NOx Emissions and Efficiency of Hydrogen, Natural Gas, and Hydrogen/Natural Gas Blended Fuels

Hoekstra, Robert; Blarigan, Peter Van; Mulligan, Neal

doi:10.4271/961103

Cited by 64 publications

(30 citation statements)

References 2 publications

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“…As a result, NO x formation in the post-flame gases is more dominant as compared to flame front NO x . As the hydrogen percentage increases, the flame speed and hence combustion efficiency increase [25]. The percentage of increase of NO x is 25% at full load when compared to neat diesel.…”

Section: Resultsmentioning

confidence: 96%

Performance, emission and combustion characteristics of CI engine fuelled with diesel and hydrogen

2015

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Hydrogen (H 2 ) is being considered as a primary automotive fuel and as a replacement for conventional fuels. Some of the desirable properties, like high flame velocity, high calorific value motivate us to use hydrogen fuel as a dual fuel mode in diesel engine. In this experiment, hydrogen was inducted in the inlet manifold with intake air. The experiments were conducted on a four stroke, single cylinder, water cooled, direct injection (DI), diesel engine at a speed of 1500 r/min. Hydrogen was stored in a high pressure cylinder and supplied to the inlet manifold through a water-and-air-based flame arrestor. A pressure regulator was used to reduce the cylinder pressure from 140 bar to 2 bar. The hydrogen was inducted with a volume flow rate of 4l pm, 6l pm and 8l pm, respectively by a digital volume flow meter. The engine performance, emission and combustion parameters were analyzed at various flow rates of hydrogen and compared with diesel fuel operation. The brake thermal efficiency (BTE) was increased and brake specific fuel consumption (BSFC) decreased for the hydrogen flow rate of 8l pm as compared to the diesel and lower volume flow rates of hydrogen. The hydrocarbon (HC) and carbon monoxide (CO) were decreased and the oxides of nitrogen (NO x ) increased for higher volume flow rates of hydrogen compared to diesel and lower volume flow rates of hydrogen. The heat release rate and cylinder pressure was increased for higher volume flow rates of hydrogen compared to diesel and lower volume flow rates of hydrogen.

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Section: Resultsmentioning

confidence: 96%

Performance, emission and combustion characteristics of CI engine fuelled with diesel and hydrogen

2015

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“…with Air-to-Fuel Ratio (AFR) greater than the stoichiometric one or, differently, for λ=AFR/AFR stoic >1. This leads to relatively low NO X emissions, especially for λ>2.5-4.0 [26][27][28][29][30][31][32][33][34]. Exhaust gas recirculation (EGR) can also be used to control the combustion duration, knocking and NO X emissions in SI hydrogen engines [13,[35][36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen SI and HCCI Combustion in a Direct-Injection Optical Engine

Rosati¹,

Aleiferis²

2009

SAE Int. J. Engines

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The Engineering Meetings Board has approved this paper for publication. It has successfully completed SAE's peer review process under the supervision of the session organizer. This process requires a minimum of three (3) reviews by industry experts. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. ISSN 0148-7191 Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. SAE ABSTRACTHydrogen has been largely proposed as a possible alternative fuel for internal combustion engines. Its wide flammability range allows higher engine efficiency with leaner operation than conventional fuels, for both reduced toxic emissions and no CO 2 gases. Independently, Homogenous Charge Compression Ignition (HCCI) also allows higher thermal efficiency and lower fuel consumption with reduced NO X emissions when compared to Spark-Ignition (SI) engine operation. For HCCI combustion, a mixture of air and fuel is supplied to the cylinder and autoignition occurs from compression; engine is operated throttle-less and load is controlled by the quality of the mixture, avoiding the large fluid-dynamic losses in the intake manifold of SI engines. HCCI can be induced and controlled by varying the mixture temperature, either by Exhaust Gas Recirculation (EGR) or intake air pre-heating. A combination of HCCI combustion with hydrogen fuelling has great potential for virtually zero CO 2 and NO X emissions. Nevertheless, combustion on such a fast burning fuel with wide flammability limits and high octane number implies many disadvantages, such as control of backfiring and speed of autoignition and there is almost no literature on the subject, particularly in optical engines. Experiments were conducted in a singlecylinder research engine equipped with both Port Fuel Injection (PFI) and Direct Injection (DI) systems running at 1000 RPM. Optical access to in-cylinder phenomena was enabled through an extended piston and optical crown. Combustion images were acquired by a highspeed camera at 1° or 2° crank angle resolution for a series of engine cycles. Spark-ignition tests were initially carried out to benchmark the operation of the engine with hydrogen against gasoline. DI of hydrogen after intake valve closure was found to be preferable in order to overcome problems related to backfiring and air displacement from hydrogen's low density. HCCI combustion of hydrogen was initially enabled by means of a pilot port injection of n-heptane preceding the main direct injection of hydrogen, along with intake air preheating. Sole hydrogen fuelling HCCI was finally achieved and made sustainable, even at the low compression ratio of the optical engine by means of closed-valve DI, in synergy with air-pre-heating and negative valve overlap to promote intern...

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“…This is not the case with premixed natural gas/hydrogen. [7,4] investigate hydrogen addition to CNG in a large passenger car engine as well as a single-cylinder research engine. It is shown that the relationship between NO X and unburned hydrocarbons parameterized by equivalence ratio can be affected by addition of various amounts of hydrogen.…”

Section: Basic Effect Of Hydrogenmentioning

confidence: 99%

Hydrogen Addition For Improved Lean Burn Capability of Slow and Fast Burning Natural Gas Combustion Chambers

Tunestål¹,

Christensen²,

Einewall³

et al. 2002

SAE Technical Paper Series

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One way to extend the lean burn limit of a natural gas engine is by addition of hydrogen to the primary fuel. This paper presents measurements made on a one cylinder 1.6 liter natural gas engine. Two combustion chambers, one slow and one fast burning, were tested with various amounts of hydrogen (0, 5, 10 and 15 %-vol) added to natural gas. Three operating points were investigated for each combustion chamber and each hydrogen content level; idle, part load (5 bar IMEP) and 13 bar IMEP (simulated turbocharging). Air/fuel ratio was varied between stoichiometric and the lean limit. For each operating point, a range of ignition timings were tested to find maximum brake torque (MBT) and/or knock. Heatrelease rate calculations were made in order to assess the influence of hydrogen addition on burn rate. Addition of hydrogen showed an increase in burn rate for both combustion chambers, resulting in more stable combustion close to the lean limit. This effect was most pronounced for lean operation with the slow combustion chamber.

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NOx Emissions and Efficiency of Hydrogen, Natural Gas, and Hydrogen/Natural Gas Blended Fuels

Cited by 64 publications

References 2 publications

Performance, emission and combustion characteristics of CI engine fuelled with diesel and hydrogen

Performance, emission and combustion characteristics of CI engine fuelled with diesel and hydrogen

Hydrogen SI and HCCI Combustion in a Direct-Injection Optical Engine

Hydrogen Addition For Improved Lean Burn Capability of Slow and Fast Burning Natural Gas Combustion Chambers

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