Hydrogen Engine

The idle performance of an 11-L, 6-cylinder engine equipped with a turbocharger and an intercooler was investigated for both compressed natural gas (CNG) and hydrogen-blended CNG (HCNG) fuels. HCNG, composed of 70% CNG and 30% hydrogen in volume, was used not only because it ensured a sufficient travel distance for each fueling, but also because it was the optimal blending rate to satisfy EURO-6 emission regulation according to the authors' previous studies. The engine test results demonstrate that the use of HCNG enhanced idle combustion stability and extended the lean operational limit from excess air ratio (l) ¼ 1.5 (CNG) to 1.6. A decrease of more than 25% in the fuel consumption rate was achieved in HCNG idle operations compared to CNG. Total hydrocarbon and carbon monoxide emissions decreased when fueled with HCNG at idle because of the low carbon content and enhanced combustion characteristics. In particular, despite hydrogen enrichment, less nitrogen oxides (NO x ) were emitted with HCNG operations because the amount of fuel supplied for a stable idle was lower than with CNG operations, which eventually induced lower peak in-cylinder combustion temperature. This low HCNG fuel quantity in idle condition also induced a continuous decrease in NO x emissions with an increase in l. The idle engine test results also indicate that cold-start performance can deteriorate owing to low exhaust gas temperature, when fueled with HCNG. Therefore, potential solutions were discussed, including combustion strategies such as retardation of spark ignition timing combined with leaner air/fuel ratios. i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 8 0 7 8 e8 0 8 6 http://dx.

The output power efficiency of the fuel cell system mainly depends on the required current, stack temperature, air excess ratio, hydrogen excess ratio, and inlet air humidity. Therefore, the operating conditions should be optimized to get maximum output power efficiency. In this paper, a dynamic model for the fuel cell stack was developed, which is comprised of a mass flow model, a gas diffusion layer model, a membrane hydration, and a stack voltage model. Experiments have been performed to calibrate the dynamic Polymer Electrolyte Membrane Fuel Cell (PEMFC) stack model. To achieve the maximum output power and the minimum use of hydrogen in a certain power condition, optimization was carried out using Response Surface Methodology (RSM) based on the proposed PEMFC stack model. Using the developed method, optimal operating conditions can be effectively selected in order to obtain minimum hydrogen consumption.

This paper studies the factors that lead automotive manufacturing firms to invest in Ultra Low Emission Vehicles (ULEVs). ULEVs are vehicles that emit extremely low levels of harmful gases compared to other vehicles. In contrast to studies that examine aggregated patterns on the market (such as sales levels, new launches and issued patents), this study 'moves into the mind' of individual car firms following a social-psychological approach to identify the barriers and drivers. As an example of a ULEV, we report on the drivers and barriers for car manufacturers around the development of hydrogen engine technology. The study reveals that different firms deal differently with hydrogen vehicle development. Broadly, three groups of firms were distinguished concerning their willingness to invest in ULEV: uncertain firms, unwilling firms and optimistic firms. It addition, it was found that the level of technological and organisational capabilities is highly correlated to the willingness of firms to engage in hydrogen technology development. Based on an integrated sustainability assessment that takes into account technological opportunities, business perceptions and policy options, we argue that current policy should strongly focus on supporting R&D capability in manufacturing firms.

Using hydrogen as an alternative fuel in spark-ignition engines has great potential for reducing exhaust emissions. Hydrogen engines have CO2- and HC-free combustion and lean operation, offering lower nitrogen oxide (NOx) emission. In this paper, a numerical study of a direct injection spark-ignition (DISI) hydrogen-fueled engine was conducted via 3-dimensional computational fluid dynamics (CFD) methods and results were compared with experimental data, showing good agreement. Injection timing, initial charge temperature, and initial charge pressure were selected as effective and controllable parameters of emissions and performance characteristics. Results showed that mixture homogeneity was more affected by injection timing, and advancing the injection timing led to improved engine performance with a slight increase in NOx emissions. Increasing the initial pressure and decreasing the initial temperature led to better engine performance and reduced NOx emissions in the DISI hydrogen-fueled engine.

Previous studies examining gasoline and hydrogen engines have typically focused on factors pertaining to air to fuel ratios, their effects on an ICE performance, combustion by-products produced during the ignition cycle and its subsequent environmental effects. Alternatively, this study examines the ways in which a hydrogen engine cavitation can be enhanced by using a graphene coated layer on the cylinder combustion chamber walls. SEM micrographs for the coated surfaces' microstructure showed a uniform distribution of the graphene layer that was free from cavities and demonstrating little to no observable defects. The study's results also showed large improvements in the BTE and exhaust temperature with respect to BMEP performance. This further resulted in significantly low levels harmful gaseous emissions, with observable reductions in the emissions of CO, NOx, and hydrocarbon derived from gasoline and pure hydrogen fuel. These results are thus indicative of a significant improvement in the performance of this particular typology of engine, in contrast to other experimentation focus found in other studies.