reforming.Accordingly, the test engine is a 505 cm₃ Lombardini twin-cylinderS.I. engine that is well suited to power the onboard electricgenerator and the activity is aimed at determining properair-ammonia-hydrogen mixture compositions at actual operatingspeeds and loads of the engine connected to the electricgenerator.Hydrogen and ammonia are separately injected in the gaseousphase. The only mechanical modification of the engine involves theintake manifold, where electro-injectors for hydrogen and forammonia (conventional ones for CNG application with appropriatemodification to inner parts) are added to the original ones forgasoline.The experimental results confirm that it is necessary to addhydrogen to air-ammonia mixture to improve ignition and to increasecombustion velocity, with ratios that depend mainly on load andless on engine speed. Brake power is less than with gasoline, dueto mixture poor volumetric heating value and to ammonia low flamespeed that penalizes engine brake thermal efficiency. The amount ofhydrogen needed by the engine is compatible with the flow rateprovided by the reformer, except at cold start. The maximumNOx emission is 11.5 g/kWh at half load and 4500 rpm,without catalytic reduction

Notes:

Vendor supplied data

Publisher Number:

2012-32-0019

Access Restriction:

Restricted for use by site license